diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml index bb02bac..5073f5e 100644 --- a/.github/workflows/ci.yml +++ b/.github/workflows/ci.yml @@ -34,6 +34,29 @@ jobs: - uses: Swatinem/rust-cache@v2 - name: Test run: cargo test -p rusty_zstd -p rusty_zstd-cli -p rzstd-alloc + # KERNEL REACH. A twin that exists but is not CALLED passes every other + # gate in this file: byte-identity passes because the two paths agree by + # design, the round-trip passes, and an arm-toggle A/B reads FLAT -- + # indistinguishable from "the kernel does not help". Exactly that shipped + # here: the xxh64 AVX2 kernel was reachable only from a test and a bench, + # and DECODE ran it on 0% of its bytes for months. This counts instead. + # + # Needs `profile` for the census taps (they compile to nothing without + # it, so the shipped build is unaffected). Slots whose ISA the runner + # lacks are skipped, not failed. + - name: Kernel reach gate + run: cargo test -p rusty_zstd --release --features profile --test kreach_gate -- --nocapture + # The gate must be able to FAIL. Forcing every arm scalar has to break + # it; if this step SUCCEEDS, the census is detached from the dispatch it + # names and the green run above meant nothing. + - name: Kernel reach gate self-check (must fail) + shell: bash + run: | + if RZSTD_KREACH_POISON=1 cargo test -p rusty_zstd --release --features profile --test kreach_gate; then + echo '::error::kreach gate passed with every arm forced scalar -- the census is not wired' + exit 1 + fi + echo 'poison check ok: the gate fails when the arms are forced scalar' - name: Doc tests (the README's examples) run: cargo test -p rusty_zstd --doc - name: CLI version + aliases diff --git a/CHANGELOG.md b/CHANGELOG.md index 40ccdac..23f5e00 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -6,6 +6,1627 @@ based on [Keep a Changelog](https://keepachangelog.com/); this project uses ## [Unreleased] +### Measured -- what the encode campaign bought: 1.08-1.27x at L3-L12 (2026-09-09) + +Every verdict in the sections below is an INSTRUCTION COUNT, because this box +runs at ~65% load from other work and cannot resolve a stopwatch. This section +is the wall-clock check on those counts, taken the only way that is admissible +here: the released `v0.2.3` (`e672cd0`) and this tree, each compiled against +ONE measurement program (`speedab`) that loops `compress` in memory with no +file I/O in the timed region; whole processes alternated ABBA, pinned to one +core at High priority; the estimator is the FLOOR (the fastest loop either arm +reached across all pairs), which is what survives a busy machine. + +**The floor of the instrument, measured first** by running the same binary +against itself: encode +-3%, decode +-0.5%. Nothing below +-3% on encode is a +result, and the rows that sit there are reported as flat rather than dressed up. + +Encode, MB/s at the floor, `v0.2.3` -> this tree: + +| L | strategy | dickens 9.7 MiB | samba 20.6 MiB | speedup | +|---|---|---|---|---| +| 1 | Fast | 189.8 -> 186.9 | 272.3 -> 275.5 | **flat** (0.99 / 1.01, inside the floor) | +| 3 | DFast | 129.4 -> 140.3 | 261.0 -> 268.4 | 1.08 / 1.03 | +| 5 | Greedy | 67.2 -> 79.1 | 101.8 -> 128.7 | **1.18 / 1.27** | +| 7 | Lazy | 11.0 -> 13.4 | 22.1 -> 28.0 | **1.23 / 1.26** | +| 9 | Lazy2 | 18.2 -> 20.9 | 38.0 -> 46.0 | **1.14 / 1.21** | +| 12 | Lazy2 | 3.5 -> 3.9 | 12.3 -> 13.3 | 1.11 / 1.08 | +| 15 | BtLazy2 | 3.0 -> 3.0 | xml 8.3 -> 8.9 | flat / 1.07 | +| 19 | BtUltra | 2.5 -> 2.5 | xml 5.3 -> 5.6 | flat / 1.05 | + +The shape matches what the bricks say they did and is the reason to trust both: +**the win is exactly where the campaign worked.** L5-L12 are the greedy and lazy +chain finders, which took nearly every brick, and they move 1.08-1.27x. L1 is the +Fast ladder, which took none, and it does not move. L15-L19 are the tree ladder, +which took a single brick (99, a per-call prologue trim), and they read flat to +1.07. A campaign that claimed a uniform win across all levels would be measuring +the box, not the code. + +Compressed sizes are IDENTICAL at every level except 3, which is DFast and is +the one ladder carrying a deliberate bitstream change in this release: the +next-long OFFSET-TRADE dispatch now defaults ON (see its section below). It +reads samba **-1.14%** (smaller) and dickens +0.04% here -- the same trade that +section measured at -0.36% across an 18-corpus L3 board, and the reason the L3 +decode row moves too. Decode is +inside the floor everywhere the bitstream is unchanged; the one row that reads ++12.5% (samba L3) is NOT a decode win but that smaller frame giving the decoder +less to do, so it is not work-parity comparable and is not claimed. + +### Changed -- rusty_alloc 2.0.0 -> 2.0.5 in the deliverable seam + +`rzstd-alloc` moves its exact pin to `=2.0.5` (`cargo tree` on the CLI shows +only 2.0.5). The doc comment beside the pin moves with it, which is the drift +this file already calls out by name. + +**Priced, and it is neutral -- recorded that way rather than as a win.** Same +codec on both arms, same instrument and floor as above: + +| workload | encode | decode | sign test | +|---|---|---|---| +| bulk (dickens, samba @ L1/5/9/12) | 0.96-1.05 | 0.97-1.02 | 17/40, z = -0.95 | +| allocation-heavy (smallmsg-8m, jsonlog-16m @ L1/L3) | 1.00-1.02 | 1.00-1.03 | 12/28 | + +Every cell is inside the instrument's floor and the sign test is a coin flip, so +the honest verdict is **no measurable throughput change on this workload**. The +allocation-heavy arm was run because bulk codec loops are the wrong place to +judge an allocator -- small inputs at fast levels are where per-call table +allocation is the biggest share -- and it reads flat too. (`zeros-1m` was +dropped from the table: at ~0.07 ms per loop it is timer quantisation, not a +measurement.) This is a dependency-currency update, and the reason to take it +is that the seam exists so the pin can move without touching feature code. +### Changed -- matchfind, the three targets: candidate, insert, position (2026-09-09) + +The diagnosis below priced three units against zstd 1.5.7's own assembly and +found them dear: the chain walk's per-CANDIDATE first-word path, the fill's +per-INSERTED-BYTE loop, and the lazy finder's per-POSITION loop. This section +works those three, round-robin. Every verdict is a shortest header-to-latch +PATH on the emitted assembly (`verdict3.py` in the census tools: the candidate +path is the one that executes the tag test and the first-word xor, the +position path the one that executes the kernel's indirect call and the +`lazy_step` shift and no direct call), never a loop total. Byte-identical +throughout: GOLD `2F6594F7EEDBD12B` / 59,680,638 and LDM `57BE83EA4E1199E8` / +57,796,847 after every landed brick; 173 tests, 176 with `profile`. + +| # | target | brick | verdict (path instrs / stack reads / stack stores) | +|---|---|---|---| +| 35 | K | `min_match` is 3..=7 by contract (`compression_params` and the advanced setter both clamp; zstd's own max is 7), but the chain-ladder finders read `.max(3)` and the kernel tested `mls > 8` on EVERY examined candidate to pick `mls_eq_wide`. Finders now `clamp(3, 7)`; `mls_xor` has no wide arm | walk loop union **176 -> 118** instrs, spills 19 -> 10, reloads 46 -> 22 (cp, walk_cont); kernel 341 -> 279. The candidate PATH is unchanged at 28 (the two freed instructions were spent by the allocator on a chain-base reload and an xor copy) -- landed for the contract and the loop body, **not counted as a path win** | +| 36 | F | the fill's packed link decode -- `(q - 1) \| (raw & 0xFF00_0000)` guarded by `q == 0` -- was seven instructions per inserted byte. Every packed writer stores `pos + 1 >= 1`, so `q == 0` is `raw == 0` and `raw - 1` cannot borrow out of the field: one `saturating_sub(1)` serves all three representations | per inserted byte **29 -> 23**, stack reloads 1 -> 0 (the freed register took `PRIME64`, which had been rematerialised per byte) | +| 37 | P | the lazy loop tested its search result twice per position (`best_ml >= mls` for the look-ahead, then `best_ml != 0` for the emit -- the same predicate by W9/W10) and spilled `best_ip`/`look_hi` across the join on the no-match path. One guard; the probes are born inside it | no-match path **27 -> 22** instrs, reads 10 -> 9, stores 1 -> 0; with the rep probe 43 -> 38 | +| 38 | P | the rep probe's four admission tests per position (`use_rep` byte flag, `rep1 == 0`, `ip + 1 < rep1`, `ip + 1 - rep1 < lowest_rep`, four stack reads) are one bound on `ip`: `rep_bar = rep1 + lowest_rep - 1`, `usize::MAX` when the probe is off, refreshed only where `rep1` changes | rep-probe path **38 -> 34**, reads 12 -> 10; no-match path reads 9 -> 8 (`rep_bar` lives in a register) | +| 39 | F | the packed head write masked `p + 1` to 24 bits per inserted byte; `pack_tags` already bounds it below 0x00FF_FFFF | per inserted byte **23 -> 22** | +| 41 | P | `lazy_step`'s `sh == 0` arm (`cmp`, `mov $1`, `cmov`, a stack read) ran on every no-match position to select the historical step of 1. The knob is mapped once per block (`0 -> 63`; `(ip - anchor) >> 63` is 0 for any span a block holds) and the step is one expression | no-match path **22 -> 19**, reads 8 -> 7; rep-probe path 34 -> 31 | +| 43 | F | the fill's stride is a runtime knob (1 by default), so LLVM could neither count nor unroll the loop and every byte paid the trip (`add`, `cmp`, `jb`). The stride-1 case is named and inserts two positions per trip, chain arms only (the rows arm ships at stride 2 and measured +3 with the pair loop present) | per inserted byte **22 -> 20** (packed), 23 -> 21 (tag array), 14 -> 11.5 (no tags); rows arm unchanged at 35 | +| 46 | K/inst | the PHANTOM position-0 candidate, counted (profile only). A chain link of 0 is both "no link" and position 0, so a walk whose chain ends inside the first window continues to m = 0 and examines it -- the reason the walk guards `m != 0` before the tag test. `phantoms` census, Silesia 5 corpora | examined at position 0: **0.29% / 0.34% / 0.20%** of all candidates at L7 / L9 / L12, accepted 3 / 3 / 3. So a representation with an unambiguous null would save the two-instruction guard and ~0.3% of examinations at the risk of three accepts per level: **not taken**; the guard stays | +| 47 | P | the chain kernel's per-CALL insert decoded the old head with the fill's old seven-instruction field split (`lz_link_from_head`); brick 36's identity applies: `raw.saturating_sub(1)` | kernel prologue (entry to walk header, per position) **89 -> 84** (cp, walk_cont), 87 -> 81 (cp) | +| 48 | P | `lz_head_put` masked `pos + 1` to 24 bits per chain insert; `pack_tags` bounds it (brick 39's argument, per position) | prologue **84 -> 83**, 81 -> 80 | +| 49 | P | the kernel's entry guard tested `ip + mls <= src_len` per call (add, compare, branch, both operands reloaded) for the caller's own invariant: `find_lazy_impl` calls at `ip <= ilimit = block_end - 8`, `mls <= 7` | prologue **83 -> 80** (cp.wc), 80 -> 75 (cp), 99 -> 86 (ca.wc), 88 -> 81 (ca), 81 -> 76, 76 -> 72; candidate path 28 -> 27 (cp.wc, ca) and **23 -> 25 on ca.wc** (the allocator re-spilled `smask` there; at 0.3 walks and 1.7 candidates per byte the two move ~equal amounts on that one kernel, the other five are clear wins) | +| 50 | P/K | the walk's `tables.wcls.0 += 1` / `.1 += 1` (the walk_cont classification, written on a rare accept) were in-loop memory read-modify-writes, so LLVM's scalar promotion loaded both at kernel ENTRY, spilled them, and stored them back at every exit -- per call. Two locals, added to the table once after the loop, guarded so the common walk never touches it | ca.wc candidate path **22 -> 19 at brick 56's state** (25 -> 22 here), tag-skip 18 -> 17; cp.wc prologue +2 (the allocator's re-shuffle) -- modelled at L9's unit rates (0.3 walks, 1.7 candidates, 0.15 skips per byte) a net **-4 instructions per byte** across the four shipping kernels | +| 56 | K | the walk's loop is register-starved (fifteen live values), and two of them existed only for the RARE long-count continuation: `ip + 8` and `ip + 16`, hoisted as `count_match` arguments and spilled at every entry. The `x == 0` continuation is outlined behind `ctx` (`walk_count8`, ~0.04 calls per byte); the `x != 0` head stays inline | kernel **283 -> 239** (cp.wc), 279 -> 190 (cp), 282 -> 254, 278 -> 198, 337 -> 234, 257 -> 178; walk-loop unions **115 -> 79** instrs, spills 8 -> 4, reloads 25 -> 17 (cp.wc). The candidate PATH: 27 -> 27 (cp.wc), 28 -> 28 (cp), 22 -> 23 (ca.wc, +1 store), 27 -> 28 (ca), 20 -> 19, 23 -> 23 -- landed for the loop body and the frame, **not counted as a path win** | +| -- | K | **CORRECTION.** Every kernel verdict above priced the candidate path that FAILS the first-word compare. `mfbudget` section B says that path is 0.5-0.6% of examined candidates at L7-L12: the bucket and the tag already guarantee the first bytes, so 99.4% of examined candidates PASS the first word and go on to `pre_eq` (the byte at the current best length), which is where most of them die. The dominant per-candidate path is first word passes -> `pre_eq` fails -> advance (~83% of candidates at L9: 5.8 examined per walk, of which one sets the best and the rest fail `pre_eq`). Re-priced on that path, brick 35 was **+4 on cp.wc and +10 on ca.wc** (36 -> 40, 30 -> 40), not neutral, and the ordering of the refuted kernel bricks changes (55 was -5 on it). From here every kernel number is the `pre_eq`-fail path, and the verdict is `score.py`'s modelled instructions per byte at L9 -- walks x frame + candidates x pre-path + skips x skip-path + fused x (fused - pre), summed over the four shipping shapes | at the session's start the model read **374.7** instrs/byte (cp.wc 100.4, cp 92.6, ca.wc 90.3, ca 91.4); after bricks 35-56 it read **396.0** -- the kernel bricks had been a net loss on the path that runs | +| 58 | K/P | the walk INLINED into the lazy finder. Every search was a call through a per-block pointer: eight pushes and pops, the marshalling, a `nop`, ~12 context loads and ~11 entry spills in the callee, a 16-instruction exit -- about 35 instructions per walk of frame at 0.3 walks per byte, which zstd's `_lazy` parser never pays. `find_lazy_impl` takes a `KIND` const for the four shipping shapes (packed / tag-array x walk_cont) and `lazy_search::` resolves to the `inline(always)` inner, so the walk lands inline at both call sites; rows and tags-off keep the pointer (`KIND == 7`). `find_lazy` grows 1200 -> 6890 instructions (five instances, one hot per block) | per-walk frame (position cycle through one candidate, minus that candidate) **116 -> 78** (cp.wc), 103 -> 47 (cp), 120 -> 73 (ca.wc), 109 -> 48 (ca); the inlined `pre_eq`-fail path 38 / 36 / 37 / 33 with 8-11 stack reads (against 40 / 31 / 46 / 28 with 2-11 before). Model **396.0 -> 338.9** instrs/byte; stack reads on the candidate path +3..+6 (a clock question this box cannot answer -- recorded, not hidden) | +| 59 | K | ONE length in the walk. `best_ml` is born `mls - 1`, so `ml > best_ml` is the accept test before and after the first accept (W7's `bar = best_ml + 1` seeded with `mls` is gone), `pre_eq` at that index is sound on the first candidate (the first-word compare just verified byte `mls - 1`), and "no match yet" is `best_ml < mls`. One fewer loop-carried value and one fewer test on the dominant path | model **338.9 -> 327.8**; inlined pre path 38 -> 36 (cp.wc), 36 -> 33 (cp), 37 -> 33 (ca.wc), 33 -> 33 (ca) | +| 61 | K | the inlined walk read its chain link through TWO dependent loads per candidate (the `&mut MatchTables` pointer from the frame, then `chain`'s base from it) because `chain_masked` goes through `self` and LLVM would not hoist the base inside a function that stores to the tables elsewhere. The bases are taken once per walk (`chain.as_ptr()`, `ctags.as_ptr()`), as the fill did in brick 12 | model **327.8 -> 319.7**; inlined pre path 36 -> 35 (cp.wc), 33 -> 32 (cp), 33 -> 31 (ca.wc), 33 -> 30 (ca); per-walk frame 82 -> 85 / 52 -> 55 / 72 -> 78 / 51 -> 56 (the bases are two more spills per walk, paid 5.8 times over per walk) | +| 62 | K | the inlined walk counted attempts UP against a limit in the frame (`cmp limit(%rbp)`, `jae`, `inc`: three instructions and a load per candidate) where the standalone kernel had `dec`/`je`. An explicit countdown that nothing else reads | model **319.7 -> 311.5**; pre path 35 -> 34 (cp.wc), 32 -> 31, 31 -> 29 (ca.wc), 30 -> 29, one read fewer on each | +| 63 | K | both miss arms wrote `missed_before = true`, so LLVM hoisted the one constant above the tag test (`movb $1` on EVERY candidate) and restored the old value at the join on the paths that never miss. The arms write different non-zero values (1 tag reject, 2 first-word reject; readers test `!= 0`), so there is nothing to hoist | model **311.5 -> 306.5**; pre path **34 -> 31** (cp.wc) | +| 64 | P | brick 50 undone for the inlined form: its two locals cost two zero stores per walk entry (duplicated across the entry's split edge: four) and a five-instruction two-load `wc0 \| wc1 != 0` test per walk exit. The direct read-modify-write on the rare accept is two instructions, there, and nothing elsewhere | model **306.5 -> 301.8**; per-walk frame 83 -> 73 (cp.wc), 81 -> 71 (ca.wc) | +| 65 | P | the walk's lower bound `lowest.max(ip.saturating_sub(window))` was a saturating subtract and a max (two compares, two `cmov`s, a zero) per walk. `lowest + window` is a block constant in the context; per walk it is one compare and a select | model **301.8 -> 292.5**; per-walk frame 73 -> 66 (cp.wc), 56 -> 48 (cp), 71 -> 66 (ca.wc), 58 -> 51 (ca) | +| 66 | F | brick 52 retried once the walk was inlined: the chain-link tag is the mls-byte product's TOP byte (`tv >> 56`, seated with `shr $32` + `and`) instead of the xor-fold (copy, shift, xor, `shl $24`); the two wide-chain producers take the byte under their bucket. Five producers changed together; sound, so byte-identical by the `taggate` argument | fill pair loop **40 -> 38** per two bytes (19 per byte); model 292.5 -> 292.0 (the walk's per-call tag is two instructions cheaper) | +| 68 | P | brick 54 retried inlined: the dead `wide_hash && ip + 8 <= src_len` arm out of the walk's per-call hash select (`mls >= 8` is outside the contract) | per-walk frame 48 -> 46 (cp), 66 -> 63 (ca.wc), 51 -> 48 (ca), cp.wc unchanged at 66; model unchanged at 292.0 (the cheapest site did not move) | +| 69 | P | the walk's per-call insert on raw table bases taken ONCE (the fill's brick 12): `lz_insert` re-derived the hash base, the chain base and the rows length from the tables pointer in the frame, and brick 61 derived the chain base a third time for the loop. One `as_mut_ptr` each at entry; the insert is the fill's body; the loop reads the same `chp` | model **292.0 -> 285.3**; per-walk frame 66 -> 58 (cp.wc), 46 -> 43 (cp), 63 -> 60 (ca.wc), 48 -> 45 (ca) | +| 70 | F | the fill's pair loop paid six instructions of overhead per pair (`lea p+2`, a reload of the spilled `stop`, `p + 3`, compare, copy, branch) because its bound was `p + 1 < stop` on the `p` that addresses every load and store. A countdown of the remaining positions carries the bound in the counter | packed pair loop **38 -> 36** per two bytes (18 per byte, from 29 at the session's start), its stack reload 1 -> 0; tag-array 38 -> 38, no-tags 23 -> 22 | +| 71 | P | the walk's per-call row mirror asked `rows.head.is_empty()` through the tables pointer (a reload and a compare at offset 160) for a per-block fact; `ChainCtx` carries it | model **285.3 -> 284.7**; per-walk frame 58 -> 57 (cp.wc) | +| -- | -- | **Second goal (2026-09-09): ten more.** Same gates, same score. Where they hide: the dominant candidate path is 72% of the modelled search cost, so its 31 instructions come first; the greedy (L5) finder's inline walk still has every shape the lazy walk shed (40 instructions, 11 reads on its dominant path); the fill's loop overhead; the emit path | | +| 74 | K | tagged NULL links. A link of 0 is both "no link" and position 0, so a chain that ends sends the walk to m = 0 and the walk exempted position 0 from the tag test (`m != 0`, two instructions on every candidate) because that link carried no real tag -- and the phantom cannot simply be dropped (`phantoms`: three accepts per level). Now every writer of an empty head's link (the fill, the walk's insert, `lz_insert`, priming, the wide-chain re-insert) writes `tag0 << 24`, position 0's own tag under the block's producer (`MatchTables::set_null_tag`), so the phantom is tag-tested like any other candidate: a sound tag rejects exactly what its first-word compare would have rejected, and both arms leave the walk in the same state. Packed shape only: the tag-array version (74a-d) cost its fill 38 -> 45..48 per pair for a walk that barely moved, so that shape keeps its guard and its writers | pre path **31 -> 28** (cp.wc and cp), tag-skip 22 -> 18; model **284.7 -> 271.8**; packed fill unchanged at 36 per pair (the select folded into the decode's `cmov`); greedy's walk 40 -> 39 | +| -- | K | **The greedy (L5) finder's inline walk**, priced the same way (`gwalk.py`: its dominant path, tag-skip path and per-walk frame; the sum below is 0.332 candidates + 0.155 skips + 0.25 walks per byte at L5 over the four shaped instances). Before this round: one instance, dominant path **40 / 11 reads**, frame 49; the sum **125.0** | +| 79 | K | the greedy finder monomorphised over its kernel shape (`find_greedy_impl::`, brick 58's dispatch): its `cp`, `ca`, `tag_filter` and `walk_cont` were RUNTIME bools, so the dominant path tested three of them per candidate (`cmpb $0, slot`, branch) and selected the link decode on the fourth | dominant path **39 -> 35 / 32 / 37 / 39** (cp, ca, cp.wc, ca.wc), reads 11 -> 8; sum **125.0 -> 118.4**; `find_greedy` 1376 -> 5460 (five instances, one hot per block) | +| 75 | K | brick 59 for the greedy walk: one length (`best_ml` born `mls - 1`, `ml > best_ml`, unconditional `pre_eq`) | dominant paths **35/32/37/39 -> 32/29/30/37**; sum 118.4 -> 115.8 | +| 76 | K | brick 62 for the greedy walk: an explicit attempt countdown | reads on the dominant path 7 -> 5 on every instance; sum 115.8 -> 114.9 | +| 77 | K | brick 63 for the greedy walk: the two miss arms write different values | one instance's dominant path 39 -> 38; sum 114.9 -> 114.6 (the weakest of the round, recorded as such) | +| 78 | P | brick 65 for the greedy walk: the lower bound as one compare | per-walk frames -3 on every instance (80 -> 77, 79 -> 74, 89 -> 86, 85 -> 82); sum **114.6 -> 111.1** | +| 80 | F | four positions per trip in the fill's stride-1 loop (the pair loop stays for the remainder) | packed **36 per 2 -> 69 per 4** (18 -> 17.25 per byte; 29 at the session's start), tag-array 38 per 2 -> 71 per 4 (19 -> 17.75), no tags 22 per 2 -> 40 per 4 (11 -> 10) | +| 82 | P | bricks 68 and 49 for the greedy finder: the dead `wide_h && ip + 8 <= src_len` hash arm out of the per-position select, and the entry guard's `ip + mls <= src_len` (the loop's own invariant) out of the per-position path | per-walk frames (cycle through the walk minus the skip path) **49/49/56/54 -> 38/39/51/51**; greedy sum 111.1 -> **105.9** | +| 85 | P | the lazy finder's emit path refreshed `rep_bar` through `rep_bar_for`, whose `rep1 != 0` arm is dead there (a match offset is never 0): LLVM's branchless helper was seven instructions. At the emit site it is the add and one select | lazy emit cycle (position loop, through the literal push and the sequence store) **77 -> 73** | +| 86 | P | the lazy finder's rep probe chose its 8-byte or 4-byte compare with `at + 8 <= block_end` (`lea 9(ip)`, a compare against `block_end` reloaded from the frame) on every probing position. The loop holds `ilimit = block_end - 8`, and `ip + 9 <= block_end` is `ip < ilimit`: one compare on operands the latch reads anyway | inlined position loops, rep-probe path **79 -> 78, 81 -> 78, 94 -> 91**; no-match paths 52 -> 51, 78 -> 75; lazy model 271.5 -> **271.2** | +| -- | -- | **Third goal (2026-09-09): five more.** Same gates, same scores | | +| 87 | K | brick 74's guard for the greedy walk: since brick 79 its `cp` is a const per instance, so `(cp \| m != 0)` folds away on the packed instances (74 had left greedy alone because `cp` was a runtime bool there and the form would have ADDED a test) | greedy dominant paths **30/29/38/32 -> 29/30/33/31**; greedy sum 105.9 -> 104.5 | +| 88 | F | the fill's dead 8-byte-hash arm (`mls >= 8`, outside the contract): the per-call test and three loop bodies | `lz_fill_range` (packed) **798 -> 387** instructions, per-call prologue 41 -> 33; packed quad loop 69 -> 68; tag-array quad 71 -> 74 (its arm re-allocated; at 0.06 calls per byte the prologue saving covers it), no-tags 40 -> 40 | +| 91 | P | brick 86 at `try_rep1` itself: the width test `at + 8 <= block_end` (`lea 9(ip)`, a compare against a reloaded `block_end`) is `ip < ilimit`, and `ilimit` is a parameter every caller passes | `lea 9(` sites: greedy **5 -> 0**, dfast 4 -> 2; greedy per-walk frames 43/45/49/47 -> 38/39/50/47, sum 104.5 -> **102.8** | +| 95 | P | the lazy finder's no-match step `((ip - anchor) >> sh) + 1` (copy, subtract, the shift count from the frame, shift, add, increment) with the `+ 1` folded into the anchor: `(ip - anchor + 2^sh) >> sh` is the same value for every span a block holds, and `anchor_adj = anchor - 2^sh` (wrapping) moves only at a match | smallest inlined no-match cycle **45 -> 44** (the `inc` gone); lazy model 264.7 -> **264.4** (the board's pre_eq feature now prices the byte-load form; on it the session's start is 374.7 and the state before this brick 264.7) | +| 99 | K | the tree ladder's kernel (`bt_find_best_runtime`, ~2 calls per byte at L13-L15) selected its hash with `wide_hash && ip + 8 <= src_len` on every call, for `mls >= 8` which the contract rules out; the three `BtCtx` builders (priming, bt-lazy, bt-opt) now clamp `mls` to 3..=7 and the select is gone | entry-to-walk prologue **65 -> 62** per call, kernel 243 -> 234; walk cycle 42 -> 42 | +| -- | -- | **Fourth goal (2026-09-09): "is there more to win here?" -- the fill re-priced.** The packed quad loop's 17 per inserted byte were: tag 4 (`and smask`, `imulq`, `shrq 32`, `andl`), link decode 2 (`sub 1`, `cmovb`), hash 2, load/stores/mask/lea 8, loop 1 | | +| 100 | F | the chain ladder's link tag is the LAST BYTE of the `mls`-byte gram (`src[pos + mls - 1]`, `link_tag`) instead of the top byte of the masked gram times a 64-bit prime -- sound (a function of the bytes an accept verifies), so byte-identical by `taggate`'s argument; and where the product's top byte rejected 255 in 256 of the same-4-bytes-differ-at-byte-`mls` mates, the byte rejects all of them (census, corpus pass: skips 10.34M -> 10.27M at L5, 8.85M -> 8.79M at L7, 10.03M -> 9.97M at L9, false skips 0 -- 0.6% fewer skips, ~61K more loads per level). Every producer takes the one function: both fills, the greedy goal, both kernels, the primer, the wide re-insert, the null tag | packed fill quad **68 -> 56** (17 -> 14 per inserted byte; the `imull` now takes its load as a memory operand), tag-array quad 74 -> 56, row fill 21 -> 18, `lz_fill_range` 387 -> 345; kernel prologues cp 75 -> 72, ca 77 -> 76, none 67 -> 66; greedy no-match cycles **49/48/49/48/57 -> 45/44/46/44/50**; lazy walk paths unchanged (28/28/25/29), frames 58/38/57/43 -> 58/37/57/42, model 264.4 -> 263.8 | + +**Refuted on the path, reverted (the numbers stay so nobody retries them):** + +- **40 (K): carry the acceptance bar only, derive `best_ml` after the loop.** + Aimed at the phi round trip on the miss arms. The `bar == mls` tests kept + `mls` live and `pre_eq`'s `bar - 1` added an op: candidate path 28 -> 28 + (reads 2 -> 3) on the walk_cont kernels, and **28 -> 31 / 28 -> 30 / + 23 -> 26** on the three without walk_cont. +- **42 (K): `missed_before` as a count identity** (`seen > passes` at the + accept, no flag write on the miss arms). LLVM turned the named attempt + counter into an up-counter with a `lea`/`cmp $1` test and re-derived + `attempts - left`, and the extra live values spilled: candidate path + **28 -> 33**, tag-skip path 22 -> 23. The one-instruction flag write is + cheaper than any identity that needs the counter observable. +- **44 (K): the search position's first word loaded once per walk** (an + invariant `src[ip..ip+8]` reloaded per candidate because the `wcls` store + hides `src` from LLVM's alias analysis). One more live value, and it + spilled: candidate path **28 -> 29** (reads 2 -> 4) on cp.wc, **23 -> 28** + on ca.wc; only the untagged kernels gained (20 -> 19, 23 -> 22). +- **45 (K): the advance duplicated on both miss arms** so they reach the + header without the accept arm's phi join (the greedy walk carries exactly + this on its tag arm). LLVM rebuilt the loop with three latches and spilled + across them: tag-skip path **22 -> 40**, candidate path 28 -> 40, 9 stack + reads and 2 stores where there were 1 and 0. +- **51 (P): the count offsets applied inside the outlined counter** + (`count_match_raw8/16`, so the walk passes `m`/`ip` as they sit). One of + the two hoisted `lea`s left the prologue; the other stayed, the prologue + moved 82 -> 81 / 75 -> 76 / 88 -> 87 / 81 -> 82, and ca.wc grew by 73 + instructions of duplicated cold count code. Neutral on every path; brick + 56 takes the same two values off the loop without the duplication. +- **52 (F): the tag as the product's TOP byte** (`tv >> 56`, two seat + instructions instead of four, five producers changed together, sound by + the `taggate` argument). Fill **22 -> 20/21** per byte and prologue 81 -> + 79 -- but the kernel loop re-allocated around the new `gtag` and the cp.wc + candidate path went 27 -> 28 with a spill store. At L9's rates the two + cancel (+0.1 per byte). Parked, to retry once the loop is stable. +- **53 (K): the link carried XOR'd with the goal tag** so the tag test is one + masked `test` instead of copy/shift/compare. LLVM carried BOTH forms: + tag-skip path **21 -> 39**, candidate path 27 -> 39, reads 1 -> 3. +- **54 (P): the dead `wide_hash` arm out of the kernel's hash select** + (`mls >= 8` is outside the contract). Prologue 82 -> 80 and kernel -21, + but the ca candidate path went **27 -> 30** (reads 3 -> 5) and cp.wc's + 27 -> 28: at the unit rates a net +7 per byte. The arm is dead; removing + it re-shuffles a loop that is one register short. Retry with 55 once the + loop has slack. +- **55 (P): the kernel's two entry tests folded to one** (`usize::MAX` for an + empty head, caught by `m < ip`). Prologue 80 -> 77 / 76 -> 73 / 69 -> 65 -- + and every candidate path +1 (cp.wc 28 -> 29, cp 28 -> 29, ca.wc 22 -> 23). + Same story as 54; same retry condition. +- **57 (P): ONE call site for the search and its look-ahead** (the first + iteration is the search, `stop = min(ip + depth, ilimit)` bounds the rest). + The merged loop's phis for seven values are materialised on every entry: + no-match path **18 -> 34** with four spill stores, for the look-ahead step + 24 -> 15. zstd's `_lazy` has three inlined searches for a reason. +- **60 (K): `ip` out of the walk's loop** (the search word and a pointer to + `src[ip + best_ml]` carried instead, `room = block_end - ip` for the accept + test). The pre path -1 (36 -> 35) but the per-walk frame +3..+4 for the + two extra invariants, and ca.wc's pre path 33 -> 35: model **327.8 -> + 335.7**. The standalone (pointer) kernels LIKED it (386.6 -> 358.0), which + is the clearest statement yet that the two forms allocate differently. +- **67 (P): brick 55 retried inlined** (one entry guard, the empty head as + `usize::MAX`). Model 292.0 -> **295.6**; the allocator re-shuffled the walk + again. Twice refuted, in both forms; not retried a third time. +- **72 (F): the head word's operands swapped** (`tag << 24 | p + 1`) so the + `or` could land in the dead tag register. Pair loop 36 -> 36; LLVM had + already chosen. Dropped as neutral. +- **73 (K): the long count outside the walk loop** (a hot inner loop with no + call, breaking to a cold block for the count, re-entering) -- aimed at the + seven per-candidate invariant reloads, which exist because a call inside + the loop confines every value live across it to Win64's six usable + callee-saved registers. The two-loop shape did what brick 57's did: model + 284.7 -> **375.7**, loop unions 66 -> 108 with 6 spills. (The first draft's + macro `break`s also targeted the wrong loop; the shape was refuted on the + count before the gate could refute the semantics.) The diagnosis stands; + the fix is not a second loop. +- **81 (K): bricks 61/69 for the greedy walk** (raw bases for the insert and + the walk's link reads). Dominant paths -1 on all four instances, but the + per-position frames +9 in total (four base loads per position against + `lz_insert`'s two): greedy sum 111.1 -> 111.3. Neutral; not kept. +- **83 (P): brick 71 for the greedy walk** (the row mirror behind a block + bool). Same instructions, one more read per position: the tables pointer + is live there anyway for the insert. Not kept. +- **84 (P): brick 38 for the greedy finder** (`rep_bar`). `find_greedy` +104 + instructions, one instance's dominant path 37 -> 39, frames +6 in total: + greedy sum 107.3 -> 109.7. The greedy position loop allocates differently + from the lazy one; refuted on its numbers. +- **89 (K): the long count as ONE outlined call** (`walk_count8` taking the + counter's body instead of calling `count_match_raw`). The callee lost a + frame; the CALLER's per-walk frames grew +2..+4 (LLVM re-allocated around + the changed callee): lazy model 271.2 -> **275.2**. Not kept. +- **90 (P): brick 55's one-guard fold for the greedy finder.** No-match paths + **+6..+10** on every instance. Third refutation of the same fold, in a + third allocation; retired. +- **94 (K): brick 53 retried inlined** (the link carried XOR'd with the goal + tag, one unsigned compare). LLVM moved the tag test ahead of the link load + and the dominant path went 28 -> 30 / 28 -> 29, tag-skip 18 -> 21: lazy + model 271.2 -> 278.8. Second refutation, second allocation; retired. +- **96 (K): the goal byte `src[ip + best_ml]` carried instead of re-addressed.** + One byte in a register cost the loop its allocation: dominant path 28 -> + 46 with three spill stores. Retired. +- **97 (P): brick 95 for the greedy finder.** Greedy no-match cycles +1/-1/+1/-1, + frames +2/-1/+1/+1: neutral. Not kept. +- **98 (P): brick 95 for the bt-lazy finder.** Its tight cycle 18 -> 17, but its + two larger position cycles +2 with +3 reads. Mixed; not kept. +- **100 -> 100b/c/d, THE LEAK (found by the curiosity discipline, not by the + gates).** The byte tag's first form loaded the byte in the kernel too, and + the lazy walk's dominant path read **28 -> 29** (packed) / 25 -> 27 (tag + array), model 264.4 -> 273.2 -- for a change of one instruction OUTSIDE the + loop. The two paths dumped side by side: the product tag's `load_u64le(src, + ip)` had been CSE'd with `mls_xor`'s hoisted goal word and lived in a frame + slot, one load per candidate; without the tag's load LLVM rematerialised the + compare's word from `src[ip]` on every candidate and added a register copy. + `link_tag_from(v, mls)` = `(v >> 8(mls-1)) as u8` -- the same byte, from the + shared word -- restored every path (261.7); but the same form in the fills' + wide arm cost a variable shift per position (wide quad 64 -> 76), in the + greedy finder gave back 4 per no-match position, and on the kernels' wide arm + moved the tag-array shapes +1 (265.4). Landed: the kernels' hash4 arm from + the word, everything else the byte load (263.8, every path at its brick-99 + value). One value, three forms, chosen per site by the emitted path. +- **101 (F): the fill's head word with the tag as the OR's first operand**, so + the tied destination would be the dead tag register rather than the `p + 1` + the next chain index needs (one copy per inserted byte). Quad 56 -> 56, + byte-identical asm: LLVM canonicalises commutative operands, so source + order cannot steer the tied register. Neutral; not kept. +- **102 (F): the source slice in `FillCtx`**, so the fill's signature is four + registers and nothing rides the stack. It IS a structural saving -- call + site 7 -> 4 (no `lea`, no two stack stores, no `len` load), callee prologue + 34 -> 33, i.e. ~5 per match; the greedy's no-match cycle 45 -> 43; the + packed lazy frames 58/37 -> 56/35. But the tag-array shapes re-rolled: `ca` + pre 29 -> 30, frame 42 -> 46, `ca.wc`'s second site +1. The sum: packed + shapes -0.6 -0.6, fill -0.6 (0.125 calls/byte), `ca` +3.0 -> lazy model + 263.8 -> 265.6, **+1.2/byte with the fill counted**. Refuted under the sum + rule; on packed frames (< 16 MiB) alone it reads -1.8/byte. Recorded with + both numbers: `brick102.py` re-applies it in one line if the tag-array + shapes' weight is judged differently. +- **103 (P/K): each lazy `KIND` body its own `#[inline(never)]` symbol**, on + the theory that five bodies sharing one allocation is why every edit + re-rolls all four shapes. Outlined (five symbols, +775 instructions of + duplicated finder code): cp.wc frame 58 -> 57, cp 37 -> 38 and its loop + 48 -> 52, ca.wc 57 -> 60 with pre 25 -> 26, ca unchanged; model 263.8 -> + **266.5**. The pressure is intrinsic to each body (Win64's six usable + callee-saved registers against a loop that wants seven invariants), not + to their union. Not kept; the board tools now read either layout + (`cfg.merged`). + +Five source shapes (40, 42, 44, 45, and 35's freed register) have now failed to +move the chain walk's candidate path below 27-28. Of its instructions, 18 are +the algorithm (bounds, link, tag, first word, next), 3 are semantics +(`m != 0`, the walk_cont flag), and 6-7 are the register allocator's: a chain +base or `smask` reload, a copy in the xor, a phi round trip on `best_ml`, a +copy of `m`. They resist source-level shaping because every hoist adds a live +value to a loop that is already one register short. + +Running score against the goal of ten path wins per target, re-based on the +dominant path and the per-byte model: **K 13** (58, 59, 61, 62, 63, 74; on the +L5 walk 79, 75, 76, 77, 87; on the tree kernel 99), **F 8** (36, 39, 43, 66, +70, 80, 88, 100), **P 18** (37, 38, 41, 47, 48, 49, 50, 64, 65, 68, 69, 71, 78, +82, 85, 86, 91, 95). Second goal (ten more): done. Third goal (five more): +done (87, 88, 91, 95, 99). Fourth goal ("is there more to win here?"): **100**; +101-103 refuted, the fill at its floor under the current link representation +and call ABI. The lazy model: 374.7 instrs/byte at the session's start, **263.8** now +(30% fewer); the greedy sum 125.0 -> 102.8 and its no-match cycles 49 -> 45; the +packed fill 29 -> **14** per inserted byte; the tree kernel's per-call prologue +123 -> 62 across the campaign. + +What the kernel loop's refutations established still holds for the miss path; +for the path that runs, the lever was the CALL, and brick 58 took it. The +inlined loops carry 8-11 stack reads per candidate where the standalone +kernels carried 2-6: the finder's frame is where the walk's invariants live +now, and every one the allocator cannot keep in a register is a load per +candidate. That is the next target, and it is countable. + +The model's history, one number per landed state (`score.py`, the L9 search, four +shipping shapes; the pointer form until brick 58, the inlined form after): + +| state | instrs/byte | note | +|---|---:|---| +| session start | 374.7 | position loop then 27, priced as 18 here | +| after 35 | 400.5 | the contract brick, on the path that runs | +| after 50 | 375.0 | | +| after 56 | 396.0 | the outlined long count | +| after 58 | 338.9 | the walk inlined | +| after 59 | 327.8 | one length | +| after 61 | 319.7 | raw chain base in the loop | +| after 62 | 311.5 | countdown | +| after 63 | 306.5 | no hoisted flag store | +| after 64 | 301.8 | `wcls` direct | +| after 65 | 292.5 | one-compare lower bound | +| after 66 | 292.0 | top-byte tag | +| after 69 | 285.3 | raw-base insert | +| after 71 | 284.7 | rows bool | +| after 74 | 271.8 | tagged null links (packed) | +| after 86 | **271.2** | second goal's last brick | +Instruments: `verdict3.py` (the three-target board: per-kernel tag-skip and +examined-candidate paths, the four fill bodies' per-byte loops, the lazy +no-match path with and without the rep probe, each as instrs / stack reads / +stack stores), `phantoms` (bench example: the walk's position-0 candidate +census, see brick 46 below when it lands). +### Diagnosis -- why the matchfind bricks do not close the gap (2026-09-09) + +Twenty-three bricks priced UNITS of work. `mfbudget` counts how many units run per +input byte, and zstd 1.5.7's finders were compiled to assembly with the same LLVM +(`third_party` source, `clang -O3`) and priced with the same path tool. Both halves +are deterministic; no clock was used. + +**Units per byte match C's algorithm.** L9: 0.30 kernel walks, 1.7 candidates +examined, 0.15 tag-skipped links, 0.69 fill inserts, 0.04 count calls per byte; +51-63% of walks exhaust their attempts budget, as C's would. L13+: one tree walk +per byte at 9-11 nodes, as C's `ZSTD_updateTree` does. Skips and routing are not +the problem. + +**Unit PRICES are the gap, like-for-like (same compiler, same flags):** + +| unit (lazy ladder, mls 5) | zstd 1.5.7 HC | this crate (packed tags) | +|---|---:|---:| +| per candidate, first-word mismatch | **14** instrs / 2 reads | 22 / 0 | +| per inserted byte (fill) | **11** (unrolled x2) | 29 (14-19 with tags off) | +| per position (block loop) | **40** / 10 reads | 65 / 22 reads / 9 stores | +| search kernel | 329 | 315 | +| dfast per position | 86 / 18 | **55** / 18 | +| fast per position | 105 / 23 | **40** / 13 | + +Modelled at L9: **~96 instructions per byte here against ~60 for C's chain finder** +-- examine 37 vs 24, insert 20 vs 11, position+call 33 vs 22. L1-L4 are at parity +or better in instruction terms. + +**Two things the instruction count cannot see, and both point the same way:** + +1. zstd 1.5.7 runs the ROW finder by default for L5-L12 on x86-64 (SSE2 tag scan + of a 16/32-entry row, one dependent load per ROW). This crate's row finder is + gated to Lazy/Lazy2 in 512 KiB..2 MiB by the size crossover recorded above: + beyond 4 MiB it saves **9-11x dependent loads at L12** for 0.5-1.6% size. C took + that trade; we did not. That is the routing decision that matters. +2. The chain-link TAGS reject only ~10% of links (0.5-0.7 per walk of 5-19) while + costing a second multiply on every inserted byte and a decode on every link. + `taggate`: tags OFF is **byte-identical at L5/L7/L9/L12** (the walk budget counts + links the same way). In instruction terms OFF wins ~13/byte at L9; the only value + ON can have is skipping the candidate load on the 10% it rejects, which is a + memory-latency question that needs a quiet box and a clock. Parked with the + knob (`set_chain_tag_arm(false)`), not flipped. + +Instruments: `mfbudget` (units/byte + modelled budget), `taggate`, and the C asm +census in `tools/asmcensus/` now accepts plain C symbols. +### Changed -- matchfind: twenty-three deterministic bricks, fifteen refutations, all byte-identical + +Every verdict below is an EMITTED-ASSEMBLY count or a deterministic profile +counter -- this box sits at ~78% CPU with same-arm nulls of 7-18%, so no +clock was admissible and none was used. Every brick is byte-identical: GOLD +`2F6594F7EEDBD12B` / 59,680,638 bytes before and after each one, 173 tests +(174 minus one phantom test retired below). + +| # | brick | verdict (static instrs unless noted) | +|---|---|---| +| 1 | `mls_eq`'s `mls > 8` tail outlined cold | greedy 1516->1494, chain 354->332; walk-path guards **6 -> 0**; `memcmp` copies 6 -> 1 | +| 2 | `count_match` on raw pointers, FOUR register args | 105 -> 68, guards **4 -> 0**; stack-arg stores at 36 call sites **30 -> 0** | +| 3 | every knob's env-resolve arm behind a cold helper (52 sites, 3 helpers) | lazy **1681 -> 1472**, bt 1016 -> 834, dfast 1446 -> 1368, opt 1971 -> 1939; `env::var`/`trim`/`from_str` sites in all finders -> 0 | +| 4 | the reserve lives in `chain_finder_prologue` | greedy 1494 -> 1400, bt 1123 -> 1033; lazy GAINS its block-0 reserve (it had none) | +| 5' | literal fast-path copy is constant-width again | `memcpy` call sites per finder **2 -> 0** (fast/dfast/greedy/lazy/emit); 16-byte vector stores +2 per site | +| 7 | dfast's default-off stride fill outlined | dfast 1378 -> 1344; L3 per-position loop **865 -> 815**, reloads 201 -> 192 | +| 8 | vestigial BT specialisation retired | bt_lazy 856 -> 791, opt 1954 -> 1890; 349 dead lines; 2 per-block knob reads -> 0 | +| 10 | per-matched-byte fill loops outlined | greedy **1430 -> 1205**, lazy **1467 -> 1135**; per byte 4 reloads -> 1-2 (chain) / 0 (row) | +| 11 | fused head in the chain walks (`mls_xor` + `fused_ml`) | DYNAMIC: 57-63.5% of accepted candidates resolve in the first word -> **-2.8M..-5.7M instrs per level** over 16 MiB (static: row -104, chain +28, greedy +5) | +| 14 | the chain kernel's ABI: `walk_cont` into `ChainCtx`, then the accept accumulator into `MatchTables` -- FIVE arguments to THREE, all in registers | chain **359 -> 336**, lazy 1135 -> 1126 -> 1086; the stack-argument store before each of the two indirect calls per position 1 -> 0, callee prologue 26 -> 23 instrs / 6 -> 4 spills | +| 19 | the fill loops take their block constants through one `&FillCtx` | stack-argument stores at the three per-MATCH fill calls **5/6/6 -> 2/2/2**; lazy 1126 -> 1097; the mid fill arms 31i/4r -> 27i/3r | +| 17 | `find_opt`'s jump-fill knobs are block constants, unconditionally: the per-jump re-read arm (an A/B hook, `set_opt_hoist_arm`, now a no-op) leaves the DP loop | DP inner loop **456 -> 354** instrs, 24 -> 19 spills, 94 -> 78 stack reads, static loads **9 -> 0** per jumped position; `find_opt` 1890 -> 1780 | +| 18 | LDM (`--long`): the per-candidate `src[m..m+mls] == src[ip..ip+mls]` -- a libc `memcmp` of 64 bytes -- was redundant with the `count_eq >= mls` that followed it; one masked 8-byte head test rejects the hash collisions and the count decides; the two checked `hash[h]` indexings go through the proven form | `find_sequences` 889 -> 858, `bcmp` **1 -> 0**, guards **2 -> 0**; over five corpora x L3/L9/L19 the head lets 0.2-45% of the 56K-108K candidates per file through to the count (`ldmgate --features profile`); `--long` output byte-identical (`ldmgate` GOLD `57BE83EA4E1199E8`, 57,796,847 bytes) | +| 20 | the L6-L12 chain kernel is specialised on its TAG REPRESENTATION (`CP` packed link+tag / `CA` tag array / neither): two per-block bools the walk re-tested on every candidate now fold, the block selects one of three instantiations through the fn pointer it already dispatches on | per-CANDIDATE paths in the packed walk (the one-shot shape): tag-mismatch **28 -> 22** instrs, stack reads **4 -> 2**; first-word reject **30 -> 25**, reads 4 -> 3; the tag-array shape 28 -> 20 / 4 -> 4; three kernels of 269/304/310 instrs replace one of 336 | +| 21 | the DEFAULT level's finder (dfast, L3-L4) is specialised on `packed` -- the tag representation reaches its probe, its insert, `dtag_on` and the after-match fill, and the per-position path tested it and kept the array-form state live | per-POSITION no-match path, packed body: **60 -> 55** instrs, stack reads **20 -> 18**, stack stores 3 -> 2; array body 60 -> 56; `find_dfast` 1344 -> 2336 (the second body), one body runs per block | +| 23 | the greedy finder's after-match fill takes the row-free loop (`lz_fill_range::`, the lazy finder's, already in the binary) whenever the row table is off -- every input outside the 512K-2M row band, and every greedy block, since `row_auto_ok` only arms rows for Lazy/Lazy2 | per inserted BYTE: the rows fill's paths 38-42 instrs / 4-5 stack reads -> the row-free fill's **25-32 / 2-3**; same head/link/tag words, GOLD unchanged | +| 24 | `walk_cont` joins `CP`/`CA` as the chain kernel's third const axis -- the last per-block flag the tag-mismatch path reloaded and tested per candidate | packed-shape mismatch path **22 instrs, stack reads 2 -> 0** (the freed slot let the chain base take a register too); tag-array shape 20 / 4 -> **18 / 1**; no-tag shape 23 / 2 -> 19 / 0; six kernels of 264-323 instrs replace three of 269-310, one runs per block | +| 26 | the chain FILL loop (every byte of every match at L5-L12) is specialised on the tag representation for its row-free shape; the rare rows body keeps runtime flags behind a `SPEC` const so it costs no extra bodies | per inserted BYTE: packed shape **32 -> 29** instrs, stack reads 2 -> 0-2; tag-array 24-27 / 2-3 -> 23-25 / 1-2; no-tag 25 / 3 -> **14-19 / 0**; the per-byte `ca` flag test is gone from every shape; four bodies of 122/171/181/371 replace two of 338/371 | +| 27 | the binary-tree walk (L13-L15, and the opt levels' fill and priming) reads ONE child per node, after the write: the eager pair of child loads spilled both words and needed a forwarding compare to stay exact; reading after `chain_set` returns `m` exactly when that compare selected it | per-NODE path **55 -> 43** instrs, stack reads **8 -> 4**, stack stores **5 -> 1**; the walk loop 155 / 8 spills / 24 reads -> 133 / 2 / 18; `bt_find_best_runtime` 269 -> 245; byte-identical by the store-forwarding argument, GOLD unchanged | +| 31 | `prime_ldm` (the `--long` primer over a dictionary, prefix or retained window) indexed `hash[h]` checked on every primed position; `ldm_hash` masks to `hash_log` bits and the table is exactly that size, the proof brick 18 already used for `collect_ldm` | guards in the emitted crate **67 -> 66**; `--long` bytes unchanged | +| 33 | `match_ok` (dfast's per-candidate validity test) ran `ip + mls > len \|\| m + mls > len` BEFORE its 8-byte arm, where both are implied (`mls <= 8`, `ip + 8 <= len`, `m < ip` from the order check); they now guard only the cold tail, which is the one path that needs them | `find_dfast` **2345 -> 2319** across the five inlined per-candidate sites; the four guards left in `match_ok` are all in the cold tail; per-position paths 55/56 -> 54/55 | +| 34 | the binary-tree kernel's PROLOGUE was per-block work done per CALL -- `bt_log`, `bt_mask`, the worst-case `chain_len` guard and both hash shifts, all functions of `chain_log`/`hash_log`/`chain_len`. Into `BtCtx`, via `bt_geom`, built once per block at its three construction sites | entry-to-loop-header **123 -> 105** instrs PER CALL, and this kernel is called per position + per look-ahead step + per fill insert (61.9% of tree work at L13-L15); `bt_find_best_runtime` 245 -> 222, walk loop 133 -> 127 | +| 12 | raw-pointer insert on lazy's fill arm | small fill loops **22i/2r -> 14-16i/1r** per matched byte (greedy's arm measured WORSE, 22/1 -> 29/6, and keeps the method call) | + +**Refuted, each on a count, recorded beside the code so it is not retried:** + +- **Dropping `push_literals`' capacity check.** It is the function's soundness + contract and its own test exercises `spare = 0`; the alternative is `unsafe` + at 13 hot sites for ~3 instructions per push (~0.3%). Pruned on arithmetic. +- **Replacing the chain kernel's function pointer.** A direct branch removed + both indirect calls but duplicated the five-argument marshalling in both + arms (+18 per-position, +70 look-ahead); inlining the walk landed its 331 + instructions TWICE (1472 -> 1982, spills 10 -> 20). W24's pointer stands. +- **Removing the fast emitter's dead `packed` parameter.** 1843 -> 1843: LLVM's + dead-argument elimination had already dropped it from these internal + functions. The source ABI is not the machine ABI. +- **The fused head in dfast.** The counter that justified brick 11 refutes it + here: dfast's long-hash candidates match eight bytes by construction, so only + 37% resolve in the first word and the net is **+43,877 instrs at L3, + +103,109 at L4**. Same idea, opposite sign, decided by the resolution rate. + +- **Const-generic split of the BT walk on its `search` flag.** `_inner` is + `#[inline(always)]` and tests `search` at ONE site per accepted candidate; + doubling a 269-instruction body to remove one predicted test is the I-cache + trade the D-notes already refused. Pruned on arithmetic. +- **An `mls == 5` shape of the chain kernel** (every default row L5-L12 has + min_match 5, so the runtime shape's `mls <= 8` test and reloaded byte mask + looked foldable). Twelve kernels instead of six, total instructions down + (211-305 against 264-323) -- and the per-candidate PATHS did not improve: + 23/1 and 30/2 against the runtime shape's 22/0 and 28/1. The same verdict + the greedy split got, for the same reason: a loop total is the union of its + arms, and the path is what a candidate pays. Reverted. +- **Hoisting `prime_tables`' chain-arm flags** (`chain_pack`, `ctags`, + `chain_wide`, the plain-head test) out of the primed-position loop without + outlining it -- brick 16 refuted the outlining, this kept the frame. The + function fell 964 -> 924 and the loop 293 -> 287 with its one spill gone, + but across the six shortest per-position paths instructions went 228 -> 224 + while stack reads went **56 -> 60**. Two counters disagreeing in sign is not + a win, and the path is off plain `compress()` regardless. Reverted. +- **Folding `try_rep1`'s `rep1 == 0 || at < rep1` into one wrapping subtract** + -- attempted, then found the guard was deliberately phrased as the caller's + own loop condition by an earlier pass, precisely so LLVM deletes it at the + six loop call sites. The assert-before-write caught it; nothing was changed. +- **Keeping `tables` out of the chain walk** by accumulating the accept + classification in locals (the premise: its pointer pinned a register across + every candidate while the chain base reloaded). After brick 24 the packed + mismatch path already read nothing from the stack; the change moved no path + and added 7 static instructions. Reverted -- the premise was stale by the + time it was built. Re-census after every brick. +- **The greedy finder specialised on its tag representation** (brick 20's split, + applied to the L5 finder that inlines its own walk): three bodies, 1211 -> + 2889 static, and the per-candidate walk path went **29 -> 30** instructions, + stack reads **10 -> 11** (cp body) / 9 (array body). Folding two flags inside + a 500-instruction per-position loop freed registers the allocator spent on + other invariants; the kernel split paid because the kernel is 300 + instructions with nothing else live. Reverted on its own verdict. +- **A fused 8-byte head for the FAST finder** (brick 11's shape, third + probe after chain/row/greedy kept it and dfast refused it). The count + histogram split at n < 3 -- the exact population a head resolves at mls 5 + -- reads **31.1%** at L1 against the 37.5% break-even of the -5/+3 model, + and the count is called on only 4.1% of positions there. Pruned on + arithmetic; the instrument (`eqshare`, six buckets) stays. +- **The finders' census counters marshalled to their `#[inline(never)]` + epilogues** (probes, hits, ...): a per-position increment each, on the + face of it. The emitted call sites say LLVM's dead-argument elimination + already strips the ones no shipping heuristic reads -- dfast's epilogue + takes 14 stack arguments in the source and 11 in the binary -- so there + is nothing to hoist. Pruned before building. +- **`emit_fast_seq`'s eleven-argument ABI** (7 on the Win64 stack per + MATCH at L1/L2): bundling the four buffers behind one pointer would force + their headers into memory across the per-position loop that reads them 18 + times a block. ~14 instructions per match at ~0.03 matches per position + is under half an instruction per byte. Pruned on arithmetic. +- **Outlining `prime_tables`' chain-strategy loop** (the bricks 10/12 shape: + own frame, invariants hoisted, mask-proven indexing). Inline, LLVM had + unswitched the two shipping arms into their own loops -- dfast 42 instrs / + 12 reloads per position, lazy 50 / 15; outlined, the function IS the loop + and LLVM no longer unswitches its eight invariant tests: 46 / 9 and 57 / 13, + 964 -> 671 + 318 static. Instructions up, reloads down: not a win. The path + also never runs on plain `compress()` (dictionary/prefix and streaming + slides only). Reverted. + +- **Folding `push_literals`' runtime `arm` test into a const generic** for the + three chain finders whose width is never zero: bt -3, but greedy **+20** and + lazy **+6** static -- the armed monomorphisation re-laid out larger. Reverted. +- **Retiring the fast finder's BMI2 twin** on the density test that retired the + dfast twin: PARKED, not decided. It converts 41 ops in 1,811 instructions, + 44 per op -- denser than every twin the D-notes retired (72-152) -- and its + conversions execute per position (`shr r, cl` is two uops where `shrx` is one), + so the 2,095-instruction static drop would RAISE executed uops. That is the + static-count trap by name; only a clock can price it, and this box has none. + +- **Word-at-a-time backward extension in the fast emitter.** `bextcount`: at + L1 only 13.7% of matches extend backward at all -- 0.195 bytes per match -- + and 7-8% at L7/L9. A word form costs ~10 fixed instructions per match to + save ~8 per extended byte, i.e. about +8 per match. Pruned on arithmetic. + +**Correction to yesterday's note.** "`BT_SPEC_PAIRS` regenerated ... so the +specialisation keeps covering everything" was wrong: `bt_resolve` and +`bt_resolve_ins` returned the runtime body on every path, the 20 pairs fed +only a test, and `bt_find_best_impl_inner` had one caller and it was dead. +The test passed while selecting nothing. Brick 8 removed all of it. + +**The rest of the matchfind surface, audited and left alone.** Named so the +next pass does not re-open them: `try_rep1` (already hoisted, above); +`fill_fast_after_match` (two conditional stores, no guards); `RowTable`'s +`insert`, `insert_h` and `insert_at` (raw-pointer throughout); `row_tag_mask` +(already SSE2/NEON with a scalar oracle); `probe_view` (raw array views); +`count_eq_len_words_raw` and `count_eq_len_avx2` (leaf kernels, no guards, no +calls); and the six per-BLOCK prologues and epilogues (`dfast_finder_prologue` +at 573 instructions is the largest) -- those run once per 256 KiB block, about +0.002 instructions per byte, so they are an arithmetic prune rather than a +target. One adjacent lead, deliberately out of scope here because it is the +emitter and not the finder: `write_literals`, 2,421 instructions with **32 +`memcpy` call sites**. + +**Instruments built for this** (all deterministic): a natural-loop census with +per-loop spill/reload/static-load counts and spill-slot provenance, a +per-symbol guard-branch and `memcpy`/`lock`/TLS census, `fusedcount` (first- +word resolution rate), `bextcount` (backward-extension histogram). +Second pass, now in-tree under `tools/asmcensus/`: a CFG-correct natural-loop +census (every jump inside a label-delimited region is an edge; dominance-checked +back edges; the first version reported phantom loops that swallowed the prologue), +a per-PATH cost tool (Dijkstra over a loop's blocks on executed instructions, with +call-free isolation of the no-match path -- the number every specialisation verdict +above is read from), hot-slot provenance per loop, and `ldmgate` (the `--long` byte +gate with candidate/count counters); `eqshare`'s histogram gained the `<3` bucket. +### Changed -- rusty_alloc 1.1.4 -> 2.0.0 in the deliverable seam + +`rzstd-alloc` now pins `rusty_alloc-api = "=2.0.0"`, so the four CLI binaries +and the bench main run the 2.x allocator. Side-by-side against the 1.1.4 +build, same source, same flags. + +**No regression found.** + +| check | result | +|---|---| +| compressed output | **byte-identical**, 72 (corpus x level) pairs | +| round-trip | 48/48 clean | +| cross-decode v1<->v2 | 6/6 clean | +| library tests | 174 pass / 177 with `profile` | +| peak RSS | flat: -0.7% .. +0.5% over 9 (corpus, level) cells | +| binary size | 760,832 -> 764,416 (+3,584, +0.47%) | +| encode speed | **not resolvable on this box** | + +Byte-identity is the load-bearing check: an allocator that changed compressed +output would be a correctness defect, not a performance one. + +**Speed is reported as UNRESOLVED, not as parity.** ABBA, min-of-3, six +(corpus, level) cells, with a same-arm null: treatment 0.968x .. 1.187x +against a null of 0.934x .. 1.089x -- treatment mean 1.029 +- 0.075 against +null mean 0.987 +- 0.053. The two distributions overlap almost entirely on a +box sitting at 94% CPU. Re-run on a quiet machine before claiming either way. + +A first attempt at that timing was DISCARDED: driving each run through +PowerShell `Start-Process -Wait` added 250-500 ms of fixed overhead per +invocation, which swamped the work and produced a fake null of 0.999x. The +tell was `dickens` (10 MB) and `webster` (41 MB) both reading exactly 1,010 ms +at L3. Timed directly they are 503 ms and 786 ms. + +### Known -- the two allocator paths are on different majors + +`rusty_zstd`'s optional `rusty-alloc` feature installs through +`rusty_alloc_default`, which as of 0.1.2 still tracks the 1.x line (it moved +1.1.4 -> 1.1.6, not 2.0.0). So: + +```text + CLI + bench -> rzstd-alloc -> rusty_alloc-api 2.0.0 -> rusty_alloc 2.0.0 + rusty-alloc -> rusty_alloc_default -> rusty_alloc-api 1.1.6 -> rusty_alloc 1.1.6 +``` + +**No single binary links both** -- `cargo tree -p rusty_zstd-cli` shows only +the 2.0.0 chain -- so this is a workspace-lock artifact rather than a shipped +defect. But the lock now carries both lines, and the feature and the CLI are +on different majors until `rusty_alloc_default` publishes a 2.x. Recorded +rather than worked around. + +`rusty_alloc 2.0.0` also adds `portable-atomic` and `libc` as target- +conditional dependencies; neither is linked on windows-msvc, where the tree +ends at `windows-sys`. + +Also fixed: `rzstd-alloc`'s own doc comment claimed the pin was `=1.1.0` while +the manifest said `=1.1.4`. A stale version in the one comment whose whole job +is to state the pin. +### Refuted -- C's `sufficient_len` look-ahead exit does NOT pay on our lazy + +Recorded in full so it is not rediscovered. `find_greedy_impl` and +`find_lazy_impl` never read `target_length`; only `find_opt` did. C's +`ZSTD_compressBlock_lazy_generic` does: + +```c + const U32 sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM - 1); + if ((matchLength > sufficient_len) || (ip + matchLength >= iend)) + goto _storeSequence; /* best possible: avoid search */ +``` + +That is the same shape as the incompressible-section accel that DID pay 3-7x, +and `target_length` is 8 at L7 and 16 at L8-L12 against measured mean match +lengths of 8-35 -- so it looked reachable exactly where MatchFind is 94-96% of +encode. Built it, swept the cut as a multiplier in sixteenths (16 = C exactly): + +```text + mul 8 mul 16 (C) mul 32 + L7 +2.366% 1.24x +0.460% 1.00x +0.217% 1.04x + L9 +0.645% 1.14x +0.268% 0.95x +0.069% 0.94x + L12 +0.256% 1.01x +0.066% 1.09x +0.010% 1.10x + L13 +0% 1.03x +0% 1.03x +0% 1.03x (BtLazy2, no path) +``` + +**C's own setting costs 0.46% of ratio at L7 and buys nothing measurable** -- +1.00x against a null of -4.4%. The reason is structural: `search_log` is 3-4 on +our lazy rows, so `depth` is 1-2 and the look-ahead being skipped was never +expensive. Skipping it just loses the match it would have found. + +**REVERTED, not kept behind a default-off knob.** This crate usually keeps a +refuted arm with its rationale, but that convention assumes the disabled form +is free, and here it was not: with the knob resolving to 0 the emitted +`find_lazy` still went **1,655 -> 1,788 instructions, +133**, because LLVM did +not fold the per-position `good_enough` test away. A refuted feature does not +get to tax the hottest loop in the encoder. Measured both ways rather than +assumed. + +Also ruled out on the same pass, so the next reader does not re-chase them: + +- **No memory leak.** Two allocations failed during these sweeps (4 MB and + 16 MB), which looked like unbounded growth. Sampling the working set across + 80 L19 compressions shows a sawtooth between ~5 and ~41 MB with peaks the + same early and late -- no trend. The box had 2.4 GB free physical of 32 GB. + A loaded machine and a leak look identical from outside; this one was the + machine. +- Each L19 call still allocates and frees ~40 MB of tables. That is the case + for a REUSABLE one-shot context (C's CLI reuses a CCtx across iterations, + our `compress()` does not), which is an API question rather than a defect. +### Changed -- source-sized hash extended to EVERY strategy + +**GOLD 7FB4E822473412A3 -> 2F6594F7EEDBD12B, 59,685,682 -> 59,680,638 bytes.** +On the identity board this is a **-5,044 byte GAIN**, not a cost: at that +board's 1 MiB cap the chain levels measure -2,522 each. The +0.1% the trade +was accepted for exists only at 64 KiB-256 KiB. + +The strategy gate is gone. What licensed removing it: + +```text + 64K 256K 1M 4M tables + L1..L3 F/DFast +0 +0 +0 +0 0% never bites + L4 DFast +469 B +0 +0 +0 -50% (64K only) + L5 Greedy +384 B +0 +0 +0 -33% + L7 Lazy +393 B +1453 B +0 +0 -33% + L9 Lazy2 +402 B +1207 B -2522 B +0 -33% + L13 BtLazy2 +1 B +144 B +0 +0 -25..-33% + L16/19/22 +0 +0 +0 +0 -25% +``` + +**Fast and DFast are untouched BY CONSTRUCTION** -- their `hash_log` already +sits at or below `src_log`, so the clamp never fires and L1-L3 read exactly +zero at every cap. Everything that does move costs at most +0.11%, only at the +two smallest caps, and is zero or negative from 1 MiB up. + +The original finding is closed: table per input byte goes **12x -> 8x** on the +chain ladder (64K/256K/1M alike) and **16x -> 12x** at L12. + +| input | L7/L9 before | after | L12 before | after | +|---|---:|---:|---:|---:| +| 64K | 12x | **8x** | 16x | **12x** | +| 256K | 12x | **8x** | 16x | **12x** | +| 1M | 12x | **8x** | 12x | **8x** | +### Changed -- the hash is now sized from the SOURCE, not the window + +**GOLD D8F9B47AD5DDD2AB -> 7FB4E822473412A3, total 59,685,682 bytes BOTH +SIDES.** The anchor moves because individual frames shift; the sum does not +move at all. This is a memory change, not a ratio change. + +C clamps `hashLog <= windowLog + 1` and we matched it. But once the window has +already been reduced to the source, two buckets per window position is two +buckets per BYTE OF INPUT -- 8 bytes of hash on top of the chain's inherent 4, +which is exactly the **12 bytes of table per input byte** measured earlier. A +1 MiB input at L9 allocated 12 MiB of table. + +| input | L7 | L9 | L12 | +|---|---:|---:|---:| +| 64K | 12x input | 12x | 16x | +| 256K | 12x | 12x | 16x | +| 1M | 6x | 12x | 12x | + +**GATED ON STRATEGY, because the cost is not uniform.** The tree finders reach +candidates through the binary tree, so extra hash buckets buy them almost +nothing; the chain finders resolve every collision by walking, so taking +buckets away lengthens their walks. Measured over 16 corpora: + +```text + 64K 256K 1M tables + L16 BtOpt +0 B +0 B +0 B -25% + L19 BtUltra2 +0 B +0 B +0 B -25% + L22 BtUltra2 +0 B +0 B +0 B -25% + L13 BtLazy2 +1 B +144 B +0 B -25..-33% + L9 Lazy2 +402 B +1207 B -2522 B -33% <- NOT taken + L7 Lazy +393 B +1453 B +0 B -33% <- NOT taken +``` + +BtLazy2 and above is the band that is free or within 0.009%. The chain ladder +keeps C's sizing, so no ratio is sold for memory it does not need. + +**Peak RSS**, sampled live (it reads 0 after exit): L16 at 1 MiB goes +**32.8 -> 28.7 MB, -12.5%**; L7/L9/L12 at 256 KiB fall 4.9-5.7%. + +**REFUTED, and worth recording: this is NOT a speed win.** Cutting the table +33% moved total encode time by -1.8%, inside the noise, and the `EncodeTables` +share did not fall. The reason is mechanical -- `vec![0; n]` for a large `n` +takes zero pages from the OS rather than memsetting, so the cost scales with +pages TOUCHED, not pages allocated. Allocating less cuts committed memory and +RSS; it does not cut work. Anyone reading the earlier "tables are 30% of small- +input encode" line should not expect to win that 30% back by shrinking the +allocation. + +**`BT_SPEC_PAIRS` regenerated.** Moving `hash_log` down one shifts the +reachable `(hash_log, chain_log)` set from `(h, h)` / `(h, h+1)` shapes to +`(h, h+1)` shapes. Left alone, every Bt level at every size would have fallen +through to the slow runtime body -- the exact regression +`bt_specialisation_covers_every_input_size` was written to catch, and it did. +Re-enumerated by `btpairs.rs` over every bt clevel x every input size x the +streaming case: still exactly TWENTY pairs, so the set moved without growing. + +`RZSTD_HASH_TIGHT=0` / `set_hash_tight_arm(0)` restores C's sizing. +### Fixed -- the chain ladder walked incompressible data ONE BYTE AT A TIME + +**GOLD 269F0EC2BA6B8550 -> D8F9B47AD5DDD2AB** (-491 bytes). Small on that +board because 14 of 18 corpora are byte-identical under the change; the win +here is SPEED, and it is large. + +C's `ZSTD_compressBlock_lazy_generic` advances a failed position by +`((ip - anchor) >> kSearchStrength) + 1`, with the comment "jump faster over +incompressible sections". `find_greedy_impl`, `find_lazy_impl` and +`find_bt_lazy` all advanced by a bare `ip += 1`, so on content that cannot +match they walked every byte while C accelerated away. Same shape as the +repcode and back-extension defects: a capability present in one finder and +absent in its neighbour -- `find_fast`/`find_dfast` have had an accel shift +for levels. + +**How it was found, and how it was separated from a noisy box.** The +head-to-head board read 11.5-12.2x slower than C on `incomp-32m` at L7/L9, +but that board's null arm was 10-17% because the machine was at 91% CPU. A +12x claim inside a 17% null is not a measurement -- so the question was +whether it was real at all. It was settled WITHOUT trusting the board, by an +internal comparison in ONE process where load cancels between the arms: L1 +took 943 us with MatchFind at 11.3%, L9 took 26,918 us with MatchFind at +86.0%. **28.5x between our own two levels on the same bytes.** Load explains ++-17%, not +2750%. + +The walk census read ZERO chain loads at L7/L9, which ruled out chain walking +and pointed at the per-position advance itself. + +| level | before | after | speedup | MatchFind share | +|---|---:|---:|---:|---| +| L5 Greedy | 9,333 us | 2,830 us | **3.3x** | 87% -> 70% | +| L7 Lazy | 23,374 us | 3,256 us | **7.2x** | 88% -> 62% | +| L9 Lazy2 | 26,918 us | 4,864 us | **5.5x** | 86% -> 54% | +| L12 Lazy2 | 26,949 us | 5,015 us | **5.4x** | 85% -> 51% | + +**Shift 12, not C's 8.** The shift trades size against skipped positions and +the two do not move together: + +```text + shift L5 size L7 size L9 size incomp speedup + 8 +2,383 +2,597 +2,990 3.2x .. 4.8x + 10 -254 -257 +155 3.1x .. 4.2x + 12 -235 -216 -15 2.8x .. 3.7x +``` + +12 is the only value SMALLER on every level at both caps tested, so it is a +strict win rather than a trade -- 4 MiB totals -655 / -365 / -193 / -42 at +L5/L7/L9/L12. 10 was rejected because `x-ray` regresses +1,581 there and is +byte-identical at 12. 144 cells round-tripped. + +`RZSTD_LAZY_ACCEL` / `set_lazy_accel_arm(0)` restores the old step. + +### Known -- table zeroing is now the top cost on small inputs + +With the search fixed, the stage profile on 1 MiB of incompressible data puts +**`EncodeTables` at 30.1% (L9) and 30.9% (L12)** -- it was invisible under the +old search cost. `MatchTables::new` zeroes hash + chain sized from the level, +and for a small input that is far more memory than the input itself: + +```text + input L7 L9 L12 + 64K 12x 12x 16x (of the input, zeroed before any work) + 256K 12x 12x 16x + 1M 6x 12x 12x +``` + +A 1 MiB input at L9 zeroes 12 MiB of table. Counted and left; the fix is to +size the tables from the source length rather than the level, and it wants its +own measurement pass. +### Changed -- the ROW match finder now defaults ON for small inputs +### (-147,812 bytes, -0.247% on the identity board) + +SHIPPED. The row arm's own doc said it "ships on `examples/rowboard.rs` or not +at all" -- so this is that board, run across input SIZES instead of at one cap. + +**GOLD EA4E12B951B48F4A -> F72C7074A2240AF7**, 59,852,335 -> 59,704,523 bytes. +A pure ratio gain: nothing was traded for it. `ROW_ARM` gains a third state, +AUTO (0), which is now the default; `set_row_arm` still FORCES either way and +`set_row_arm_auto` restores AUTO. Out of band the output is byte-identical to +the previous default, so only in-band cells of the identity table moved, and +all 174 tests pass -- including the C cross-compatibility suites, so the new +bitstream is still ordinary zstd. + +The gate fires only for `Strategy::Lazy | Lazy2` with a KNOWN source length in +512 KiB..2 MiB. Streaming and the dictionary harvest pass `None` and keep the +chain, because the band is a source-length band and they do not know the +length. Verified cell by cell (`rowauto.rs`, every cell round-tripped): + +```text + L5 Greedy off at every size (not the lazy ladder) + L7 Lazy 512K 0.9866 1M 0.9880 2M 0.9895 256K/3M/8M byte-identical + L9 Lazy2 512K 0.9882 1M 0.9882 2M 0.9894 256K/3M/8M byte-identical + L12 Lazy2 512K 0.9959 1M 0.9968 2M 0.9992 256K/3M/8M byte-identical + L13 BtLazy2 off at every size +``` + +Every ON cell is a win and every OFF cell is unchanged, so the gate is +STRICTLY non-regressing on the board. + +`rowboard` caps every corpus at 8 MiB and reports L9 aggregate **1.0005x** -- +a wash, which is why the arm has stayed `Defaults OFF`. Swept across caps, the +verdict is monotone in input size and 8 MiB is just past the crossover: + +```text + L9 cap size ratio dependent loads saved + 256K 1.0059 6.84x + 512K 0.9882 2.47x + 1M 0.9882 3.08x + 2M 0.9894 3.32x + 4M 0.9944 3.42x + 6M 1.0018 3.73x + 8M 1.0005 <- the only cap rowboard measures +``` + +So in **512 KiB .. 4 MiB** the row finder is smaller AND does far less work -- +both currencies moving the right way at once, which is precisely the case the +rowboard header says it cannot assume ("A row finder that costs size must EARN +it in speed"). It does not cost size there; it saves it. + +| level | win band | size ratio | dependent loads saved | +|---|---|---:|---:| +| L7 Lazy | 512K..4M | 0.9866 .. 0.9936 | 1.96x .. 2.57x | +| L9 Lazy2 | 512K..4M | 0.9882 .. 0.9944 | 2.47x .. 3.42x | +| L12 Lazy2 | 512K..2M | 0.9959 .. 0.9992 | 5.63x .. 8.53x | + +336 cells, every one round-tripped. Beyond the crossover L12 still saves 9-11x +loads while costing 0.5-1.6% size -- the size-for-speed case rowboard was +written for, and a separate decision. + +**The mechanism, and why it has a crossover.** A row holds the last 16 +positions for its bucket where the chain held all of them linked. That trades +DEPTH for RECENCY -- and recent means SMALL OFFSETS, which cost fewer bits. +While the chain is shallow the row gives up almost no depth and banks the +offset saving; once the window fills, the chain's extra depth finds matches the +row cannot. Same offset-cost mechanism as the `nl_dispatch` result above: a +finder can win MATCH LENGTH and still lose COMPRESSED BYTES, and any signal +built on length alone is blind to it. + +**The dispatch signal is size, not content.** Three content signals were tested +against the per-corpus win/loss split and ALL THREE overlap -- literal share +wins [0.029, 0.474] vs losses [0.136, 0.568]; mean match length wins +[8.80, 35.34] vs losses [5.30, 20.89]; sequences/KiB wins [27.5, 103.2] vs +losses [39.0, 138.5]. No empty interval, so no content gate. The separating +variable is how full the window is, which the encoder already knows. + +Row memory is not the objection: `RowTable::reset` sizes `1 << hash_log` +entries and 16 buckets share a row, "which is what keeps this table the same +size as the chain". + +### Also found on the same board + +- **`lazy_gain` ON is -7,111 B at L9** (and +140 at L7, 0 at L13) -- level- + dependent, so it is a dispatch question rather than a default flip. +- Defaults CONFIRMED correct for `lazy_fill` (off costs 101K-163K), `walk_cont` + (off costs 5K-12K) and `wide_chain` (off costs 0.3K-0.8K). These had never + been boarded at all -- `allgates` could not see their levels until today. + +### Two more harness defects, both caught by disagreeing instruments + +- **`take_row_census()` returns `(ROW_EXAM, ROW_LOADS)` -- candidates first.** + Reading `.0` as "loads" compares chain LOADS against row CANDIDATES, two + different units, and reports a flat 1.00x saving. `rowboard` destructures it + correctly; a fresh harness did not, and the 3.81x claim looked refuted until + the field order was checked. +- **These arms are THREE-state and have no public "unset".** `set_*(true|false)` + FORCES; the untouched state resolves through an env knob or a dispatch. A + board that sets arm A and then measures arm B has no valid baseline: the + first attempt produced an identical **+10,462 B at L13 for thirteen + unrelated arms** -- one stuck forced arm, read thirteen times as if it were + each arm's own result. The fix is one arm per PROCESS (`armone.rs`). +### Changed -- the next-long OFFSET-TRADE dispatch now defaults ON (-0.36% at L3) + +SHIPPED. **GOLD F72C7074A2240AF7 -> 269F0EC2BA6B8550**, 59,704,523 -> +59,686,173 bytes. `NL_DISPATCH_ON` now initialises to 2 and +`dfast_good_ml_raised()` returns 48 instead of 24; `set_nl_dispatch_arm(false)` +restores the old behaviour. + +The bytegate delta (-18,350 B) is small because that board spans nine levels +and only one of them is DFast. On an 18-corpus L3-only board the same change +is **-82,653 bytes, -0.360%**, and -0.27% to -0.30% across 2/4/8 MiB caps at +both L3 and L4, with 72/72 round-trips. + +It required widening the adjudicated L3->L5 ladder tie from 0.1% to 0.2%. That +is the same event the exception was written for: on full osdb L3 goes +3,517,111 -> 3,514,780 while **L5 stays at 3,519,696 -- the exact value the +test's own doc already recorded** -- so the cheaper level gained, Greedy did +not lose, and `L5_CEILING` (3,530,000) is untouched. The historical DEFECT +inversions on this pair were +1.25% and +0.33%, both still above the new bar. + +**Why size and not speed.** This box's paired timing harness has a +-1.5% null +band (`eqlever.rs`, ABBA, pinned, min-of-15). Compressed bytes have no null +band at all -- same input, same arm, same number, any machine, any load. So +size is the only currency in which a sub-1% effect is decidable here. + +`sizehunt.rs` swept the arms reaching the two Fast/DFast finders and found that +turning `next_long` OFF makes **`sao` 15,001 bytes SMALLER** at L3 while making +all fifteen other corpora larger. `nlhunt.rs` then showed why the obvious +signal cannot route it: the probe wins **468,072 match bytes** on `sao` and +still costs 15,001 compressed bytes, because it COMMITS at `ip + 1` and can +take a longer match at a worse OFFSET. `next_long_yield` does not separate that +case -- `x-ray`'s yield is 0.0002 against `sao`'s 0.0241 and the probe HELPS +`x-ray`. + +The encoder already counts the offset trade (`band_worse / band_hits` -> +`tables.nl_off_worse`) and `nl_cut_for` already dispatches on it. **That +dispatch is off by default** (`NL_DISPATCH_ON != 2` returns the bare 8, so +`dfast_good_ml_raised()` is never consulted -- which is also why sweeping +`dfast_good_ml` with the dispatch off moves nothing at all). + +| config (L3, 18 corpora, 4 MiB each) | bytes | vs shipped | +|---|---:|---:| +| shipped default | 22,934,391 | -- | +| `nl_dispatch` on | 22,865,392 | **-68,999 (-0.301%)** | +| + `dfast_good_ml` 48 | 22,851,738 | **-82,653 (-0.360%)** | + +Eleven corpora improve, two regress (`reymont` -33,804, `webster` -18,406, +`samba` -5,136, `jsonlog` -4,852 against `dickens` +1,716, `mr` +517). + +**Priced in work, not guessed.** The dispatch raises the "good enough, stop +searching" cut, so it must be bought with search -- but the longer matches it +finds leave less to scan and encode, and three of the four counters go DOWN: + +| L3 | candidates | fills | positions | sequences | +|---|---:|---:|---:|---:| +| nl_dispatch | +9.00% | -1.28% | -0.45% | -1.18% | +| + good_ml 48 | +10.88% | -1.41% | -0.50% | -- | + +**Stability and correctness.** 72/72 round-trips with checksums; the win holds +across a 4x range of input, so it is not a warm-up artefact: + +```text + cap L3 L4 + 2 MiB -0.257% -0.221% + 4 MiB -0.254% -0.258% + 8 MiB -0.232% -0.273% (nl_dispatch alone) + 4 MiB -0.304% -0.284% + 8 MiB -0.271% -0.274% (+ good_ml 48) +``` + +**48 is off the plateau, not the argmax.** The `mlgrid` 2-D sweep's best cell is +`good_ml=64, good_ml2=24` at -82,975 B; `48`/follow is -82,653, i.e. 322 bytes +(0.0014%) worse and not at an edge. Everything in 40..64 lands within 0.03%, so +the extreme cell is far more likely to be this corpus set than a real optimum. + +Smaller size results from the same sweep, all at their true defaults: + +- `dfast_good_ml2` = 48 with the dispatch OFF: **-10,808 B (-0.047%)** at L3 -- + independent of the above, because the second-candidate cut only ADDS a + candidate at `ip` and cannot shorten the match. +- `pair_hi` = 4.0 at L1: **-7,702 B (-0.031%)**, flat from 4.0 to 9.0. +- `dfast_step` = 1 at L3: **-5,051 B (-0.022%)**. +- `search_log_d` = +1 at L9: **-86,421 B (-0.399%)** -- a depth increase, so a + size-for-speed trade of a different character. + +### Two harness defects caught in this sweep, recorded because both read as +### code defects + +- **`set_pair_hi_arm(-1.0)` does not reset the arm, it PINS it to -1.0.** The + f32 arms cache raw bits with `u32::MAX` as "unset" and the setter stores + `v.to_bits()`, so there is no public reset. A sweep that used -1.0 as its + baseline measured every delta from a changed config and reported + `pair_hi=4.0` as **-47,965 B**; against the documented default (1.0) the same + cell is **-7,702 B**. Set baselines explicitly; never assume a sentinel. +- **`accel_shift` is inert without `--features profile`.** `accel_shift_for` is + consulted only under `cfg!(feature = "profile")`; release builds take the + constant 7 (Fast) / 8 (DFast). Swept without it, all nine values read exactly + +0 -- which is the signature of a dead knob and was a dead harness. +### Fixed -- two correctness gates were passing on SILENCE, not on evidence + +Both gates covered a *level list* and believed they covered a *strategy set*. +They do not coincide, and nothing checked that they did. + +**`tests/kreach_gate.rs` -- the gate that enforces >=95% kernel routing -- +exercised three of the nine match finders.** Levels were `[1, 3, 9]` under a +comment claiming they "cover the distinct match-finder strategies"; they +resolve to Fast, DFast and Lazy2. Nothing reached `find_greedy`, `find_lazy`, +`find_bt_lazy` or `find_opt`'s BtOpt/BtUltra arms -- so a kernel reached only +from one of those scored `(0 kernel, 0 scalar)`, and the verdict loop **skips** +any slot with `h + m == 0` as "not exercised on this side". A dispatch that +never took its twin in five of nine finders would have passed. + +Now `[(1,4M) (3,4M) (5,4M) (7,4M) (9,4M) (13,2M) (16,1M) (18,1M) (19,1M)]` -- +one level per strategy, with a smaller prefix for the levels that are orders of +magnitude slower per byte, because reach is a RATIO and does not need the whole +corpus to be non-zero. `count_eq_len wide` traffic goes 9,316,212 -> 9,477,458 +calls; all eleven slots read 100.00%; the run still takes 1.6 s; and the +`RZSTD_KREACH_POISON=1` self-check still fails, so the gate is proven live. + +**`examples/simdparity.rs` never parity-checked BtLazy2.** Its doc lists the +families it claims to cover -- "fast, dfast, greedy, lazy, lazy2, btlazy2, +btopt, btultra" -- but the list said `12`, and **L12 resolves to Lazy2**; +BtLazy2 starts at L13. The gate that exists to catch a `simd.rs` defect in +every finder skipped `find_bt_lazy` entirely. `12 -> 13`, plus `18` for +BtUltra. + +Both now carry an `assert!` that resolves each level's strategy and fails if +the set stops covering every finder, so the doc comment is enforceable instead +of aspirational. + +### Fixed -- `allgates` reported a live ratio gate as dead + +`LEVELS` was `[1, 3, 19, 22]` = Fast, DFast, BtUltra2, BtUltra2: **three of +nine strategies**, and none of levels 5-18. Every arm whose only call sites +live in an untested finder read SZ-DEAD for a reason that has nothing to do +with the arm -- the exact failure this tool exists to prevent. + +`lazy_fill` is read only in `find_lazy_impl` and `find_bt_lazy`, so it read +SZ-DEAD at every prefix. Toggled at L9 it moves **266,695 compressed bytes +(1.53% of a 40 MiB board) and 4,133,134 probes**. Widening the list flips it +to LIVE with 28 moved cells (`mr` +23,482, `ooffice` +18,025). `pair_gain`'s +`0.0` arm flipped dead -> live too, and resolution improved throughout: +`search_log_d` 2/3 -> 61/52 moved cells, `strategy` 65 -> 111, `rep1_mode` +13/22 -> 42/71. + +A `strategy_coverage` self-check now prints what the list exercises and names +anything missing. It earned its keep immediately: the first widened list +(`[1,3,5,9,13,16,19,22]`) still missed Lazy and BtUltra, and the check said so. + +### Fixed -- two counters that do not mean what a reader assumes + +- **`EncodeCounts::hash_probes` is not comparable across finders.** + `find_fast_impl_inner` bumps it at the TOP of the scan loop (POSITIONS); + `find_dfast_impl_inner` bumps it inside `if let Some(m8)`, after a tag filter + (SURVIVORS). A `probe_hits / hash_probes` "hit rate" therefore reads ~12% at + L1 and ~94% at L3 for reasons entirely about the denominator. Use + `encode::take_mm`, bumped at the loop top in both. Documented at the field. +- **`EncodeCounts::hash_fills` reads a FALSE ZERO at L5 and above.** + `note_hash_fill` is called only from the Fast/DFast fill helpers; the chain + inserters Greedy/Lazy/Lazy2/BtLazy2 fill through never report. Deliberately + not wired there -- `lazyfill.rs` measures 41,742,765 fill inserts at L9 and a + `lock xaddq` on each would be the instrument dominating what it measures. + +### Refuted, recorded so they are not retried + +- **Removing the ten zero-caller functions is worth ZERO emitted bytes.** The + release asm contains none of them; LLVM already eliminates every one, so the + `#[allow(dead_code)]`-with-rationale convention costs nothing. +- **Packing the paired gate counters two-per-`u64`** (`nl_probes`/`nl_hits`, + `band_hits`/`band_worse`, `spec_made`/`spec_dropped`) to relieve the DFast + loop's register pressure measured **`find_dfast` 1448 -> 1469 instructions**, + spills 184 -> 185, reloads 248 -> 251. The `1 << 32` constants and the unpack + cost more than the register saved. Built, measured, reverted. +- **Hoisting the table bases out of the main loops** the way W9 did for the + (default-off) fill stride buys nothing: the emitted innermost loops of both + `find_fast_impl` and `find_dfast` contain **no repeated pointer-relative + loads**. LLVM already hoists them; the repeated `%rbp`-relative loads are + spill/reload of a live set that is simply too large. +- **No panic landing pads to remove**: `find_fast_impl`, `find_dfast`, + `find_lazy` and `find_greedy` have zero guard branches already. +- **`find_fast`'s BMI2 twin converts 41 shifts across 1,817 instructions** + (44 instrs/op) -- DENSER than every twin this crate retired (dfast 72, + bt 97, lazy 111, greedy 123, chain 152), and retiring it would drop + `K_FIND_FAST` to a miss against the >=95% reach gate. Left alone. +### Fixed -- a knob cache whose sentinel collided with its own default + +`dfast_step_forced` cached its env knob in an `AtomicU32` and treated 0 as +"not yet read". But 0 is also what the UNSET knob resolves to -- the shipping +default -- so the store never took and every call re-read the environment: an +OS lookup and a `String` allocation, once per block, forever, for a value fixed +for the life of the process. Storing `v + 1` makes 0 mean "unread" and nothing +else. The public `set_dfast_step_arm` is biased to match, or a set value would +read back one low. + +**-829 allocations per 88 MiB at L3.** This crate has been bitten by the +per-call `std::env::var` shape repeatedly -- one instance is recorded in-source +as having cost 60% of L19 encode -- and every previous fix was a cache. This one +HAD a cache; it just never engaged. + +Two durable consequences: + +- **All 33 direct `std::env::var` calls now route through the counted + `env_knob` shim**, so one counter sees every knob read in the crate. +- **`tests/env_reads_gate.rs` makes it a gate**: a correctly cached knob costs a + fixed number of reads no matter how much data is compressed, so the test + compresses 128 KiB and 1 MiB and fails if the count SCALES. Verified by + poisoning -- with the old sentinel restored it reads 2 vs 11 and fails with a + diagnostic naming the cause. + +### Changed -- encoder allocations halved + +With the three pool leaks, the stack histogram, the knob cache and a pooled RLE +header: + +| encode, 88 MiB | before | after | +|---|---:|---:| +| allocations per MiB @ L1 | 116.8 | **64.9** | +| allocations per MiB @ L3 | 143.7 | **71.1** | +| allocations per MiB @ L9 | 128.9 | **69.5** | +| scratch-pool hit rate | 78.2% | **99.8%** | +| copies per input byte | 0.430 | **0.371** | + +`ct_pool` (which keeps its own free list) is now covered by the same census, so +one number answers for every pool in the crate. It measured ~100%, which is +only knowable by looking. + +Byte-identical across 48 (level x corpus) pairs with exact round-trip. + +### Known -- the finder scratch reallocates ~80 times per corpus + +`dfast_finder_prologue` discards its pooled scratch and allocates a fresh one +whenever capacity falls short. `lit_scratch` is sized `block_len + +LIT_PUSH_WIDTH_MAX`, i.e. past the 128 KiB large-allocation threshold, so each +is a VirtualAlloc and a page-table edit. Measured: **80 reallocations, 7.89 MB** +over twelve corpora -- roughly per-frame rather than per-block, so mostly +amortised already (~0.15% priced). Counted and left, not fixed. +### Changed -- encoder allocations down 44%, and three scratch-pool leaks closed + +An allocation-site census (backtrace-sampled, so it FINDS sites rather than +confirming suspected ones) put the encoder at 143.7 allocations per MiB against +the decoder's 1.6. Five landed changes, each byte-identical: + +1. **`ncount_seq_table` copied a histogram to the heap to decrement one entry.** + `counts.to_vec()`, three times per block (ll/of/ml), was **half of all + encoder allocations**. The sequence tables' alphabets are fixed by the format + (LL 36, OF 32, ML 53), so the copy is now a `[u32; 64]` on the stack with the + heap path kept for any future wider caller. **-10,007 allocations (-30%).** +2. **`normalize_count` leaked its pooled buffer on the low-probability branch.** + It takes `norm` from `SC_NORM` and returns `n2` instead; `norm` was dropped. +3. **`write_tree_fse` never returned its `norm` buffer.** `ncount_and_ctable` + closes that loop for its own callers; a caller using `normalize_count` + directly owns the give-back and this one did not do it. +4. **`write_tree_fse` never returned its `ncount` buffer either** -- same defect, + different pool. +5. **`ct_pool` is now covered by the same census.** It keeps its own free list, + so the `scratch` counters could not see it; it turned out healthy (~100%), + which is itself worth knowing. + +| encode, 88 MiB, L3 | before | after | +|---|---:|---:| +| allocations | 12,671 | **7,105** | +| allocations per MiB | 143.7 | **80.6** | +| scratch-pool hit rate | 78.2% | **99.8%** | +| pool misses (each an allocation) | 1,437 | **24** | + +**REFUTED TWICE: raising the pool's free-list cap.** 6 -> 32 changed hits and +misses not at all, first at the 78.2% rate (5,167 / 1,437 both ways) and again +after the leaks were fixed (5,885 / 719 at caps 6, 12 and 32 alike). Only drops +moved. The cap stays at 6 with the refutation recorded beside it -- the misses +were leaks and first-use, never capacity. + +The ordering matters and is the lesson: the cap experiment was run FIRST, came +back flat, and was correctly recorded as a refutation. It stayed a refutation +after the leaks were fixed -- but the leaks were only found by asking why the +hit rate was 78% when the cap plainly was not the reason. + +Byte-identical across 36 (level x corpus) pairs with exact round-trip. +### Changed -- the literals section is written straight into the frame + +`encode_literals_section_into` packed every candidate into a staging buffer and +copied the winner into `dst`. The staging was blamed on the header needing the +compressed size before the body can be placed -- but at PACK time the body is +already encoded, so `csize` is known and `write_lit_huff_header_into` takes it +as a parameter. The real constraint is only that candidates compete on size and +a loser must be discardable. + +The new table is Huffman-OPTIMAL for the block's frequencies, so `body_new <= +body_prev` always and it is the candidate that usually wins. It is now appended +straight into `dst` and `dst` is truncated on the rare loss; only a +previous-table winner still pays a copy. + +| one-shot encode, 208 MB corpus, L3 | before | after | +|---|---:|---:| +| section -> dst bytes | 17,730,842 | **5,515,309** (-69%) | +| sections needing the copy | 1,384 | **495** (64% now zero-copy) | +| all encode copies | 0.430 B/input | **0.371 B/input** | + +Byte-identical across 48 (level x corpus) pairs with exact round-trip. +`pack_huff_section_append` shares its header arithmetic with the `Vec` form +through `lit_huff_header_bytes`, so the two cannot drift on a format-visible +layout. + +### Known -- the encoder's copy surface, fully decomposed + +Two rounds took one-shot encode from **0.633 to 0.371 copies per input byte**. +What remains is 77.3 MB, and every part of it is now categorised rather than +merely un-attacked: + +| site | MB | status | +|---|---:|---| +| raw block -> dst | 33.6 | **irreducible** -- src must reach the output once | +| src -> lits | 24.0 | **architectural** -- literals are scattered src ranges and must be gathered before entropy coding | +| huffman body -> section | 14.2 | **blocked** -- the header precedes the body and needs the body's length; the only escapes change the bitstream | +| section -> dst (residual) | 5.5 | previous-table winners only, 36% of sections | + +The `huffman body` entry is worth stating precisely because the neighbouring +`section -> dst` copy looked identical and was NOT blocked. The difference: at +pack time the body exists, so its length is known; at encode time it does not, +and the header that must precede it needs that length. Reserving a maximum +header and backfilling does not help either -- the header is 3, 4 or 5 bytes by +size class, so a shorter one leaves a gap that costs a memmove of the body, +which is the copy being removed. + +### Known -- the scratch pool runs at 78% and is not capacity-starved + +A new pool census (`take_pool_census`, profile-only) measures hit/miss/drop/give +on every `scratch` free list. Over four corpora at L3: **5,167 hits, 1,437 +misses, 708 drops**, a 78.2% hit rate -- and every miss is an allocation, worth +~11% of all encoder allocations. + +**REFUTED: raising the free-list cap from 6 to 32 changed hits and misses NOT AT +ALL** (5,167 / 1,437 both ways); only drops moved, 708 -> 682. Takes and gives +are near-balanced (webster: 2,304 takes against 2,048 capacity-carrying gives), +so it is not a leak either. 78% appears to be this design's structural rate, and +the cap is left at 6 with the refutation recorded next to it. +### Changed -- ten copy reductions, batched + +Each is byte-identical and carries its own deterministic counter; the batch +carries the timing verdict, per the sub-1% brick discipline. Every one was +found with the emitted-assembly census rather than a source grep. + +**Encode** + +1. **The streaming compressor's `in_acc` staging buffer is gone.** Every input + byte was copied twice before encoding began -- caller -> `in_acc` -> + `hist` -- at exactly 1.000 + 1.000 B/input. `hist` was always the buffer the + finders read, so a cursor into it does the same job. **-98.9 MB**; streaming + encode 3.336 -> 2.336 copies/input. The slide now triggers on the ENCODED + cursor (sliding on `hist.len()` would drop pending caller bytes) and the + block checksum covers exactly `[block_start..block_end]`. +2. **The compressed block payload is emitted straight into the frame.** It was + built into a scratch `Vec` purely to learn its length, then copied in whole. + A zstd block header is FIXED at three bytes, so the payload is now written + past a three-byte hole and the header patched in place; if raw wins, `out` + truncates back. **-42.2 MB**, the largest reducible copy in the encoder. +3. **`MatchTables::payload_scratch` deleted** -- dead once (2) landed, so a + block-sized buffer per table set goes with it. +4. **The MT concat reserves the exact total.** Job outputs were concatenated + into a `Vec::new()`, so the buffer grew to the whole compressed stream by + doubling -- ~1x the output again in realloc copies. The job lengths are + known when the jobs finish. **32.1 MB concat, no longer paid twice.** +5. **The seekable concat reserves too**, extrapolated from the first frame's + MEASURED compressed size rather than a guessed ratio; `entries` is now exact + from the frame count. + +**Decode** + +6. **A frame with no declared content size now reserves.** `out.try_reserve` + only ran when the header carried a size -- and our own streaming compressor + omits it unless the caller pledges one, so unpledged streams grew the output + by doubling. Extrapolated from the first block: measured 0.27-0.98x of the + true size on frames that previously got nothing. +7. **The decoded-window compaction fires half as often** (`window + min(window, + 8 MiB)`). Unlike the encoder's slide this has NO ratio cost -- decode output + is fixed by the bitstream. Compactions 4/10/16/15 -> 2/5/8/8, traffic + **-53%** (0.941 -> 0.441 B/output on webster). +8. **The input compaction fires half as often again** (`3 * dead >= 2 * live`, + so each reclaim is worth twice its move). **-50%**: 0.290 -> 0.145 B/output. + +**Training** + +9. **`fallback_content` and the segment concat reserve and trim in place.** Both + grew unreserved and then copied the tail into a SECOND allocation. Only the + last `max_dict` bytes are ever kept, so the buffer is now bounded at ~2x + `max_dict` instead of the whole sample set. +10. **The dictionary tail trim is a `drain`, not a `to_vec`** -- was a fresh + allocation and a full copy to discard a prefix. + +Net, per the byte census: one-shot encode **0.633 -> 0.430** copies per input +byte, streaming encode **3.336 -> 2.336**, streaming decode **2.53 -> 1.75-1.99** +per output byte. + +Gates: encode byte-identical and round-trip exact over 50 (level x corpus) +pairs including `--ultra -22`; 63 streaming round-trips byte-exact across +corpora x levels x chunk geometries; dictionary byte-identical across the +trainers; 141 lib tests plus the full suite. + +**Two of these were found only because a census slot read ZERO.** `C_SEQ_TO_DST` +and `C_BLOCK_TO_FRAME` were declared and never wired, and an unwired slot reads +exactly like a site that costs nothing -- which is how the previous pass closed +on 0.36 copies/input when the true figure was 0.633. +### Changed -- the streaming compressor's `in_acc` staging buffer is gone + +Every input byte was copied TWICE before encoding began: caller -> `in_acc`, +then `in_acc` -> `hist`. Measured at exactly **1.000 + 1.000 bytes per input +byte**. `hist` was always the buffer the match finders read; `in_acc` only held +a partial block until one was ready, which a cursor into `hist` does just as +well. `in_acc` and `compact_in` are deleted. + +| streaming encode, 98.9 MB corpus, L3 | before | after | +|---|---:|---:| +| caller -> in_acc | 1.0000 B/input | (gone) | +| in_acc -> hist | 1.0000 B/input | **0** | +| total copies | 3.336 B/input | **2.336 B/input** | +| bytes moved | 330.0 MB | **231.1 MB** (-98.9 MB) | + +Compressed output is bit-for-bit unchanged and one-shot encode is byte-identical +across 20 (level x corpus) pairs. Two details carry the correctness: the window +slide now triggers on the ENCODED cursor rather than `hist.len()` (sliding on the +buffer length would drop pending caller bytes), and the block checksum covers +exactly `[block_start..block_end]` rather than "to the end of hist", which now +has pending bytes past it. `encode_block_from_scratch` takes an explicit +`block_end` for the same reason. + +Worth **0.25-0.55% of streaming encode** at measured memmove rates -- a counter +win, not a clock win, and recorded as such. + +### Known -- the encoder's copy surface is now fully tapped, and it was under-counted + +Two census slots were declared and never wired. Tapping `C_BLOCK_TO_FRAME` -- +the `out.extend_from_slice(&payload)` that copies every compressed block into the +frame -- added **42.2 MB, 0.2026 B/input**, the largest reducible copy in the +encoder. One-shot encode is **0.633 copies per input byte, not the 0.36** +previously reported and closed on. A declared-but-unwired slot reads exactly like +a site that costs nothing. + +Priced against measured (not peak) memmove rates, every remaining candidate is +an order of magnitude below the ~0.4-0.5% at which this workspace has previously +pruned copy work -- block->frame 0.040-0.089%, src->lits 0.023-0.051%, +section->dst 0.017-0.037%, huffman emit 0.014-0.030%, out_acc->caller +0.080-0.178%. They are pruned on arithmetic, not abandoned. + +The one exception is `decoded -> caller` in the streaming decoder at +**0.454-1.008%** (98.9 MB). That is not a copy fix: removing it means decoding +directly into the caller's buffer when it is large enough, which requires the +caller's buffer to become the match window -- what libzstd does, and an +architecture change rather than a copy tweak. +### Fixed -- the streaming decoder's input compaction was an O(n^2) front-drain + +`Decompressor::compact_input` reclaimed the consumed input prefix when that +prefix passed an ABSOLUTE 64 KiB -- but the drain memmoves the LIVE remainder, +and Brick A deliberately stops decoding the moment the caller's buffer can be +filled, so the remainder grows against a fixed trigger. The doc comment claimed +"total moved is bounded by the bytes fed"; measured, it was not: + +| 32 MiB streamed, 64 KiB feed, L3 | before | after | +|---|---:|---:| +| webster in-compaction memmove | 7.633 B/output (244 MB) | 0.290 B/output | +| mozilla | 5.135 (164 MB) | 0.290 | +| samba | 2.923 | 0.220 | +| dickens | 1.874 | 0.333 | +| **all streaming-decode copies** | **3.87-9.87 B/output** | **2.33-2.56** | + +Adding `2 * in_off >= input.len()` makes each compaction reclaim at least as +much as it moves, which is what makes the documented bound real -- `in_compact` +now sits at ~0.29 B/output, i.e. the compressed ratio, i.e. the bytes fed. It +also bounds the buffer: the live tail is never more than half, so `input` holds +at most ~2x what the caller has fed ahead. + +**Kept on the deterministic counter, NOT on a clock.** Removing 244 MB of +memmove did not move the wall: streaming-vs-one-shot measured 0.568x before and +0.550x after on webster (null arm 0.91-0.98x, |z| <= 0.77). That is this +crate's own copy-handling law landing on its author -- A/B every obvious hop, +most measure ~0 -- and the honest label is *below instrument resolution*, not +*a speedup*. It is kept because the work removed is real and reproducible, the +memory bound is now genuine, and the comment is no longer false. + +Decode output is identical to the pre-change binary across 24 (level x corpus) +round-trips. + +### Known -- streaming decode is ~1.3-1.4x slower than one-shot; EIGHT causes ruled out + +Measured admissibly (one process, ABBA-interleaved, null arm 0.95-1.08x): +one-shot -> streaming is **0.703-0.776x, z = -1.67 to -3.00**, on identical +bytes. + +**This figure is REVISED DOWN from an earlier 1.5-1.8x, and the difference was +the harness.** The benchmark fed a chunk and read the output ONCE; the decoder +consumes all input it is handed but emits only what fits the caller's buffer, +so at a 3:1 ratio a 64 KiB chunk yields ~192 KiB and the read under-drained. +`decoded` accumulated a backlog no real consumer would build. Draining fully +before feeding again accounts for 5-8 points of the gap. An even earlier +attempt was wholly inadmissible -- sequential best-of-N blocks whose one-shot +arm drifted 29% between runs, producing a 1.20x "streaming is faster" row. + +Eight causes have been eliminated BY MEASUREMENT, so none is worth re-testing +without new information: + +1. **Copy traffic** -- cut 74% (9.87 -> 2.53 B/output); ratio unchanged. +2. **Structural re-entry** -- stage call counts are IDENTICAL (256/256). +3. **A single hot stage** -- scoped stages grow only 1.09x. +4. **The decoded-window compaction** -- ablated; no change. +5. **Per-call overhead** -- 32x fewer `stream` calls (128 KiB -> 4 MiB output + buffer); no change. +6. **Buffer reallocation** -- a header-time reserve already exists. +7. **Buffer shape** -- made structurally one-shot-like (no compaction, no early + exit, full reserve); the gap persists. +8. **The content checksum** -- disabled on both arms; no change. + +The stage profiler CANNOT resolve this: its rdtsc tax is 27-29% of wall in both +arms and compresses the measured 1.4x into 1.04x. The next instrument is a +sampling profiler on the two binaries, not another hypothesis. + +### Changed -- streaming window slide fires half as often (14-47% faster streaming encode) + +A second copy pass, this time over the STREAMING encoder -- which the one-shot +census never exercises, and which turns out to move **1.80 bytes per input +byte against one-shot's 0.36**. 80% of that is the window slide. + +Each slide memmoves the retained window, zeroes six match tables, and +re-primes every position of what is left. Section 20 already moved the trigger +from `hist > window` to `hist >= 2 * window`. This moves it again, to +`2 * window + min(window, 8 MiB)`, which halves how often all three costs are +paid: + +| per 98.9 MB streamed, L3 | before | after | +|---|---:|---:| +| slides | 42 | 19 | +| window memmoved | 88.08 MB | 39.85 MB | +| tables zeroed | 55.05 MB | 24.90 MB | +| **prime inserts** | **88,080,048** | **39,845,736** | + +**The prime inserts are the prize, not the copies.** The memmove and the memset +are sequential streaming and, priced against measured encode throughput, all of +the slide's copy traffic is under 1% of encode time -- which is why this looked +like a wash at first. The 48.2 million table inserts removed alongside them are +hashes followed by random-access stores into multi-megabyte tables, i.e. cache +misses, and they dominate. Pricing only the bytes moved was the analytical +error; the counter that mattered had to be added before the trade could be read +correctly. + +Measured, one process, arms ABBA-interleaved, with a NULL arm to establish what +the box can resolve (null: 0.98-1.02x, |z| <= 1.81): + +| corpus | median | min-of-N | paired | size | +|---|---:|---:|---:|---:| +| samba | 1.466x | 1.395x | 15/15, z=+3.87 | +0.137% | +| webster | 1.245x | 1.144x | 13/15, z=+2.84 | +0.109% | +| mozilla | 1.318x | 1.298x | 14/15, z=+3.36 | +0.058% | + +**It is a trade, not a free win.** Compressed size grows 0.06-0.14%, and the +direction is counterintuitive on purpose: the re-prime inserts EVERY position +of the retained window, which is denser than the strided inserts normal +encoding does, so frequent sliding was accidentally acting as a table +densification pass. Sliding less often gives that up. The regression has the +same sign on all four corpora, so it is a uniform cost rather than a +content-dependent one -- a straight keep/revert decision, not a dispatch. + +**The extra history is capped in ABSOLUTE bytes, and that matters more than the +multiplier.** The win scales with slide FREQUENCY (high when the window is +small) while the memory cost scales with window SIZE, so a flat 3x would spend +**+128 MiB at L22** to remove slides that a 128 MiB window mostly never +performs. Capping the extra at 8 MiB keeps the entire win at every level up to +L19 and bounds the worst case at +8 MiB. `slide_threshold_caps_the_extra_history` +pins that, including that `k = 2` reproduces the previous threshold exactly at +every window size. + +One-shot encode is untouched and byte-identical across 42 (level x corpus) +pairs -- the slide is streaming-only. `RZSTD_ENC_SLIDE_MUL=2` restores the +previous behaviour exactly; `Compressor::set_slide_mul` overrides per instance. +### Changed -- encoder copy catalogue, one elimination, and a measured prune + +Catalogued every byte-moving call on the encode path two ways, because neither +alone answers the question. `tools/copycat.py` reads the emitted asm and says +WHERE the `memcpy`/`memset`/`memmove` calls are (106/32/2 on the encode side, +flagging the ones inside loops); `rusty_zstd::copies` counts BYTES per site at +run time, which is what says whether a call matters. A call count is a bad +proxy: one call on the literal path moves a whole block, six in a table-setup +loop move a few hundred bytes between them. + +Census over 9 corpora, 208 MB, L3 -- deterministic, same numbers anywhere: + +| site | bytes | per input byte | verdict | +|---|---:|---:|---| +| `src -> lits` | 23.96 MB | 0.115 | architectural: literals are scattered `src` ranges and must be gathered | +| `section -> dst` | 17.73 MB | 0.085 | one copy of the Huffman winner; candidates compete on size so it needs staging | +| `raw block -> dst` | 33.55 MB | 0.161 | irreducible: `src` to output, the minimum possible | +| `lits -> raw section` | **4.67 MB -> 0** | 0.022 -> 0 | **removed** | + +**The elimination.** The four literals arms that decide immediately -- empty, +RLE, tiny, not-worth-Huffman -- each built their section into a fresh `Vec` +which the caller then copied into `dst` and dropped. A raw literal byte was +therefore touched three times: staged out of `src`, materialised into a +section, copied to the output, for a byte the format says to store verbatim. +`encode_literals_section_into` writes through `dst` instead, so those arms emit +once. **4,669,394 bytes and 439 allocations per corpus pass, gone**; the +allocating twin now has no caller anywhere and was deleted. Output is +byte-identical across 60 (level x corpus) pairs. + +It cost **+136 static instructions** in `write_literals` -- specialised emit +arms are new code. The byte count is the right instrument for a copy removal; +the instruction count is confounded here because the change adds paths rather +than shortening one. + +**The prune, which is the more useful result.** Further copy elimination cannot +pay, and this is arithmetic rather than opinion: + +* all 75.2 MB of remaining copy traffic, at 10-20 GB/s, is 3.8-7.5 ms; +* the encoder runs at 39 MiB/s, so that corpus is ~5.27 s of encode; +* every copy in the encoder is therefore **0.07%-0.14% of encode time**, and + the one removable item left (`section -> dst`) is ~0.02%. + +The stage profiler agrees from the other side: **match-finding is 76.3% of +encode and entropy coding 21.0%**. Copies do not register as a stage. Two +thirds of what remains is irreducible by construction anyway -- raw blocks must +move `src` to the output, and scattered literals must be gathered before they +can be entropy-coded. + +So "zero copies" is not reachable and would not be worth reaching. The +`copies` census stays wired (it compiles to nothing without `profile`) so the +`lits -> raw section` row reading 0 is a standing check that the +materialise-then-copy path has not come back. +### Changed -- deterministic instruction/guard reductions (byte-identical) + +A hunt for straight-line wins measured on DETERMINISTIC counters only -- static +instruction counts and guard-branch counts from the emitted release asm -- because +this box cannot resolve effects this size with a clock. Same toolchain and source +give the same number on any machine at any load, so a two-instruction change is a +verdict rather than noise. + +Two instruments were built for it, and both are in `tools/`: + +* `panic_census.py` -- ranks conditional branches whose target's FIRST control + transfer is a panic call, and resolves each back to the line of our code that + failed to prove its index (via the `Location` rustc emits beside every panic, + since debug line tables just blame `core/src/slice/index.rs`). The detector has + no tunable window on purpose: a line-budget version is a knob, and a knob has to + be swept before it can be quoted. +* `loopscan.py` -- flags HALF-STORE / NARROW / INVARIANT / SELECT shapes in + innermost loops. +* `icount.sh` -- per-symbol instruction counts, with a `--diff` mode. + +**Result: guard branches 87 -> 28 (-68%), 309 net instructions removed.** Compress +output is byte-identical to the pre-campaign binary across 48 (level x corpus) +pairs, and trained dictionaries are byte-identical across four trainers. + +| change | effect | +|---|---| +| `fse::normalize` -- zip `count` with `norm`/`n2` so one length bounds both | -112 instrs over 3 inlined sites, and deletes an `unsafe` | +| `fse::weights_into_body` -- narrow `dst` to its cap once | -71 / -64 (decode side) | +| `huffman::pop_min` -- carry the index out of `.get()` instead of re-indexing | -12 | +| `encode_block` -- `.last()` once instead of `len() - 1` indexed 9x | -6 | +| `mt` worker -- `.get()` replaces the `idx >= n` test AND its bounds check | -11 net | +| `train::hash_dmer` / `packed_dmer` -- iterate the tail, don't index it | -33 guards, -19 net | +| `build_coded_pass` -- no-op clamps on two LUT-derived indices | -1 instr, -2 guards | + +Two results that were NOT wins are recorded rather than dropped, because a +refutation nobody writes down gets re-attempted: + +* `prime_tables` routing its `chain[..]` write through the `chain_masked_set` + accessor the hot finders use measured **guards -1, instructions +1**. Two + deterministic counters disagreeing in sign is not a win. Reverted; the reason + is in the source at the call site. +* `code_from_base` zipping `base` with `bits` measured **0 and 0** -- LLVM had + already proven the second table's index. The zip is kept only because it also + removes a `len() - 1` underflow on an empty table, and its comment says so. + +`train::hash_dmer` is the one entry whose instruction count needs a caveat: it is +inlined into two callers and moved them in OPPOSITE directions (`train` -117, +`select_fastcover` +98). A static count cannot price a change across an inlining +boundary, which is exactly why the guard count -- which does not move when +inlining shifts -- is the primary number for this class. +### Added -- kernel-reach census and a standing gate against unwired twins + +A `#[target_feature]` twin that exists but is never CALLED is invisible to +every gate this crate already had. Byte-identity passes, because the two paths +agree by design. The round-trip and conformance suites pass. And an arm-toggle +A/B reads FLAT -- which is indistinguishable from "this kernel does not help", +so it gets recorded as a refutation nobody revisits. + +That defect shipped here. Before D8a/D8b the xxh64 AVX2 kernel was reachable +only from `xxh64_seed`, whose callers were one unit test and one benchmark; the +encoder, decoder and streaming API all used `Xxh64::update`, which was scalar. +The compress side reached the kernel on **50%** of checksummed bytes and the +**decode side on 0%**, for months, with every gate green. + +The repair landed earlier. What was still missing was the instrument that would +have caught it, so this adds one: + +* `rusty_zstd::kreach` -- a per-dispatch-site census of how many calls reach the + kernel versus the scalar arm. Counters sit AT the dispatch, never at an + eligibility test upstream of it: `simd`'s existing `wide_eligible` counter is + not kernel reach, because most calls it counts are resolved by the 32-byte + word ladder before any kernel runs. Thread-local `Cell` bumps, not atomics -- + `count_eq_len` runs ~247M times at L19 and a `lock xaddq` there would be the + instrument dominating the measurement. Compiles to nothing without `profile`; + compressed output is byte-identical between the two builds (verified over + 4 levels x 2 corpora). +* `tests/kreach_gate.rs` -- a standing gate asserting every exercised site + routes >=95% of its calls to its kernel. Skips a slot whose ISA the host + lacks; fails if fewer sites were exercised than the host can route, so it + cannot pass on silence. That floor is HOST-DERIVED (6 with BMI2, 2 with only + a vector ISA, else 1) -- it began as a flat 6 and that failed every aarch64 + runner, where the eight BMI2 slots are skipped by design and a correct build + can only ever check two. `RZSTD_KREACH_POISON=1` forces the arms scalar and + the gate must then FAIL -- CI runs both directions, because an assertion that + has never fired is not evidence. The poison still bites on aarch64 because + `set_xxh_avx2_arm(false)` gates the NEON stripe path too; `count_eq_len`'s + NEON arm is compile-time and cannot be poisoned, and one poisonable slot is + enough. +* `rusty_zstd-bench/examples/kreach.rs` -- the corpus-scale report, encode and + decode censused separately (a combined number is exactly what hides + "50% of encode and 0% of decode"). + +Measured over 16 corpora, 298.4 MiB, at levels 1/3/5/9/12/19: **every dispatch +site routes 100.00% of its calls to its kernel, on both sides.** L19 alone is +188,398,067 `count_eq_len` wide calls, all reaching AVX2. `scripts/isaudit.sh` +separately confirms none of the twins is a do-nothing thunk -- each carries the +BMI2 ops its baseline sibling carries in `%cl` (`decode_4x_x1_bmi2` 60, +`encode_stream_unrolled_bmi2_into` 118, `find_fast_impl_bmi2` 41). + +Two twins are deliberately NOT routed, and are recorded here so they are not +mistaken for this defect: the `bt_*_spec_bmi2` chain (retired by D5/D11 on its +own measurement -- 291 instructions to convert three BMI2 ops) and +`simd::look_n_bits_bmi2` (`#[cfg(test)]`; production gets BMI2 through the +enclosing twins, which the asm confirms). + ## [0.2.0] - 2026-08-27 ### Changed — compressed output moves at levels 1 through 4 diff --git a/Cargo.lock b/Cargo.lock index c5c15b7..5d6f6f3 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -74,6 +74,12 @@ version = "2.8.3" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98" +[[package]] +name = "portable-atomic" +version = "1.15.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "05c8b63e8d9609db387f0324918f81d68fe27748f084ef092fb35954d0539a85" + [[package]] name = "proc-macro2" version = "1.0.107" @@ -94,30 +100,50 @@ dependencies = [ [[package]] name = "rusty_alloc" -version = "1.0.0" +version = "1.1.6" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "e09c7d84ef8e88c65d1f4ae1e957cfe39a14de339ddb94ffdb5c465931b84e8c" +checksum = "c93620fee9935a120a50df2086fe48fa072f7d391f129a5e04bf20ea9b83097d" dependencies = [ "libc", "windows-sys", ] +[[package]] +name = "rusty_alloc" +version = "2.0.5" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "d59f4e6793d58ca76f11c5138939761fbabb6978b1fe404e1c097fa6bd45e706" +dependencies = [ + "libc", + "portable-atomic", + "windows-sys", +] + +[[package]] +name = "rusty_alloc-api" +version = "1.1.6" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "05ce52d7f72842a590e4588013d70ea02d27edbf6b6af9bc193f6e1ac173845a" +dependencies = [ + "rusty_alloc 1.1.6", +] + [[package]] name = "rusty_alloc-api" -version = "1.1.4" +version = "2.0.5" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "02301ad2df6159237fe4087334310d48543aa626ae9b89410b38a9d5b77e04e0" +checksum = "66795d559e48d97cc9e5df15471c98ffd6a95870110fec8ca49ad22318e546c0" dependencies = [ - "rusty_alloc", + "rusty_alloc 2.0.5", ] [[package]] name = "rusty_alloc_default" -version = "0.1.1" +version = "0.1.2" source = "registry+https://github.com/rust-lang/crates.io-index" -checksum = "ca0c6742832d23b2b2a0647903d8ff867d0681e189fdc0f74774fed871a026db" +checksum = "b6f400a8794f3e626b615ef98c97b89cf1085822f7247f2f9e78247e23fce873" dependencies = [ - "rusty_alloc-api", + "rusty_alloc-api 1.1.6", ] [[package]] @@ -152,7 +178,7 @@ dependencies = [ name = "rzstd-alloc" version = "0.2.3" dependencies = [ - "rusty_alloc-api", + "rusty_alloc-api 2.0.5", ] [[package]] diff --git a/bench/ledger.jsonl b/bench/ledger.jsonl index 5ab6edf..353c19b 100644 --- a/bench/ledger.jsonl +++ b/bench/ledger.jsonl @@ -1917,3 +1917,100 @@ {"kind":"m7_speed","ts":"1786929788Z","git_sha":"e6b6e654089f6efed7bf598768d152935d344946","host":"windows-x86_64","c_zstd":{"tag":"v1.5.7","version_line":"*** Zstandard CLI (64-bit) v1.5.7, by Yann Collet ***","path":"C:\\Users\\talmo\\coding\\rusty_zstd\\third_party\\zstd\\extracted\\zstd-v1.5.7-win64\\zstd.exe","sha256":"8076aae03feac7c66b319579e82172eed168deed2a3f25e5e2d3c60f55e84111"},"corpus":{"id":"nci","split":"train","bytes":33553445,"sha256":"fc63a31770947b8c2062d3b19ca94c00485a232bb91b502021948fee983e1635"},"level":1,"c_flag":"zstd -1","src_bytes":33553445,"us_compressed_bytes":3716514,"c_compressed_bytes":2853982,"us_over_c":1.3022205465906933,"us_compress_mbps":499.0591729705771,"us_decompress_mbps":1192.7866037688898,"c_compress_mbps":1059.8,"c_decompress_mbps":2856.2,"compress_c_over_us":2.12359587279339,"decompress_c_over_us":2.394560762985738,"us_loops":44,"us_cores_busy":1.0020710421077315,"c_cores_busy":null,"us_roundtrip_ok":true,"c_decode_us_ok":true,"method":"m7-speed ABBA pinned=yes affinity=4 us=in-process C=zstd_-b_T1 i=3 estimator=best_of_n(both_arms) timer=wall null_arm=0.9948 flags=-1,--fast=1,--fast=4,-3","gates":{"correctness":"pass","ratio":"quantified","speed":"measured_not_exit","footprint":"not_measured"},"notes":"M7 speed vs C 1.5.7 brag flags; 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Pinned to ONE core it contends with the codec +# thread -- `cores_busy` reads ~2.0 against the reference's 1.0, which is a +# work-parity violation and voids the comparison. Our CLI uses the system +# allocator (control measured: cores_busy 0.72-0.91), so CLI-vs-CLI is +# like-for-like. +# +# Discipline: arms ABBA-alternated so drift cancels instead of landing on one +# arm; min-of-N, because the floor is what survives a noisy box; a NULL arm +# (ours against itself) to establish what this box can resolve; and work parity +# asserted per row by decoding BOTH outputs and comparing byte counts. +set -u +Z=${Z:-./third_party/zstd/extracted/zstd-v1.5.7-win64/zstd.exe} +US=${US:-./target/release/rzstd.exe} +REPS=${REPS:-5} +LEVELS=${LEVELS:-"1 3 9"} +CORPORA=${CORPORA:-"dickens samba webster mozilla x-ray nci xml osdb"} + +t() { python -c "import time;print(repr(time.perf_counter()))"; } +mn() { python -c "print(repr(min($1,$2)))"; } + +printf "%-9s %2s %9s %10s %10s %7s %9s %7s\n" \ + corpus L src_MiB us_MB/s zstd_MB/s "zstd/us" size_us/c null +for id in $CORPORA; do + f="corpora/data/silesia/$id"; [ -f "$f" ] || f="corpora/data/generated/$id" + [ -f "$f" ] || continue + src=$(stat -c%s "$f") + for L in $LEVELS; do + "$US" -"$L" -c "$f" > /tmp/vs_us.zst 2>/dev/null + "$Z" -"$L" -T1 -c "$f" > /tmp/vs_c.zst 2>/dev/null + us_b=$(stat -c%s /tmp/vs_us.zst); c_b=$(stat -c%s /tmp/vs_c.zst) + d1=$("$US" -d -c /tmp/vs_us.zst 2>/dev/null | wc -c) + d2=$("$Z" -d -c /tmp/vs_c.zst 2>/dev/null | wc -c) + if [ "$d1" != "$src" ] || [ "$d2" != "$src" ]; then + printf "%-9s %2s VOID work parity: decoded %s / %s vs src %s\n" "$id" "$L" "$d1" "$d2" "$src" + continue + fi + bu=1e9; bc=1e9; bn=1e9 + for i in $(seq 1 "$REPS"); do + if [ $((i % 2)) -eq 0 ]; then + a0=$(t); "$US" -"$L" -c "$f" >/dev/null 2>&1; a1=$(t) + b0=$(t); "$Z" -"$L" -T1 -c "$f" >/dev/null 2>&1; b1=$(t) + else + b0=$(t); "$Z" -"$L" -T1 -c "$f" >/dev/null 2>&1; b1=$(t) + a0=$(t); "$US" -"$L" -c "$f" >/dev/null 2>&1; a1=$(t) + fi + n0=$(t); "$US" -"$L" -c "$f" >/dev/null 2>&1; n1=$(t) + bu=$(mn "$bu" "$a1-$a0"); bc=$(mn "$bc" "$b1-$b0"); bn=$(mn "$bn" "$n1-$n0") + done + python - <2} {mib:9.1f} {mib/bu:10.1f} {mib/bc:10.1f} " + f"{bu/bc:7.2f} {$us_b/$c_b:9.4f} {bn/bu:7.3f}") +PY + done +done +echo +echo "zstd/us = how many times faster the C reference is. size_us/c = our output" +echo "over theirs. null = our arm against itself; a result no further from 1.0" +echo "than the null is not a result. Work parity asserted per row." diff --git a/crates/rusty_zstd-bench/examples/accel10.rs b/crates/rusty_zstd-bench/examples/accel10.rs new file mode 100644 index 0000000..cd51a7a --- /dev/null +++ b/crates/rusty_zstd-bench/examples/accel10.rs @@ -0,0 +1,37 @@ +//! Per-corpus size impact of the incompressible-section acceleration, and a +//! round-trip on every cell. An aggregate near zero can hide a big regression +//! cancelled by a big gain; this checks. +use rusty_zstd as rz; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","versions-16m","mr","ooffice","osdb", + "reymont","sao","webster","dickens","mozilla","nci","samba","xml","x-ray", + "text-32m","incomp-32m","zeros-32m"]; +fn main() { + let sh: usize = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(10); + for cap in [1usize << 20, 4 << 20] { + println!("\n===== shift {sh}, cap {} MiB =====", cap >> 20); + println!("{:<14}{:>10}{:>10}{:>10}{:>10}", "corpus", "L5 d", "L7 d", "L9 d", "L12 d"); + println!("{}", "-".repeat(54)); + let mut tot = [0i64; 4]; + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) else { continue }; + let s = &f[..f.len().min(cap)]; + print!("{:<14}", id); + for (k, lvl) in [5i32, 7, 9, 12].iter().enumerate() { + let o = rz::CompressOptions { level: *lvl, checksum: false }; + rz::set_lazy_accel_arm(0); + let a = rz::compress_with(s, o).unwrap().len() as i64; + rz::set_lazy_accel_arm(sh); + let z = rz::compress_with(s, o).unwrap(); + assert_eq!(rz::decompress(&z).unwrap(), s, "{id} L{lvl} round-trip"); + let d = z.len() as i64 - a; + tot[k] += d; + print!("{:>10}", d); + } + println!(); + } + rz::set_lazy_accel_arm(0); + println!("{:<14}{:>10}{:>10}{:>10}{:>10} <== TOTAL", + "", tot[0], tot[1], tot[2], tot[3]); + } +} diff --git a/crates/rusty_zstd-bench/examples/accelsweep.rs b/crates/rusty_zstd-bench/examples/accelsweep.rs new file mode 100644 index 0000000..51b06d8 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/accelsweep.rs @@ -0,0 +1,50 @@ +//! Sweep C's incompressible-section acceleration on our chain ladder. +//! +//! Two questions, two currencies: +//! * SIZE across the board -- exact, load-immune. +//! * TIME on incompressible data -- measured ONLY as an arm-vs-arm ratio in +//! ONE process with a null, so a loaded box moves both arms together. +use rusty_zstd as rz; +use std::time::Instant; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","mr","ooffice","osdb","reymont","sao", + "webster","dickens","mozilla","nci","samba","xml","x-ray","text-32m","incomp-32m"]; +fn main() { + let cap = 1usize << 20; + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + let inc: Vec = srcs.iter().find(|(i, _)| *i == "incomp-32m").unwrap().1.clone(); + let go = |lvl: i32| -> u64 { srcs.iter().map(|(_, s)| + rz::compress_with(s, rz::CompressOptions { level: lvl, checksum: false }) + .unwrap().len() as u64).sum() }; + let t_inc = |lvl: i32| -> f64 { + let p = rz::compression_params(lvl, Some(inc.len() as u64)).unwrap(); + let mut b = f64::MAX; + for _ in 0..9 { + let t = Instant::now(); + let z = rz::compress_with_params(&inc, p, false).unwrap(); + let e = t.elapsed().as_secs_f64(); + std::hint::black_box(z.len()); + if e < b { b = e } + } + b * 1000.0 + }; + for lvl in [5i32, 7, 9, 12] { + rz::set_lazy_accel_arm(0); + let base = go(lvl); + let tb = t_inc(lvl); + let tb2 = t_inc(lvl); // null arm: same setting twice + println!("\n=== L{lvl} === base {base} B | incomp {tb:.2} ms (null {:+.1}%)", + (tb2 / tb - 1.0) * 100.0); + println!(" {:>6}{:>12}{:>10}{:>12}{:>10}", "shift", "bytes", "d size", "incomp ms", "speedup"); + for sh in [4usize, 6, 7, 8, 9, 10, 12] { + rz::set_lazy_accel_arm(sh); + let n = go(lvl); + let t = t_inc(lvl); + println!(" {:>6}{:>12}{:>+10}{:>12.2}{:>9.2}x", sh, n, n as i64 - base as i64, t, tb / t); + } + rz::set_lazy_accel_arm(0); + } +} diff --git a/crates/rusty_zstd-bench/examples/allgates.rs b/crates/rusty_zstd-bench/examples/allgates.rs index 954314d..db1479e 100644 --- a/crates/rusty_zstd-bench/examples/allgates.rs +++ b/crates/rusty_zstd-bench/examples/allgates.rs @@ -61,11 +61,41 @@ use rusty_zstd::{AdvancedOptions, CompressOptions, DecompressOptions}; use std::io::Write; const IDS: &[&str] = &[ - "zeros-32m", "text-32m", "incomp-32m", "jsonlog-16m", "smallmsg-8m", "versions-16m", "mr", - "ooffice", "osdb", "reymont", "sao", "webster", "dickens", "mozilla", "nci", "samba", "xml", + "zeros-32m", + "text-32m", + "incomp-32m", + "jsonlog-16m", + "smallmsg-8m", + "versions-16m", + "mr", + "ooffice", + "osdb", + "reymont", + "sao", + "webster", + "dickens", + "mozilla", + "nci", + "samba", + "xml", "x-ray", ]; -const LEVELS: &[i32] = &[1, 3, 19, 22]; +// STRATEGY COVERAGE, not level coverage. This list was [1, 3, 19, 22], which +// resolves to Fast, DFast, BtUltra2, BtUltra2 -- THREE of the seven +// strategies, and none of Greedy (L5), Lazy (L7), Lazy2 (L9), BtLazy2 (L13) +// or BtOpt (L16). Every gate whose only call sites live in an untested +// finder was therefore reported SZ-DEAD for a reason that has nothing to do +// with the gate -- the exact failure this tool exists to prevent. +// +// MEASURED INSTANCE that found it: `lazy_fill` is read only in +// `find_lazy_impl` and `find_bt_lazy`, so no tested level reached it and it +// read SZ-DEAD at every prefix. Toggled at L9 on a 40 MiB board it moves +// 266,695 compressed bytes (1.53%) and 4,133,134 probes. A campaign trusting +// the old table would have deleted a live ratio gate. +// +// The `strategy_coverage` check below fails LOUDLY if this list ever stops +// covering all seven, so the hole cannot silently reopen. +const LEVELS: &[i32] = &[1, 3, 5, 7, 9, 13, 16, 18, 19, 22]; fn load(cap: usize) -> Vec<(&'static str, Vec)> { IDS.iter() @@ -136,39 +166,206 @@ fn b(f: impl Fn() + 'static) -> Box { fn encode_arms() -> Vec { use rusty_zstd::*; vec![ - Arm { name: "fast_lazy", vals: vec![("on", b(|| set_fast_lazy_arm(true))), ("off", b(|| set_fast_lazy_arm(false)))] }, - Arm { name: "lazy_fill", vals: vec![("on", b(|| set_lazy_fill_arm(true))), ("off", b(|| set_lazy_fill_arm(false)))] }, - Arm { name: "rep1_mode", vals: vec![("dispatch", b(|| set_rep1_mode(None))), ("on", b(|| set_rep1_mode(Some(true)))), ("off", b(|| set_rep1_mode(Some(false))))] }, - Arm { name: "step0", vals: vec![("2", b(|| set_step0_arm(2))), ("1", b(|| set_step0_arm(1))), ("3", b(|| set_step0_arm(3)))] }, - Arm { name: "pipe_rep1", vals: vec![("on", b(|| set_pipe_rep1_arm(true))), ("off", b(|| set_pipe_rep1_arm(false)))] }, - Arm { name: "pipe", vals: vec![("on", b(|| set_pipe_arm(true))), ("off", b(|| set_pipe_arm(false)))] }, - Arm { name: "huff_fast", vals: vec![("on", b(|| set_huff_fast_arm(true))), ("off", b(|| set_huff_fast_arm(false)))] }, - Arm { name: "payload_reserve", vals: vec![("on", b(|| set_payload_arm(true))), ("off", b(|| set_payload_arm(false)))] }, - Arm { name: "litpush_hoist", vals: vec![("on", b(|| set_litpush_hoist_arm(true))), ("off", b(|| set_litpush_hoist_arm(false)))] }, - Arm { name: "litpush", vals: vec![("on", b(|| set_litpush_arm(true))), ("off", b(|| set_litpush_arm(false)))] }, - Arm { name: "dfast_step", vals: vec![("dispatch", b(|| set_dfast_step_arm(0))), ("1", b(|| set_dfast_step_arm(1))), ("2", b(|| set_dfast_step_arm(2)))] }, - Arm { name: "dfast_spec_min", vals: vec![("0.70", b(|| set_dfast_spec_min_arm(0.70))), ("0.0", b(|| set_dfast_spec_min_arm(0.0))), ("2.0", b(|| set_dfast_spec_min_arm(2.0)))] }, - Arm { name: "dfast_pipe", vals: vec![("on", b(|| set_dfast_pipe_arm(true))), ("off", b(|| set_dfast_pipe_arm(false)))] }, - Arm { name: "search_log_d", vals: vec![("0", b(|| set_search_log_delta(0))), ("-1", b(|| set_search_log_delta(-1))), ("+1", b(|| set_search_log_delta(1)))] }, - Arm { name: "opt_lit", vals: vec![("auto", b(|| set_opt_lit_arm(u32::MAX))), ("6", b(|| set_opt_lit_arm(6))), ("9", b(|| set_opt_lit_arm(9)))] }, - Arm { name: "opt_rep", vals: vec![("on", b(|| set_opt_rep_arm(true))), ("off", b(|| set_opt_rep_arm(false)))] }, - Arm { name: "dfast_spec", vals: vec![("on", b(|| set_dfast_spec_arm(true))), ("off", b(|| set_dfast_spec_arm(false)))] }, - Arm { name: "fast_spec", vals: vec![("on", b(|| set_fast_spec_arm(true))), ("off", b(|| set_fast_spec_arm(false)))] }, - Arm { name: "bt_spec", vals: vec![("on", b(|| set_bt_spec_arm(true))), ("off", b(|| set_bt_spec_arm(false)))] }, - Arm { name: "next_long", vals: vec![("on", b(|| set_next_long_arm(true))), ("off", b(|| set_next_long_arm(false)))] }, - Arm { name: "pair_on", vals: vec![("on", b(|| set_pair_on_arm(true))), ("off", b(|| set_pair_on_arm(false)))] }, - Arm { name: "tag", vals: vec![("on", b(|| set_tag_arm(true))), ("off", b(|| set_tag_arm(false)))] }, - Arm { name: "tag_alloc", vals: vec![("on", b(|| set_tag_alloc_arm(true))), ("off", b(|| set_tag_alloc_arm(false)))] }, - Arm { name: "pair_hi", vals: vec![("1.0", b(|| set_pair_hi_arm(1.0))), ("0.0", b(|| set_pair_hi_arm(0.0))), ("9.0", b(|| set_pair_hi_arm(9.0)))] }, - Arm { name: "pair_gain", vals: vec![("0.20", b(|| set_pair_gain_arm(0.20))), ("0.0", b(|| set_pair_gain_arm(0.0))), ("1.0", b(|| set_pair_gain_arm(1.0)))] }, - Arm { name: "incomp_skip", vals: vec![("level", b(|| set_incomp_skip_arm(None))), ("on", b(|| set_incomp_skip_arm(Some(true)))), ("off", b(|| set_incomp_skip_arm(Some(false))))] }, - Arm { name: "strategy", vals: vec![("level", b(|| set_strategy_arm(None))), ("Greedy", b(|| set_strategy_arm(Some(Strategy::Greedy))))] }, + Arm { + name: "fast_lazy", + vals: vec![ + ("on", b(|| set_fast_lazy_arm(true))), + ("off", b(|| set_fast_lazy_arm(false))), + ], + }, + Arm { + name: "lazy_fill", + vals: vec![ + ("on", b(|| set_lazy_fill_arm(true))), + ("off", b(|| set_lazy_fill_arm(false))), + ], + }, + Arm { + name: "rep1_mode", + vals: vec![ + ("dispatch", b(|| set_rep1_mode(None))), + ("on", b(|| set_rep1_mode(Some(true)))), + ("off", b(|| set_rep1_mode(Some(false)))), + ], + }, + Arm { + name: "step0", + vals: vec![ + ("2", b(|| set_step0_arm(2))), + ("1", b(|| set_step0_arm(1))), + ("3", b(|| set_step0_arm(3))), + ], + }, + Arm { + name: "pipe_rep1", + vals: vec![ + ("on", b(|| set_pipe_rep1_arm(true))), + ("off", b(|| set_pipe_rep1_arm(false))), + ], + }, + Arm { + name: "pipe", + vals: vec![ + ("on", b(|| set_pipe_arm(true))), + ("off", b(|| set_pipe_arm(false))), + ], + }, + Arm { + name: "huff_fast", + vals: vec![ + ("on", b(|| set_huff_fast_arm(true))), + ("off", b(|| set_huff_fast_arm(false))), + ], + }, + Arm { + name: "payload_reserve", + vals: vec![ + ("on", b(|| set_payload_arm(true))), + ("off", b(|| set_payload_arm(false))), + ], + }, + Arm { + name: "litpush_hoist", + vals: vec![ + ("on", b(|| set_litpush_hoist_arm(true))), + ("off", b(|| set_litpush_hoist_arm(false))), + ], + }, + Arm { + name: "litpush", + vals: vec![ + ("on", b(|| set_litpush_arm(true))), + ("off", b(|| set_litpush_arm(false))), + ], + }, + Arm { + name: "dfast_step", + vals: vec![ + ("dispatch", b(|| set_dfast_step_arm(0))), + ("1", b(|| set_dfast_step_arm(1))), + ("2", b(|| set_dfast_step_arm(2))), + ], + }, + Arm { + name: "dfast_spec_min", + vals: vec![ + ("0.70", b(|| set_dfast_spec_min_arm(0.70))), + ("0.0", b(|| set_dfast_spec_min_arm(0.0))), + ("2.0", b(|| set_dfast_spec_min_arm(2.0))), + ], + }, + Arm { + name: "dfast_pipe", + vals: vec![ + ("on", b(|| set_dfast_pipe_arm(true))), + ("off", b(|| set_dfast_pipe_arm(false))), + ], + }, + Arm { + name: "search_log_d", + vals: vec![ + ("0", b(|| set_search_log_delta(0))), + ("-1", b(|| set_search_log_delta(-1))), + ("+1", b(|| set_search_log_delta(1))), + ], + }, + Arm { + name: "opt_lit", + vals: vec![ + ("auto", b(|| set_opt_lit_arm(u32::MAX))), + ("6", b(|| set_opt_lit_arm(6))), + ("9", b(|| set_opt_lit_arm(9))), + ], + }, + Arm { + name: "opt_rep", + vals: vec![ + ("on", b(|| set_opt_rep_arm(true))), + ("off", b(|| set_opt_rep_arm(false))), + ], + }, + Arm { + name: "dfast_spec", + vals: vec![ + ("on", b(|| set_dfast_spec_arm(true))), + ("off", b(|| set_dfast_spec_arm(false))), + ], + }, + Arm { + name: "fast_spec", + vals: vec![ + ("on", b(|| set_fast_spec_arm(true))), + ("off", b(|| set_fast_spec_arm(false))), + ], + }, + Arm { + name: "next_long", + vals: vec![ + ("on", b(|| set_next_long_arm(true))), + ("off", b(|| set_next_long_arm(false))), + ], + }, + Arm { + name: "pair_on", + vals: vec![ + ("on", b(|| set_pair_on_arm(true))), + ("off", b(|| set_pair_on_arm(false))), + ], + }, + Arm { + name: "tag", + vals: vec![ + ("on", b(|| set_tag_arm(true))), + ("off", b(|| set_tag_arm(false))), + ], + }, + Arm { + name: "tag_alloc", + vals: vec![ + ("on", b(|| set_tag_alloc_arm(true))), + ("off", b(|| set_tag_alloc_arm(false))), + ], + }, + Arm { + name: "pair_hi", + vals: vec![ + ("1.0", b(|| set_pair_hi_arm(1.0))), + ("0.0", b(|| set_pair_hi_arm(0.0))), + ("9.0", b(|| set_pair_hi_arm(9.0))), + ], + }, + Arm { + name: "pair_gain", + vals: vec![ + ("0.20", b(|| set_pair_gain_arm(0.20))), + ("0.0", b(|| set_pair_gain_arm(0.0))), + ("1.0", b(|| set_pair_gain_arm(1.0))), + ], + }, + Arm { + name: "incomp_skip", + vals: vec![ + ("level", b(|| set_incomp_skip_arm(None))), + ("on", b(|| set_incomp_skip_arm(Some(true)))), + ("off", b(|| set_incomp_skip_arm(Some(false)))), + ], + }, + Arm { + name: "strategy", + vals: vec![ + ("level", b(|| set_strategy_arm(None))), + ("Greedy", b(|| set_strategy_arm(Some(Strategy::Greedy)))), + ], + }, ] } fn arm_sweep(srcs: &[(&'static str, Vec)], hi_cap: usize) -> (usize, usize, usize, usize) { println!("\n================ 1. ARM SWEEP — every encode arm, all 4 levels ================"); - println!("{:<16} {:<8} {:<28} {}", "arm", "verdict", "deployed / values", "moved cells"); + println!( + "{:<16} {:<8} {:<28} {}", + "arm", "verdict", "deployed / values", "moved cells" + ); println!("{}", "-".repeat(112)); let mut base = fingerprint(srcs, hi_cap); let (mut live, mut dead, mut drift, mut stuck) = (0, 0, 0, 0); @@ -243,10 +440,34 @@ fn decode_sweep(srcs: &[(&'static str, Vec)]) { use rusty_zstd::*; println!("\n================ 2. DECODE ARM SWEEP — output must NEVER move ================"); let arms: Vec<(&str, Vec<(&str, Box)>)> = vec![ - ("seqcheck", vec![("on", b(|| set_seqcheck_arm(true))), ("off", b(|| set_seqcheck_arm(false)))]), - ("lut", vec![("on", b(|| set_lut_arm(true))), ("off", b(|| set_lut_arm(false)))]), - ("litcopy", vec![("on", b(|| set_litcopy_arm(true))), ("off", b(|| set_litcopy_arm(false)))]), - ("matchcopy", vec![("on", b(|| set_matchcopy_arm(true))), ("off", b(|| set_matchcopy_arm(false)))]), + ( + "seqcheck", + vec![ + ("on", b(|| set_seqcheck_arm(true))), + ("off", b(|| set_seqcheck_arm(false))), + ], + ), + ( + "lut", + vec![ + ("on", b(|| set_lut_arm(true))), + ("off", b(|| set_lut_arm(false))), + ], + ), + ( + "litcopy", + vec![ + ("on", b(|| set_litcopy_arm(true))), + ("off", b(|| set_litcopy_arm(false))), + ], + ), + ( + "matchcopy", + vec![ + ("on", b(|| set_matchcopy_arm(true))), + ("off", b(|| set_matchcopy_arm(false))), + ], + ), ]; // one frame per corpus per level, encoded once let mut frames = Vec::new(); @@ -308,22 +529,58 @@ fn caller_sweep(srcs: &[(&'static str, Vec)]) { }; // Gate 4 — checksum - let ck_on = rusty_zstd::compress_with(src, CompressOptions { level: lvl, checksum: true }).unwrap(); + let ck_on = rusty_zstd::compress_with( + src, + CompressOptions { + level: lvl, + checksum: true, + }, + ) + .unwrap(); row( "4 checksum", ck_on.len() != base.len(), - format!("{} vs {} bytes (Δ{})", ck_on.len(), base.len(), ck_on.len() as i64 - base.len() as i64), + format!( + "{} vs {} bytes (Δ{})", + ck_on.len(), + base.len(), + ck_on.len() as i64 - base.len() as i64 + ), ); // Gate 1 — nb_workers (MT). Must round-trip and must not corrupt. // `job_size = 0` means `4 * window`, which at L3 is 8 MiB -- larger than this // source, so MT would run ONE job and emit byte-identical output. That is a // null A/B dressed as a verdict; pin the job size so >1 job actually exists. - let adv_mt = AdvancedOptions { nb_workers: 2, job_size: 128 * 1024, ..Default::default() }; - match rusty_zstd::compress_with_advanced(src, rusty_zstd::compression_params(lvl, Some(src.len() as u64)).unwrap(), false, None, &[], true, adv_mt) { + let adv_mt = AdvancedOptions { + nb_workers: 2, + job_size: 128 * 1024, + ..Default::default() + }; + match rusty_zstd::compress_with_advanced( + src, + rusty_zstd::compression_params(lvl, Some(src.len() as u64)).unwrap(), + false, + None, + &[], + true, + adv_mt, + ) { Ok(z) => { - let ok = rusty_zstd::decompress(&z).map(|d| d == src).unwrap_or(false); - row("1 nb_workers=2", z != base, format!("{} vs {} bytes ({} jobs of 128 KiB), round-trip {}", z.len(), base.len(), src.len().div_ceil(128 << 10), if ok { "OK" } else { "FAILED" })); + let ok = rusty_zstd::decompress(&z) + .map(|d| d == src) + .unwrap_or(false); + row( + "1 nb_workers=2", + z != base, + format!( + "{} vs {} bytes ({} jobs of 128 KiB), round-trip {}", + z.len(), + base.len(), + src.len().div_ceil(128 << 10), + if ok { "OK" } else { "FAILED" } + ), + ); } Err(e) => row("1 nb_workers=2", false, format!("ERROR {e:?}")), } @@ -333,8 +590,19 @@ fn caller_sweep(srcs: &[(&'static str, Vec)]) { let p_base = enc(tail, lvl); match rusty_zstd::compress_using_prefix(tail, pre, lvl) { Ok(z) => { - let ok = rusty_zstd::decompress_using_prefix(&z, pre).map(|d| d == tail).unwrap_or(false); - row("2/10 prefix", z.len() != p_base.len(), format!("{} vs {} bytes, round-trip {}", z.len(), p_base.len(), if ok { "OK" } else { "FAILED" })); + let ok = rusty_zstd::decompress_using_prefix(&z, pre) + .map(|d| d == tail) + .unwrap_or(false); + row( + "2/10 prefix", + z.len() != p_base.len(), + format!( + "{} vs {} bytes, round-trip {}", + z.len(), + p_base.len(), + if ok { "OK" } else { "FAILED" } + ), + ); } Err(e) => row("2/10 prefix", false, format!("ERROR {e:?}")), } @@ -347,49 +615,134 @@ fn caller_sweep(srcs: &[(&'static str, Vec)]) { row( "5 BLOCK_KB=32", z32.len() != base.len(), - format!("{} vs {} bytes ({:+.3}%), restored {}", z32.len(), base.len(), (z32.len() as f64 / base.len() as f64 - 1.0) * 100.0, if z_re == base { "OK" } else { "FAILED" }), + format!( + "{} vs {} bytes ({:+.3}%), restored {}", + z32.len(), + base.len(), + (z32.len() as f64 / base.len() as f64 - 1.0) * 100.0, + if z_re == base { "OK" } else { "FAILED" } + ), ); // Gate 14 — target_cblock_size - let adv_t = AdvancedOptions { target_cblock_size: 16384, ..Default::default() }; + let adv_t = AdvancedOptions { + target_cblock_size: 16384, + ..Default::default() + }; let params = rusty_zstd::compression_params(lvl, Some(src.len() as u64)).unwrap(); match rusty_zstd::compress_with_advanced(src, params, false, None, &[], true, adv_t) { - Ok(z) => row("14 target_cblock", z.len() != base.len(), format!("{} vs {} bytes ({:+.3}%)", z.len(), base.len(), (z.len() as f64 / base.len() as f64 - 1.0) * 100.0)), + Ok(z) => row( + "14 target_cblock", + z.len() != base.len(), + format!( + "{} vs {} bytes ({:+.3}%)", + z.len(), + base.len(), + (z.len() as f64 / base.len() as f64 - 1.0) * 100.0 + ), + ), Err(e) => row("14 target_cblock", false, format!("ERROR {e:?}")), } // Gate 15 — rsyncable - let adv_r = AdvancedOptions { rsyncable: true, ..Default::default() }; + let adv_r = AdvancedOptions { + rsyncable: true, + ..Default::default() + }; match rusty_zstd::compress_with_advanced(src, params, false, None, &[], true, adv_r) { Ok(z) => { - let ok = rusty_zstd::decompress(&z).map(|d| d == src).unwrap_or(false); - row("15 rsyncable", z.len() != base.len(), format!("{} vs {} bytes ({:+.3}%), round-trip {}", z.len(), base.len(), (z.len() as f64 / base.len() as f64 - 1.0) * 100.0, if ok { "OK" } else { "FAILED" })); + let ok = rusty_zstd::decompress(&z) + .map(|d| d == src) + .unwrap_or(false); + row( + "15 rsyncable", + z.len() != base.len(), + format!( + "{} vs {} bytes ({:+.3}%), round-trip {}", + z.len(), + base.len(), + (z.len() as f64 / base.len() as f64 - 1.0) * 100.0, + if ok { "OK" } else { "FAILED" } + ), + ); } Err(e) => row("15 rsyncable", false, format!("ERROR {e:?}")), } // Gate 16 — LDM - let adv_l = AdvancedOptions { ldm: rusty_zstd::LdmParams::enabled(), ..Default::default() }; + let adv_l = AdvancedOptions { + ldm: rusty_zstd::LdmParams::enabled(), + ..Default::default() + }; match rusty_zstd::compress_with_advanced(src, params, false, None, &[], true, adv_l) { Ok(z) => { - let ok = rusty_zstd::decompress(&z).map(|d| d == src).unwrap_or(false); - row("16 ldm", z.len() != base.len(), format!("{} vs {} bytes ({:+.3}%), round-trip {}", z.len(), base.len(), (z.len() as f64 / base.len() as f64 - 1.0) * 100.0, if ok { "OK" } else { "FAILED" })); + let ok = rusty_zstd::decompress(&z) + .map(|d| d == src) + .unwrap_or(false); + row( + "16 ldm", + z.len() != base.len(), + format!( + "{} vs {} bytes ({:+.3}%), round-trip {}", + z.len(), + base.len(), + (z.len() as f64 / base.len() as f64 - 1.0) * 100.0, + if ok { "OK" } else { "FAILED" } + ), + ); } Err(e) => row("16 ldm", false, format!("ERROR {e:?}")), } // Gate 9 — decoder window_max rejection - let tiny = DecompressOptions { window_max: 1024, ..Default::default() }; + let tiny = DecompressOptions { + window_max: 1024, + ..Default::default() + }; let rejected = rusty_zstd::decompress_with(&base, tiny).is_err(); - row("9 window_max=1KiB", rejected, format!("over-large-window frame {}", if rejected { "REJECTED (correct)" } else { "ACCEPTED — the cap does not bind" })); + row( + "9 window_max=1KiB", + rejected, + format!( + "over-large-window frame {}", + if rejected { + "REJECTED (correct)" + } else { + "ACCEPTED — the cap does not bind" + } + ), + ); // Gate 20 — force_ignore_checksum: must CONSUME the 4 bytes, not verify them let mut corrupt = ck_on.clone(); let n = corrupt.len(); corrupt[n - 1] ^= 0xFF; let strict = rusty_zstd::decompress(&corrupt).is_err(); - let lax = rusty_zstd::decompress_with(&corrupt, DecompressOptions { force_ignore_checksum: true, ..Default::default() }).is_ok(); - row("20 force_ignore_ck", strict && lax, format!("corrupt trailer: strict {}, lax {}", if strict { "rejects" } else { "ACCEPTS — verification is not running" }, if lax { "accepts" } else { "REJECTS — the flag is not honoured" })); + let lax = rusty_zstd::decompress_with( + &corrupt, + DecompressOptions { + force_ignore_checksum: true, + ..Default::default() + }, + ) + .is_ok(); + row( + "20 force_ignore_ck", + strict && lax, + format!( + "corrupt trailer: strict {}, lax {}", + if strict { + "rejects" + } else { + "ACCEPTS — verification is not running" + }, + if lax { + "accepts" + } else { + "REJECTS — the flag is not honoured" + } + ), + ); // Gate 11 — frame magic: a skippable frame must be consumed and ignored let mut skip = Vec::new(); @@ -397,13 +750,36 @@ fn caller_sweep(srcs: &[(&'static str, Vec)]) { skip.extend_from_slice(&8u32.to_le_bytes()); skip.extend_from_slice(&[0u8; 8]); skip.extend_from_slice(&base); - let ok = rusty_zstd::decompress(&skip).map(|d| d == src).unwrap_or(false); - row("11 frame magic", ok, format!("skippable+zstd concatenation {}", if ok { "decodes to the payload (correct)" } else { "FAILED" })); + let ok = rusty_zstd::decompress(&skip) + .map(|d| d == src) + .unwrap_or(false); + row( + "11 frame magic", + ok, + format!( + "skippable+zstd concatenation {}", + if ok { + "decodes to the payload (correct)" + } else { + "FAILED" + } + ), + ); // Gate 12 — empty frame let ez = enc(&[], lvl); - let ok = rusty_zstd::decompress(&ez).map(|d| d.is_empty()).unwrap_or(false); - row("12 empty frame", ok, format!("{} bytes, round-trips to empty {}", ez.len(), if ok { "OK" } else { "FAILED" })); + let ok = rusty_zstd::decompress(&ez) + .map(|d| d.is_empty()) + .unwrap_or(false); + row( + "12 empty frame", + ok, + format!( + "{} bytes, round-trips to empty {}", + ez.len(), + if ok { "OK" } else { "FAILED" } + ), + ); println!("\n *UNWIRED means setting the option changed nothing observable. For a"); println!(" CALLER gate that is a DEFECT, not a verdict — a corpus board would then"); @@ -413,7 +789,9 @@ fn caller_sweep(srcs: &[(&'static str, Vec)]) { // --------------------------------------------------------------------------- fn knob_census() { - println!("\n================ 4. KNOB CENSUS — counted from source, never quoted ================"); + println!( + "\n================ 4. KNOB CENSUS — counted from source, never quoted ================" + ); let files = [ "crates/rusty_zstd/src/encode.rs", "crates/rusty_zstd/src/compressed.rs", @@ -451,9 +829,7 @@ fn knob_census() { for blk in s.split("\nfn ").skip(1) { let name = blk.split('(').next().unwrap_or("").trim().to_string(); let body = blk.split("\n}").next().unwrap_or(""); - if body.contains("env::var") - && !body.contains("OnceLock") - && !body.contains(".store(") + if body.contains("env::var") && !body.contains("OnceLock") && !body.contains(".store(") { for seg in body.split("env::var(\"").skip(1) { if let Some(k) = seg.split('"').next() { @@ -484,6 +860,33 @@ fn main() { let hi_cap = (cap / 4).max(65536); let srcs = load(cap); println!("ALL GATES — {} corpora, levels {LEVELS:?}", srcs.len()); + { + // SELF-CHECK: which strategies does this level list actually exercise? + let mut seen: Vec = LEVELS + .iter() + .filter_map(|&l| rusty_zstd::compression_params(l, None).ok()) + .map(|p| format!("{:?}", p.strategy)) + .collect(); + seen.sort(); + seen.dedup(); + const ALL: &[&str] = &[ + "Fast", "DFast", "Greedy", "Lazy", "Lazy2", "BtLazy2", "BtOpt", "BtUltra", "BtUltra2", + ]; + let missing: Vec<&str> = ALL + .iter() + .copied() + .filter(|s| !seen.iter().any(|x| x == s)) + .collect(); + println!(" strategies covered: {}", seen.join(", ")); + if !missing.is_empty() { + println!( + " !! STRATEGY HOLE: {} never exercised. Every gate whose only", + missing.join(", ") + ); + println!(" call sites are in those finders will read SZ-DEAD for a reason"); + println!(" that has nothing to do with the gate. Add a level for each."); + } + } println!( " prefix {} KiB = {} blocks (L1/L3), {} KiB = {} blocks (L19/L22); encode checksum OFF", cap >> 10, @@ -492,8 +895,12 @@ fn main() { hi_cap.div_ceil(128 << 10) ); if cap.div_ceil(128 << 10) < 16 { - println!(" !! WARNING: under 16 blocks. Gates keyed on a RUN of blocks (fast_lazy needs 4,"); - println!(" raw_probe re-probes every 16) are structurally inert — their DEAD is UNPROVEN."); + println!( + " !! WARNING: under 16 blocks. Gates keyed on a RUN of blocks (fast_lazy needs 4," + ); + println!( + " raw_probe re-probes every 16) are structurally inert — their DEAD is UNPROVEN." + ); } println!(" every verdict below is DETERMINISTIC (compressed sizes) — valid on a busy box"); let t0 = std::time::Instant::now(); diff --git a/crates/rusty_zstd-bench/examples/allocsites.rs b/crates/rusty_zstd-bench/examples/allocsites.rs index 2e5d0a6..07d2dd0 100644 --- a/crates/rusty_zstd-bench/examples/allocsites.rs +++ b/crates/rusty_zstd-bench/examples/allocsites.rs @@ -23,7 +23,7 @@ unsafe impl GlobalAlloc for C { let n = N.fetch_add(1, Ordering::Relaxed); // sample: backtrace capture allocates, so guard against reentry let big = l.size() >= MIN.load(Ordering::Relaxed); - if big || n % 37 == 0 { + if big || true { REENTRY.with(|r| { if !r.get() { r.set(true); @@ -65,7 +65,7 @@ fn main() { let lvl: i32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(3); if let Ok(m) = std::env::var("ALLOC_MIN") { if let Ok(v) = m.parse() { MIN.store(v, Ordering::Relaxed); } } let full = std::fs::read("corpora/data/silesia/dickens").expect("corpus"); - let src = &full[..full.len().min(8 << 20)]; + let src = &full[..full.len().min(1 << 20)]; ON.store(1, Ordering::Relaxed); let _ = rusty_zstd::compress(src, lvl).unwrap(); ON.store(0, Ordering::Relaxed); diff --git a/crates/rusty_zstd-bench/examples/armone.rs b/crates/rusty_zstd-bench/examples/armone.rs new file mode 100644 index 0000000..772c977 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/armone.rs @@ -0,0 +1,98 @@ +//! ONE ARM PER PROCESS. The only contamination-proof way to board these. +//! +//! cargo run --release -p rusty_zstd-bench --example armone -- +//! +//! Every arm here is THREE-state: unset resolves through an env knob or a +//! dispatch, and `set_*(true|false)` FORCES. There is no public "unset", so a +//! single process cannot measure arm B after touching arm A and still trust its +//! baseline. A first attempt did exactly that and produced an identical +//! +10,462 at L13 for thirteen unrelated arms -- one stuck forced arm, read +//! thirteen times as if it were each arm's own result. +//! +//! So: baseline measured first, exactly one setter called, process exits. +use rusty_zstd as rz; +const IDS: &[&str] = &[ + "jsonlog-16m", + "smallmsg-8m", + "mr", + "ooffice", + "osdb", + "reymont", + "sao", + "webster", + "dickens", + "mozilla", + "nci", + "samba", + "xml", + "x-ray", +]; +fn main() { + let a: Vec = std::env::args().collect(); + let arm = a.get(1).cloned().unwrap_or_default(); + let lvl: i32 = a.get(2).and_then(|s| s.parse().ok()).unwrap_or(9); + let cap: usize = a.get(3).and_then(|s| s.parse().ok()).unwrap_or(1 << 20); + let srcs: Vec> = IDS + .iter() + .filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok() + .map(|f| { + let n = f.len().min(cap); + f[..n].to_vec() + }) + }) + .collect(); + let go = || -> usize { + srcs.iter() + .map(|s| { + rz::compress_with( + s, + rz::CompressOptions { + level: lvl, + checksum: false, + }, + ) + .unwrap() + .len() + }) + .sum() + }; + let base = go(); // untouched: nothing set yet + type S = fn(bool); + let f: S = match arm.as_str() { + "lazy_fill" => rz::set_lazy_fill_arm, + "lazy_gain" => rz::set_lazy_gain_arm, + "row" => rz::set_row_arm, + "walk_cont" => rz::set_walk_cont_arm, + "rep_reprobe" => rz::set_rep_reprobe_arm, + "chain_tag" => rz::set_chain_tag_arm, + "wide_chain" => rz::set_wide_chain_arm, + "prime_bt" => rz::set_prime_bt_arm, + "prime_bt_tree" => rz::set_prime_bt_tree_arm, + "step_probe" => rz::set_step_probe_arm, + "replen_pipe" => rz::set_replen_pipe_arm, + "raw_skip" => rz::set_raw_skip_arm, + "dfast_bext" => rz::set_dfast_bext_arm, + "opt_mlbits" => rz::set_opt_mlbits_arm, + "opt_rep" => rz::set_opt_rep_arm, + "long_tag" => rz::set_long_tag_arm, + "bt_depth_cached" => rz::set_bt_depth_cached_arm, + _ => { + println!("unknown arm {arm}"); + return; + } + }; + let setting = a.get(4).map(|s| s.as_str() == "on").unwrap_or(true); + f(setting); + let d = go() as i64 - base as i64; + println!( + "{} {} {} {} {}", + arm, + lvl, + base, + if setting { "on" } else { "off" }, + d + ); +} diff --git a/crates/rusty_zstd-bench/examples/armwork.rs b/crates/rusty_zstd-bench/examples/armwork.rs new file mode 100644 index 0000000..be4d7d5 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/armwork.rs @@ -0,0 +1,100 @@ +//! ARM WORK CENSUS -- the proof `allgates` explicitly leaves open. +//! +//! cargo run --release --features profile -p rusty_zstd-bench --example armwork +//! +//! `allgates` reports 13 arms SZ-DEAD and then says the honest thing: "SZ-DEAD +//! on a byte-identical SPEED capability = the identity proof it owes; the speed +//! question is still open and belongs on the clock." On this box the clock has +//! a +-1.5% null band (see `eqlever.rs`), so for a capability worth ~1% the +//! clock cannot answer it -- ever. +//! +//! But a speed capability that is real must move some WORK counter: fewer +//! probes, fewer fills, fewer copied bytes, fewer allocations. If toggling an +//! arm moves neither the output bytes NOR any work counter, the arm is dead in +//! both currencies and no clock is needed to say so. +//! +//! A row that moves nothing is a REMOVABLE BRANCH. A row that moves work but +//! not bytes is a live byte-identical capability -- exactly what it claims. +use rusty_zstd as rz; + +const IDS: &[&str] = &["dickens", "webster", "mozilla", "samba", "nci", "x-ray", + "osdb", "sao", "jsonlog-16m", "smallmsg-8m"]; + +#[derive(Default, Clone, Copy, PartialEq, Debug)] +struct Work { bytes: u64, probes: u64, fills: u64, hits: u64, seqs: u64, + allocs: u64, pos: u64, copy: u64, lit: u64, mb: u64 } + +fn run(lvl: i32, srcs: &[Vec]) -> Work { + let mut w = Work::default(); + let _ = rz::take_mm(); + let _ = rz::copies::take(); + for s in srcs { + rz::prof_reset(); + let out = rz::compress(s, lvl).unwrap(); + w.bytes += out.len() as u64; + let c = rz::prof_encode_counts(); + w.probes += c.hash_probes; w.fills += c.hash_fills; w.hits += c.probe_hits; + w.seqs += c.seqs; w.allocs += c.scratch_allocs; + w.lit += c.lit_bytes; w.mb += c.match_bytes; + } + w.pos = rz::take_mm().0; + w.copy = rz::copies::take().iter().map(|x| x.1).sum(); + w +} + +fn main() { + let cap: usize = 4 << 20; + let srcs: Vec> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) + .ok().map(|f| f[..f.len().min(cap)].to_vec()) + }).collect(); + println!("board: {} corpora, {} MiB\n", srcs.len(), + srcs.iter().map(|s| s.len()).sum::() >> 20); + + type Setter = fn(bool); + let arms: &[(&str, Setter, bool, i32)] = &[ + ("pipe", rz::set_pipe_arm as Setter, true, 1), + ("fast_spec", rz::set_fast_spec_arm, true, 1), + ("litpush", rz::set_litpush_arm, true, 1), + ("litpush_hoist", rz::set_litpush_hoist_arm, true, 1), + ("payload_reserve", rz::set_payload_arm, true, 1), + ("huff_fast", rz::set_huff_fast_arm, true, 1), + ("finder_scratch", rz::set_finder_scratch_arm, true, 1), + ("fast_lazy", rz::set_fast_lazy_arm, true, 1), + ("dfast_pipe", rz::set_dfast_pipe_arm, true, 3), + ("dfast_spec", rz::set_dfast_spec_arm, true, 3), + ("dfast_tag", rz::set_dfast_tag_arm, true, 3), + ("lazy_fill", rz::set_lazy_fill_arm, true, 9), + ]; + // CONTROL FIRST. A zero delta is only evidence once the counter is proven + // REACHED -- the lesson this session already paid for twice. Print the + // ABSOLUTE baseline of every counter before any delta is believed. + let base = run(1, &srcs); + println!("CONTROL (L1 defaults, absolute): bytes {} probes {} fills {} pos {} copyB {} allocs {} seqs {}", + base.bytes, base.probes, base.fills, base.pos, base.copy, base.allocs, base.seqs); + let b3 = run(3, &srcs); + println!("CONTROL (L3 defaults, absolute): bytes {} probes {} fills {} pos {} copyB {} allocs {} seqs {} +", + b3.bytes, b3.probes, b3.fills, b3.pos, b3.copy, b3.allocs, b3.seqs); + println!("{:<17}{:>3} {:>9} {:>9} {:>9} {:>9} {:>9} {:>9} {}", + "arm", "L", "d bytes", "d probes", "d fills", "d pos", "d copyB", "d allocs", "verdict"); + println!("{}", "-".repeat(108)); + for (name, set, deflt, lvl) in arms { + set(*deflt); + let a = run(*lvl, &srcs); + set(!*deflt); + let b = run(*lvl, &srcs); + set(*deflt); // restore + let d = |x: u64, y: u64| y as i64 - x as i64; + let (db, dp, df, dc, da) = (d(a.bytes,b.bytes), d(a.probes,b.probes), + d(a.fills,b.fills), d(a.copy,b.copy), d(a.allocs,b.allocs)); + let moved_work = dp != 0 || df != 0 || dc != 0 || da != 0 + || a.pos != b.pos || a.seqs != b.seqs; + let verdict = if db != 0 { "LIVE (changes bytes)" } + else if moved_work { "live: byte-identical, moves work" } + else { "DEAD IN BOTH -- removable branch" }; + println!("{:<17}{:>3} {:>9} {:>9} {:>9} {:>9} {:>9} {:>9} {}", + name, lvl, db, dp, df, d(a.pos, b.pos), dc, da, verdict); + } +} diff --git a/crates/rusty_zstd-bench/examples/bextcount.rs b/crates/rusty_zstd-bench/examples/bextcount.rs new file mode 100644 index 0000000..a4f0db8 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/bextcount.rs @@ -0,0 +1,56 @@ +//! Backward-extension census: is a word-at-a-time backward extension worth +//! building? The byte loop costs ~8 instructions per extended byte; a word +//! form costs ~10 fixed per match. So it pays iff extended bytes per match is +//! comfortably above one -- a count, not a clock. +//! +//! cargo run --release --features profile -p rusty_zstd-bench --example bextcount +const IDS: &[&str] = &[ + "jsonlog-16m", + "smallmsg-8m", + "mr", + "ooffice", + "osdb", + "reymont", + "sao", + "webster", + "dickens", + "mozilla", + "nci", + "samba", + "xml", + "x-ray", + "text-32m", + "incomp-32m", +]; +fn main() { + let cap = 1usize << 20; + let srcs: Vec> = IDS + .iter() + .filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok() + .map(|f| { + let n = f.len().min(cap); + f[..n].to_vec() + }) + }) + .collect(); + for lvl in [1i32, 3, 7, 9] { + let _ = rusty_zstd::take_bext(); + for s in &srcs { + let _ = rusty_zstd::compress_with( + s, + rusty_zstd::CompressOptions { + level: lvl, + checksum: false, + }, + ) + .unwrap(); + } + println!( + "L{lvl}: take_bext() = {:?} (matches, extended>0, bytes, >=8 -- see note_bext)", + rusty_zstd::take_bext() + ); + } +} diff --git a/crates/rusty_zstd-bench/examples/btpairs.rs b/crates/rusty_zstd-bench/examples/btpairs.rs new file mode 100644 index 0000000..9031f65 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/btpairs.rs @@ -0,0 +1,27 @@ +//! Enumerate the REACHABLE (hash_log, chain_log) pairs for the Bt strategies, +//! the way the original dead-copy census did: every bt clevel x every input +//! size across the range x the streaming case (size unknown). +fn main() { + let mut set: Vec<(u32, u32)> = Vec::new(); + let mut push = |p: rusty_zstd::CompressionParameters| { + let pair = (p.hash_log.min(24), p.chain_log.min(24)); + if !set.contains(&pair) { set.push(pair); } + }; + for lvl in 13i32..=22 { + // streaming: size unknown + push(rusty_zstd::compression_params(lvl, None).unwrap()); + let mut n: u64 = 1024; + while n <= (256 << 20) { + push(rusty_zstd::compression_params(lvl, Some(n)).unwrap()); + n += (n / 4).max(1024); + } + } + set.sort(); + println!("{} reachable pairs", set.len()); + let mut line = String::from(" "); + for (i, (h, c)) in set.iter().enumerate() { + line.push_str(&format!("({h}, {c}) ")); + if (i + 1) % 7 == 0 { println!("{}", line.trim_end()); line = String::from(" "); } + } + if !line.trim().is_empty() { println!("{}", line.trim_end()); } +} diff --git a/crates/rusty_zstd-bench/examples/bwprobe.rs b/crates/rusty_zstd-bench/examples/bwprobe.rs new file mode 100644 index 0000000..53160b1 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/bwprobe.rs @@ -0,0 +1,59 @@ +//! What is a copy ACTUALLY worth on this box, at the sizes the codec uses? +//! +//! Every ceiling in this campaign divided bytes-moved by "10-20 GB/s". That is +//! the peak figure for cache-resident data. The decoder's `decoded` window is +//! 2-8 MiB and its compaction memmoves most of it, which is out of L2 and +//! often out of L3 -- so the honest divisor is the measured rate AT THAT SIZE, +//! and using the peak understates every copy by whatever the ratio turns out +//! to be. +fn best(n: u32, mut f: F) -> f64 { + let mut b = f64::MAX; + for _ in 0..n { + let t = std::time::Instant::now(); + f(); + b = b.min(t.elapsed().as_secs_f64()); + } + b +} + +fn main() { + println!( + "{:>10}{:>14}{:>14}{:>14}", + "size", "copy GB/s", "memmove GB/s", "fill GB/s" + ); + for kb in [64usize, 256, 1024, 2048, 4096, 8192, 32768] { + let n = kb << 10; + let src = vec![7u8; n]; + let mut dst = vec![0u8; n]; + let mut big = vec![3u8; n + (n / 2)]; + // Enough reps that a single call's overhead is negligible, few enough + // that a 32 MiB pass does not dominate the run. + let reps = (64 << 20) / n.max(1); + let reps = reps.clamp(3, 2000) as u32; + + let c = best(9, || { + for _ in 0..reps { + dst.copy_from_slice(&src); + } + }); + let m = best(9, || { + for _ in 0..reps { + big.copy_within(n / 2.., 0); + } + }); + let fl = best(9, || { + for _ in 0..reps { + dst.fill(0); + } + }); + let gbs = |secs: f64, bytes: usize| (bytes as f64 * reps as f64) / secs / 1e9; + println!( + "{:>8} KB{:>14.2}{:>14.2}{:>14.2}", + kb, + gbs(c, n), + gbs(m, n), + gbs(fl, n) + ); + } + println!("\nThe codec's decoded window at L3 is ~2 MiB and its compaction moves most of it."); +} diff --git a/crates/rusty_zstd-bench/examples/bytegate.rs b/crates/rusty_zstd-bench/examples/bytegate.rs index 7dc2b72..8df27b6 100644 --- a/crates/rusty_zstd-bench/examples/bytegate.rs +++ b/crates/rusty_zstd-bench/examples/bytegate.rs @@ -15,6 +15,11 @@ //! BE0071FB0CB0CED9 59,760,356 bytes until 2026-08-27 //! CAE84167220B70DA 59,841,188 bytes DFAST_FILL_N_ARM -> start-only //! EA4E12B951B48F4A 59,852,335 bytes dfast_bext ON + walk_first_max -0.15 +//! F72C7074A2240AF7 59,704,523 bytes ROW finder AUTO on the lazy ladder +//! 269F0EC2BA6B8550 59,686,173 bytes nl_dispatch ON + raised cut 24->48 +//! D8F9B47AD5DDD2AB 59,685,682 bytes lazy/greedy/bt incompressible accel +//! 7FB4E822473412A3 59,685,682 bytes source-sized hash on the Bt ladder +//! 2F6594F7EEDBD12B 59,680,638 bytes source-sized hash on EVERY strategy //! ``` //! //! The 2026-08-27 move is +0.135% of total bytes and buys HALF the per-match @@ -32,7 +37,53 @@ //! trade in this encoder. `RZSTD_WALK_FIRST_MAX=0.70` restores the old //! bitstream exactly at L7/L9. //! -//! bext also introduced two LADDER INVERSIONS by making L3 beat L5 outright -- +//! The 2026-09-08 move is **-147,812 bytes, -0.247%**, and is a pure ratio +//! gain -- no size was traded for anything. The row match finder existed, +//! round-tripped and defaulted OFF because THIS BOARD'S SIBLING measured it at +//! one input size. `rowboard.rs` caps every corpus at 8 MiB and reported L9 +//! aggregate 1.0005x, a wash. Swept across caps the verdict is monotone in +//! source length and 8 MiB sits just past the crossover: +//! +//! ```text +//! L9 256K 1.0059 | 512K 0.9882 | 1M 0.9882 | 2M 0.9894 | 4M 0.9944 | 6M 1.0018 +//! ``` +//! +//! A row holds the last 16 positions for its bucket where the chain held all +//! of them: DEPTH traded for RECENCY, and recent means SMALL OFFSETS, which +//! cost fewer bits. While the window is not full the row gives up almost no +//! depth and banks the offset saving. So the arm now defaults to AUTO and +//! fires only for Lazy/Lazy2 with a KNOWN source length in 512 KiB..2 MiB -- +//! the band that wins at L7, L9 and L12 alike. Outside it, output is +//! byte-identical to the previous default, which is why only the in-band +//! cells of this table moved. +//! +//! In band it is a DOUBLE win: 1.1-1.3% smaller AND 2.5-8.5x fewer dependent +//! loads. Streaming keeps the chain -- the band is a source-length band and +//! streaming does not know the length. +//!//! The second 2026-09-08 move is **-18,350 bytes** and touches L3 only -- the +//! next-long probe COMMITS at `ip + 1`, so it can take a longer match at a +//! worse OFFSET and lose more in the offset code than it gains in the length +//! code. On `sao` it wins 468,072 match bytes and still costs 15,001 +//! compressed bytes. `next_long_yield` cannot see that (x-ray's yield is 100x +//! lower and the probe HELPS it), but `band_worse / band_hits` measures the +//! offset trade directly and `nl_cut_for` already dispatched on it -- the +//! dispatch had simply never been switched on, so the sweep that tuned its +//! 0.60 bar was tuning a threshold nothing consulted. +//! +//! On an 18-corpus L3-only board it is -82,653 bytes (-0.360%); here it is +//! diluted across nine levels, only one of which is DFast. +//! +//! It also widened the adjudicated L3->L5 ladder tie from 0.1% to 0.2%: L3 +//! goes 3,517,111 -> 3,514,780 on full osdb while L5 stays at 3,519,696, the +//! exact value already recorded -- the cheaper level gaining again, not Greedy +//! losing. See `higher_level_never_larger_osdb`. +//!//! The source-sized-hash move is the only entry here that changes GOLD while +//! the TOTAL stays byte-for-byte identical (59,685,682 both sides). It sizes +//! the hash from the source rather than the window for BtLazy2 and above, so +//! individual frames shift while the sum does not -- measured +0 bytes at +//! L16/L19/L22 at every cap, +144 at L13/256K. What it buys is MEMORY: the +//! table allocation falls 25% and peak RSS 4.9-12.5%. +//!//! bext also introduced two LADDER INVERSIONS by making L3 beat L5 outright -- //! dickens +1.020%, osdb +0.074%. Both are the cheaper level GAINING a //! capability, not the dearer one losing it; `higher_level_never_larger_osdb` //! records the adjudication and keeps a ceiling on L5 so the exception cannot @@ -57,6 +108,44 @@ fn main() { let mut gold = 0xCBF2_9CE4_8422_2325u64; let mut total = 0usize; println!("BYTE-IDENTITY GATE cap={cap} corpora={} levels={:?}\n", srcs.len(), LEVELS); + { + // STRATEGY COVERAGE, reported but NOT enforced -- deliberately. + // + // This list resolves to Fast, DFast, Greedy, Lazy, Lazy2, BtLazy2 and + // BtUltra2, but NOT BtOpt: L12 is Lazy2 and L15 is BtLazy2, so the + // first BtOpt level (16) is never compressed here. `find_opt` itself + // is reached at L19, but through the BtUltra2 arm -- a defect confined + // to the non-ultra BtOpt path would not move GOLD. + // + // NOT fixed by adding L16, because GOLD is this campaign's identity + // anchor and its history is a curated record; widening the input set + // moves it for a reason unrelated to any bitstream change, which would + // corrupt exactly the signal the anchor exists to carry. `determall.rs` + // (L16 included) and `simdparity.rs` both cover BtOpt today, so the + // strategy is not unguarded -- only this gate does not see it. Whoever + // next moves GOLD deliberately should fold L16 in at the same time and + // record both reasons in the history block above. + let mut seen: Vec = LEVELS + .iter() + .filter_map(|&l| rusty_zstd::compression_params(l, None).ok()) + .map(|p| format!("{:?}", p.strategy)) + .collect(); + seen.sort(); + seen.dedup(); + const ALL: &[&str] = &["Fast", "DFast", "Greedy", "Lazy", "Lazy2", "BtLazy2", + "BtOpt", "BtUltra", "BtUltra2"]; + let missing: Vec<&str> = ALL + .iter() + .copied() + .filter(|a| !seen.iter().any(|x| x == a)) + .collect(); + println!("strategies in GOLD: {}", seen.join(", ")); + if !missing.is_empty() { + println!("NOT in GOLD: {} -- a bitstream change confined to those", + missing.join(", ")); + println!(" finders will NOT move this number."); + } + } print!("{:<14}", "corpus"); for l in LEVELS { print!("{:>10}", format!("L{l}")); } println!(); diff --git a/crates/rusty_zstd-bench/examples/copies.rs b/crates/rusty_zstd-bench/examples/copies.rs new file mode 100644 index 0000000..6816fca --- /dev/null +++ b/crates/rusty_zstd-bench/examples/copies.rs @@ -0,0 +1,95 @@ +//! COPY CENSUS -- bytes moved per input byte, per site, on the encode path. +//! +//! Deterministic: byte totals are a property of the input and the code path, +//! so this reads the same on any machine at any load. +//! +//! The number to look at is the LAST column: copies per input byte. It has a +//! floor above zero -- an encoder must place literal bytes into its output -- +//! so the target is not "0", it is "no byte moved a SECOND time". +use rusty_zstd::copies::{self, COPY_NAMES, N_COPY_SLOTS}; + +const IDS: &[&str] = &[ + "incomp-32m", + "text-32m", + "jsonlog-16m", + "versions-16m", + "dickens", + "samba", + "webster", + "x-ray", + "mozilla", +]; + +fn load(id: &str) -> Option> { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok() +} + +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + println!("ENCODE COPY CENSUS (L{lvl}) -- bytes, not clocks\n"); + println!( + "{:<14}{:>9}{:>14}{:>14}{:>14}{:>10}", + "corpus", "MiB", "src->lits", "lits->rawsec", "sec->dst", "cp/byte" + ); + + let mut tot = [(0u64, 0u64); N_COPY_SLOTS]; + let mut tsrc = 0u64; + for id in IDS { + let Some(f) = load(id) else { continue }; + let src = &f[..f.len().min(32 << 20)]; + let _ = copies::take(); + let z = rusty_zstd::compress(src, lvl).expect("compress"); + let c = copies::take(); + // Round-trip so a copy change can never silently break output. + let out = rusty_zstd::decompress(&z).expect("decompress"); + assert_eq!(out, src, "{id} roundtrip"); + let _ = copies::take(); + + let moved: u64 = c.iter().map(|(b, _)| *b).sum(); + let per = moved as f64 / src.len() as f64; + println!( + "{id:<14}{:>9.1}{:>14}{:>14}{:>14}{:>10.3}", + src.len() as f64 / (1 << 20) as f64, + c[copies::C_LIT_PUSH].0, + c[copies::C_LIT_RAW_SECTION].0, + c[copies::C_SECTION_TO_DST].0, + per + ); + tsrc += src.len() as u64; + for i in 0..N_COPY_SLOTS { + tot[i].0 += c[i].0; + tot[i].1 += c[i].1; + } + } + + println!( + "\n{:<24}{:>16}{:>14}{:>12}", + "site", "bytes", "calls", "B/input" + ); + let mut moved = 0u64; + for i in 0..N_COPY_SLOTS { + let (b, n) = tot[i]; + if b == 0 && n == 0 { + continue; + } + moved += b; + println!( + "{:<24}{b:>16}{n:>14}{:>12.4}", + COPY_NAMES[i], + b as f64 / tsrc as f64 + ); + } + println!( + "\nTOTAL {moved} bytes moved for {tsrc} input bytes = {:.3} copies per input byte", + moved as f64 / tsrc as f64 + ); + println!( + "floor is ~1.0 on literal-heavy input (the bytes must reach the output);\n\ + anything above that is a byte moved a second time." + ); +} diff --git a/crates/rusty_zstd-bench/examples/coresbusy.rs b/crates/rusty_zstd-bench/examples/coresbusy.rs new file mode 100644 index 0000000..68c0b1a --- /dev/null +++ b/crates/rusty_zstd-bench/examples/coresbusy.rs @@ -0,0 +1,43 @@ +//! CPU-time / wall-time for a plain one-shot compress. +//! +//! `cores_busy` above 1.0 on a single-threaded workload means threads we are +//! not accounting for. The `rzstd-bench` BINARY installs `rzstd-alloc` as its +//! global allocator; examples do not, so this is the control that says whether +//! the extra CPU belongs to the codec or to the allocator. +fn cpu_ms() -> f64 { + #[cfg(windows)] + unsafe { + // GetProcessTimes via std is not exposed; use the process CPU clock + // through a cheap proxy: sum of thread times is what the harness reads, + // so approximate with the same quantity the OS reports for the process. + extern "system" { + fn GetCurrentProcess() -> isize; + fn GetProcessTimes(h: isize, a: *mut u64, b: *mut u64, k: *mut u64, u: *mut u64) -> i32; + } + let (mut c, mut e, mut k, mut u) = (0u64, 0u64, 0u64, 0u64); + if GetProcessTimes(GetCurrentProcess(), &mut c, &mut e, &mut k, &mut u) != 0 { + return (k + u) as f64 / 10_000.0; // 100ns units -> ms + } + 0.0 + } + #[cfg(not(windows))] + 0.0 +} + +fn main() { + let f = std::fs::read("corpora/data/silesia/dickens").expect("corpus"); + let src = &f[..f.len().min(8 << 20)]; + for lvl in [1, 3, 9] { + let c0 = cpu_ms(); + let t = std::time::Instant::now(); + let z = rusty_zstd::compress(src, lvl).expect("c"); + let wall = t.elapsed().as_secs_f64() * 1000.0; + let cpu = cpu_ms() - c0; + assert!(!z.is_empty()); + println!( + "L{lvl}: wall {wall:8.1} ms cpu {cpu:8.1} ms cores_busy {:.2}", + cpu / wall.max(0.001) + ); + } + println!("\n~1.0 = genuinely single-threaded. ~2.0 = a second thread is being charged to us."); +} diff --git a/crates/rusty_zstd-bench/examples/deccopies.rs b/crates/rusty_zstd-bench/examples/deccopies.rs new file mode 100644 index 0000000..3a06348 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/deccopies.rs @@ -0,0 +1,122 @@ +//! DECODER streaming compaction census + ceiling. +//! +//! The encoder's window slide bundles three costs (memmove, six table clears, +//! a full re-prime) and the re-prime dominated. The decoder's compaction is +//! the SAME shape of trigger with only ONE of those costs: a memmove. So the +//! bundle argument does not transfer, and the question becomes purely how big +//! that memmove is against how fast decode runs -- and decode runs an order of +//! magnitude faster than encode, so a fixed byte cost is a much larger share. +//! +//! That is the whole reason to measure instead of assuming the encoder's +//! answer carries over. +use rusty_zstd::Decompressor; + +const IDS: &[&str] = &["dickens", "samba", "webster", "mozilla"]; + +fn load(id: &str) -> Option> { + std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) + .ok() +} + +fn decode_streaming(z: &[u8], chunk: usize) -> (f64, usize) { + let mut d = Decompressor::new(); + let mut buf = vec![0u8; 128 << 10]; + let mut n = 0usize; + let t = std::time::Instant::now(); + let mut i = 0usize; + while i < z.len() { + let end = (i + chunk).min(z.len()); + let mut inp = &z[i..end]; + loop { + let st = d.stream(inp, &mut buf, false).expect("stream"); + n += st.output_produced; + inp = &inp[st.input_consumed..]; + if inp.is_empty() || (st.input_consumed == 0 && st.output_produced == 0) { + break; + } + } + i = end; + } + loop { + let st = d.stream(&[], &mut buf, true).expect("drain"); + n += st.output_produced; + if st.output_produced == 0 { + break; + } + } + (t.elapsed().as_secs_f64(), n) +} + +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + let chunk: usize = std::env::args() + .nth(2) + .and_then(|s| s.parse().ok()) + .unwrap_or(64 << 10); + println!("DECODER STREAMING COMPACTION CENSUS (L{lvl}, {chunk} B chunks)\n"); + println!( + "{:<12}{:>8}{:>10}{:>16}{:>10}{:>10}{:>22}", + "corpus", "MiB", "compacts", "bytes memmoved", "B/out", "MiB/s", "memmove as % decode" + ); + let (mut tb, mut tn, mut tsec) = (0u64, 0u64, 0.0f64); + for id in IDS { + let Some(f) = load(id) else { continue }; + let src = &f[..f.len().min(32 << 20)]; + let z = rusty_zstd::compress(src, lvl).expect("compress"); + let _ = rusty_zstd::take_dec_compact(); + let _ = rusty_zstd::copies::take(); + let (secs, n) = decode_streaming(&z, chunk); + let c = rusty_zstd::take_dec_compact(); + let cp = rusty_zstd::copies::take(); + assert_eq!(n, src.len(), "{id} decoded length"); + let mbps = src.len() as f64 / (1 << 20) as f64 / secs; + // At 10-20 GB/s the memmove costs this many ms; against the measured + // decode wall that is the share a perfect fix could remove. + let lo = c[1] as f64 / 20e9 / secs * 100.0; + let hi = c[1] as f64 / 10e9 / secs * 100.0; + println!( + "{id:<12}{:>8.1}{:>10}{:>16}{:>10.3}{:>10.0}{:>17.2}-{:.2}%", + src.len() as f64 / (1 << 20) as f64, + c[0], + c[1], + c[1] as f64 / src.len() as f64, + mbps, + lo, + hi + ); + println!( + " copies/out: in_acc {:.3} + out {:.3} + compact {:.3} + in_compact {:.3} = {:.3}", + cp[rusty_zstd::copies::C_DEC_IN_ACC].0 as f64 / src.len() as f64, + cp[rusty_zstd::copies::C_DEC_OUT].0 as f64 / src.len() as f64, + cp[rusty_zstd::copies::C_DEC_COMPACT].0 as f64 / src.len() as f64, + cp[rusty_zstd::copies::C_DEC_IN_COMPACT].0 as f64 / src.len() as f64, + (cp[rusty_zstd::copies::C_DEC_IN_COMPACT].0 + + cp[rusty_zstd::copies::C_DEC_IN_ACC].0 + + cp[rusty_zstd::copies::C_DEC_OUT].0 + + cp[rusty_zstd::copies::C_DEC_COMPACT].0) as f64 + / src.len() as f64 + ); + tb += c[1]; + tn += src.len() as u64; + tsec += secs; + } + println!( + "\nTOTAL {tb} bytes memmoved for {tn} decoded = {:.3} B/output byte", + tb as f64 / tn as f64 + ); + println!( + "ceiling: {:.2}%-{:.2}% of streaming decode ({:.3}s total)", + tb as f64 / 20e9 / tsec * 100.0, + tb as f64 / 10e9 / tsec * 100.0, + tsec + ); + println!( + "\nUnlike the encoder's slide, the decoder's compaction is a memmove ALONE --\n\ + no table clear, no re-prime -- so there is no hidden bundled term here.\n\ + That makes this ceiling the whole prize, not a lower bound on it." + ); +} diff --git a/crates/rusty_zstd-bench/examples/decgap.rs b/crates/rusty_zstd-bench/examples/decgap.rs new file mode 100644 index 0000000..cd72a8a --- /dev/null +++ b/crates/rusty_zstd-bench/examples/decgap.rs @@ -0,0 +1,133 @@ +//! One-shot vs streaming decode of the SAME bytes, measured admissibly. +//! +//! The first cut of this compared two sequential best-of-N blocks and produced +//! ratios from 0.49x to 1.20x -- including "streaming is FASTER than one-shot", +//! which is not a thing. The one-shot arm itself moved 29% between runs, i.e. +//! the denominator drifted further than the effect. codec-measurement: never +//! headline a ratio whose denominator moves more than your improvement. +//! +//! So: both arms in ONE process, ABBA-interleaved so drift cancels instead of +//! landing on one arm, paired win-rate with a z-score, and a NULL arm +//! (one-shot against itself) to establish what this box can resolve at all. +use rusty_zstd::Decompressor; + +fn one_shot(z: &[u8], out: &mut Vec) -> f64 { + let t = std::time::Instant::now(); + out.clear(); + rusty_zstd::decompress_into(out, z).unwrap(); + t.elapsed().as_secs_f64() +} + +fn streaming(z: &[u8], buf: &mut [u8], chunk: usize) -> (f64, usize) { + let t = std::time::Instant::now(); + let mut d = Decompressor::new(); + let (mut n, mut i) = (0usize, 0usize); + while i < z.len() { + let end = (i + chunk).min(z.len()); + let mut inp = &z[i..end]; + // DRAIN FULLY before feeding more. The decoder consumes all input it + // is handed but emits only what fits `buf`, so feeding a chunk and + // reading ONCE under-drains: at a 3:1 ratio a 64 KiB chunk yields + // ~192 KiB, `decoded` accumulates, and the harness measures a + // backlog no real consumer would build. Loop until it stops emitting. + loop { + let st = d.stream(inp, buf, false).expect("s"); + n += st.output_produced; + inp = &inp[st.input_consumed..]; + if st.input_consumed == 0 && st.output_produced == 0 { + break; + } + } + i = end; + } + loop { + let st = d.stream(&[], buf, true).expect("d"); + n += st.output_produced; + if st.output_produced == 0 { + break; + } + } + (t.elapsed().as_secs_f64(), n) +} + +fn verdict(name: &str, a: &[f64], b: &[f64]) { + let wins = a.iter().zip(b).filter(|(x, y)| y < x).count(); + let ties = a + .iter() + .zip(b) + .filter(|(x, y)| (**y - **x).abs() < 1e-9) + .count(); + let eff = a.len() - ties; + let z = if eff == 0 { + 0.0 + } else { + (wins as f64 - eff as f64 / 2.0) / (0.5 * (eff as f64).sqrt()) + }; + let med = |v: &[f64]| { + let mut s = v.to_vec(); + s.sort_by(|x, y| x.partial_cmp(y).unwrap()); + s[s.len() / 2] + }; + let mn = |v: &[f64]| v.iter().cloned().fold(f64::MAX, f64::min); + println!(" {name:<26} median {:.4}->{:.4}s ({:.3}x) min {:.4}->{:.4} ({:.3}x) {wins}/{eff} z={z:+.2}", + med(a), med(b), med(a)/med(b), mn(a), mn(b), mn(a)/mn(b)); +} + +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + let reps: usize = std::env::args() + .nth(2) + .and_then(|s| s.parse().ok()) + .unwrap_or(15); + let obits: u32 = std::env::args() + .nth(3) + .and_then(|s| s.parse().ok()) + .unwrap_or(17); + let cbits: u32 = std::env::args() + .nth(4) + .and_then(|s| s.parse().ok()) + .unwrap_or(16); + let chunk = 1usize << cbits; + for id in ["samba", "webster", "mozilla"] { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) else { + continue; + }; + let src = &f[..f.len().min(32 << 20)]; + let ck = std::env::var("RZSTD_BENCH_NO_CK").is_err(); + let z = rusty_zstd::compress_with( + src, + rusty_zstd::CompressOptions { + level: lvl, + checksum: ck, + }, + ) + .expect("compress"); + let mut out = Vec::with_capacity(src.len()); + let mut buf = vec![0u8; 1usize << obits]; + let (_, n) = streaming(&z, &mut buf, chunk); + assert_eq!(n, src.len()); + println!("\n{id} {:.1} MiB", src.len() as f64 / (1 << 20) as f64); + let (mut a, mut b, mut na, mut nb) = (vec![], vec![], vec![], vec![]); + for r in 0..reps { + if r % 2 == 0 { + a.push(one_shot(&z, &mut out)); + b.push(streaming(&z, &mut buf, chunk).0); + na.push(one_shot(&z, &mut out)); + nb.push(one_shot(&z, &mut out)); + } else { + b.push(streaming(&z, &mut buf, chunk).0); + a.push(one_shot(&z, &mut out)); + nb.push(one_shot(&z, &mut out)); + na.push(one_shot(&z, &mut out)); + } + } + verdict("NULL (one-shot twice)", &na, &nb); + verdict("one-shot -> streaming", &a, &b); + } + println!( + "\nRead the NULL first. 'one-shot -> streaming' RATIO BELOW 1.0 means streaming is SLOWER." + ); +} diff --git a/crates/rusty_zstd-bench/examples/decstage.rs b/crates/rusty_zstd-bench/examples/decstage.rs new file mode 100644 index 0000000..a1908d0 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/decstage.rs @@ -0,0 +1,156 @@ +//! Stage breakdown: one-shot decode vs streaming decode, SAME bytes. +//! +//! The copy census says streaming decode moves ~2.1 B per output byte, which +//! prices at 1-2% of decode -- while the measured gap is 1.4-2.0x. So the +//! copies are not the gap, and the question is which STAGE grows. That is the +//! stage profiler's job. +//! +//! Profiled build: scope guards are rdtsc pairs, so absolute numbers carry the +//! instrument's own tax. Read the RATIO between the two arms per stage, since +//! both arms pay the same per-scope cost for the same call counts. +use rusty_zstd::{Decompressor, ProfStage}; + +const STAGES: &[(ProfStage, &str)] = &[ + (ProfStage::DecodeTotal, "DecodeTotal"), + (ProfStage::DecodeBlocks, "DecodeBlocks"), + (ProfStage::DecodeLiterals, "DecodeLiterals"), + (ProfStage::DecodeSeq, "DecodeSeq"), + (ProfStage::DecodeChecksum, "DecodeChecksum"), + (ProfStage::DecSeqHeader, " DecSeqHeader"), + (ProfStage::DecSeqTables, " DecSeqTables"), + (ProfStage::DecSeqLoop, " DecSeqLoop"), + (ProfStage::DecSeqTail, " DecSeqTail"), + (ProfStage::StreamInAcc, "StreamInAcc"), + (ProfStage::StreamProgress, "StreamProgress"), + (ProfStage::StreamOutCopy, "StreamOutCopy"), + (ProfStage::StreamCompact, "StreamCompact"), +]; + +fn snap() -> Vec<(u64, u64)> { + STAGES + .iter() + .map(|(s, _)| { + ( + rusty_zstd::prof_stage_ns(*s), + rusty_zstd::prof_stage_calls(*s), + ) + }) + .collect() +} + +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + let id = std::env::args().nth(2).unwrap_or_else(|| "webster".into()); + let f = std::fs::read(format!("corpora/data/silesia/{id}")).expect("corpus"); + let src = &f[..f.len().min(32 << 20)]; + let z = rusty_zstd::compress(src, lvl).expect("compress"); + let chunk = 64 << 10; + + let mut out = Vec::with_capacity(src.len()); + rusty_zstd::prof_reset(); + let t = std::time::Instant::now(); + rusty_zstd::decompress_into(&mut out, &z).unwrap(); + let wall_a = t.elapsed().as_secs_f64(); + let a = snap(); + + let mut buf = vec![0u8; 128 << 10]; + rusty_zstd::prof_reset(); + let t = std::time::Instant::now(); + let mut d = Decompressor::new(); + let (mut n, mut i) = (0usize, 0usize); + while i < z.len() { + let end = (i + chunk).min(z.len()); + let mut inp = &z[i..end]; + loop { + let st = d.stream(inp, &mut buf, false).expect("s"); + n += st.output_produced; + inp = &inp[st.input_consumed..]; + if inp.is_empty() || (st.input_consumed == 0 && st.output_produced == 0) { + break; + } + } + i = end; + } + loop { + let st = d.stream(&[], &mut buf, true).expect("d"); + n += st.output_produced; + if st.output_produced == 0 { + break; + } + } + let wall_b = t.elapsed().as_secs_f64(); + let b = snap(); + assert_eq!(n, src.len()); + + println!( + "{id} L{lvl} {:.1} MiB -- stage ns and CALLS, one-shot vs streaming\n", + src.len() as f64 / (1 << 20) as f64 + ); + println!( + "{:<16}{:>13}{:>13}{:>8} {:>11}{:>11}{:>8}", + "stage", "oneshot ms", "stream ms", "x", "os calls", "st calls", "x" + ); + for (k, (s, name)) in STAGES.iter().enumerate() { + let _ = s; + let (na, ca) = a[k]; + let (nb, cb) = b[k]; + if na == 0 && nb == 0 { + continue; + } + println!( + "{name:<16}{:>13.2}{:>13.2}{:>8.2} {ca:>11}{cb:>11}{:>8.2}", + na as f64 / 1e6, + nb as f64 / 1e6, + if na > 0 { nb as f64 / na as f64 } else { 0.0 }, + if ca > 0 { cb as f64 / ca as f64 } else { 0.0 } + ); + } + // Residue = wall MINUS the stages that were scoped. Both arms are measured + // in the SAME profiled build, so the per-scope rdtsc tax is common to both + // and the comparison is like-for-like; mixing a profiled stage total + // against an unprofiled wall is not. + let sa = (a[2].0 + a[3].0 + a[4].0) as f64 / 1e9; + let sb = (b[2].0 + b[3].0 + b[4].0) as f64 / 1e9; + println!( + "\n{:<16}{:>13}{:>13}{:>8}", + "", "oneshot ms", "stream ms", "x" + ); + println!( + "{:<16}{:>13.2}{:>13.2}{:>8.2}", + "WALL", + wall_a * 1e3, + wall_b * 1e3, + wall_b / wall_a + ); + println!( + "{:<16}{:>13.2}{:>13.2}{:>8.2}", + "scoped stages", + sa * 1e3, + sb * 1e3, + sb / sa + ); + println!( + "{:<16}{:>13.2}{:>13.2}{:>8.2} <-- everything OUTSIDE the decode stages", + "RESIDUE", + (wall_a - sa) * 1e3, + (wall_b - sb) * 1e3, + if wall_a - sa > 0.0 { + (wall_b - sb) / (wall_a - sa) + } else { + 0.0 + } + ); + println!( + "residue share: one-shot {:.1}%, streaming {:.1}% of its own wall", + (wall_a - sa) / wall_a * 100.0, + (wall_b - sb) / wall_b * 100.0 + ); + println!( + "\nA stage whose CALL count matches but whose ns grows is doing the same work slower\n\ + (locality, allocation, or a per-call cost). A stage whose CALLS grow is being\n\ + re-entered more often -- a structural difference in how the path is driven." + ); +} diff --git a/crates/rusty_zstd-bench/examples/encwhere.rs b/crates/rusty_zstd-bench/examples/encwhere.rs new file mode 100644 index 0000000..6651b24 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/encwhere.rs @@ -0,0 +1,36 @@ +//! Where does encode time actually go? Stage shares, not guesses. +use rusty_zstd::ProfStage as S; +const ST: &[(S, &str)] = &[ + (S::EncodeTotal, "EncodeTotal"), + (S::EncodeBlocks, " EncodeBlocks"), + (S::EncodeMatchFind, " MatchFind"), + (S::EncodeEntropy, " Entropy"), + (S::EncodeHuff, " Huff"), + (S::EncodeSeqCode, " SeqCode"), + (S::EncodeTableSelect, " TableSelect"), + (S::EncodeFseSeq, " FseSeq"), + (S::EncodeTables, " EncodeTables"), + (S::EncodeChecksum, " Checksum"), +]; +fn main() { + let lvl: i32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(3); + let id = std::env::args().nth(2).unwrap_or_else(|| "dickens".into()); + let f = std::fs::read(format!("corpora/data/silesia/{id}")).expect("corpus"); + let src = &f[..f.len().min(16 << 20)]; + rusty_zstd::prof_reset(); + let z = rusty_zstd::compress(src, lvl).expect("c"); + let tot = rusty_zstd::prof_stage_ns(S::EncodeTotal).max(1) as f64; + println!("{id} L{lvl} {:.1} MiB -> {:.1} MiB\n", src.len() as f64/(1<<20) as f64, z.len() as f64/(1<<20) as f64); + println!("{:<20}{:>12}{:>9}{:>12}", "stage", "ms", "% total", "calls"); + for (s, n) in ST { + let ns = rusty_zstd::prof_stage_ns(*s); + let c = rusty_zstd::prof_stage_calls(*s); + if ns == 0 && c == 0 { continue; } + println!("{n:<20}{:>12.1}{:>8.1}%{c:>12}", ns as f64/1e6, ns as f64/tot*100.0); + } + let mf = rusty_zstd::prof_stage_ns(S::EncodeMatchFind) as f64; + let en = rusty_zstd::prof_stage_ns(S::EncodeEntropy) as f64; + println!("\nmatch-find {:.1}% entropy {:.1}% everything else {:.1}%", + mf/tot*100.0, en/tot*100.0, (tot-mf-en)/tot*100.0); + println!("(profiled build: rdtsc scope pairs inflate absolute ms; read the SHARES)"); +} diff --git a/crates/rusty_zstd-bench/examples/envreads.rs b/crates/rusty_zstd-bench/examples/envreads.rs new file mode 100644 index 0000000..2e267b2 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/envreads.rs @@ -0,0 +1,26 @@ +//! How many times does a compress read the ENVIRONMENT? +//! +//! Every `env_knob` is an OS lookup and a `String` allocation for a value fixed +//! for the life of the process. The right number is "once per knob, ever". A +//! count that scales with blocks means a cache whose sentinel collides with the +//! value it caches -- e.g. storing 0 for "unset" when 0 is also the default. +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + let f = std::fs::read("corpora/data/silesia/dickens").expect("corpus"); + for mib in [1usize, 2, 4, 8] { + let src = &f[..f.len().min(mib << 20)]; + let _ = rusty_zstd::take_env_reads(); + let z = rusty_zstd::compress(src, lvl).expect("c"); + let n = rusty_zstd::take_env_reads(); + assert_eq!(rusty_zstd::decompress(&z).expect("d"), src); + let _ = rusty_zstd::take_env_reads(); + println!( + "{mib:>3} MiB -> {n:>7} env reads ({:.1} per MiB)", + n as f64 / mib as f64 + ); + } + println!("\nFlat across sizes = cached. Growing with input = a broken cache."); +} diff --git a/crates/rusty_zstd-bench/examples/eqlever.rs b/crates/rusty_zstd-bench/examples/eqlever.rs new file mode 100644 index 0000000..a2314f2 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/eqlever.rs @@ -0,0 +1,86 @@ +//! DOES IMPROVING THE ONE SHARED PRIMITIVE LIFT BOTH FINDERS? +//! +//! cargo run --release --features profile -p rusty_zstd-bench --example eqlever +//! +//! `find_fast_impl` and `find_dfast_impl` share exactly one primitive: +//! `count_match` -> `count_eq_len_ge8`. This measures the SENSITIVITY of each +//! finder to that primitive by swapping its implementation wholesale -- +//! `set_eqlen_arm(1)` forces the scalar word-at-a-time path, bypassing the +//! ladder+AVX2 kernels entirely. Output is byte-identical (asserted); only the +//! instruction mix inside the shared primitive changes. +//! +//! This is a CEILING, not an estimate: swapping vector for scalar is a larger +//! perturbation than any realistic improvement to that primitive could be. If +//! encode time does not separate here, no improvement to the shared primitive +//! can lift either finder -- and a fortiori not both. +//! +//! CONSERVATIVE BY CONSTRUCTION: the arm is only live under `profile`, whose +//! `eq_call` counter fires on EVERY comparator entry, before the arm branch. +//! That tax is identical on both arms and lands on the comparator path +//! specifically, so it INFLATES this primitive's apparent share. A null result +//! under inflation is a safe null. +//! +//! ABBA-phased with a paired estimator (cancels monotone drift), plus a NULL +//! arm (arm 0 against itself) to establish what this box can resolve. +fn phase(src: &[u8], lvl: i32, arm: u8, n: usize) -> (f64, u64) { + rusty_zstd::set_eqlen_arm(arm); + let mut b = f64::MAX; + let mut h = 0u64; + for _ in 0..n { + let t = std::time::Instant::now(); + let out = rusty_zstd::compress(src, lvl).unwrap(); + let e = t.elapsed().as_secs_f64() * 1000.0; + if e < b { b = e; } + h = out.iter().fold(1469598103934665603u64, + |a, &c| (a ^ c as u64).wrapping_mul(1099511628211)); + } + (b, h) +} +fn main() { + let ids = ["dickens", "webster", "mozilla", "samba", "nci", "x-ray"]; + for (lvl, finder) in [(1i32, "find_fast_impl"), (3, "find_dfast_impl")] { + println!("\n=== L{lvl} {finder} ==="); + println!("{:<10}{:>12}{:>12} {}", "corpus", "TREAT %", "NULL %", "bytes"); + let mut rows: Vec<(f64, f64)> = Vec::new(); + for id in ids { + let Ok(full) = std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) else { continue }; + let src = &full[..full.len().min(2 << 20)]; + let (mut treat, mut null) = (vec![], vec![]); + let (mut h0, mut h1) = (0u64, 0u64); + for _ in 0..7 { + // treatment: A = vector arm, B = words-only arm, ABBA + let (a1, x) = phase(src, lvl, 0, 15); let (b1, y) = phase(src, lvl, 1, 15); + let (b2, _) = phase(src, lvl, 1, 15); let (a2, _) = phase(src, lvl, 0, 15); + h0 = x; h1 = y; + treat.push(0.5 * (100.0*(b1-a1)/a1 + 100.0*(b2-a2)/a2)); + // null: both phases the SAME arm + let (c1, _) = phase(src, lvl, 0, 15); let (d1, _) = phase(src, lvl, 0, 15); + let (d2, _) = phase(src, lvl, 0, 15); let (c2, _) = phase(src, lvl, 0, 15); + null.push(0.5 * (100.0*(d1-c1)/c1 + 100.0*(d2-c2)/c2)); + } + let m = |v: &Vec| v.iter().sum::() / v.len() as f64; + let (t, n) = (m(&treat), m(&null)); + // NO PER-ROW VERDICT. An earlier version flagged "separates" when + // |treat| > 3*|null|, which is unstable exactly when the null lands + // near zero: webster L3 drew null 0.08%, so any treatment above + // 0.24% "separated". The null is an estimate of a SPREAD, not a + // per-row threshold -- it is only meaningful pooled across corpora, + // which is what the summary below does. + rows.push((t, n)); + println!("{id:<10}{:>12.2}{:>12.2} {}", t, n, + if h0 == h1 { "identical" } else { "MISMATCH" }); + } + let sp = |v: Vec| { + let m = v.iter().sum::() / v.len() as f64; + let sd = (v.iter().map(|x| (x - m) * (x - m)).sum::() / v.len() as f64).sqrt(); + (m, sd, v.iter().cloned().fold(f64::MAX, f64::min), v.iter().cloned().fold(f64::MIN, f64::max)) + }; + let (tm, ts, tlo, thi) = sp(rows.iter().map(|r| r.0).collect()); + let (nm, ns, nlo, nhi) = sp(rows.iter().map(|r| r.1).collect()); + println!(" treatment mean {tm:+.2}% sd {ts:.2} range [{tlo:+.2}, {thi:+.2}]"); + println!(" null mean {nm:+.2}% sd {ns:.2} range [{nlo:+.2}, {nhi:+.2}]"); + println!(" => {}", if tm.abs() > nm.abs() + ns { "RESOLVES" } else { "NOT RESOLVED: treatment lies inside the null band" }); + } + rusty_zstd::set_eqlen_arm(0); +} diff --git a/crates/rusty_zstd-bench/examples/eqshare.rs b/crates/rusty_zstd-bench/examples/eqshare.rs new file mode 100644 index 0000000..a891a00 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/eqshare.rs @@ -0,0 +1,38 @@ +//! Price the ONE primitive both finders share: count_match -> count_eq_len_ge8. +//! calls per scanned position, and the returned-length histogram that decides +//! whether a wider kernel could ever help. +const IDS: &[&str] = &["x-ray", "osdb", "jsonlog-16m", "smallmsg-8m", "ooffice", "sao", + "dickens", "samba", "nci", "webster", "mozilla", "mr"]; +fn main() { + #[cfg(feature = "profile")] + { + let cap: usize = 8 << 20; + for lvl in [1i32, 3] { + let p = rusty_zstd::compression_params(lvl, None).unwrap(); + let _ = rusty_zstd::take_eqlen_stats(); + let _ = rusty_zstd::take_mm(); + let (mut pos, mut bytes) = (0u64, 0f64); + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) else { continue }; + let s = &f[..f.len().min(cap)]; + let _ = rusty_zstd::compress(s, lvl).unwrap(); + bytes += s.len() as f64; + } + pos += rusty_zstd::take_mm().0; + let (calls, work, h) = rusty_zstd::take_eqlen_stats(); + let t: u64 = h.iter().sum::().max(1); + println!("\n=== L{lvl} ({:?}) ===", p.strategy); + println!(" positions scanned {pos}"); + println!(" count_eq_len_ge8 calls {calls} ({:.3} per position)", calls as f64 / pos.max(1) as f64); + println!(" bytes compared {work} ({:.1} per call)", work as f64 / calls.max(1) as f64); + println!(" board {:.1} MB", bytes / 1e6); + println!(" returned-length histogram:"); + for (i, n) in ["<3","3-7","8-31","32-63","64-255","256+"].iter().zip(h.iter()) { + println!(" {:<8} {:>12} {:>5.1}%", i, n, *n as f64 / t as f64 * 100.0); + } + } + } + #[cfg(not(feature = "profile"))] + println!("needs --features rusty_zstd/profile"); +} diff --git a/crates/rusty_zstd-bench/examples/eqwork.rs b/crates/rusty_zstd-bench/examples/eqwork.rs index 596d262..4aed41e 100644 --- a/crates/rusty_zstd-bench/examples/eqwork.rs +++ b/crates/rusty_zstd-bench/examples/eqwork.rs @@ -13,7 +13,7 @@ fn main() { let _ = rusty_zstd::compress_with(s, rusty_zstd::CompressOptions { level: lvl, checksum: false }).unwrap(); } let (calls, _we, h) = rusty_zstd::take_eqlen_stats(); - println!("L{lvl}: calls {calls}, len-hist [<8:{} 8-31:{} 32-63:{} 64-255:{} 256+:{}]", h[0],h[1],h[2],h[3],h[4]); + println!("L{lvl}: calls {calls}, len-hist [<3:{} 3-7:{} 8-31:{} 32-63:{} 64-255:{} 256+:{}]", h[0],h[1],h[2],h[3],h[4],h[5]); } } } diff --git a/crates/rusty_zstd-bench/examples/fillcensus.rs b/crates/rusty_zstd-bench/examples/fillcensus.rs new file mode 100644 index 0000000..0c1a435 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/fillcensus.rs @@ -0,0 +1,80 @@ +//! Fill / walk census for the link-representation and tag levers. +//! +//! cargo run --release --features profile -p rusty_zstd-bench --example fillcensus +//! +//! Per level, over the silesia sample: walks by exit reason (index 0 = the +//! head was EMPTY, no walk), candidates examined, first-word misses, tag +//! skips (and false skips, which must be 0), fill inserts, and the phantom +//! position-0 census. The empty-head count is what "heads hold the decoded +//! link" would turn into a one-iteration walk; the skip/exam pair prices a +//! weaker tag. +#[cfg(feature = "profile")] +const IDS: &[&str] = &["dickens", "mozilla", "webster", "xml", "samba"]; +fn main() { + #[cfg(not(feature = "profile"))] + { + println!("needs --features rusty_zstd/profile"); + } + #[cfg(feature = "profile")] + { + let levels: Vec = std::env::args() + .skip(1) + .filter_map(|a| a.parse().ok()) + .collect(); + let levels = if levels.is_empty() { + vec![5, 7, 9, 12] + } else { + levels + }; + println!( + "{:>3} {:>11} {:>11} {:>7} {:>11} {:>11} {:>11} {:>9} {:>11} {:>9} {:>6}", + "L", "walks", "empty", "empty%", "exam", "bytemiss", "skips", "false", "inserts", "m0", "acc" + ); + for lvl in levels { + let mut walks = 0u64; + let mut empty = 0u64; + let (mut exam, mut miss, mut skips, mut falses, mut ins, mut m0, mut acc) = + (0u64, 0u64, 0u64, 0u64, 0u64, 0u64, 0u64); + for id in IDS { + let Ok(full) = std::fs::read(format!("corpora/data/silesia/{id}")) else { + continue; + }; + let src = &full[..full.len().min(16 << 20)]; + let _ = rusty_zstd::take_walk_exit(); + let _ = rusty_zstd::take_walk_census(); + let _ = rusty_zstd::take_link_tag(); + let _ = rusty_zstd::take_lazy_fill(); + let _ = rusty_zstd::take_walk_phantom(); + let _ = rusty_zstd::compress(src, lvl).unwrap(); + let ex = rusty_zstd::take_walk_exit(); + walks += ex.iter().sum::(); + empty += ex[0]; + let (e, b) = rusty_zstd::take_walk_census(); + exam += e; + miss += b; + let (s, f) = rusty_zstd::take_link_tag(); + skips += s; + falses += f; + let (_, _, i) = rusty_zstd::take_lazy_fill(); + ins += i; + let (a, c) = rusty_zstd::take_walk_phantom(); + m0 += a; + acc += c; + } + println!( + "{:>3} {:>11} {:>11} {:>6.2}% {:>11} {:>11} {:>11} {:>9} {:>11} {:>9} {:>6}", + lvl, + walks, + empty, + 100.0 * empty as f64 / walks.max(1) as f64, + exam, + miss, + skips, + falses, + ins, + m0, + acc + ); + } + } +} diff --git a/crates/rusty_zstd-bench/examples/fusedcount.rs b/crates/rusty_zstd-bench/examples/fusedcount.rs new file mode 100644 index 0000000..edab106 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/fusedcount.rs @@ -0,0 +1,70 @@ +//! BRICK 11's deterministic verdict: how often does the fused head resolve the +//! match length from the xor it already had (SHORT: first differing byte inside +//! the first word, no second load pair) versus falling through to the counter +//! (LONG: all eight bytes equal)? Per accepted candidate the fused form is about +//! five instructions cheaper on SHORT and three dearer on LONG, so the mix +//! decides -- and the mix is a count, not a clock. +//! +//! cargo run --release --features profile -p rusty_zstd-bench --example fusedcount +const IDS: &[&str] = &[ + "jsonlog-16m", + "smallmsg-8m", + "mr", + "ooffice", + "osdb", + "reymont", + "sao", + "webster", + "dickens", + "mozilla", + "nci", + "samba", + "xml", + "x-ray", + "text-32m", + "incomp-32m", +]; +fn main() { + let cap = 1usize << 20; + let srcs: Vec> = IDS + .iter() + .filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok() + .map(|f| { + let n = f.len().min(cap); + f[..n].to_vec() + }) + }) + .collect(); + println!( + "{:>4}{:>14}{:>14}{:>9}{:>16}", + "L", "short", "long", "short%", "net instrs" + ); + for lvl in [3i32, 4, 5, 7, 9, 12] { + let _ = rusty_zstd::take_fused(); + for s in &srcs { + let _ = rusty_zstd::compress_with( + s, + rusty_zstd::CompressOptions { + level: lvl, + checksum: false, + }, + ) + .unwrap(); + } + let (short, long) = rusty_zstd::take_fused(); + let tot = (short + long).max(1); + let net = short as i64 * -5 + long as i64 * 3; + println!( + "{:>4}{:>14}{:>14}{:>8.1}%{:>+16}", + lvl, + short, + long, + short as f64 / tot as f64 * 100.0, + net + ); + } + println!("\nnet < 0 at a level = the fused head removes instructions there (modelled -5 per SHORT, +3 per LONG)."); +} diff --git a/crates/rusty_zstd-bench/examples/g12l19.rs b/crates/rusty_zstd-bench/examples/g12l19.rs deleted file mode 100644 index 4815ab9..0000000 --- a/crates/rusty_zstd-bench/examples/g12l19.rs +++ /dev/null @@ -1,35 +0,0 @@ -//! GATE 12 @ L19, part 1: what did the per-jump `std::env::var` cost? -//! text-32m and versions-16m hold 93% of all jumped positions. -const IDS:&[&str]=&["text-32m","versions-16m","zeros-32m","dickens","samba","nci","xml","x-ray","mozilla"]; -fn ms(src:&[u8],h:bool,lvl:i32,r:usize)->f64{ - rusty_zstd::set_opt_hoist_arm(h); - let mut b=f64::MAX; - for _ in 0..r { let t=std::time::Instant::now(); let _=rusty_zstd::compress(src,lvl).unwrap(); - let e=t.elapsed().as_secs_f64()*1000.0; if ef64{ - let mut d=vec![]; - for _ in 0..3 { let a1=ms(src,a,lvl,r); let b1=ms(src,b,lvl,r); - let b2=ms(src,b,lvl,r); let a2=ms(src,a,lvl,r); - d.push(0.5*(100.0*(b1-a1)/a1+100.0*(b2-a2)/a2)); } - d.sort_by(|x,y|x.partial_cmp(y).unwrap()); d[1] -} -fn main(){ - let lvl:i32=std::env::args().nth(1).and_then(|s|s.parse().ok()).unwrap_or(19); - println!("L{lvl}: env lookup per jumped position -> hoisted to per block"); - println!("negative = the hoist is FASTER\n"); - println!("{:<14}{:>9}{:>11}","corpus","null","hoist"); - let (mut tn,mut tf,mut k)=(0.0,0.0,0.0); - for id in IDS{ - let Ok(full)=std::fs::read(format!("corpora/data/generated/{id}")) - .or_else(|_|std::fs::read(format!("corpora/data/silesia/{id}"))) else{continue}; - let src=&full[..full.len().min(2<<20)]; - let n=paired(src,false,false,lvl,3); - let f=paired(src,false,true,lvl,3); - println!("{id:<14}{n:>8.2}%{f:>10.2}%"); - tn+=n.abs(); tf+=f; k+=1.0; - } - println!("\nmean |null| {:.2}% mean hoist {:+.2}%", tn/k, tf/k); - rusty_zstd::set_opt_hoist_arm(true); -} diff --git a/crates/rusty_zstd-bench/examples/incomp.rs b/crates/rusty_zstd-bench/examples/incomp.rs new file mode 100644 index 0000000..fa80935 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/incomp.rs @@ -0,0 +1,33 @@ +//! The one head-to-head signal that survives a 16% null: at L7/L9 we read +//! 11.5-12.2x slower than C on INCOMPRESSIBLE data. An 11x gap is not noise, +//! so it should be visible in a deterministic counter -- and if it is, the +//! clock is not needed at all. +//! +//! `incomp_skip` is a LIVE arm at L1/L3 (`allgates`), but the levels above +//! run the chain/lazy finders. If the skip is not reaching them, we walk full +//! hash chains over random bytes that can never match. +use rusty_zstd as rz; +fn main() { + let f = std::fs::read("corpora/data/generated/incomp-32m") + .expect("incomp-32m"); + let src = &f[..f.len().min(1 << 20)]; + println!("incompressible input: {} KiB\n", src.len() >> 10); + println!("{:>4}{:>10}{:>14}{:>14}{:>14}{:>12}", + "L", "strategy", "positions", "candidates", "chain loads", "out bytes"); + println!("{}", "-".repeat(70)); + for lvl in [1i32, 3, 5, 7, 9, 12] { + let p = rz::compression_params(lvl, Some(src.len() as u64)).unwrap(); + rz::prof_reset(); + let _ = rz::take_mm(); + let _ = rz::take_walk_census(); + let out = rz::compress_with(src, rz::CompressOptions { level: lvl, checksum: false }).unwrap(); + let c = rz::prof_encode_counts(); + let pos = rz::take_mm().0; + let walk = rz::take_walk_census().0; + println!("{:>4}{:>10}{:>14}{:>14}{:>14}{:>12}", + lvl, format!("{:?}", p.strategy), pos, c.hash_probes, walk, out.len()); + } + println!("\npositions/candidates are Fast/DFast counters; `chain loads` (WALK_EXAM)"); + println!("is the Greedy/Lazy ladder's. A large chain-load count on data that"); + println!("cannot match is work spent proving there is no match."); +} diff --git a/crates/rusty_zstd-bench/examples/incwhere.rs b/crates/rusty_zstd-bench/examples/incwhere.rs new file mode 100644 index 0000000..d3bc7ae --- /dev/null +++ b/crates/rusty_zstd-bench/examples/incwhere.rs @@ -0,0 +1,41 @@ +//! WHERE does incompressible data spend its time, by level? +//! +//! The head-to-head board reads 11.5-12.2x slower than C at L7/L9 on +//! `incomp-32m`. A 12x effect cannot be a 16% null -- load explains +-16%, not +//! +1100% -- so if the number is wrong it is wrong for a STRUCTURAL reason, not +//! a noise reason. The deterministic counters already ruled out search work +//! (0 chain loads at L7). This asks the stage profiler where it actually goes. +//! +//! Stage timers are distorted by their own instrumentation and are read ONLY as +//! shares, and only to rank -- but a 12x gap does not need precision to locate. +use rusty_zstd::ProfStage as S; +fn main() { + let f = std::fs::read("corpora/data/generated/incomp-32m").expect("incomp-32m"); + let src = &f[..f.len().min(1 << 20)]; + println!("incompressible, {} KiB\n", src.len() >> 10); + println!("{:>4}{:>10}{:>12}{:>9}{:>9}{:>9}{:>9}{:>9}", + "L", "strategy", "total us", "tables", "find%", "entropy%", "huff%", "other%"); + println!("{}", "-".repeat(72)); + for tight in [0u32, 1] { + println!("--- hash_tight = {tight} ---"); + for lvl in [1i32, 3, 5, 7, 9, 12] { + rusty_zstd::set_hash_tight_arm(tight); + let p = rusty_zstd::compression_params(lvl, Some(src.len() as u64)).unwrap(); + // warm, then measure + for _ in 0..3 { let _ = rusty_zstd::compress_with_params(src, p, false).unwrap(); } + rusty_zstd::prof_reset(); + for _ in 0..5 { let _ = rusty_zstd::compress_with_params(src, p, false).unwrap(); } + let tot = rusty_zstd::prof_stage_ns(S::EncodeTotal) as f64; + let g = |s: S| rusty_zstd::prof_stage_ns(s) as f64 / tot * 100.0; + let tbl = rusty_zstd::prof_stage_ns(S::EncodeTables) as f64 / tot * 100.0; + let find = g(S::EncodeMatchFind); + let ent = g(S::EncodeEntropy); + let huff = g(S::EncodeHuff); + println!("{:>4}{:>10}{:>12.0}{:>8.1}%{:>8.1}%{:>8.1}%{:>8.1}%{:>8.1}%", + lvl, format!("{:?}", p.strategy), tot / 1000.0 / 5.0, + tbl, find, ent, huff, 100.0 - tbl - find - ent); + } + } + rusty_zstd::set_hash_tight_arm(0); + println!("\n(entropy% includes huff%; other% = 100 - tables - find - entropy)"); +} diff --git a/crates/rusty_zstd-bench/examples/kreach.rs b/crates/rusty_zstd-bench/examples/kreach.rs new file mode 100644 index 0000000..6fb6b33 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/kreach.rs @@ -0,0 +1,154 @@ +//! KERNEL REACH CENSUS -- one line per shipping dispatch site, encode and decode. +//! +//! Deterministic: same numbers on any machine, at any load. No clock, no +//! pinning, no ABBA, no z-score. Anything under 100% on the arch you ship is +//! a finding; the goal bar for this crate is >=95% per site. +//! +//! Encode and decode are censused SEPARATELY, because "50% of encode and 0% +//! of decode" is exactly the shape a combined number hides. +//! +//! Usage: `cargo run --release -p rusty_zstd-bench --example kreach \ +//! --features rusty_zstd/profile -- [level]` +use rusty_zstd::kreach::{self, N_SLOTS, SLOT_NAMES}; + +const IDS: &[&str] = &[ + "zeros-32m", + "text-32m", + "incomp-32m", + "versions-16m", + "jsonlog-16m", + "smallmsg-8m", + "dickens", + "mozilla", + "samba", + "webster", + "x-ray", + "osdb", + "reymont", + "nci", + "xml", + "sao", +]; + +fn load(id: &str) -> Option> { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok() +} + +fn add(t: &mut [(u64, u64); N_SLOTS], s: [(u64, u64); N_SLOTS]) { + for i in 0..N_SLOTS { + t[i].0 += s[i].0; + t[i].1 += s[i].1; + } +} + +fn report(title: &str, t: &[(u64, u64); N_SLOTS], want: &str) -> bool { + println!("\n{title}"); + println!( + " {:<24}{:>16}{:>16}{:>10} {}", + "dispatch site", "kernel calls", "scalar calls", "reach", "verdict" + ); + let mut all_ok = true; + let mut any = false; + for i in 0..N_SLOTS { + let (side, name) = (SLOT_NAMES[i].1, SLOT_NAMES[i].0); + if side != want && want != "all" { + continue; + } + let (h, m) = t[i]; + if h + m == 0 { + println!(" {name:<24}{:>16}{:>16}{:>10} NOT EXERCISED", h, m, "-"); + continue; + } + any = true; + let pct = 100.0 * h as f64 / (h + m) as f64; + let ok = pct >= 95.0; + all_ok &= ok; + println!( + " {name:<24}{h:>16}{m:>16}{:>9.2}% {}", + pct, + if ok { "OK" } else { "*** UNDER 95% ***" } + ); + } + if !any { + println!(" (no site on this side was exercised)"); + } + all_ok +} + +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + // POISON MODE. An all-100% census is worth nothing until the instrument + // has been shown to REPORT A MISS -- otherwise "100%" and "the counter is + // not wired" print identically. `--poison` forces every arm this crate + // exposes a knob for onto its scalar side; those slots MUST then fall and + // the run MUST exit non-zero. A poisoned run that still reads 100% is a + // broken tap, not a reachable kernel. + let poison = std::env::args().any(|a| a == "--poison"); + if poison { + println!("*** POISON MODE: arms forced scalar; slots with a knob MUST drop ***"); + rusty_zstd::set_xxh_avx2_arm(false); + rusty_zstd::set_seqloop_avx2_arm(false); + // Arm 3, not 1: arm 1 short-circuits ABOVE the wide dispatch and so + // never exercises the scalar side of that tap. Arm 3 routes through + // the same site a non-AVX2 CPU takes, which is the branch under test. + rusty_zstd::set_eqlen_arm(3); + } else { + rusty_zstd::set_xxh_avx2_arm(true); + } + + let mut enc = [(0u64, 0u64); N_SLOTS]; + let mut dec = [(0u64, 0u64); N_SLOTS]; + let mut mib = 0f64; + let mut n = 0; + + for id in IDS { + let Some(f) = load(id) else { continue }; + let src = &f[..f.len().min(32 << 20)]; + n += 1; + mib += src.len() as f64 / (1 << 20) as f64; + + // ENCODE arm, censused alone. + let _ = kreach::take(); + let z = rusty_zstd::compress(src, lvl).expect("compress"); + add(&mut enc, kreach::take()); + + // DECODE arm, censused alone. The separation is the whole point. + let out = rusty_zstd::decompress(&z).expect("decompress"); + add(&mut dec, kreach::take()); + assert_eq!(out, src, "{id} roundtrip"); + } + + println!("KERNEL REACH CENSUS -- L{lvl}, {n} corpora, {mib:.1} MiB"); + println!("counts, not clocks: identical on any machine at any load"); + let e = report("ENCODE", &enc, "enc"); + let d = report("DECODE", &dec, "dec"); + let b = report("BOTH SIDES (checksum)", &enc, "both"); + let b2 = report("BOTH SIDES (checksum) -- decode arm", &dec, "both"); + + println!( + "\nVERDICT: encode {} decode {} checksum-enc {} checksum-dec {}", + if e { "PASS" } else { "FAIL" }, + if d { "PASS" } else { "FAIL" }, + if b { "PASS" } else { "FAIL" }, + if b2 { "PASS" } else { "FAIL" } + ); + if poison { + // Inverted expectation: the poisoned run must FAIL, and a PASS here + // means the taps are not measuring what their labels claim. + if e && d && b && b2 { + println!("\nPOISON CHECK FAILED: every slot still reads >=95% with the arms"); + println!("forced scalar. The census is not wired to the dispatch it names."); + std::process::exit(1); + } + println!("\nPOISON CHECK PASSED: forcing the arms scalar moved the census."); + return; + } + if !(e && d && b && b2) { + std::process::exit(1); + } +} diff --git a/crates/rusty_zstd-bench/examples/lazyboard.rs b/crates/rusty_zstd-bench/examples/lazyboard.rs new file mode 100644 index 0000000..bd8a167 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/lazyboard.rs @@ -0,0 +1,120 @@ +//! SIZE BOARD for the arms that live in the finders no census could see. +//! +//! cargo run --release -p rusty_zstd-bench --example lazyboard +//! +//! `allgates` covered levels [1, 3, 19, 22] = Fast, DFast, BtUltra2 until this +//! session. Every arm whose call sites are in `find_greedy`, `find_lazy_impl` +//! or `find_bt_lazy` has therefore NEVER been size-boarded -- `lazy_fill` was +//! the first one checked and it had been reported dead for the whole campaign +//! while being worth 266,695 bytes. +//! +//! DISCIPLINE, both learned the hard way earlier today: +//! * the BASELINE is measured FIRST, before any setter is called, because the +//! f32/usize arms cache raw bits with a sentinel and their public setters +//! cannot restore "unset" -- `set_pair_hi_arm(-1.0)` PINS -1.0, and a sweep +//! that used it as a reset read a 6x inflated win. +//! * both arms of every bool are measured against that baseline, so which one +//! is the shipped default is DERIVED, never assumed. +use rusty_zstd as rz; +const IDS: &[&str] = &[ + "jsonlog-16m", + "smallmsg-8m", + "mr", + "ooffice", + "osdb", + "reymont", + "sao", + "webster", + "dickens", + "mozilla", + "nci", + "samba", + "xml", + "x-ray", +]; +const LEVELS: &[(i32, &str)] = &[ + (5, "Greedy"), + (7, "Lazy"), + (9, "Lazy2"), + (13, "BtLazy2"), + (16, "BtOpt"), +]; +fn main() { + let srcs: Vec> = IDS + .iter() + .filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok() + .map(|f| { + let n = f.len().min(1 << 20); + f[..n].to_vec() + }) + }) + .collect(); + let go = |lvl: i32| -> usize { + srcs.iter() + .map(|s| { + rz::compress_with( + s, + rz::CompressOptions { + level: lvl, + checksum: false, + }, + ) + .unwrap() + .len() + }) + .sum() + }; + type S = fn(bool); + let arms: &[(&str, S)] = &[ + ("lazy_fill", rz::set_lazy_fill_arm as S), + ("lazy_gain", rz::set_lazy_gain_arm), + ("row", rz::set_row_arm), + ("walk_cont", rz::set_walk_cont_arm), + ("rep_reprobe", rz::set_rep_reprobe_arm), + ("chain_tag", rz::set_chain_tag_arm), + ("wide_chain", rz::set_wide_chain_arm), + ("prime_bt", rz::set_prime_bt_arm), + ("prime_bt_tree", rz::set_prime_bt_tree_arm), + ("step_probe", rz::set_step_probe_arm), + ("replen_pipe", rz::set_replen_pipe_arm), + ("raw_skip", rz::set_raw_skip_arm), + ]; + // BASELINE FIRST -- nothing has been set yet in this process. + let base: Vec = LEVELS.iter().map(|(l, _)| go(*l)).collect(); + println!("baseline (untouched defaults):"); + for (i, (l, s)) in LEVELS.iter().enumerate() { + println!(" L{l:<3}{s:<9}{}", base[i]); + } + println!( + "\n{:<16}{:>4}{:>12}{:>12} verdict", + "arm", "L", "d(on)", "d(off)" + ); + println!("{}", "-".repeat(62)); + for (name, set) in arms { + for (i, (lvl, strat)) in LEVELS.iter().enumerate() { + set(true); + let on = go(*lvl) as i64 - base[i] as i64; + set(false); + let off = go(*lvl) as i64 - base[i] as i64; + if on == 0 && off == 0 { + continue; + } // inert here + let win = on.min(off); + let tag = if win < 0 { + format!("WIN {win:+} B ({})", if on < off { "on" } else { "off" }) + } else { + format!("default already best ({strat})") + }; + println!("{:<16}{:>4}{:>+12}{:>+12} {tag}", name, lvl, on, off); + } + // restore: whichever arm equals the baseline at the first live level + set(true); + let a = go(LEVELS[2].0) as i64 - base[2] as i64; + if a != 0 { + set(false); + } + } +} diff --git a/crates/rusty_zstd-bench/examples/ldmgate.rs b/crates/rusty_zstd-bench/examples/ldmgate.rs new file mode 100644 index 0000000..91601a8 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/ldmgate.rs @@ -0,0 +1,66 @@ +//! Byte gate for the `--long` (LDM) path, which `bytegate` never exercises: +//! compress a few corpora with LDM enabled at L3/L9/L19 and fold every output +//! byte into one FNV-1a hash. Run before and after an LDM change; the GOLD +//! line must not move. Under `--features profile` it also prints BRICK 18's +//! deterministic counters: candidates that passed the window tests (the +//! population the old per-candidate `memcmp` ran on) and those the 8-byte +//! head let through to the count. +use rusty_zstd::{compress_with_advanced, compression_params, AdvancedOptions, LdmParams}; + +const IDS: &[&str] = &["dickens", "mozilla", "webster", "xml", "samba"]; + +fn main() { + let mut h: u64 = 0xcbf2_9ce4_8422_2325; + let mut total = 0usize; + println!( + "{:<10} {:>4} {:>10} {:>10} ldm candidates -> counted", + "corpus", "L", "in", "out" + ); + for id in IDS { + let Ok(full) = std::fs::read(format!("corpora/data/silesia/{id}")) else { + continue; + }; + let src = &full[..full.len().min(16 << 20)]; + for lvl in [3i32, 9, 19] { + let params = compression_params(lvl, Some(src.len() as u64)).unwrap(); + #[cfg(feature = "profile")] + let _ = rusty_zstd::take_ldm_stats(); + let out = compress_with_advanced( + src, + params, + true, + None, + &[], + true, + AdvancedOptions { + ldm: LdmParams::enabled(), + ..AdvancedOptions::default() + }, + ) + .unwrap(); + for &b in &out { + h ^= u64::from(b); + h = h.wrapping_mul(0x0000_0100_0000_01b3); + } + total += out.len(); + #[cfg(feature = "profile")] + { + let (c, k) = rusty_zstd::take_ldm_stats(); + println!( + "{:<10} {:>4} {:>10} {:>10} {:>10} -> {:<10} ({:.1}% counted)", + id, + lvl, + src.len(), + out.len(), + c, + k, + 100.0 * k as f64 / c.max(1) as f64 + ); + } + #[cfg(not(feature = "profile"))] + println!("{:<10} {:>4} {:>10} {:>10}", id, lvl, src.len(), out.len()); + } + } + println!("total compressed bytes {total}"); + println!("LDM GOLD {h:016X}"); +} diff --git a/crates/rusty_zstd-bench/examples/mfbudget.rs b/crates/rusty_zstd-bench/examples/mfbudget.rs new file mode 100644 index 0000000..4706ad9 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/mfbudget.rs @@ -0,0 +1,299 @@ +//! MATCHFIND WORK BUDGET, per input byte, per level. Deterministic, no clock. +//! +//! cargo run --release --features rusty_zstd/profile -p rusty_zstd-bench --example mfbudget +//! +//! The static census prices a UNIT of work (a scanned position, an examined +//! candidate, a tag-skipped link, a count call, an inserted byte, an emitted +//! match). This example counts how many of each unit run per input byte, so +//! the two multiply into a modelled instruction budget per byte -- and the +//! split says where the encoder's matchfind time goes and which multiplier a +//! reference implementation does not pay. +use std::collections::BTreeMap; + +const IDS: &[&str] = &["dickens", "mozilla", "webster", "xml", "samba"]; +const CAP: usize = 16 << 20; + +#[derive(Default, Clone, Copy)] +struct W { + bytes: f64, + out: f64, + positions: f64, // fast/dfast main-loop positions (MM_TOTAL) + walks: f64, // chain/row kernel calls (sum of walk exits) + exam: f64, // candidates whose first word was compared + bytemiss: f64, // ... of which missed + tagskip: f64, // links rejected by the tag alone + exits: [f64; 8], + counts: f64, // count_match calls + count_hist: [f64; 6], + fused_short: f64, + fused_long: f64, + inserts: f64, // fill inserts (lazy/greedy) -- bytes of matches re-inserted + fills: f64, // fill sites = matches at lazy/greedy + dfast_seqs: f64, + dfast_mb: f64, + fast_seqs: f64, + fast_mb: f64, + rep_probes: f64, + rep_hits: f64, + bt_walks: f64, + bt_iters: f64, + bt_full: f64, + bt_probe: f64, + bt_short: f64, + bt_nogain: f64, + routes: [f64; 3], +} + +fn reset() { + let _ = rusty_zstd::take_mm(); + let _ = rusty_zstd::take_walk_exit(); + let _ = rusty_zstd::take_walk_census(); + let _ = rusty_zstd::take_link_tag(); + let _ = rusty_zstd::take_eqlen_stats(); + let _ = rusty_zstd::take_fused(); + let _ = rusty_zstd::take_lazy_fill(); + let _ = rusty_zstd::take_dfast_match_stats(); + let _ = rusty_zstd::take_rep_rate(); + let _ = rusty_zstd::take_bt_iters(); + let _ = rusty_zstd::take_bt_probe_stats(); + let _ = rusted_route(); +} + +fn rusted_route() -> (u64, u64, u64) { + let (a, b, c, _, _) = rusty_zstd::take_route_hist(); + (a, b, c) +} + +fn main() { + #[cfg(not(feature = "profile"))] + { + println!("needs --features rusty_zstd/profile"); + return; + } + #[cfg(feature = "profile")] + { + let mut per_level: BTreeMap = BTreeMap::new(); + for lvl in [1i32, 3, 5, 7, 9, 12, 13, 16, 19] { + let mut acc = W::default(); + for id in IDS { + let Ok(full) = std::fs::read(format!("corpora/data/silesia/{id}")) else { + continue; + }; + let src = &full[..full.len().min(CAP)]; + reset(); + let out = rusty_zstd::compress(src, lvl).unwrap(); + let (pos, _miss) = rusty_zstd::take_mm(); + let ex = rusty_zstd::take_walk_exit(); + let (exam, bytemiss) = rusty_zstd::take_walk_census(); + let (skips, _false) = rusty_zstd::take_link_tag(); + let (calls, _wide, hist) = rusty_zstd::take_eqlen_stats(); + let (fs, fl) = rusty_zstd::take_fused(); + let (fills, _ne, inserts) = rusty_zstd::take_lazy_fill(); + let (dmb, dseqs, _bb, _drb, _drh) = rusty_zstd::take_dfast_match_stats(); + let (rp, _rb, rh, amb, aseqs) = rusty_zstd::take_rep_rate(); + let (bw, bi, bf) = rusty_zstd::take_bt_iters(); + let (bp, bs, bn) = rusty_zstd::take_bt_probe_stats(); + let (r0, r1, r2) = rusted_route(); + acc.bytes += src.len() as f64; + acc.out += out.len() as f64; + acc.positions += pos as f64; + acc.walks += ex.iter().sum::() as f64; + acc.exam += exam as f64; + acc.bytemiss += bytemiss as f64; + acc.tagskip += skips as f64; + for i in 0..8 { + acc.exits[i] += ex[i] as f64; + } + acc.counts += calls as f64; + for i in 0..6 { + acc.count_hist[i] += hist[i] as f64; + } + acc.fused_short += fs as f64; + acc.fused_long += fl as f64; + acc.inserts += inserts as f64; + acc.fills += fills as f64; + acc.dfast_seqs += dseqs as f64; + acc.dfast_mb += dmb as f64; + acc.fast_seqs += aseqs as f64; + acc.fast_mb += amb as f64; + acc.rep_probes += rp as f64; + acc.rep_hits += rh as f64; + acc.bt_walks += bw as f64; + acc.bt_iters += bi as f64; + acc.bt_full += bf as f64; + acc.bt_probe += bp as f64; + acc.bt_short += bs as f64; + acc.bt_nogain += bn as f64; + acc.routes[0] += r0 as f64; + acc.routes[1] += r1 as f64; + acc.routes[2] += r2 as f64; + } + per_level.insert(lvl, acc); + } + let mib = |w: &W| w.bytes / 1e6; + println!( + "board: {} corpora, {} MB\n", + IDS.len(), + mib(per_level.values().next().unwrap()) as u64 + ); + println!("=== A. units of work PER INPUT BYTE ==="); + println!( + "{:>3} {:>7} {:>8} {:>8} {:>8} {:>8} {:>8} {:>8} {:>8} {:>8}", + "L", + "ratio", + "pos/B", + "walk/B", + "exam/B", + "tagskip", + "count/B", + "ins/B", + "match/B", + "bytes/m" + ); + for (lvl, w) in &per_level { + let matches = if w.fills > 0.0 { + w.fills + } else if w.dfast_seqs > 0.0 { + w.dfast_seqs + } else { + w.fast_seqs + }; + println!( + "{:>3} {:>7.3} {:>8.3} {:>8.3} {:>8.3} {:>8.3} {:>8.3} {:>8.3} {:>8.4} {:>8.1}", + lvl, + w.bytes / w.out.max(1.0), + w.positions / w.bytes, + w.walks / w.bytes, + w.exam / w.bytes, + w.tagskip / w.bytes, + w.counts / w.bytes, + w.inserts / w.bytes, + matches / w.bytes, + if matches > 0.0 { + w.bytes / matches + } else { + 0.0 + } + ); + } + println!("\n=== B. per WALK (chain/row kernel call): candidates examined, tag-skipped, first-word misses, exit reasons ==="); + println!( + "{:>3} {:>9} {:>8} {:>8} {:>8} {:<60}", + "L", + "walks", + "exam/wk", + "skip/wk", + "miss/ex", + "exits: nohead ip+mls>len m = w.exits[..6] + .iter() + .map(|e| format!("{:.1}%", 100.0 * e / w.walks)) + .collect(); + println!( + "{:>3} {:>9.0} {:>8.2} {:>8.2} {:>7.1}% {}", + lvl, + w.walks, + w.exam / w.walks, + w.tagskip / w.walks, + 100.0 * w.bytemiss / w.exam.max(1.0), + ex.join(" ") + ); + } + println!("\n=== C. count_match calls: per byte, and the returned-length histogram [<3, 3-7, 8-31, 32-63, 64-255, 256+] ==="); + for (lvl, w) in &per_level { + let t: f64 = w.count_hist.iter().sum::().max(1.0); + let h: Vec = w + .count_hist + .iter() + .map(|x| format!("{:>5.1}%", 100.0 * x / t)) + .collect(); + println!( + "{:>3} {:>8.3}/B {} fused short {:.1}%", + lvl, + w.counts / w.bytes, + h.join(" "), + 100.0 * w.fused_short / (w.fused_short + w.fused_long).max(1.0) + ); + } + println!("\n=== D. binary tree (L13+): walks/B, nodes per walk, walks using ALL attempts, probes too short / no gain ==="); + for (lvl, w) in &per_level { + if w.bt_walks == 0.0 { + continue; + } + println!( + "{:>3} {:>8.3}/B {:>6.1} nodes/walk {:>5.1}% full short {:.1}% nogain {:.1}%", + lvl, + w.bt_walks / w.bytes, + w.bt_iters / w.bt_walks, + 100.0 * w.bt_full / w.bt_walks, + 100.0 * w.bt_short / w.bt_probe.max(1.0), + 100.0 * w.bt_nogain / w.bt_probe.max(1.0) + ); + } + println!("\n=== E. rep probes / hits per byte, routes per block ==="); + for (lvl, w) in &per_level { + println!( + "{:>3} rep {:>7.3}/B probes, {:>7.4}/B hits ({:.1}% of probes) routes {:?}", + lvl, + w.rep_probes / w.bytes, + w.rep_hits / w.bytes, + 100.0 * w.rep_hits / w.rep_probes.max(1.0), + w.routes.map(|r| r as u64) + ); + } + // F. the modelled budget: the campaign's measured per-unit costs (emitted-asm path counts) + println!("\n=== F. MODELLED instructions per input byte = units/byte x per-unit path cost (this crate's measured paths) ==="); + println!( + "{:>3} {:>8} {:>8} {:>8} {:>8} {:>8} {:>8} {:>8} {}", + "L", + "position", + "walk", + "examine", + "tagskip", + "count", + "insert", + "TOTAL", + "unit costs used" + ); + for (lvl, w) in &per_level { + let b = w.bytes; + // per-unit costs from the paths tool: position (finder loop, no-match path), walk (kernel entry+exit), + // examined candidate (first-word reject path), tag-skipped link, count call (entry + 8B/iter), + // inserted byte (fill loop, packed shape). + let (c_pos, c_walk, c_exam, c_skip, c_cnt, c_ins) = match lvl { + 1 => (40.0, 0.0, 0.0, 0.0, 75.0, 0.0), + 3 | 4 => (55.0, 0.0, 15.0, 0.0, 75.0, 15.0), + 5 => (60.0, 0.0, 30.0, 26.0, 75.0, 29.0), + 6..=12 => (65.0, 45.0, 25.0, 22.0, 75.0, 29.0), + 13..=15 => (59.0, 105.0, 43.0, 0.0, 75.0, 0.0), + _ => (80.0, 105.0, 43.0, 0.0, 75.0, 0.0), + }; + let units_pos = if w.positions > 0.0 { + w.positions + } else if w.walks > 0.0 { + w.walks + } else { + b + }; + let exam = if w.bt_iters > 0.0 { w.bt_iters } else { w.exam }; + let walks = if w.bt_walks > 0.0 { + w.bt_walks + } else { + w.walks + }; + let p = units_pos * c_pos / b; + let wk = walks * c_walk / b; + let e = exam * c_exam / b; + let s = w.tagskip * c_skip / b; + let c = w.counts * c_cnt / b; + let i = w.inserts * c_ins / b; + println!("{:>3} {:>8.1} {:>8.1} {:>8.1} {:>8.1} {:>8.1} {:>8.1} {:>8.1} pos {} walk {} exam {} skip {} cnt {} ins {}", + lvl, p, wk, e, s, c, i, p + wk + e + s + c + i, c_pos, c_walk, c_exam, c_skip, c_cnt, c_ins); + } + } +} diff --git a/crates/rusty_zstd-bench/examples/mfsplit.rs b/crates/rusty_zstd-bench/examples/mfsplit.rs new file mode 100644 index 0000000..748eba3 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/mfsplit.rs @@ -0,0 +1,50 @@ +//! MATCH-FIND WORK SPLIT, per SCANNED POSITION. Deterministic, no clock. +//! +//! cargo run --release --features rusty_zstd/profile -p rusty_zstd-bench --example mfsplit +//! +//! WHY THE OBVIOUS COMPARISON IS INVALID (checked, recorded so it is not +//! redone): `hash_probes` does NOT mean the same thing in the two finders. +//! In `find_fast_impl_inner` it is bumped at the TOP of the scan loop, before +//! the hash is computed -- so it counts POSITIONS. In `find_dfast_impl_inner` +//! it is bumped inside `if let Some(m8)`, i.e. only once a tag filter has +//! already returned a candidate -- so it counts SURVIVORS. Dividing either by +//! input bytes and putting them in one column compares a flow to a filtered +//! flow, and the "hit%" built on them compares 12% (hits/position) against +//! 94% (hits/candidate). Different denominators, not different quality. +//! +//! `MM_TOTAL` (via `take_mm`) IS bumped at the loop top in BOTH, so it is the +//! common denominator. Everything below is per scanned position. +const IDS: &[&str] = &["x-ray", "osdb", "jsonlog-16m", "smallmsg-8m", "ooffice", "sao", + "dickens", "samba", "nci", "webster", "mozilla", "mr"]; +fn main() { + let cap: usize = 8 << 20; + for lvl in [1i32, 3] { + let p = rusty_zstd::compression_params(lvl, None).unwrap(); + let (mut tpos, mut tf, mut tc, mut th, mut tb) = (0u64, 0u64, 0u64, 0u64, 0f64); + println!("\n=== L{lvl} ({:?}) ===", p.strategy); + println!("{:<13} {:>10} {:>10} {:>10} {:>10} {:>9}", + "corpus", "pos/B", "fills/pos", "cand/pos", "fills/B", "adv B/pos"); + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) else { continue }; + let s = &f[..f.len().min(cap)]; + rusty_zstd::prof_reset(); + let _ = rusty_zstd::take_mm(); + let _ = rusty_zstd::compress(s, lvl).unwrap(); + let c = rusty_zstd::prof_encode_counts(); + let (pos, _miss) = rusty_zstd::take_mm(); + let n = s.len() as f64; + tpos += pos; tf += c.hash_fills; tc += c.hash_probes; th += c.probe_hits; tb += n; + let pf = if pos == 0 { 0.0 } else { pos as f64 }; + println!("{:<13} {:>10.3} {:>10.3} {:>10.3} {:>10.3} {:>9.2}", + id, pos as f64 / n, c.hash_fills as f64 / pf, + c.hash_probes as f64 / pf, c.hash_fills as f64 / n, + if pos == 0 { 0.0 } else { n / pos as f64 }); + } + let pf = tpos as f64; + println!("{:<13} {:>10.3} {:>10.3} {:>10.3} {:>10.3} {:>9.2}", + "TOTAL", tpos as f64 / tb, tf as f64 / pf, tc as f64 / pf, + tf as f64 / tb, tb / pf); + println!(" positions {tpos}, fills {tf}, candidates {tc}, hits {th}"); + } +} diff --git a/crates/rusty_zstd-bench/examples/mlgrid.rs b/crates/rusty_zstd-bench/examples/mlgrid.rs new file mode 100644 index 0000000..7e8c70e --- /dev/null +++ b/crates/rusty_zstd-bench/examples/mlgrid.rs @@ -0,0 +1,44 @@ +//! 2-D sweep of DFast's two search cuts, with the nl dispatch on. +//! Size only; exact. Prints the grid and the best cell. +use rusty_zstd as rz; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","mr","ooffice","osdb","reymont","sao", + "webster","dickens","mozilla","nci","samba","xml","x-ray"]; +fn main() { + let cap: usize = 4 << 20; + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + let o = rz::CompressOptions { level: 3, checksum: false }; + let go = || -> usize { srcs.iter().map(|(_, s)| + rz::compress_with(s, o).unwrap().len()).sum() }; + rz::set_nl_dispatch_arm(false); + rz::set_dfast_good_ml_arm(0); + rz::set_dfast_good_ml2_arm(0); + let ship = go(); + println!("shipped default (nl_dispatch off, cuts 8/8): {ship}\n"); + let ml1 = [24usize, 32, 40, 48, 56, 64]; + let ml2 = [0usize, 12, 16, 20, 24, 32, 48]; + print!("{:>8}", "ml/ml2"); + for b in ml2 { print!("{:>10}", if b == 0 { "follow".to_string() } else { b.to_string() }); } + println!(); + let mut best = (isize::MAX, 0usize, 0usize); + rz::set_nl_dispatch_arm(true); + for a in ml1 { + print!("{a:>8}"); + for b in ml2 { + rz::set_dfast_good_ml_arm(a); + rz::set_dfast_good_ml2_arm(b); + let d = go() as isize - ship as isize; + if d < best.0 { best = (d, a, b); } + print!("{d:>+10}"); + } + println!(); + } + rz::set_nl_dispatch_arm(false); + rz::set_dfast_good_ml_arm(0); + rz::set_dfast_good_ml2_arm(0); + println!("\nBEST: good_ml={} good_ml2={} {:+} B ({:+.3}%)", + best.1, best.2, best.0, best.0 as f64 / ship as f64 * 100.0); +} diff --git a/crates/rusty_zstd-bench/examples/mlsweep.rs b/crates/rusty_zstd-bench/examples/mlsweep.rs new file mode 100644 index 0000000..9664ce7 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/mlsweep.rs @@ -0,0 +1,41 @@ +//! Sweep DFast's two "good enough, stop searching" cuts for SIZE. +//! +//! `nl_dispatch` buys -0.25% by raising `good_ml` 8 -> 24 when the offset trade +//! is paying. Both cuts were hardcoded `8` and are now knobs; nothing has swept +//! them for the value that is actually best. Size is exact -- no clock. +use rusty_zstd as rz; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","mr","ooffice","osdb","reymont","sao", + "webster","dickens","mozilla","nci","samba","xml","x-ray"]; +fn main() { + let cap: usize = 4 << 20; + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + let o = rz::CompressOptions { level: 3, checksum: false }; + let go = || -> usize { srcs.iter().map(|(_, s)| + rz::compress_with(s, o).unwrap().len()).sum() }; + for disp in [false, true] { + rz::set_nl_dispatch_arm(disp); + rz::set_dfast_good_ml_arm(0); + rz::set_dfast_good_ml2_arm(0); + let base = go(); + println!("\n=== nl_dispatch {} === base {base}", if disp {"ON"} else {"off"}); + println!(" {:>10} {:>12} {:>10} {:>12} {:>10}", + "value", "good_ml", "delta", "good_ml2", "delta"); + for v in [4usize, 6, 8, 12, 16, 20, 24, 32, 48, 64] { + rz::set_dfast_good_ml_arm(v); + rz::set_dfast_good_ml2_arm(0); + let a = go(); + rz::set_dfast_good_ml_arm(0); + rz::set_dfast_good_ml2_arm(v); + let b = go(); + println!(" {:>10} {:>12} {:>+10} {:>12} {:>+10}", + v, a, a as i64 - base as i64, b, b as i64 - base as i64); + } + rz::set_dfast_good_ml_arm(0); + rz::set_dfast_good_ml2_arm(0); + } + rz::set_nl_dispatch_arm(false); +} diff --git a/crates/rusty_zstd-bench/examples/mtcopies.rs b/crates/rusty_zstd-bench/examples/mtcopies.rs new file mode 100644 index 0000000..6957cec --- /dev/null +++ b/crates/rusty_zstd-bench/examples/mtcopies.rs @@ -0,0 +1,37 @@ +//! MT path copy census + byte-identity gate. +//! +//! The multi-threaded compressor was the one region never instrumented. Its +//! job outputs are concatenated into a frame buffer that used to be a +//! `Vec::new()` -- grown to the whole compressed stream by doubling, which +//! copies ~N bytes in reallocs on top of the concat itself. +use rusty_zstd::{copies, AdvancedOptions}; + +fn main() { + let lvl: i32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(3); + let nw: usize = std::env::args().nth(2).and_then(|s| s.parse().ok()).unwrap_or(4); + println!("MT COPY CENSUS (L{lvl}, {nw} workers)\n"); + println!("{:<14}{:>9}{:>14}{:>14}{:>12}", "corpus", "MiB", "compressed", "concat B", "B/input"); + let (mut tb, mut tsrc) = (0u64, 0u64); + for id in ["dickens", "samba", "webster", "mozilla"] { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) else { continue }; + let src = &f[..f.len().min(32 << 20)]; + let _ = copies::take(); + let params = rusty_zstd::compression_params(lvl, Some(src.len() as u64)).expect("params"); + let mut adv = AdvancedOptions::default(); + adv.nb_workers = nw as u32; + let z = rusty_zstd::compress_mt(src, params, true, None, &[], true, adv).expect("mt"); + let c = copies::take(); + let back = rusty_zstd::decompress(&z).expect("decompress"); + assert_eq!(back, src, "{id} mt roundtrip"); + // The MT frame must equal the single-threaded frame for the same job + // split, or the concat changed more than allocation behaviour. + let n = c[copies::C_MT_CONCAT].0; + println!("{id:<14}{:>9.1}{:>14}{:>14}{:>12.4}", + src.len() as f64 / (1 << 20) as f64, z.len(), n, + n as f64 / src.len() as f64); + tb += n; tsrc += src.len() as u64; + let _ = copies::take(); + } + println!("\nconcat total {tb} B for {tsrc} input = {:.4} B/input", tb as f64 / tsrc as f64); + println!("an UNRESERVED concat would have moved that AGAIN in realloc copies."); +} diff --git a/crates/rusty_zstd-bench/examples/nlcost.rs b/crates/rusty_zstd-bench/examples/nlcost.rs new file mode 100644 index 0000000..77b5fcd --- /dev/null +++ b/crates/rusty_zstd-bench/examples/nlcost.rs @@ -0,0 +1,45 @@ +//! Price the nl_dispatch size win in WORK, deterministically. +//! +//! The dispatch raises DFast's "good enough, stop searching" cut from 8 to 24, +//! so it must be bought with search. This measures the exact cost in the +//! encoder's own counters -- positions scanned, candidates evaluated, table +//! fills -- alongside the byte win. No clock: this box cannot resolve the +//! likely effect anyway (+-1.5% null, `eqlever.rs`). +use rusty_zstd as rz; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","mr","ooffice","osdb","reymont","sao", + "webster","dickens","mozilla","nci","samba","xml","x-ray"]; +fn run(srcs: &Vec<(&str, Vec)>, lvl: i32) -> (u64, u64, u64, u64, u64) { + let (mut b, mut p, mut f, mut s) = (0u64, 0u64, 0u64, 0u64); + let _ = rz::take_mm(); + for (_, x) in srcs { + rz::prof_reset(); + b += rz::compress_with(x, rz::CompressOptions { level: lvl, checksum: false }) + .unwrap().len() as u64; + let c = rz::prof_encode_counts(); + p += c.hash_probes; f += c.hash_fills; s += c.seqs; + } + (b, p, f, s, rz::take_mm().0) +} +fn main() { + let cap: usize = 4 << 20; + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + for lvl in [3i32, 4] { + rz::set_nl_dispatch_arm(false); + let a = run(&srcs, lvl); + rz::set_nl_dispatch_arm(true); + let b = run(&srcs, lvl); + rz::set_nl_dispatch_arm(false); + let pc = |x: u64, y: u64| (y as f64 - x as f64) / x as f64 * 100.0; + println!("=== L{lvl} ==="); + println!(" bytes {:>12} -> {:>12} {:+.3}% ({:+} B)", + a.0, b.0, pc(a.0, b.0), b.0 as i64 - a.0 as i64); + println!(" positions {:>12} -> {:>12} {:+.2}%", a.4, b.4, pc(a.4, b.4)); + println!(" candidates {:>12} -> {:>12} {:+.2}%", a.1, b.1, pc(a.1, b.1)); + println!(" fills {:>12} -> {:>12} {:+.2}%", a.2, b.2, pc(a.2, b.2)); + println!(" sequences {:>12} -> {:>12} {:+.2}%", a.3, b.3, pc(a.3, b.3)); + } +} diff --git a/crates/rusty_zstd-bench/examples/nldisp.rs b/crates/rusty_zstd-bench/examples/nldisp.rs new file mode 100644 index 0000000..471e839 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/nldisp.rs @@ -0,0 +1,50 @@ +//! Does the EXISTING nl dispatch capture the sao loss? Size only -- exact. +//! +//! cargo run --release -p rusty_zstd-bench --example nldisp +//! +//! `nlhunt` showed the next-long probe wins 468,072 match bytes on `sao` and +//! still costs 15,001 compressed bytes: it commits at `ip + 1`, so it can take +//! a LONGER match at a WORSE OFFSET and lose more in the offset code than it +//! gains in the length code. `next_long_yield` cannot separate that case +//! (x-ray's yield is 100x lower and the probe HELPS it) -- but the encoder +//! already counts the offset trade in `band_worse / band_hits` -> +//! `tables.nl_off_worse`, and `nl_cut_for` already dispatches on it. +//! +//! That dispatch is OFF by default (`NL_DISPATCH_ON != 2` returns the bare 8). +//! This asks the only question that matters: turned on, does it recover sao +//! without costing the fifteen corpora the probe genuinely helps? +use rusty_zstd as rz; +const IDS: &[&str] = &["zeros-32m","text-32m","incomp-32m","jsonlog-16m","smallmsg-8m", + "versions-16m","mr","ooffice","osdb","reymont","sao","webster","dickens","mozilla", + "nci","samba","xml","x-ray"]; +fn main() { + let cap: usize = 4 << 20; + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + let o = rz::CompressOptions { level: 3, checksum: false }; + let go = |srcs: &Vec<(&str, Vec)>| -> Vec { + srcs.iter().map(|(_, s)| rz::compress_with(s, o).unwrap().len()).collect() + }; + rz::set_nl_dispatch_arm(false); + let base = go(&srcs); + println!("{:<14}{:>12}{:>14}{:>14}", "corpus", "base", "nl_dispatch", "next_long off"); + println!("{}", "-".repeat(56)); + rz::set_nl_dispatch_arm(true); + let disp = go(&srcs); + rz::set_nl_dispatch_arm(false); + rz::set_next_long_arm(false); + let off = go(&srcs); + rz::set_next_long_arm(true); + let (mut nd, mut nf) = (0i64, 0i64); + for (i, (id, _)) in srcs.iter().enumerate() { + let d = disp[i] as i64 - base[i] as i64; + let f = off[i] as i64 - base[i] as i64; + nd += d; nf += f; + println!("{:<14}{:>12}{:>+14}{:>+14}", id, base[i], d, f); + } + println!("{:<14}{:>12}{:>+14}{:>+14}", "NET", base.iter().sum::(), nd, nf); + println!("\nnl_dispatch column: negative = smaller than shipped default."); +} diff --git a/crates/rusty_zstd-bench/examples/nlhunt.rs b/crates/rusty_zstd-bench/examples/nlhunt.rs new file mode 100644 index 0000000..7aab5e2 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/nlhunt.rs @@ -0,0 +1,55 @@ +//! Is there a DETERMINISTIC SIGNAL that identifies the corpora where the +//! next-long probe COSTS ratio instead of buying it? +//! +//! cargo run --release --features profile -p rusty_zstd-bench --example nlhunt +//! +//! `sizehunt` found that turning `next_long` off at L3 makes `sao` 15,001 bytes +//! SMALLER while making all 15 other corpora larger. The probe commits at +//! `ip + 1`, so it can change the parse for the worse -- it is not a pure +//! filter. The encoder already maintains `next_long_yield = nl_hits/nl_probes` +//! per block, and `NL_GAIN_G` accumulates the match bytes the probe won. +//! +//! If sao separates from the other 15 on a signal the encoder ALREADY has, +//! the 15,001 bytes are a dispatch away and cost no new instrumentation. +//! Size is the currency here: exact, no clock, no null band. +use rusty_zstd as rz; +const IDS: &[&str] = &["zeros-32m","text-32m","incomp-32m","jsonlog-16m","smallmsg-8m", + "versions-16m","mr","ooffice","osdb","reymont","sao","webster","dickens","mozilla", + "nci","samba","xml","x-ray"]; +fn main() { + let cap: usize = 4 << 20; + println!("{:<14}{:>12}{:>12}{:>10}{:>12}{:>11}", + "corpus", "nl_probes", "nl_hits", "yield", "gain B", "d bytes off"); + println!("{}", "-".repeat(72)); + let mut rows = vec![]; + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) else { continue }; + let s = &f[..f.len().min(cap)]; + let o = rz::CompressOptions { level: 3, checksum: false }; + rz::set_next_long_arm(true); + let _ = rz::take_next_long(); + let on = rz::compress_with(s, o).unwrap().len(); + let (p, h, g) = rz::take_next_long(); + rz::set_next_long_arm(false); + let off = rz::compress_with(s, o).unwrap().len(); + rz::set_next_long_arm(true); + let y = if p == 0 { f64::NAN } else { h as f64 / p as f64 }; + rows.push((*id, p, h, y, g, off as i64 - on as i64)); + } + rows.sort_by(|a, b| a.5.cmp(&b.5)); + for (id, p, h, y, g, d) in &rows { + println!("{:<14}{:>12}{:>12}{:>10.4}{:>12}{:>+11}", id, p, h, y, g, d); + } + println!("\nsorted by `d bytes off`: NEGATIVE = the probe COSTS ratio there."); + let bad: Vec<_> = rows.iter().filter(|r| r.5 < 0).collect(); + let good: Vec<_> = rows.iter().filter(|r| r.5 > 0).collect(); + if !bad.is_empty() && !good.is_empty() { + let by = bad.iter().map(|r| r.3).fold(f64::MIN, f64::max); + let gy = good.iter().map(|r| r.3).fold(f64::MAX, f64::min); + println!("highest yield among COSTS-ratio corpora: {by:.4}"); + println!("lowest yield among BUYS-ratio corpora: {gy:.4}"); + println!("{}", if by < gy { ">>> SEPARABLE: an empty interval exists <<<" } + else { "NOT separable on yield alone -- the classes overlap" }); + } +} diff --git a/crates/rusty_zstd-bench/examples/nlship.rs b/crates/rusty_zstd-bench/examples/nlship.rs new file mode 100644 index 0000000..c1696fd --- /dev/null +++ b/crates/rusty_zstd-bench/examples/nlship.rs @@ -0,0 +1,49 @@ +//! The candidate shipping config vs the shipped default: size, work, round-trip. +//! nl_dispatch ON + dfast_good_ml 48 (good_ml2 follows) +//! Chosen off the `mlgrid` plateau rather than its argmax: 40..64 all land +//! within 0.03% of each other, so the extreme cell (64/24, -82,975) is 322 B +//! better than 48/follow (-82,653) and far more likely to be this corpus set. +use rusty_zstd as rz; +const IDS: &[&str] = &["zeros-32m","text-32m","incomp-32m","jsonlog-16m","smallmsg-8m", + "versions-16m","mr","ooffice","osdb","reymont","sao","webster","dickens","mozilla", + "nci","samba","xml","x-ray"]; +fn set(on: bool) { + rz::set_nl_dispatch_arm(on); + rz::set_dfast_good_ml_arm(if on { 48 } else { 0 }); +} +fn main() { + for cap in [4usize << 20, 8 << 20] { + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + for lvl in [3i32, 4] { + let o = rz::CompressOptions { level: lvl, checksum: true }; + let mut r = [(0u64, 0u64, 0u64, 0u64); 2]; + let mut rt = 0; + for (i, on) in [false, true].iter().enumerate() { + set(*on); + let _ = rz::take_mm(); + for (_, s) in &srcs { + rz::prof_reset(); + let z = rz::compress_with(s, o).unwrap(); + r[i].0 += z.len() as u64; + let c = rz::prof_encode_counts(); + r[i].1 += c.hash_probes; r[i].2 += c.hash_fills; + if *on { + assert_eq!(&rz::decompress(&z).expect("dec"), s, "ROUND-TRIP L{lvl}"); + rt += 1; + } + } + r[i].3 = rz::take_mm().0; + } + set(false); + let pc = |a: u64, b: u64| (b as f64 - a as f64) / a as f64 * 100.0; + println!("cap {:>2} MiB L{lvl} size {:+.3}% ({:+} B) cand {:+.2}% fills {:+.2}% \ +pos {:+.2}% rt {rt}/{}", + cap >> 20, pc(r[0].0, r[1].0), r[1].0 as i64 - r[0].0 as i64, + pc(r[0].1, r[1].1), pc(r[0].2, r[1].2), pc(r[0].3, r[1].3), srcs.len()); + } + } +} diff --git a/crates/rusty_zstd-bench/examples/nlverify.rs b/crates/rusty_zstd-bench/examples/nlverify.rs new file mode 100644 index 0000000..e4da4ff --- /dev/null +++ b/crates/rusty_zstd-bench/examples/nlverify.rs @@ -0,0 +1,38 @@ +//! Verification for the nl_dispatch size win: round-trip every corpus at every +//! DFast level with the dispatch ON, and confirm the win is stable in the +//! corpus prefix (a win that shrinks as you add data is a warm-up artefact). +use rusty_zstd as rz; +const IDS: &[&str] = &["zeros-32m","text-32m","incomp-32m","jsonlog-16m","smallmsg-8m", + "versions-16m","mr","ooffice","osdb","reymont","sao","webster","dickens","mozilla", + "nci","samba","xml","x-ray"]; +fn main() { + for cap in [2usize << 20, 4 << 20, 8 << 20] { + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + let total: usize = srcs.iter().map(|(_, s)| s.len()).sum(); + for lvl in [3i32, 4] { + let o = rz::CompressOptions { level: lvl, checksum: true }; + let mut a = 0usize; + let mut b = 0usize; + let mut rt = 0usize; + for (_, s) in &srcs { + rz::set_nl_dispatch_arm(false); + a += rz::compress_with(s, o).unwrap().len(); + rz::set_nl_dispatch_arm(true); + let z = rz::compress_with(s, o).unwrap(); + b += z.len(); + let d = rz::decompress(&z).expect("decompress"); + assert_eq!(&d, s, "ROUND-TRIP FAILED L{lvl}"); + rt += 1; + } + rz::set_nl_dispatch_arm(false); + println!("cap {:>2} MiB L{lvl} in {:>9} B base {:>9} disp {:>9} \ +{:+.3}% ({:+} B) round-trips {rt}/{}", + cap >> 20, total, a, b, + (b as f64 - a as f64) / a as f64 * 100.0, b as i64 - a as i64, srcs.len()); + } + } +} diff --git a/crates/rusty_zstd-bench/examples/nofcs.rs b/crates/rusty_zstd-bench/examples/nofcs.rs new file mode 100644 index 0000000..6d4c75f --- /dev/null +++ b/crates/rusty_zstd-bench/examples/nofcs.rs @@ -0,0 +1,51 @@ +//! Does a frame with NO declared content size still grow its output by doubling? +//! +//! Our streaming compressor omits the Frame_Content_Size unless the caller +//! pledges one, so this is the common shape for streamed frames. Before the +//! extrapolated reserve there was no `reserve` on that path at all. +use rusty_zstd::{copies, Compressor, Flush}; + +fn no_fcs_frame(src: &[u8], lvl: i32) -> Vec { + let mut c = Compressor::new(lvl).expect("c"); // NO set_pledged_src_size + let mut out = Vec::new(); + let mut buf = vec![0u8; 128 << 10]; + let mut i = 0usize; + while i < src.len() { + let end = (i + (64 << 10)).min(src.len()); + let mut inp = &src[i..end]; + loop { + let st = c.stream(inp, &mut buf, Flush::Continue).expect("s"); + out.extend_from_slice(&buf[..st.output_produced]); + inp = &inp[st.input_consumed..]; + if inp.is_empty() { break; } + } + i = end; + } + loop { + let st = c.stream(&[], &mut buf, Flush::End).expect("e"); + out.extend_from_slice(&buf[..st.output_produced]); + if st.done { break; } + } + out +} + +fn main() { + let lvl: i32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(3); + println!("{:<12}{:>9}{:>12}{:>16}{:>12}", "corpus", "MiB", "has FCS", "reserved B", "vs output"); + for id in ["dickens", "samba", "webster"] { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) else { continue }; + let src = &f[..f.len().min(32 << 20)]; + let z = no_fcs_frame(src, lvl); + let fcs = rusty_zstd::content_size(&z).expect("hdr"); + let _ = copies::take(); + let out = rusty_zstd::decompress(&z).expect("d"); + let c = copies::take(); + assert_eq!(out, src, "{id} roundtrip"); + println!("{id:<12}{:>9.1}{:>12}{:>16}{:>11.2}x", + src.len() as f64 / (1<<20) as f64, + format!("{:?}", fcs.is_some()), + c[copies::C_DEC_RESERVE].0, + c[copies::C_DEC_RESERVE].0 as f64 / src.len() as f64); + } + println!("\n'has FCS false' + a non-zero reserve = the extrapolation fired on the\npath that previously had none."); +} diff --git a/crates/rusty_zstd-bench/examples/numsweep.rs b/crates/rusty_zstd-bench/examples/numsweep.rs new file mode 100644 index 0000000..7236c26 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/numsweep.rs @@ -0,0 +1,44 @@ +//! Broad numeric-arm sweep for SIZE. Exact bytes, no clock, no null band. +use rusty_zstd as rz; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","versions-16m","mr","ooffice","osdb", + "reymont","sao","webster","dickens","mozilla","nci","samba","xml","x-ray","text-32m"]; +fn main() { + let cap: usize = 4 << 20; + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + let go = |lvl: i32| -> usize { srcs.iter().map(|(_, s)| + rz::compress_with(s, rz::CompressOptions { level: lvl, checksum: false }) + .unwrap().len()).sum() }; + println!("{:<20}{:>4}{:>10}{:>12}{:>10}", "arm = value", "L", "bytes", "delta", "pct"); + println!("{}", "-".repeat(58)); + macro_rules! sweep { + ($name:expr, $lvl:expr, $set:expr, $reset:expr, $vals:expr) => {{ + $reset; + let base = go($lvl); + println!("{:<20}{:>4}{:>10}{:>12}{:>10}", format!("{} (default)", $name), $lvl, base, 0, ""); + for v in $vals { + $set(v); + let s = go($lvl); + let d = s as i64 - base as i64; + println!("{:<20}{:>4}{:>10}{:>+12}{:>9.3}%", + format!(" {} = {:?}", $name, v), $lvl, s, d, + d as f64 / base as f64 * 100.0); + } + $reset; + }}; + } + sweep!("accel_shift", 3, rz::set_accel_shift_arm, rz::set_accel_shift_arm(0), + [2u32, 3, 4, 5, 6, 8]); + sweep!("accel_shift", 1, rz::set_accel_shift_arm, rz::set_accel_shift_arm(0), + [2u32, 3, 4, 5, 6, 8]); + sweep!("dfast_step", 3, rz::set_dfast_step_arm, rz::set_dfast_step_arm(0), [1usize, 2, 3]); + sweep!("search_log_d", 9, rz::set_search_log_delta, rz::set_search_log_delta(0), + [-1i32, 1]); + sweep!("pair_hi", 1, rz::set_pair_hi_arm, rz::set_pair_hi_arm(-1.0), + [0.0f32, 0.5, 2.0, 4.0, 9.0]); + sweep!("pair_gain", 1, rz::set_pair_gain_arm, rz::set_pair_gain_arm(-1.0), + [0.0f32, 0.05, 0.1, 0.4, 1.0]); +} diff --git a/crates/rusty_zstd-bench/examples/numsweep2.rs b/crates/rusty_zstd-bench/examples/numsweep2.rs new file mode 100644 index 0000000..c389983 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/numsweep2.rs @@ -0,0 +1,57 @@ +//! Corrected numeric sweep. Two harness defects fixed from the first attempt: +//! +//! 1. `accel_shift_for` is consulted ONLY under `cfg!(feature = "profile")` +//! -- release builds take the constant 7/8. Swept without that feature the +//! arm is inert and every cell reads +0, which looks like a dead knob and +//! is really a dead harness. Run this with --features profile. +//! 2. The f32 arms cache RAW BITS with `u32::MAX` as "unset", and the public +//! setter stores `v.to_bits()`. So `set_pair_hi_arm(-1.0)` does not RESET +//! the arm, it PINS it to -1.0 -- and every delta taken against that +//! baseline is measured from a changed config. The first run read +//! `pair_hi=4.0` as -47,965 B; against the true default (1.0) the same +//! cell is -7,702. Baselines here are the documented defaults, set +//! explicitly. +use rusty_zstd as rz; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","versions-16m","mr","ooffice","osdb", + "reymont","sao","webster","dickens","mozilla","nci","samba","xml","x-ray","text-32m"]; +fn main() { + let cap: usize = 4 << 20; + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + let go = |lvl: i32| -> usize { srcs.iter().map(|(_, s)| + rz::compress_with(s, rz::CompressOptions { level: lvl, checksum: false }) + .unwrap().len()).sum() }; + println!("profile feature: {}", cfg!(feature = "profile")); + println!("{:<22}{:>4}{:>11}{:>12}{:>10}", "arm = value", "L", "bytes", "delta", "pct"); + println!("{}", "-".repeat(60)); + + // accel_shift: default is 7 at Fast, 8 at DFast. 0 = "not pinned". + for (lvl, deflt) in [(1i32, 7u32), (3, 8)] { + rz::set_accel_shift_arm(0); + let base = go(lvl); + println!("{:<22}{:>4}{:>11}{:>12}", format!("accel_shift ({deflt})"), lvl, base, 0); + for v in [3u32, 4, 5, 6, 7, 8, 9, 10, 12] { + rz::set_accel_shift_arm(v); + let s = go(lvl); + println!("{:<22}{:>4}{:>11}{:>+12}{:>9.3}%", format!(" accel_shift = {v}"), + lvl, s, s as i64 - base as i64, + (s as i64 - base as i64) as f64 / base as f64 * 100.0); + } + rz::set_accel_shift_arm(0); + } + // pair_hi: documented default 1.0. Baseline set EXPLICITLY, not by a sentinel. + rz::set_pair_hi_arm(1.0); + let base = go(1); + println!("{:<22}{:>4}{:>11}{:>12}", "pair_hi (1.0)", 1, base, 0); + for v in [0.0f32, 0.5, 1.5, 2.0, 3.0, 4.0, 6.0, 9.0] { + rz::set_pair_hi_arm(v); + let s = go(1); + println!("{:<22}{:>4}{:>11}{:>+12}{:>9.3}%", format!(" pair_hi = {v}"), + 1, s, s as i64 - base as i64, + (s as i64 - base as i64) as f64 / base as f64 * 100.0); + } + rz::set_pair_hi_arm(1.0); +} diff --git a/crates/rusty_zstd-bench/examples/phantoms.rs b/crates/rusty_zstd-bench/examples/phantoms.rs new file mode 100644 index 0000000..930355f --- /dev/null +++ b/crates/rusty_zstd-bench/examples/phantoms.rs @@ -0,0 +1,49 @@ +//! BRICK 46 census: the chain walk's PHANTOM position-0 candidate. +//! +//! cargo run --release --features profile -p rusty_zstd-bench --example phantoms +//! +//! A chain link of 0 is both "no link" and position 0, so a walk whose chain +//! ends inside the first window continues to m = 0 and examines it. Per level: +//! how many candidates were examined at position 0, how many were ACCEPTED +//! (the byte-identity question for an unambiguous null), against all +//! candidates examined. +#[cfg(feature = "profile")] +const IDS: &[&str] = &["dickens", "mozilla", "webster", "xml", "samba"]; +fn main() { + #[cfg(not(feature = "profile"))] + { + println!("needs --features rusty_zstd/profile"); + } + #[cfg(feature = "profile")] + { + println!( + "{:>3} {:>12} {:>12} {:>10} {:>8}", + "L", "examined", "at pos 0", "accepted", "share" + ); + for lvl in [5i32, 7, 9, 12] { + let (mut exam, mut m0, mut acc) = (0u64, 0u64, 0u64); + for id in IDS { + let Ok(full) = std::fs::read(format!("corpora/data/silesia/{id}")) else { + continue; + }; + let src = &full[..full.len().min(16 << 20)]; + let _ = rusty_zstd::take_walk_census(); + let _ = rusty_zstd::take_walk_phantom(); + let _ = rusty_zstd::compress(src, lvl).unwrap(); + let (e, _) = rusty_zstd::take_walk_census(); + let (a, b) = rusty_zstd::take_walk_phantom(); + exam += e; + m0 += a; + acc += b; + } + println!( + "{:>3} {:>12} {:>12} {:>10} {:>7.2}%", + lvl, + exam, + m0, + acc, + 100.0 * m0 as f64 / exam.max(1) as f64 + ); + } + } +} diff --git a/crates/rusty_zstd-bench/examples/poolcensus.rs b/crates/rusty_zstd-bench/examples/poolcensus.rs new file mode 100644 index 0000000..e4d1ac5 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/poolcensus.rs @@ -0,0 +1,52 @@ +//! Scratch-pool hit/miss/drop census. +//! +//! The allocation census puts the encoder at ~144 allocations per MiB against +//! the decoder's 2.1, and attribution lands on functions that ALREADY pool +//! their buffers. A pool that misses allocates, and at the call site a miss is +//! indistinguishable from never having pooled -- so the hit rate is the whole +//! question, and a DROP (free list full) is what starves the next take. +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + println!( + "{:<12}{:>7}{:>10}{:>9}{:>8}{:>9}{:>10}{:>8}", + "corpus", "MiB", "hits", "misses", "drops", "gives", "give0", "hit%" + ); + let (mut th, mut tm, mut td, mut tg, mut tge) = (0u64, 0u64, 0u64, 0u64, 0u64); + for id in ["dickens", "samba", "webster", "mozilla"] { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) else { + continue; + }; + let src = &f[..f.len().min(32 << 20)]; + let _ = rusty_zstd::take_pool_census(); + let z = rusty_zstd::compress(src, lvl).expect("c"); + let (h, m, d, g, ge) = rusty_zstd::take_pool_census(); + assert_eq!(rusty_zstd::decompress(&z).expect("d"), src); + let _ = rusty_zstd::take_pool_census(); + println!( + "{id:<12}{:>7.1}{h:>10}{m:>9}{d:>8}{g:>9}{ge:>10}{:>7.1}%", + src.len() as f64 / (1 << 20) as f64, + if h + m == 0 { + 0.0 + } else { + 100.0 * h as f64 / (h + m) as f64 + } + ); + th += h; + tm += m; + td += d; + tg += g; + tge += ge; + } + println!( + "\nTOTAL hits {th} misses {tm} drops {td} -> {:.1}% hit rate", + if th + tm == 0 { + 0.0 + } else { + 100.0 * th as f64 / (th + tm) as f64 + } + ); + println!("every MISS is an allocation; every DROP is a buffer thrown away that a\nlater take then had to allocate."); +} diff --git a/crates/rusty_zstd-bench/examples/rowauto.rs b/crates/rusty_zstd-bench/examples/rowauto.rs new file mode 100644 index 0000000..5e42d04 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/rowauto.rs @@ -0,0 +1,30 @@ +//! Verify the row AUTO gate: fires in the measured band, silent outside, +//! round-trips everywhere. +use rusty_zstd as rz; +const IDS: &[&str] = &["dickens","mozilla","samba","webster","xml","x-ray","osdb", + "reymont","nci","sao","mr","ooffice","jsonlog-16m","smallmsg-8m"]; +fn main() { + println!("{:>9}{:>5}{:>12}{:>12}{:>10} {}", + "cap", "L", "old(chain)", "new(auto)", "ratio", "gate"); + println!("{}", "-".repeat(64)); + for lvl in [5i32, 7, 9, 12, 13] { + for cap in [256usize << 10, 512 << 10, 1 << 20, 2 << 20, 3 << 20, 8 << 20] { + let (mut a, mut b) = (0u64, 0u64); + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) else { continue }; + let src = &f[..f.len().min(cap)]; + rz::set_row_arm(false); // old shipped default + a += rz::compress(src, lvl).unwrap().len() as u64; + rz::set_row_arm_auto(); // new default + let z = rz::compress(src, lvl).unwrap(); + assert_eq!(rz::decompress(&z).unwrap(), src, "round-trip L{lvl} cap{cap}"); + b += z.len() as u64; + } + let r = b as f64 / a as f64; + println!("{:>8}K{:>5}{:>12}{:>12}{:>10.4} {}", cap >> 10, lvl, a, b, r, + if (r - 1.0).abs() < 1e-9 { "off" } else { "ON" }); + } + } + rz::set_row_arm_auto(); +} diff --git a/crates/rusty_zstd-bench/examples/rowcap.rs b/crates/rusty_zstd-bench/examples/rowcap.rs new file mode 100644 index 0000000..bbfeda7 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/rowcap.rs @@ -0,0 +1,39 @@ +//! Is the row finder's size verdict CAP-DEPENDENT? +//! +//! The chain deepens as input grows; the row is fixed at 16 positions per +//! bucket. So the depth the row gives up is a function of how much data has +//! been seen -- which would make any single-cap verdict a statement about that +//! cap and not about the finder. +use rusty_zstd as rz; +const IDS: &[&str] = &["dickens","mozilla","samba","webster","xml","x-ray","osdb", + "reymont","nci","sao","mr","ooffice","jsonlog-16m","smallmsg-8m"]; +fn main() { + let lvl: i32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(9); + let caps = [512usize << 10, 1 << 20, 2 << 20, 4 << 20, 8 << 20]; + print!("{:<14}", "corpus"); + for c in caps { print!("{:>10}", format!("{}K", c >> 10)); } + println!(); + println!("{}", "-".repeat(64)); + let mut agg = vec![(0u64, 0u64); caps.len()]; + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) else { continue }; + print!("{:<14}", id); + for (i, cap) in caps.iter().enumerate() { + let src = &f[..f.len().min(*cap)]; + rz::set_row_arm(false); + let a = rz::compress(src, lvl).unwrap().len(); + rz::set_row_arm(true); + let b = rz::compress(src, lvl).unwrap().len(); + rz::set_row_arm(false); + agg[i].0 += a as u64; agg[i].1 += b as u64; + print!("{:>10.4}", b as f64 / a as f64); + } + println!(); + } + print!("{:<14}", "AGGREGATE"); + for (a, b) in &agg { print!("{:>10.4}", *b as f64 / *a as f64); } + println!(); + print!("{:<14}", "EQUAL-WEIGHT"); + println!(" (per-corpus mean is the row above averaged, not size-weighted)"); +} diff --git a/crates/rusty_zstd-bench/examples/rowcross.rs b/crates/rusty_zstd-bench/examples/rowcross.rs new file mode 100644 index 0000000..68266b5 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/rowcross.rs @@ -0,0 +1,38 @@ +//! Where does the row finder stop paying, and does the load saving survive +//! there? Round-trips every cell. +use rusty_zstd as rz; +const IDS: &[&str] = &["dickens","mozilla","samba","webster","xml","x-ray","osdb", + "reymont","nci","sao","mr","ooffice","jsonlog-16m","smallmsg-8m"]; +fn main() { + let lvl: i32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(9); + println!("L{lvl} (round-trip asserted on every row cell)\n"); + println!("{:>9}{:>12}{:>12}{:>10}{:>14}{:>14}{:>9}", + "cap", "chain B", "row B", "ratio", "chain loads", "row loads", "saved"); + println!("{}", "-".repeat(80)); + for cap in [256usize << 10, 512 << 10, 1 << 20, 1536 << 10, 2 << 20, 3 << 20, 4 << 20, 6 << 20] { + let (mut a, mut b, mut cl, mut rl) = (0u64, 0u64, 0u64, 0u64); + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) else { continue }; + let src = &f[..f.len().min(cap)]; + rz::set_row_arm(false); + let _ = rz::take_walk_census(); + let x = rz::compress(src, lvl).unwrap(); + cl += rz::take_walk_census().0; + rz::set_row_arm(true); + let _ = rz::take_row_census(); + let y = rz::compress(src, lvl).unwrap(); + // .0 is ROW_EXAM (candidates), .1 is ROW_LOADS. Using .0 here + // compares chain LOADS against row CANDIDATES and reads ~1.00x, + // which is not a result -- it is two different units. + let (_cands, loads) = rz::take_row_census(); + rl += loads; + assert_eq!(rz::decompress(&y).unwrap(), src, "{id} @ {cap} round-trip"); + rz::set_row_arm(false); + a += x.len() as u64; b += y.len() as u64; + } + println!("{:>8}K{:>12}{:>12}{:>10.4}{:>14}{:>14}{:>8.2}x", + cap >> 10, a, b, b as f64 / a as f64, cl, rl, + if rl == 0 { 0.0 } else { cl as f64 / rl as f64 }); + } +} diff --git a/crates/rusty_zstd-bench/examples/rowsig.rs b/crates/rusty_zstd-bench/examples/rowsig.rs new file mode 100644 index 0000000..5761bdd --- /dev/null +++ b/crates/rusty_zstd-bench/examples/rowsig.rs @@ -0,0 +1,63 @@ +//! Is there a DETERMINISTIC CONTENT SIGNAL that separates the corpora the row +//! finder helps from the ones it hurts? +//! +//! cargo run --release --features profile -p rusty_zstd-bench --example rowsig +//! +//! `rowboard` reports L9 aggregate 1.0005x and calls the row finder a wash. +//! Per corpus it is not a wash at all -- it wins on 8 and loses on 4, and the +//! aggregate only lands at 1.0 because the four losers happen to be the two +//! largest files. Weight the corpora equally (1 MiB each) and the same arm +//! reads -1.18%. +//! +//! A split that clean asks for a dispatch. The row holds the last 16 positions +//! for its bucket, so it trades DEPTH for RECENCY -- and recent means SMALL +//! OFFSETS, which cost fewer bits. That should pay where matches are dense and +//! cost where they are sparse and the deep candidate was the only one. This +//! prints the signals the encoder already maintains against the measured +//! ratio, and looks for an empty interval. +use rusty_zstd as rz; +const IDS: &[&str] = &["dickens","mozilla","samba","webster","xml","x-ray","osdb", + "reymont","nci","sao","mr","ooffice","jsonlog-16m","smallmsg-8m"]; +fn main() { + let lvl: i32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(9); + let cap = 8usize << 20; + let mut rows = vec![]; + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) else { continue }; + let src = &f[..f.len().min(cap)]; + rz::set_row_arm(false); + rz::prof_reset(); + let a = rz::compress(src, lvl).unwrap(); + let c = rz::prof_encode_counts(); + rz::set_row_arm(true); + let b = rz::compress(src, lvl).unwrap(); + assert_eq!(rz::decompress(&b).unwrap(), src, "{id} round-trip"); + rz::set_row_arm(false); + let n = src.len() as f64; + // Signals the encoder already has, all from the CHAIN (default) run. + let lit = c.lit_bytes as f64 / n; // literal share + let mml = if c.seqs == 0 { 0.0 } else { c.match_bytes as f64 / c.seqs as f64 }; + let seqd = c.seqs as f64 / n * 1000.0; // sequences per KiB + rows.push((*id, b.len() as f64 / a.len() as f64, lit, mml, seqd)); + } + rows.sort_by(|x, y| x.1.partial_cmp(&y.1).unwrap()); + println!("{:<14}{:>9}{:>10}{:>10}{:>11}", "corpus", "row/chain", "lit share", "mean ml", "seqs/KiB"); + println!("{}", "-".repeat(54)); + for (id, r, lit, mml, sd) in &rows { + println!("{:<14}{:>9.4}{:>10.4}{:>10.2}{:>11.2}", id, r, lit, mml, sd); + } + for (name, idx) in [("lit share", 2usize), ("mean ml", 3), ("seqs/KiB", 4)] { + let g = |t: &(&str, f64, f64, f64, f64)| match idx { 2 => t.2, 3 => t.3, _ => t.4 }; + let win: Vec = rows.iter().filter(|t| t.1 < 1.0).map(&g).collect(); + let los: Vec = rows.iter().filter(|t| t.1 > 1.0).map(&g).collect(); + if win.is_empty() || los.is_empty() { continue; } + let wmax = win.iter().cloned().fold(f64::MIN, f64::max); + let wmin = win.iter().cloned().fold(f64::MAX, f64::min); + let lmax = los.iter().cloned().fold(f64::MIN, f64::max); + let lmin = los.iter().cloned().fold(f64::MAX, f64::min); + let sep = wmax < lmin || lmax < wmin; + println!("\n{name}: wins [{wmin:.4}, {wmax:.4}] losses [{lmin:.4}, {lmax:.4}] {}", + if sep { ">>> SEPARABLE <<<" } else { "overlap" }); + } +} diff --git a/crates/rusty_zstd-bench/examples/rssgrow.rs b/crates/rusty_zstd-bench/examples/rssgrow.rs new file mode 100644 index 0000000..464cb01 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/rssgrow.rs @@ -0,0 +1,35 @@ +//! Does repeated compression GROW the process, or is it flat? +//! +//! Two allocations failed during this session's sweeps (4 MB and 16 MB) on a +//! 64-bit box. The machine is genuinely short of memory, but that is a reason +//! to CHECK rather than to assume -- a leak and a loaded box look identical +//! from the outside. This compresses the same input many times at a high level +//! and reports the process working set as it goes. +use rusty_zstd as rz; +// NOT `#[cfg(windows)]`: `main` calls this unconditionally, so gating the +// definition made every non-Windows build fail to compile (E0425). The body +// is a stub on every platform, so there was nothing for the gate to protect. +fn rss() -> u64 { + // No winapi dependency: read our own working set via the same counter the + // parent would sample, through GlobalMemoryStatus-free means -- fall back + // to reporting allocation totals if unavailable. + 0 +} +fn main() { + let lvl: i32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(19); + let iters: usize = std::env::args().nth(2).and_then(|s| s.parse().ok()).unwrap_or(60); + let f = std::fs::read("corpora/data/silesia/dickens").expect("dickens"); + let src = &f[..f.len().min(2 << 20)]; + let _ = rss(); + println!("L{lvl}, {} KiB input, {iters} iterations", src.len() >> 10); + for i in 0..iters { + let p = rz::compression_params(lvl, Some(src.len() as u64)).unwrap(); + let z = rz::compress_with_params(src, p, false).unwrap(); + std::hint::black_box(z.len()); + if i % 10 == 0 || i == iters - 1 { + println!(" iter {i:>3}"); + } + } + println!("done"); + std::thread::sleep(std::time::Duration::from_millis(600)); +} diff --git a/crates/rusty_zstd-bench/examples/rssone.rs b/crates/rusty_zstd-bench/examples/rssone.rs new file mode 100644 index 0000000..8b53205 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/rssone.rs @@ -0,0 +1,25 @@ +//! Compress one file once at a given level and tightening, then exit, so the +//! caller can read this process's PEAK WORKING SET. Table footprint is a +//! MEMORY question, not a time one -- `vec![0; n]` for a large n takes zero +//! pages from the OS rather than memsetting, so cutting the allocation shows +//! up in RSS, not on the clock. +fn main() { + let a: Vec = std::env::args().collect(); + let lvl: i32 = a.get(1).and_then(|s| s.parse().ok()).unwrap_or(9); + let tight: u32 = a.get(2).and_then(|s| s.parse().ok()).unwrap_or(0); + let cap: usize = a.get(3).and_then(|s| s.parse().ok()).unwrap_or(1 << 20); + let id = a.get(4).cloned().unwrap_or_else(|| "dickens".into()); + let f = std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) + .expect("corpus"); + let s = &f[..f.len().min(cap)]; + rusty_zstd::set_hash_tight_arm(tight); + let p = rusty_zstd::compression_params(lvl, Some(s.len() as u64)).unwrap(); + let z = rusty_zstd::compress_with_params(s, p, false).unwrap(); + println!("L{lvl} tight={tight} in={} out={} hash_log={} chain_log={} window_log={}", + s.len(), z.len(), p.hash_log, p.chain_log, p.window_log); + // Hold the tables alive and the process sampleable: PeakWorkingSet64 reads + // 0 once the process has exited, so the parent must sample it live. + std::hint::black_box(&z); + std::thread::sleep(std::time::Duration::from_millis(700)); +} diff --git a/crates/rusty_zstd-bench/examples/simdparity.rs b/crates/rusty_zstd-bench/examples/simdparity.rs index 9665bae..bc37b9c 100644 --- a/crates/rusty_zstd-bench/examples/simdparity.rs +++ b/crates/rusty_zstd-bench/examples/simdparity.rs @@ -15,6 +15,10 @@ use sha2::{Digest, Sha256}; +/// One level per strategy family. Asserted against the resolved strategies +/// in `main`, so the claim cannot drift away from the list again. +const LEVELS: &[i32] = &[1, 3, 5, 7, 9, 13, 16, 18, 19]; + fn main() { let ids = [ ("generated", "jsonlog-16m"), @@ -39,8 +43,41 @@ fn main() { // One level per strategy family, so every finder that calls // `count_eq_len_ge8` is exercised: fast, dfast, greedy, lazy, lazy2, // btlazy2, btopt, btultra. + // + // FIXED: the list said `12` where it meant BtLazy2, but L12 resolves to + // **Lazy2** -- BtLazy2 starts at L13. So this gate's own doc claimed a + // strategy it did not exercise, and `find_bt_lazy` -- which calls + // `count_match` like every other finder -- was never parity-checked. L9 + // already covers Lazy2, so 12 is replaced rather than added. + // + // The assertion below makes the doc comment enforceable: if a future + // level-table edit moves a boundary, this fails loudly instead of + // silently dropping a finder out of the gate. let mut files = 0usize; - for lvl in [1i32, 3, 5, 7, 9, 12, 16, 19] { + { + let mut seen: Vec = LEVELS + .iter() + .filter_map(|&l| rusty_zstd::compression_params(l, None).ok()) + .map(|p| format!("{:?}", p.strategy)) + .collect(); + seen.sort(); + seen.dedup(); + const WANT: &[&str] = &["Fast", "DFast", "Greedy", "Lazy", "Lazy2", + "BtLazy2", "BtOpt", "BtUltra", "BtUltra2"]; + let missing: Vec<&str> = WANT + .iter() + .copied() + .filter(|w| !seen.iter().any(|x| x == w)) + .collect(); + assert!( + missing.is_empty(), + "simdparity LEVELS no longer cover every finder: missing {missing:?} \ + (covered: {seen:?}). A simd defect in a missing finder would not \ + move this gate's output." + ); + eprintln!("simdparity strategies covered: {}", seen.join(", ")); + } + for &lvl in LEVELS { for (dir, id) in ids { let path = format!("corpora/data/{dir}/{id}"); let Ok(f) = std::fs::read(&path) else { diff --git a/crates/rusty_zstd-bench/examples/sizehunt.rs b/crates/rusty_zstd-bench/examples/sizehunt.rs new file mode 100644 index 0000000..03d480a --- /dev/null +++ b/crates/rusty_zstd-bench/examples/sizehunt.rs @@ -0,0 +1,73 @@ +//! SIZE HUNT -- deterministic wins in the one currency that has no noise floor. +//! +//! cargo run --release -p rusty_zstd-bench --example sizehunt +//! +//! Every speed verdict on this box fights a +-1.5% null band (`eqlever.rs`). +//! COMPRESSED BYTES have no null band at all: same input, same arm, same +//! number, on any machine at any load. So an arm value that is strictly +//! SMALLER on some corpus is a deterministic win the moment a signal separates +//! it from the corpora it hurts -- which is the content-adaptive dispatch this +//! encoder already uses for `pair_gain`, `rep1_mode`, `incomp_skip`. +//! +//! `allgates` prints only the first four moved cells per arm, so the negative +//! ones are mostly invisible there. This prints EVERY cell, sorted, and flags +//! the arms where a non-default value never loses. +use rusty_zstd as rz; + +const IDS: &[&str] = &["zeros-32m","text-32m","incomp-32m","jsonlog-16m","smallmsg-8m", + "versions-16m","mr","ooffice","osdb","reymont","sao","webster","dickens","mozilla", + "nci","samba","xml","x-ray"]; + +fn sizes(lvl: i32, srcs: &[(&str, Vec)]) -> Vec { + srcs.iter().map(|(_, s)| rz::compress_with(s, + rz::CompressOptions { level: lvl, checksum: false }).unwrap().len()).collect() +} + +fn main() { + let cap: usize = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(4 << 20); + let srcs: Vec<(&str, Vec)> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); (*id, f[..n].to_vec()) }) + }).collect(); + println!("SIZE HUNT cap={} KiB corpora={}\n", cap >> 10, srcs.len()); + + type S = fn(bool); + // (name, setter, default, level) -- arms reaching the two finders under study. + let bools: &[(&str, S, bool, i32)] = &[ + ("pair_on", rz::set_pair_on_arm as S, true, 1), + ("tag_alloc", rz::set_tag_alloc_arm, true, 1), + ("pipe_rep1", rz::set_pipe_rep1_arm, true, 1), + ("next_long", rz::set_next_long_arm, true, 3), + ("dfast_bext", rz::set_dfast_bext_arm, true, 3), + ("fast_pack", rz::set_fast_pack_arm, true, 1), + ("fast_hash", rz::set_fast_hash_arm, true, 1), + ("long_tag", rz::set_long_tag_arm, true, 3), + ("dfast_tag", rz::set_dfast_tag_arm, true, 3), + ]; + for (name, set, deflt, lvl) in bools { + set(*deflt); + let a = sizes(*lvl, &srcs); + set(!*deflt); + let b = sizes(*lvl, &srcs); + set(*deflt); + let mut cells: Vec<(i64, &str)> = a.iter().zip(b.iter()).zip(srcs.iter()) + .map(|((x, y), (id, _))| (*y as i64 - *x as i64, *id)).collect(); + cells.sort(); + let wins: Vec<&(i64, &str)> = cells.iter().filter(|(d, _)| *d < 0).collect(); + let loss: Vec<&(i64, &str)> = cells.iter().filter(|(d, _)| *d > 0).collect(); + let net: i64 = cells.iter().map(|(d, _)| d).sum(); + if wins.is_empty() && loss.is_empty() { continue; } + println!("{name} @ L{lvl} (flipping to {}) net {net:+}", !*deflt); + print!(" SMALLER on {}: ", wins.len()); + for (d, id) in wins.iter().take(6) { print!("{id}{d} "); } + println!(); + print!(" larger on {}: ", loss.len()); + for (d, id) in loss.iter().rev().take(6) { print!("{id}+{d} "); } + println!(); + if !wins.is_empty() && loss.is_empty() { + println!(" >>> STRICT WIN: never larger on any corpus <<<"); + } + println!(); + } +} diff --git a/crates/rusty_zstd-bench/examples/sizevsc.rs b/crates/rusty_zstd-bench/examples/sizevsc.rs new file mode 100644 index 0000000..accc989 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/sizevsc.rs @@ -0,0 +1,46 @@ +//! SIZE-ONLY head-to-head vs C zstd. No clock, so a loaded box cannot corrupt +//! it -- compressed bytes are the same number under any load. +//! +//! Shows our output before and after the row-finder AUTO gate against the same +//! C reference, so the win is priced against zstd rather than against ourselves. +use std::process::Command; +use rusty_zstd as rz; +const SIL: &[&str] = &["mr","ooffice","osdb","reymont","sao","webster","dickens", + "mozilla","nci","samba","xml","x-ray"]; +fn c_size(zstd: &str, path: &str, lvl: i32) -> Option { + let o = Command::new(zstd).args(["-q", "-f", &format!("-{lvl}"), "--no-check", + path, "-o", &format!("{path}.zst")]).output().ok()?; + let _ = o; + let n = std::fs::metadata(format!("{path}.zst")).ok()?.len() as usize; + let _ = std::fs::remove_file(format!("{path}.zst")); + Some(n) +} +fn main() { + let zstd = "third_party/zstd/extracted/zstd-v1.5.7-win64/zstd.exe"; + let cap: usize = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(1 << 20); + let tmp = std::env::temp_dir().join("sizevsc.bin"); + println!("SILESIA, cap {} KiB, vs zstd 1.5.7 -- SIZE ONLY (load-immune)\n", cap >> 10); + println!("{:<10}{:>4}{:>11}{:>11}{:>11}{:>10}{:>10}", "corpus", "L", "C", "us(old)", "us(new)", "old/C", "new/C"); + println!("{}", "-".repeat(68)); + for lvl in [7i32, 9] { + let (mut sc, mut so, mut sn) = (0u64, 0u64, 0u64); + for id in SIL { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) else { continue }; + let src = &f[..f.len().min(cap)]; + std::fs::write(&tmp, src).unwrap(); + let Some(c) = c_size(zstd, tmp.to_str().unwrap(), lvl) else { continue }; + let p = rz::compression_params(lvl, Some(src.len() as u64)).unwrap(); + rz::set_row_arm(false); + let old = rz::compress_with_params(src, p, false).unwrap().len(); + rz::set_row_arm_auto(); + let new = rz::compress_with_params(src, p, false).unwrap().len(); + sc += c as u64; so += old as u64; sn += new as u64; + println!("{:<10}{:>4}{:>11}{:>11}{:>11}{:>10.4}{:>10.4}", + id, lvl, c, old, new, old as f64 / c as f64, new as f64 / c as f64); + } + println!("{:<10}{:>4}{:>11}{:>11}{:>11}{:>10.4}{:>10.4} <== L{lvl} TOTAL", + "TOTAL", lvl, sc, so, sn, so as f64 / sc as f64, sn as f64 / sc as f64); + println!(); + } + let _ = std::fs::remove_file(&tmp); +} diff --git a/crates/rusty_zstd-bench/examples/slidead.rs b/crates/rusty_zstd-bench/examples/slidead.rs new file mode 100644 index 0000000..8d9218b --- /dev/null +++ b/crates/rusty_zstd-bench/examples/slidead.rs @@ -0,0 +1,133 @@ +//! Paired A/B of the streaming slide multiplier, in ONE process. +//! +//! Both arms are in this binary and the arm is chosen per Compressor, so there +//! is no rebuild and no second executable between the two measurements. +//! +//! Discipline (codec-measurement): arms ABBA-interleaved so machine drift +//! cancels rather than landing between blocks; a NULL arm (k=2 against itself) +//! establishes what this box can resolve at all; paired win-rate with a z-score +//! rather than a ratio of medians, because on a drifting box the medians move +//! more than the effect. The deterministic counters -- prime inserts, bytes +//! moved, compressed size -- are the primary evidence; this only prices them. +use rusty_zstd::{Compressor, Flush}; +use std::time::Instant; + +fn load(id: &str) -> Option> { + std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) + .ok() +} + +fn run(src: &[u8], lvl: i32, mul: usize, chunk: usize) -> (f64, usize) { + let mut c = Compressor::new(lvl).expect("compressor"); + c.set_slide_mul(mul); + let mut out = Vec::with_capacity(src.len() / 2 + (1 << 20)); + let mut buf = vec![0u8; 128 << 10]; + let t = Instant::now(); + let mut i = 0usize; + while i < src.len() { + let end = (i + chunk).min(src.len()); + let mut inp = &src[i..end]; + loop { + let st = c.stream(inp, &mut buf, Flush::Continue).expect("stream"); + out.extend_from_slice(&buf[..st.output_produced]); + inp = &inp[st.input_consumed..]; + if inp.is_empty() || (st.input_consumed == 0 && st.output_produced == 0) { + break; + } + } + i = end; + } + loop { + let st = c.stream(&[], &mut buf, Flush::End).expect("end"); + out.extend_from_slice(&buf[..st.output_produced]); + if st.done || st.output_produced == 0 { + break; + } + } + (t.elapsed().as_secs_f64(), out.len()) +} + +fn verdict(name: &str, a: &[f64], b: &[f64]) { + let n = a.len(); + let wins = a.iter().zip(b).filter(|(x, y)| y < x).count(); + let ties = a + .iter() + .zip(b) + .filter(|(x, y)| (**y - **x).abs() < 1e-9) + .count(); + let eff = n - ties; + let z = if eff == 0 { + 0.0 + } else { + (wins as f64 - eff as f64 / 2.0) / (0.5 * (eff as f64).sqrt()) + }; + let med = |v: &[f64]| { + let mut s = v.to_vec(); + s.sort_by(|x, y| x.partial_cmp(y).unwrap()); + s[s.len() / 2] + }; + let (ma, mb) = (med(a), med(b)); + let mn = |v: &[f64]| v.iter().cloned().fold(f64::MAX, f64::min); + println!( + " {name:<22} median {ma:.4}s -> {mb:.4}s ({:.3}x) min {:.4} -> {:.4} ({:.3}x) \ +{wins}/{eff} z={z:+.2}", + ma / mb, + mn(a), + mn(b), + mn(a) / mn(b) + ); +} + +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + let reps: usize = std::env::args() + .nth(2) + .and_then(|s| s.parse().ok()) + .unwrap_or(21); + let ka: usize = std::env::args() + .nth(3) + .and_then(|s| s.parse().ok()) + .unwrap_or(2); + let kb: usize = std::env::args() + .nth(4) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + let chunk = 64 << 10; + for id in ["samba", "webster", "mozilla"] { + let Some(f) = load(id) else { continue }; + let src = &f[..f.len().min(32 << 20)]; + let (_, s2) = run(src, lvl, ka, chunk); + let (_, s3) = run(src, lvl, kb, chunk); + println!( + "\n{id} {:.1} MiB compressed k=2 {s2} B, k=3 {s3} B ({:+.4}% size)", + src.len() as f64 / (1 << 20) as f64, + (s3 as f64 - s2 as f64) / s2 as f64 * 100.0 + ); + let (mut a, mut b, mut na, mut nb) = (vec![], vec![], vec![], vec![]); + for r in 0..reps { + // ABBA: alternate which arm leads, so "the second one runs warmer" + // cancels instead of accumulating into one arm. + if r % 2 == 0 { + a.push(run(src, lvl, ka, chunk).0); + b.push(run(src, lvl, kb, chunk).0); + na.push(run(src, lvl, ka, chunk).0); + nb.push(run(src, lvl, ka, chunk).0); + } else { + b.push(run(src, lvl, kb, chunk).0); + a.push(run(src, lvl, ka, chunk).0); + nb.push(run(src, lvl, ka, chunk).0); + na.push(run(src, lvl, ka, chunk).0); + } + } + verdict("NULL (same arm twice)", &na, &nb); + verdict("A -> B", &a, &b); + } + println!( + "\nRead the NULL arm first: it is what this box can resolve. A k=3 verdict\n\ + inside the null's spread is not a result." + ); +} diff --git a/crates/rusty_zstd-bench/examples/speedab.rs b/crates/rusty_zstd-bench/examples/speedab.rs new file mode 100644 index 0000000..53970dc --- /dev/null +++ b/crates/rusty_zstd-bench/examples/speedab.rs @@ -0,0 +1,89 @@ +//! In-process compress/decompress speed, for A/B-ing two BUILDS of the library. +//! +//! cargo run --release -p rusty_zstd-bench --example speedab -- +//! +//! Why a separate program rather than `--m7-speed`: that harness shells out to +//! the pinned C zstd and writes the ledger; this one measures ONLY us, in +//! memory (no file I/O in the timed region), so the same source compiled +//! against two library versions is the whole comparison. The estimator is +//! BEST-of-N per run (the floor is what survives a busy box), and the driver +//! alternates whole processes ABBA and takes the median across pairs. +//! +//! The allocator is installed here deliberately: a deliverable declares one, +//! and the rusty_alloc pin is exactly one of the things being measured. + +#[global_allocator] +static ALLOC: rzstd_alloc::Alloc = rzstd_alloc::Alloc; + +use std::time::{Duration, Instant}; + +fn bench(src: &[u8], level: i32, budget: Duration) -> (f64, f64, usize, u32) { + // one warm pass, outside the timed region, so tables/scratch are hot + let warm = rusty_zstd::compress(src, level).expect("compress"); + let csize = warm.len(); + + let mut best_c = f64::MAX; + let mut loops = 0u32; + let t0 = Instant::now(); + loop { + let t = Instant::now(); + let out = rusty_zstd::compress(src, level).expect("compress"); + let ms = t.elapsed().as_secs_f64() * 1000.0; + std::hint::black_box(&out); + if ms < best_c { + best_c = ms; + } + loops += 1; + if t0.elapsed() >= budget && loops >= 3 { + break; + } + } + + let mut best_d = f64::MAX; + let t0 = Instant::now(); + let mut dloops = 0u32; + loop { + let t = Instant::now(); + let raw = rusty_zstd::decompress(&warm).expect("decompress"); + let ms = t.elapsed().as_secs_f64() * 1000.0; + assert_eq!(raw.len(), src.len(), "round trip length"); + std::hint::black_box(&raw); + if ms < best_d { + best_d = ms; + } + dloops += 1; + if t0.elapsed() >= budget && dloops >= 3 { + break; + } + } + (best_c, best_d, csize, loops) +} + +fn main() { + let a: Vec = std::env::args().skip(1).collect(); + if a.len() < 3 { + eprintln!("usage: speedab "); + std::process::exit(2); + } + let level: i32 = a[0].parse().expect("level"); + let secs: u64 = a[1].parse().expect("secs"); + let budget = Duration::from_secs(secs); + for id in &a[2..] { + let mut p = format!("corpora/data/silesia/{id}"); + if !std::path::Path::new(&p).exists() { + p = format!("corpora/data/generated/{id}"); + } + let Ok(src) = std::fs::read(&p) else { + eprintln!("missing {p}"); + continue; + }; + let (c_ms, d_ms, csize, loops) = bench(&src, level, budget); + let mb = src.len() as f64 / 1_048_576.0; + println!( + "{id}\t{level}\t{}\t{csize}\t{c_ms:.3}\t{d_ms:.3}\t{:.2}\t{:.2}\t{loops}", + src.len(), + mb / (c_ms / 1000.0), + mb / (d_ms / 1000.0), + ); + } +} diff --git a/crates/rusty_zstd-bench/examples/streamcopies.rs b/crates/rusty_zstd-bench/examples/streamcopies.rs new file mode 100644 index 0000000..eb6cf15 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/streamcopies.rs @@ -0,0 +1,148 @@ +//! STREAMING copy census -- the path the one-shot census never touches. +//! +//! `Compressor` keeps a history window. When it overflows it slides: the +//! retained window is memmoved down by `hist.drain(..drop)`, six match tables +//! are zeroed, and the whole window is re-primed. None of that exists in the +//! one-shot encoder, so a census taken there reads zero for all of it. +//! +//! Deterministic: byte totals depend only on the input and the chunk size. +use rusty_zstd::copies::{self, COPY_NAMES, N_COPY_SLOTS}; +use rusty_zstd::{Compressor, Flush}; + +const IDS: &[&str] = &["dickens", "samba", "webster", "mozilla"]; + +fn load(id: &str) -> Option> { + std::fs::read(format!("corpora/data/silesia/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/generated/{id}"))) + .ok() +} + +fn main() { + let lvl: i32 = std::env::args() + .nth(1) + .and_then(|s| s.parse().ok()) + .unwrap_or(3); + let chunk: usize = std::env::args() + .nth(2) + .and_then(|s| s.parse().ok()) + .unwrap_or(64 << 10); + println!("STREAMING COPY CENSUS (L{lvl}, {chunk} B chunks) -- bytes, not clocks\n"); + println!( + "{:<12}{:>8}{:>8}{:>16}{:>16}{:>10}", + "corpus", "MiB", "slides", "hist memmoved", "tables zeroed", "B/input" + ); + + let mut tot = [(0u64, 0u64); N_COPY_SLOTS]; + let mut tsrc = 0u64; + let mut tcsize = 0u64; + for id in IDS { + let Some(f) = load(id) else { continue }; + let src = &f[..f.len().min(32 << 20)]; + let _ = copies::take(); + let _ = rusty_zstd::take_enc_slide(); + + let mut c = Compressor::new(lvl).expect("compressor"); + let mut out = Vec::with_capacity(src.len() / 2 + (1 << 20)); + let t0 = std::time::Instant::now(); + let mut buf = vec![0u8; 128 << 10]; + let mut i = 0usize; + while i < src.len() { + let end = (i + chunk).min(src.len()); + let mut inp = &src[i..end]; + loop { + let st = c.stream(inp, &mut buf, Flush::Continue).expect("stream"); + out.extend_from_slice(&buf[..st.output_produced]); + inp = &inp[st.input_consumed..]; + if inp.is_empty() || (st.input_consumed == 0 && st.output_produced == 0) { + break; + } + } + i = end; + } + loop { + let st = c.stream(&[], &mut buf, Flush::End).expect("end"); + out.extend_from_slice(&buf[..st.output_produced]); + if st.done { + break; + } + if st.output_produced == 0 { + break; + } + } + let csize = out.len(); + let cc = copies::take(); + let sl = rusty_zstd::take_enc_slide(); + drop(buf); + { + let back = rusty_zstd::decompress(&out).expect("decompress"); + assert_eq!(back, src, "{id} streaming roundtrip"); + } + drop(out); + let _ = copies::take(); + + // Prime inserts are POSITIONS, not bytes. Summing them into a byte + // total mixes two units that differ by an order of magnitude in cost + // per unit, which is how a census starts reporting a number that means + // nothing. Counted and reported, never added. + let moved: u64 = cc + .iter() + .enumerate() + .filter(|(i, _)| *i != copies::C_PRIME_INSERT) + .map(|(_, (b, _))| *b) + .sum(); + println!( + "{id:<12}{:>8.1}{:>8}{:>16}{:>16}{:>10.3}", + src.len() as f64 / (1 << 20) as f64, + sl[0], + cc[copies::C_HIST_SLIDE].0, + cc[copies::C_TABLE_CLEAR].0, + moved as f64 / src.len() as f64 + ); + let secs = t0.elapsed().as_secs_f64(); + let slide_b = (cc[copies::C_HIST_SLIDE].0 + cc[copies::C_TABLE_CLEAR].0) as f64; + println!( + " encode {:.3}s ({:.0} MiB/s); slide traffic {:.1} MB = {:.2}-{:.2} ms at 10-20 GB/s = {:.3}%-{:.3}% of encode", + secs, + src.len() as f64 / (1 << 20) as f64 / secs, + slide_b / 1e6, + slide_b / 10e9 * 1e3, + slide_b / 20e9 * 1e3, + slide_b / 10e9 / secs * 100.0, + slide_b / 20e9 / secs * 100.0 + ); + println!( + " compressed {csize} B ({:.4} ratio)", + src.len() as f64 / csize as f64 + ); + tcsize += csize as u64; + tsrc += src.len() as u64; + for i in 0..N_COPY_SLOTS { + tot[i].0 += cc[i].0; + tot[i].1 += cc[i].1; + } + } + + println!( + "\n{:<24}{:>16}{:>12}{:>12}", + "site", "bytes", "calls", "B/input" + ); + let mut moved = 0u64; + for i in 0..N_COPY_SLOTS { + let (b, n) = tot[i]; + if b == 0 && n == 0 { + continue; + } + if i != copies::C_PRIME_INSERT { + moved += b; + } + println!( + "{:<24}{b:>16}{n:>12}{:>12.4}", + COPY_NAMES[i], + b as f64 / tsrc as f64 + ); + } + println!( + "\nTOTAL {moved} bytes moved for {tsrc} input bytes = {:.3} copies per input byte", + moved as f64 / tsrc as f64 + ); +} diff --git a/crates/rusty_zstd-bench/examples/streamgate.rs b/crates/rusty_zstd-bench/examples/streamgate.rs new file mode 100644 index 0000000..b242183 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/streamgate.rs @@ -0,0 +1,82 @@ +//! Streaming round-trip CONTENT gate for the compaction-frequency changes. +//! +//! `deccopies` asserts only the decoded LENGTH. These changes alter when +//! buffers are reclaimed, which cannot change output -- but "cannot" is a claim +//! to test. This compares every byte, across chunk sizes chosen to straddle the +//! compaction triggers, and both streaming and one-shot decode of the same +//! frame must agree. +use rusty_zstd::{Compressor, Decompressor, Flush}; + +fn stream_compress(src: &[u8], lvl: i32, chunk: usize) -> Vec { + let mut c = Compressor::new(lvl).expect("c"); + let mut out = Vec::new(); + let mut buf = vec![0u8; 128 << 10]; + let mut i = 0; + while i < src.len() { + let end = (i + chunk).min(src.len()); + let mut inp = &src[i..end]; + loop { + let st = c.stream(inp, &mut buf, Flush::Continue).expect("s"); + out.extend_from_slice(&buf[..st.output_produced]); + inp = &inp[st.input_consumed..]; + if inp.is_empty() { break; } + } + i = end; + } + loop { + let st = c.stream(&[], &mut buf, Flush::End).expect("e"); + out.extend_from_slice(&buf[..st.output_produced]); + if st.done { break; } + } + out +} + +fn stream_decompress(z: &[u8], chunk: usize, obuf: usize) -> Vec { + let mut d = Decompressor::new(); + let mut buf = vec![0u8; obuf]; + let mut out = Vec::new(); + let mut i = 0; + while i < z.len() { + let end = (i + chunk).min(z.len()); + let mut inp = &z[i..end]; + loop { + let st = d.stream(inp, &mut buf, false).expect("d"); + out.extend_from_slice(&buf[..st.output_produced]); + inp = &inp[st.input_consumed..]; + if st.input_consumed == 0 && st.output_produced == 0 { break; } + } + i = end; + } + loop { + let st = d.stream(&[], &mut buf, true).expect("f"); + out.extend_from_slice(&buf[..st.output_produced]); + if st.output_produced == 0 { break; } + } + out +} + +fn main() { + let mut checks = 0usize; + for id in ["dickens", "samba", "webster"] { + let Ok(f) = std::fs::read(format!("corpora/data/silesia/{id}")) else { continue }; + let src = &f[..f.len().min(12 << 20)]; + for lvl in [1, 3, 9] { + let z_one = rusty_zstd::compress(src, lvl).expect("one-shot"); + // one-shot frame, streamed out at several chunk/buffer geometries + for (ic, ob) in [(1usize << 12, 1usize << 12), (64 << 10, 128 << 10), (1 << 20, 1 << 16)] { + let got = stream_decompress(&z_one, ic, ob); + assert_eq!(got.len(), src.len(), "{id} L{lvl} len ic={ic} ob={ob}"); + assert!(got == src, "{id} L{lvl} CONTENT ic={ic} ob={ob}"); + checks += 1; + } + // streamed frame, both decoders must agree with the source + for ic in [16usize << 10, 256 << 10] { + let z = stream_compress(src, lvl, ic); + assert!(rusty_zstd::decompress(&z).expect("os") == src, "{id} L{lvl} one-shot dec"); + assert!(stream_decompress(&z, 64 << 10, 128 << 10) == src, "{id} L{lvl} stream dec"); + checks += 2; + } + } + } + println!("PASS: {checks} streaming round-trips byte-exact across corpora x levels x geometries"); +} diff --git a/crates/rusty_zstd-bench/examples/taggate.rs b/crates/rusty_zstd-bench/examples/taggate.rs new file mode 100644 index 0000000..011a3cf --- /dev/null +++ b/crates/rusty_zstd-bench/examples/taggate.rs @@ -0,0 +1,51 @@ +//! Are the chain-link TAGS byte-identical when off? The lazy ladder pays a +//! second multiply per inserted byte and a tag decode per link to reject ~10% +//! of candidates that the first-word compare would reject anyway. If the +//! walk's budget counts links the same way with tags off, the output cannot +//! move -- this checks it, per level, on the bytegate corpora. +fn fnv(h: &mut u64, b: &[u8]) { + for &x in b { + *h ^= u64::from(x); + *h = h.wrapping_mul(0x0000_0100_0000_01b3); + } +} +const IDS: &[&str] = &["dickens", "mozilla", "webster", "xml", "samba"]; +fn board(levels: &[i32]) -> Vec<(i32, u64, usize)> { + let mut out = Vec::new(); + for &lvl in levels { + let mut h = 0xcbf2_9ce4_8422_2325u64; + let mut total = 0usize; + for id in IDS { + let Ok(full) = std::fs::read(format!("corpora/data/silesia/{id}")) else { + continue; + }; + let src = &full[..full.len().min(16 << 20)]; + let z = rusty_zstd::compress(src, lvl).unwrap(); + fnv(&mut h, &z); + total += z.len(); + } + out.push((lvl, h, total)); + } + out +} +fn main() { + let levels = [5i32, 7, 9, 12]; + let on = board(&levels); // the default, measured FIRST (armone's rule) + rusty_zstd::set_chain_tag_arm(false); + let off = board(&levels); + println!( + "{:>3} {:>18} {:>18} {:>11} {:>11} verdict", + "L", "tags ON", "tags OFF", "bytes ON", "bytes OFF" + ); + for ((l, h1, n1), (_, h2, n2)) in on.iter().zip(off.iter()) { + println!( + "{:>3} {:>018X} {:>018X} {:>11} {:>11} {}", + l, + h1, + h2, + n1, + n2, + if h1 == h2 { "IDENTICAL" } else { "DIFFERENT" } + ); + } +} diff --git a/crates/rusty_zstd-bench/examples/tblcost.rs b/crates/rusty_zstd-bench/examples/tblcost.rs new file mode 100644 index 0000000..e38eb1d --- /dev/null +++ b/crates/rusty_zstd-bench/examples/tblcost.rs @@ -0,0 +1,32 @@ +//! How much table does a SMALL input have to zero before it can be compressed? +//! +//! `incomp-32m` at 1 MiB does almost no search at any level (0 chain loads at +//! L7/L9) and emits raw blocks -- yet the head-to-head board reads 149 MB/s +//! against C's 1719. Near-zero search plus raw output means the time is not in +//! the finder; it is in the SETUP. `MatchTables::new` allocates and zeroes the +//! hash/chain/long tables, and `vec![0; n]` on a fresh allocation is a memset. +//! +//! This prints the zeroed footprint per level against the input it serves. +use rusty_zstd as rz; +fn main() { + let f = std::fs::read("corpora/data/generated/incomp-32m").expect("incomp-32m"); + println!("{:>7}{:>4}{:>10}{:>11}{:>11}{:>11}{:>12}{:>9}", + "input", "L", "strategy", "hash KiB", "long KiB", "chain KiB", "total KiB", "x input"); + println!("{}", "-".repeat(76)); + for cap in [64usize << 10, 256 << 10, 1 << 20, 4 << 20] { + let src = &f[..f.len().min(cap)]; + for lvl in [1i32, 3, 7, 9, 12] { + let p = rz::compression_params(lvl, Some(src.len() as u64)).unwrap(); + rz::prof_reset(); + let _ = rz::compress_with(src, rz::CompressOptions { level: lvl, checksum: false }).unwrap(); + let c = rz::prof_encode_counts(); + let tot = c.table_hash_bytes + c.table_hash_long_bytes + c.table_chain_bytes; + println!("{:>6}K{:>4}{:>10}{:>11}{:>11}{:>11}{:>12}{:>8.1}x", + cap >> 10, lvl, format!("{:?}", p.strategy), + c.table_hash_bytes / 1024, c.table_hash_long_bytes / 1024, + c.table_chain_bytes / 1024, tot / 1024, + tot as f64 / src.len() as f64); + } + println!(); + } +} diff --git a/crates/rusty_zstd-bench/examples/tblfoot.rs b/crates/rusty_zstd-bench/examples/tblfoot.rs new file mode 100644 index 0000000..e73c7e7 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/tblfoot.rs @@ -0,0 +1,29 @@ +//! Table footprint of the two finders, against this box's cache levels. +//! Decides whether a slot access is an L2 hit or a DRAM round trip -- i.e. +//! whether the slot primitive is instruction-bound or latency-bound. +const IDS: &[&str] = &["dickens", "webster", "mozilla", "samba", "nci", "x-ray"]; +fn main() { + let cap: usize = 8 << 20; + println!("{:<6} {:<8} {:>9} {:>10} {:>10} {:>10} {:>11}", + "level", "strategy", "hash_log", "short KiB", "long KiB", "tags KiB", "total KiB"); + for lvl in [1i32, 3] { + let p = rusty_zstd::compression_params(lvl, None).unwrap(); + let mut agg = (0u64, 0u64, 0u64); + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) else { continue }; + let s = &f[..f.len().min(cap)]; + rusty_zstd::prof_reset(); + let _ = rusty_zstd::compress(s, lvl).unwrap(); + let c = rusty_zstd::prof_encode_counts(); + agg.0 = agg.0.max(c.table_hash_bytes); + agg.1 = agg.1.max(c.table_hash_long_bytes); + agg.2 = agg.2.max(c.table_chain_bytes); + } + let tot = agg.0 + agg.1 + agg.2; + println!("{:<6} {:<8} {:>9} {:>10} {:>10} {:>10} {:>11}", + format!("L{lvl}"), format!("{:?}", p.strategy), p.hash_log, + agg.0 / 1024, agg.1 / 1024, agg.2 / 1024, tot / 1024); + } + println!("\n(table_chain_bytes doubles as the tag-array column for fast/dfast.)"); +} diff --git a/crates/rusty_zstd-bench/examples/tight1.rs b/crates/rusty_zstd-bench/examples/tight1.rs new file mode 100644 index 0000000..fd12ad3 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/tight1.rs @@ -0,0 +1,46 @@ +//! Per-corpus verdict for the source-sized hash at tight=1 (one bucket per +//! position instead of C's two), with a round-trip on every cell. +use rusty_zstd as rz; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","versions-16m","mr","ooffice","osdb", + "reymont","sao","webster","dickens","mozilla","nci","samba","xml","x-ray", + "text-32m","incomp-32m","zeros-32m"]; +fn main() { + let t: u32 = std::env::args().nth(1).and_then(|s| s.parse().ok()).unwrap_or(1); + for cap in [64usize << 10, 256 << 10, 1 << 20, 4 << 20] { + let mut tot = [0i64; 5]; + let mut tbl = [0i64; 5]; + let mut base = [0u64; 5]; + let mut tb0 = [0u64; 5]; + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) else { continue }; + let s = &f[..f.len().min(cap)]; + for (k, lvl) in [1i32, 2, 3, 4, 5].iter().enumerate() { + let p0 = { rz::set_hash_tight_arm(0); + rz::compression_params(*lvl, Some(s.len() as u64)).unwrap() }; + rz::prof_reset(); + let a = rz::compress_with_params(s, p0, false).unwrap().len() as i64; + let ca = rz::prof_encode_counts(); + rz::set_hash_tight_arm(t); + let p1 = rz::compression_params(*lvl, Some(s.len() as u64)).unwrap(); + rz::prof_reset(); + let z = rz::compress_with_params(s, p1, false).unwrap(); + let cb = rz::prof_encode_counts(); + assert_eq!(rz::decompress(&z).unwrap(), s, "{id} L{lvl} cap{cap}"); + rz::set_hash_tight_arm(0); tot[k] += z.len() as i64 - a; + base[k] += a as u64; + let ta = ca.table_hash_bytes + ca.table_hash_long_bytes + ca.table_chain_bytes; + let tbb = cb.table_hash_bytes + cb.table_hash_long_bytes + cb.table_chain_bytes; + tb0[k] += ta; + tbl[k] += tbb as i64 - ta as i64; + } + } + println!("cap {:>5}K tight={t}", cap >> 10); + for (k, lvl) in [1i32, 2, 3, 4, 5].iter().enumerate() { + println!(" L{:<3} size {:>+9} ({:>+7.4}%) tables {:>+10} KiB ({:>+6.1}%)", + lvl, tot[k], tot[k] as f64 / base[k] as f64 * 100.0, + tbl[k] / 1024, tbl[k] as f64 / tb0[k] as f64 * 100.0); + } + println!(); + } +} diff --git a/crates/rusty_zstd-bench/examples/tighthash.rs b/crates/rusty_zstd-bench/examples/tighthash.rs new file mode 100644 index 0000000..cc4ddf3 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/tighthash.rs @@ -0,0 +1,61 @@ +//! Size the hash from the SOURCE rather than the window: what it saves in +//! zeroed table, what it costs in ratio, what it buys in time. +//! +//! Ratio is exact. Time is measured only as an arm-vs-arm ratio in ONE process +//! with a null, so a loaded box moves both arms together. +use rusty_zstd as rz; +use std::time::Instant; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","mr","ooffice","osdb","reymont","sao", + "webster","dickens","mozilla","nci","samba","xml","x-ray","text-32m","incomp-32m"]; +fn main() { + for cap in [256usize << 10, 1 << 20] { + let srcs: Vec> = IDS.iter().filter_map(|id| { + std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) + .ok().map(|f| { let n = f.len().min(cap); f[..n].to_vec() }) + }).collect(); + let n_in: u64 = srcs.iter().map(|s| s.len() as u64).sum(); + for lvl in [5i32, 7, 9, 12] { + let go = || -> (u64, u64) { + let (mut b, mut t) = (0u64, 0u64); + for s in &srcs { + rz::prof_reset(); + let p = rz::compression_params(lvl, Some(s.len() as u64)).unwrap(); + b += rz::compress_with_params(s, p, false).unwrap().len() as u64; + let c = rz::prof_encode_counts(); + t += c.table_hash_bytes + c.table_hash_long_bytes + c.table_chain_bytes; + } + (b, t) + }; + let time = || -> f64 { + let mut best = f64::MAX; + for _ in 0..5 { + let t0 = Instant::now(); + for s in &srcs { + let p = rz::compression_params(lvl, Some(s.len() as u64)).unwrap(); + std::hint::black_box(rz::compress_with_params(s, p, false).unwrap().len()); + } + let e = t0.elapsed().as_secs_f64(); + if e < best { best = e } + } + best * 1000.0 + }; + rz::set_hash_tight_arm(0); + let (b0, t0) = go(); + let m0 = time(); + let m0b = time(); + println!("\n=== L{lvl} cap {} KiB in {} KiB === C-sizing: {} B, tables {} KiB, {:.1} ms (null {:+.1}%)", + cap >> 10, n_in >> 10, b0, t0 >> 10, m0, (m0b / m0 - 1.0) * 100.0); + println!(" {:>6}{:>12}{:>10}{:>12}{:>10}{:>10}", "tight", "bytes", "d size", "tables KiB", "d tbl", "speedup"); + for t in [1u32, 2, 3] { + rz::set_hash_tight_arm(t); + let (b, tb) = go(); + let m = time(); + println!(" {:>6}{:>12}{:>+10}{:>12}{:>9.0}%{:>9.2}x", + t, b, b as i64 - b0 as i64, tb >> 10, + (tb as f64 / t0 as f64 - 1.0) * 100.0, m0 / m); + } + rz::set_hash_tight_arm(0); + } + } +} diff --git a/crates/rusty_zstd-bench/examples/tighttree.rs b/crates/rusty_zstd-bench/examples/tighttree.rs new file mode 100644 index 0000000..f360292 --- /dev/null +++ b/crates/rusty_zstd-bench/examples/tighttree.rs @@ -0,0 +1,39 @@ +//! Is the source-sized hash FREE on the tree strategies? +//! +//! `tight1.rs` showed L16 (BtOpt) costing exactly zero bytes at every cap while +//! cutting the table 25%. The tree finders address candidates through the +//! binary tree, not through a hash chain, so extra hash buckets buy them very +//! little. This checks that across the whole tree ladder and more sizes. +use rusty_zstd as rz; +const IDS: &[&str] = &["jsonlog-16m","smallmsg-8m","mr","ooffice","osdb","reymont","sao", + "webster","dickens","mozilla","nci","samba","xml","x-ray","text-32m","incomp-32m"]; +fn main() { + println!("{:>5}{:>9}{:>12}{:>11}{:>10}{:>13}{:>9}", + "L", "cap KiB", "base bytes", "d size", "d size %", "tables KiB", "d tbl %"); + println!("{}", "-".repeat(70)); + for lvl in [13i32, 16, 19, 22] { + for cap in [64usize << 10, 256 << 10, 1 << 20, 4 << 20] { + let (mut b0, mut b1, mut t0v, mut t1v) = (0u64, 0u64, 0u64, 0u64); + for id in IDS { + let Ok(f) = std::fs::read(format!("corpora/data/generated/{id}")) + .or_else(|_| std::fs::read(format!("corpora/data/silesia/{id}"))) else { continue }; + let s = &f[..f.len().min(cap)]; + for (t, bs, ts) in [(0u32, &mut b0, &mut t0v), (1, &mut b1, &mut t1v)] { + rz::set_hash_tight_arm(t); + let p = rz::compression_params(lvl, Some(s.len() as u64)).unwrap(); + rz::prof_reset(); + let z = rz::compress_with_params(s, p, false).unwrap(); + if t == 1 { assert_eq!(rz::decompress(&z).unwrap(), s, "{id} L{lvl}"); } + *bs += z.len() as u64; + let c = rz::prof_encode_counts(); + *ts += c.table_hash_bytes + c.table_hash_long_bytes + c.table_chain_bytes; + } + } + rz::set_hash_tight_arm(0); + println!("{:>5}{:>9}{:>12}{:>+11}{:>9.4}%{:>13}{:>8.1}%", + lvl, cap >> 10, b0, b1 as i64 - b0 as i64, + (b1 as i64 - b0 as i64) as f64 / b0 as f64 * 100.0, + t0v >> 10, (t1v as f64 / t0v as f64 - 1.0) * 100.0); + } + } +} diff --git a/crates/rusty_zstd/Cargo.toml b/crates/rusty_zstd/Cargo.toml index 5c40307..3ad3d36 100644 --- a/crates/rusty_zstd/Cargo.toml +++ b/crates/rusty_zstd/Cargo.toml @@ -63,7 +63,7 @@ pfcensus = ["profile"] # Optional, and off unless `rusty-alloc` is enabled: with the feature off this # crate still resolves to zero dependencies, which is the property the crate # description claims. -rusty_alloc_default = { version = "0.1.1", optional = true } +rusty_alloc_default = { version = "0.1.2", optional = true } [lints] workspace = true diff --git a/crates/rusty_zstd/src/compressed.rs b/crates/rusty_zstd/src/compressed.rs index a20718e..03916e8 100644 --- a/crates/rusty_zstd/src/compressed.rs +++ b/crates/rusty_zstd/src/compressed.rs @@ -604,6 +604,7 @@ pub(crate) fn decode_sequences( // D15: gate matches payload -- see the twin. It was `has_avx2() && // has_bmi2()` for a body with zero ymm. if seqloop_avx2_on() && crate::simd::has_bmi2() { + crate::kreach::hit(crate::kreach::K_DEC_SEQ); // SAFETY: guarded by a runtime AVX2 check; the body is identical. #[allow(unsafe_code)] return unsafe { @@ -620,6 +621,7 @@ pub(crate) fn decode_sequences( ) }; } + crate::kreach::miss(crate::kreach::K_DEC_SEQ); decode_sequences_inner( src, literals, @@ -2438,16 +2440,22 @@ fn prefetch_hist(out: &[u8], litlen: u32, offset_value: u32) { /// ~36 iterations for LL and ~53 for ML on a typical sequence. This stays as /// the correctness reference and as the path for values above the LUT. pub(crate) fn code_from_base(val: u32, base: &[u32], bits: &[u8]) -> (u8, u32, u8) { - let mut i = base.len() - 1; - loop { - if val >= base[i] { - return (i as u8, val - base[i], bits[i]); - } - if i == 0 { - return (0, val, 0); + // NOT a speed change -- MEASURED at zero, and recorded so nobody re-runs + // it expecting one. The hypothesis was that `bits[i]` needed a bounds check + // the decrementing index could not discharge (nothing states + // `bits.len() >= base.len()`); the emitted asm says LLVM had already proven + // it, and the zip form measures **0 instructions and 0 guard branches** + // either way. + // + // Kept purely because it is safer and shorter: the old `base.len() - 1` + // underflowed to `usize::MAX` on an empty `base`, and this cannot. Same + // top-down scan order, same first-match-wins, same `(0, val, 0)` fall-off. + for (i, (&b, &nb)) in base.iter().zip(bits).enumerate().rev() { + if val >= b { + return (i as u8, val - b, nb); } - i -= 1; } + (0, val, 0) } /// Direct value-to-code lookup covering the common range (C keeps `LL_Code[64]` diff --git a/crates/rusty_zstd/src/copies.rs b/crates/rusty_zstd/src/copies.rs new file mode 100644 index 0000000..c194a69 --- /dev/null +++ b/crates/rusty_zstd/src/copies.rs @@ -0,0 +1,240 @@ +//! COPY CENSUS -- how many times does the encoder move each input byte? +//! +//! The catalogue in `tools/copycat.py` reads the emitted asm and says WHERE the +//! `memcpy` calls are. It cannot say how much traffic each one carries, and a +//! call count is a bad proxy: one call on the literal path moves a whole block, +//! while six in a table-setup loop move a few hundred bytes between them. +//! +//! So this counts BYTES, at each site, and the useful figure it produces is +//! **copies per input byte**. That number has a floor and the floor is not +//! zero: an encoder must physically place literal bytes into its output, so one +//! traversal of the literal volume is the job. Anything above one traversal is +//! a byte moved a second time, and that is what is worth removing. +//! +//! Deterministic: byte totals are a property of the input and the code path, so +//! the same corpus gives the same numbers on any machine at any load. No +//! pinning, no interleaving, no noise floor. +//! +//! The counters are thread-local `Cell` bumps folded into process totals, for +//! the same reason as `kreach`: `lock xaddq` per copy would be the instrument +//! dominating what it measures. All of it compiles to nothing without +//! `profile`. + +/// `src` -> the block's literal buffer (`push_literals`). +pub const C_LIT_PUSH: usize = 0; +/// literal buffer -> a materialised raw/RLE section. +/// +/// Reads ZERO since the raw/RLE arms began writing through `dst`: the +/// allocating twin that produced this traffic has no caller left. Kept as the +/// standing proof that the materialise-then-copy path has not come back. +pub const C_LIT_RAW_SECTION: usize = 1; +/// the finished literals section -> `dst` (`write_literals_inner`). +pub const C_SECTION_TO_DST: usize = 2; +/// Huffman-coded literal bytes emitted into the section. +pub const C_HUFF_EMIT: usize = 3; +/// sequence bytes -> `dst`. +pub const C_SEQ_TO_DST: usize = 4; +/// a finished block -> the frame buffer. +pub const C_BLOCK_TO_FRAME: usize = 5; + +/// a RAW block -> `dst` (incompressible input; src to output directly). +pub const C_RAW_BLOCK_TO_DST: usize = 6; + +/// STREAMING: the retained window memmoved down by `hist.drain(..drop)`. +pub const C_HIST_SLIDE: usize = 7; +/// STREAMING: the six match tables zeroed by `MatchTables::reset`. +pub const C_TABLE_CLEAR: usize = 8; + +/// STREAMING: positions re-inserted by `prime_tables` after a slide. +/// +/// NOT a copy -- it is table WORK, counted here because it scales with slide +/// frequency exactly as the memmove and the table clear do, and it is the +/// part of the slide that actually decides whether the frequency is worth +/// tuning. Section 20 measured 503,314,800 of these before the trigger moved. +pub const C_PRIME_INSERT: usize = 9; + +/// STREAMING DECODE: compressed bytes copied into the input accumulator. +pub const C_DEC_IN_ACC: usize = 10; +/// STREAMING DECODE: decoded bytes copied out into the caller's buffer. +/// +/// Inherent to the streaming contract -- the caller owns the destination -- +/// and therefore a cost one-shot `decompress_into` does not pay at all. +pub const C_DEC_OUT: usize = 11; +/// STREAMING DECODE: the decoded-window compaction memmove. +pub const C_DEC_COMPACT: usize = 12; + +/// STREAMING DECODE: the INPUT accumulator compaction memmove. +/// +/// Distinct from `C_DEC_IN_ACC`, which counts bytes copied IN. This counts +/// the memmove that reclaims the consumed prefix, and it fires per call once +/// the consumed prefix passes 64 KiB -- so with a 64 KiB feed it can fire on +/// every single call, moving whatever is still unconsumed each time. +pub const C_DEC_IN_COMPACT: usize = 13; + +/// STREAMING ENCODE: the input-accumulator compaction memmove. +/// +/// Sibling of `C_DEC_IN_COMPACT`, same absolute-trigger shape. Measured so +/// the decoder finding is not assumed to transfer. +pub const C_ENC_IN_COMPACT: usize = 14; + +/// STREAMING ENCODE: reclaims taken by the free `clear` arm (count, not bytes). +/// +/// The CONTROL for `C_ENC_IN_COMPACT`: a zero on the drain arm only means +/// something once this one is non-zero, otherwise the tap is simply unreached. +pub const C_ENC_IN_CLEAR: usize = 15; + +/// STREAMING ENCODE: caller bytes -> `in_acc` staging buffer. +pub const C_ENC_IN_ACC: usize = 16; +/// STREAMING ENCODE: `in_acc` -> `hist`, the match window. +/// +/// The SECOND copy of every input byte before encoding begins. `in_acc` +/// stages a partial block and `hist` is the window the finders read, so a +/// byte lands in both. +pub const C_ENC_TO_HIST: usize = 17; +/// STREAMING ENCODE: `out_acc` -> the caller's buffer. +pub const C_ENC_OUT: usize = 18; +/// STREAMING ENCODE: the `out_acc` compaction memmove. +pub const C_ENC_OUT_COMPACT: usize = 19; + +/// MT: per-job compressed output concatenated into the frame buffer. +pub const C_MT_CONCAT: usize = 20; +/// MT: bytes the concat buffer moved because it GREW instead of reserving. +/// +/// A `Vec::new()` grown to N by doubling copies ~N bytes in reallocs, on top +/// of the concat itself -- so an unreserved concatenation of job outputs pays +/// for the compressed stream roughly TWICE. +pub const C_MT_REGROW: usize = 21; + +/// DECODE: bytes reserved by extrapolation when the header declared no size. +pub const C_DEC_RESERVE: usize = 22; + +/// ENCODE: a finder scratch buffer DISCARDED and reallocated because the +/// pooled one was too small. Bytes = the new capacity. +/// +/// `lit_scratch` is sized `block_len + LIT_PUSH_WIDTH_MAX`, i.e. past the +/// 128 KiB large-allocation threshold, so each of these is a fresh VirtualAlloc +/// and a page-table edit. Once per frame is fine; once per BLOCK is not. +pub const C_SCRATCH_REALLOC: usize = 23; + +/// Number of census slots. +pub const N_COPY_SLOTS: usize = 24; + +/// Human names, index-aligned with the `C_*` constants. +pub const COPY_NAMES: [&str; N_COPY_SLOTS] = [ + "src -> lits", + "lits -> raw section", + "section -> dst", + "huffman emit", + "sequences -> dst", + "block -> frame", + "raw block -> dst", + "hist slide (memmove)", + "table clear (memset)", + "prime inserts (positions)", + "dec: in -> in_acc", + "dec: decoded -> caller", + "dec: compaction memmove", + "dec: in_acc compaction", + "enc: in_acc compaction", + "enc: in_acc clear (control)", + "enc: caller -> in_acc", + "enc: in_acc -> hist", + "enc: out_acc -> caller", + "enc: out_acc compaction", + "mt: job -> frame", + "mt: concat regrow", + "dec: extrapolated reserve", + "enc: scratch realloc", +]; + +#[cfg(not(feature = "profile"))] +mod imp { + /// Shipping build: the tap folds to nothing. + #[inline(always)] + pub fn add(_slot: usize, _bytes: usize) {} + /// Shipping build: the tap folds to nothing. + #[inline(always)] + pub fn flush_this_thread() {} +} + +#[cfg(feature = "profile")] +mod imp { + use super::N_COPY_SLOTS; + use core::cell::Cell; + use core::sync::atomic::{AtomicU64, Ordering::Relaxed}; + + pub(super) static G_BYTES: [AtomicU64; N_COPY_SLOTS] = + [const { AtomicU64::new(0) }; N_COPY_SLOTS]; + pub(super) static G_CALLS: [AtomicU64; N_COPY_SLOTS] = + [const { AtomicU64::new(0) }; N_COPY_SLOTS]; + + struct Tls { + bytes: [Cell; N_COPY_SLOTS], + calls: [Cell; N_COPY_SLOTS], + } + + fn fold(c: &Cell, g: &AtomicU64) { + let v = c.replace(0); + if v != 0 { + g.fetch_add(v, Relaxed); + } + } + + impl Tls { + const fn new() -> Self { + Tls { + bytes: [const { Cell::new(0) }; N_COPY_SLOTS], + calls: [const { Cell::new(0) }; N_COPY_SLOTS], + } + } + fn flush(&self) { + for (c, g) in self.bytes.iter().zip(G_BYTES.iter()) { + fold(c, g); + } + for (c, g) in self.calls.iter().zip(G_CALLS.iter()) { + fold(c, g); + } + } + } + + impl Drop for Tls { + fn drop(&mut self) { + self.flush(); + } + } + + std::thread_local! { + static TLS: Tls = const { Tls::new() }; + } + + /// Record `bytes` moved at `slot`. + #[inline(always)] + pub fn add(slot: usize, bytes: usize) { + let _ = TLS.try_with(|t| { + t.bytes[slot].set(t.bytes[slot].get() + bytes as u64); + t.calls[slot].set(t.calls[slot].get() + 1); + }); + } + + /// Fold this thread's cells into the process totals. + pub fn flush_this_thread() { + let _ = TLS.try_with(|t| t.flush()); + } +} + +pub use imp::{add, flush_this_thread}; + +/// Read and clear the census: `[(bytes, calls); N_COPY_SLOTS]`. +#[cfg(feature = "profile")] +pub fn take() -> [(u64, u64); N_COPY_SLOTS] { + use core::sync::atomic::Ordering::Relaxed; + imp::flush_this_thread(); + let mut out = [(0u64, 0u64); N_COPY_SLOTS]; + for (i, o) in out.iter_mut().enumerate() { + *o = ( + imp::G_BYTES[i].swap(0, Relaxed), + imp::G_CALLS[i].swap(0, Relaxed), + ); + } + out +} diff --git a/crates/rusty_zstd/src/decode.rs b/crates/rusty_zstd/src/decode.rs index db1894d..d8c8516 100644 --- a/crates/rusty_zstd/src/decode.rs +++ b/crates/rusty_zstd/src/decode.rs @@ -411,6 +411,15 @@ fn decode_zstd_frame( out.try_reserve(extra) .map_err(|_| Error::ContentSizeTooLarge)?; } + // A frame with NO declared content size got no reserve at all, so `out` + // grew to the whole decompressed stream by doubling -- ~1x the output in + // realloc copies. Our own streaming compressor omits the size unless the + // caller pledges one, so this is the common case for streamed frames, not + // a corner. There is nothing to reserve EXACTLY here (the size is what the + // header failed to say), so it is extrapolated from the first block's + // measured ratio inside the loop below rather than from a guessed + // constant. `reserve_from_first_block` is that hook. + let mut sized_from_first_block = header.content_size.is_some(); let block_max = header.block_size_max(); let start_len = out.len(); @@ -471,6 +480,28 @@ fn decode_zstd_frame( let _b = crate::prof::scope(crate::prof::Stage::DecodeBlocks); loop { let bh = parse_block_header(r)?; + if !sized_from_first_block { + // One block has landed (or is about to); extrapolate the whole + // output from what the compressed stream and this block say, + // then stop asking. `saturating_*` throughout: these are + // attacker-controlled header fields. + // Only mark it done once a block has actually landed -- + // setting the flag on the first iteration (when nothing has + // been produced yet) makes the whole thing a permanent no-op. + let produced = out.len().saturating_sub(start_len); + if produced > 0 { + sized_from_first_block = true; + let ratio = produced.max(1); + let want = ratio + .saturating_mul(r.remaining().saturating_add(1)) + .saturating_div(bh.payload_len().max(1) as usize); + let cap = want.min(64 << 20); + if cap > out.capacity().saturating_sub(out.len()) { + crate::copies::add(crate::copies::C_DEC_RESERVE, cap); + let _ = out.try_reserve(cap); + } + } + } match bh.ty { BlockType::Raw => { if bh.size > block_max { diff --git a/crates/rusty_zstd/src/encode.rs b/crates/rusty_zstd/src/encode.rs index e004787..be598f8 100644 --- a/crates/rusty_zstd/src/encode.rs +++ b/crates/rusty_zstd/src/encode.rs @@ -303,6 +303,17 @@ struct Seq { // use, exactly as a fresh encoder would. Byte-identical by construction. pub(crate) struct MatchTables { hash: Vec, + /// BRICK 14b: the chain walk's (first-miss, later-miss) accept counts. It was + /// a `&mut (u32, u32)` argument of the kernel -- a pointer marshalled per + /// call, forcing the caller's copy into memory and making the kernel a + /// five-argument function whose fifth rode the stack. The kernel already + /// holds `&mut MatchTables`; the pair is two words inside it. + wcls: (u32, u32), + /// BRICK 74 (K14): the link written for an EMPTY head under the packed + /// representation -- position 0's own tag under the block's producer, + /// seated in the tag byte (0 when links carry no tag). See + /// `set_null_tag`. + null_link: u32, hash_long: Vec, /// 1a array route: the long table's tag byte array, for frames where the /// packed form is refused (>= 16 MiB, streaming). Mirrors `tags` exactly: @@ -409,9 +420,6 @@ pub(crate) struct MatchTables { /// so the reserve landed exactly on the large-allocation threshold and /// bought a fresh VirtualAlloc, and its page-table edit, for every block. /// - /// Keeping the buffer sidesteps the choice: it reaches its steady-state - /// capacity once per frame and then neither grows nor is freed. - payload_scratch: Vec, /// GATE 6 @ L1: the finder's sequence and literal buffers, kept on the /// frame for the same reason as `payload_scratch`. `lit_scratch` is the /// expensive one -- sized `block_len + LIT_PUSH_WIDTH_MAX`, it cleared the @@ -601,6 +609,8 @@ impl Clone for MatchTables { fn clone(&self) -> Self { Self { hash: self.hash.clone(), + wcls: (0, 0), + null_link: 0, hash_long: Vec::new(), ltags: Vec::new(), rep_yield: self.rep_yield, @@ -627,7 +637,6 @@ impl Clone for MatchTables { bits_scratch: Vec::new(), chain_wide: self.chain_wide, blocks_done: self.blocks_done, - payload_scratch: Vec::new(), seq_scratch: Vec::new(), lit_scratch: Vec::new(), opt_ops: Vec::new(), @@ -667,6 +676,13 @@ impl Clone for MatchTables { impl MatchTables { pub(crate) fn new(params: CompressionParameters) -> Self { + // Size unknown (streaming, dict harvest, tests): the row finder's + // AUTO band is a source-length band, so an unknown length must + // resolve to the chain. See `row_auto_ok`. + Self::new_sized(params, None) + } + + pub(crate) fn new_sized(params: CompressionParameters, src_len: Option) -> Self { let hash_log = params.hash_log.clamp(6, 24); let hsz = 1usize << hash_log; let csz = 1usize << params.chain_log.min(24); @@ -722,6 +738,8 @@ impl MatchTables { rep_yield: 1.0, hash_log, hash: vec![0; hsz], + wcls: (0, 0), + null_link: 0, hash_long: if use_long { vec![0; hsz] } else { Vec::new() }, ltags: Vec::new(), chain: if use_chain { vec![0; csz] } else { Vec::new() }, @@ -730,7 +748,7 @@ impl MatchTables { // default build allocates nothing and branches once per insert. rows: { let mut r = crate::rowfind::RowTable::default(); - if use_chain && row_find_enabled() { + if use_chain && row_auto_ok(params, src_len) { r.reset(params.chain_log.min(24)); } r @@ -756,7 +774,6 @@ impl MatchTables { coded_scratch: Vec::new(), bits_scratch: Vec::new(), blocks_done: 0, - payload_scratch: Vec::new(), seq_scratch: Vec::new(), lit_scratch: Vec::new(), opt_ops: Vec::new(), @@ -798,6 +815,15 @@ impl MatchTables { } pub(crate) fn reset(&mut self) { + crate::copies::add( + crate::copies::C_TABLE_CLEAR, + self.tags.len() + + self.hash.len() * 4 + + self.hash_long.len() * 4 + + self.ltags.len() + + self.chain.len() * 4 + + self.ctags.len(), + ); self.tags.fill(0); self.hash.fill(0); self.hash_long.fill(0); @@ -1059,8 +1085,10 @@ impl MatchTables { // per POSITION across L5-L12, guarding an input no frame produces. debug_assert!(pos < u32::MAX as usize); let v = if cp { + // BRICK 48 (P6): no field mask -- the bound above is the whole + // proof, and the `and` was one instruction per chain insert. debug_assert!(pos + 1 < 0x00FF_FFFF); - (((pos as u32) + 1) & 0x00FF_FFFF) | (u32::from(tag) << 24) + ((pos as u32) + 1) | (u32::from(tag) << 24) } else { (pos as u32) + 1 }; @@ -1082,19 +1110,40 @@ impl MatchTables { (raw >> 24) as u8 } + /// BRICK 74 (K14): the tag every EMPTY head's packed link will carry -- + /// position 0's tag under the producer the block inserts with. Set at + /// the start of every chain-ladder block, before priming, and before + /// the wide-chain re-insert, so a link written by this block carries the + /// tag the block's walks compare against. With it the packed walk needs + /// no `m != 0` exemption: a phantom position-0 candidate is tag-tested + /// like any other, and a sound tag rejects only what the first-word + /// compare would reject. Links without a tag byte stay 0. + #[inline(always)] + fn set_null_tag(&mut self, tag0: u8) { + self.null_link = if self.chain_pack { + u32::from(tag0) << 24 + } else { + 0 + }; + } + /// The link stored for a new position is the OLD head, re-encoded from /// `(pos+1) | tag<<24` to `pos | tag<<24` (empty stays 0). + /// + /// BRICK 47 (P5): one decode for all three representations, the fill's + /// brick 36 applied to the per-POSITION insert. A packed head's low 24 + /// bits are `pos + 1 >= 1` unless the whole word is 0 (every writer + /// stores `pos + 1` under `pack_tags`' `len < 0x00FF_FFFF`; the reset + /// writes 0), so `raw - 1` cannot borrow out of the field and the + /// seven-instruction split + guard + cmov was decode overhead on every + /// chain-kernel call. #[inline(always)] - fn lz_link_from_head(raw: u32, cp: bool) -> u32 { - if cp { - let p = raw & 0x00FF_FFFF; - if p == 0 { - 0 - } else { - (p - 1) | (raw & 0xFF00_0000) - } - } else if raw == 0 { - 0 + fn lz_link_from_head(raw: u32, null_link: u32) -> u32 { + debug_assert!(raw == 0 || raw & 0x00FF_FFFF != 0); + // BRICK 74: an empty head links to position 0 WITH its tag (packed); + // `null_link` is 0 otherwise, and this is the saturating decode. + if raw == 0 { + null_link } else { raw - 1 } @@ -1151,7 +1200,10 @@ impl MatchTables { } else { 0 }; - self.chain_masked_set(ip & chain_mask, Self::lz_link_from_head(raw, cp)); + self.chain_masked_set( + ip & chain_mask, + Self::lz_link_from_head(raw, self.null_link), + ); if ca { debug_assert!((ip & chain_mask) < self.ctags.len() && h < self.tags.len()); #[allow(unsafe_code)] @@ -1196,7 +1248,10 @@ impl MatchTables { } else { 0 }; - self.chain_masked_set(ip & chain_mask, Self::lz_link_from_head(raw, cp)); + self.chain_masked_set( + ip & chain_mask, + Self::lz_link_from_head(raw, self.null_link), + ); if ca { debug_assert!((ip & chain_mask) < self.ctags.len() && h < self.tags.len()); unsafe { @@ -1491,7 +1546,9 @@ pub(crate) fn encode_oneshot( }; let mut tables = { let _t = crate::prof::scope(crate::prof::Stage::EncodeTables); - MatchTables::new(params) + // The one-shot path KNOWS the source length, which is what the row + // finder's AUTO band is measured against. + MatchTables::new_sized(params, Some(src.len() as u64)) }; // T1: DFast's short-table rejection tag, packed into the slot it already // loads. Decided against the real buffer length, so the 24-bit bound is @@ -1594,11 +1651,9 @@ pub(crate) fn encode_oneshot( // where we emit 128 KiB, so it re-adapts its entropy tables ~1.56x more // often. This knob tests whether that explains our literals gap. Ratio is // deterministic, so the answer needs no quiet box. - if let Ok(v) = crate::env_knob("RZSTD_BLOCK_KB") { - if let Ok(kb) = v.trim().parse::() { - if kb > 0 { - block_max = block_max.min(kb * 1024); - } + if let Some(kb) = crate::env_knob_parse::("RZSTD_BLOCK_KB") { + if kb > 0 { + block_max = block_max.min(kb * 1024); } } if adv.target_cblock_size > 0 { @@ -1763,9 +1818,7 @@ fn prime_bt_chain_write() -> bool { _ => { #[cfg(feature = "std")] { - let keep = std::env::var("RZSTD_PRIME_BT") - .map(|v| v.trim() == "1") - .unwrap_or(false); + let keep = crate::env_knob_is1("RZSTD_PRIME_BT"); PRIME_BT_ARM.store(u8::from(keep) + 1, core::sync::atomic::Ordering::Relaxed); keep } @@ -1838,9 +1891,7 @@ fn prime_stride() -> usize { if v != 0 { return (v - 1) as usize; } - let n: usize = std::env::var("RZSTD_PRIME_STRIDE") - .ok() - .and_then(|x| x.trim().parse().ok()) + let n: usize = crate::env_knob_parse("RZSTD_PRIME_STRIDE") .filter(|x| *x >= 1) .unwrap_or(1); PRIME_STRIDE_ARM.store(n as u32 + 1, Ordering::Relaxed); @@ -1956,9 +2007,7 @@ fn prime_bt_tree_enabled() -> bool { _ => { #[cfg(feature = "std")] { - let on = std::env::var("RZSTD_PRIME_BT_TREE") - .map(|v| v.trim() == "1") - .unwrap_or(false); + let on = crate::env_knob_is1("RZSTD_PRIME_BT_TREE"); PRIME_BT_TREE_ARM.store(u8::from(on) + 1, core::sync::atomic::Ordering::Relaxed); on } @@ -2004,10 +2053,8 @@ fn prime_bt_depth() -> u32 { if v != u32::MAX { return v; } - let d: u32 = std::env::var("RZSTD_PRIME_BT_DEPTH") - .ok() - .and_then(|x| x.trim().parse().ok()) - .unwrap_or(PRIME_BT_DEPTH_DEFAULT); + let d: u32 = + crate::env_knob_parse("RZSTD_PRIME_BT_DEPTH").unwrap_or(PRIME_BT_DEPTH_DEFAULT); PRIME_BT_DEPTH_ARM.store(d, Ordering::Relaxed); d } @@ -2472,7 +2519,9 @@ pub(crate) fn prime_tables( let packed = tables.pack_tags; let stag_live = !tables.tags.is_empty(); let ltag_live = !tables.ltags.is_empty(); - let mls = params.min_match.max(3) as usize; + // BRICK 99 (K18): the contract's bound (brick 35) -- `wide_hash` below is + // then provably false and the tree kernel's 8-byte-hash arm is gone. + let mls = params.min_match.clamp(3, 7) as usize; let from = payload_off.saturating_sub(window); let ilimit = payload_off.saturating_sub(8); if from >= ilimit || src.len() < mls { @@ -2497,6 +2546,13 @@ pub(crate) fn prime_tables( // Hoisted: both were re-tested on EVERY primed position. let do_long = !tables.hash_long.is_empty(); let stride = prime_stride(); + // Counted ONCE per call from the loop bounds, never per position: this + // walk runs tens of millions of times per slide and a per-iteration tap + // would be the instrument dominating what it measures. + crate::copies::add( + crate::copies::C_PRIME_INSERT, + ilimit.saturating_sub(from) / stride.max(1), + ); // GATE 2 @ L1 -- prime the TAG as well, or the priming is thrown away. // // `put_h` writes `hash` and nothing else. `store_fast` writes `hash` AND @@ -2552,6 +2608,8 @@ pub(crate) fn prime_tables( }; let prime_attempts = bt_depth_apply(search_attempts(pparams), pparams, tables.opt_rep_rate); let btf = bt_resolve_ins(tables.hash_log, pparams.chain_log.min(24)); + // BRICK 34: the block's tree geometry, once. + let (bt_mask, bt_ok) = bt_geom(pparams.chain_log.min(24), tables.chain.len()); let prime_ctx = BtCtx { src, block_start: payload_off, @@ -2563,6 +2621,10 @@ pub(crate) fn prime_tables( bt_lowest: payload_off.saturating_sub(window).max(tables.frame_start), chain_len: tables.chain.len(), wide_hash: mls >= 8, + bt_mask, + bt_shift32: 32u32.saturating_sub(tables.hash_log.min(32)), + bt_shift64: 64u32.saturating_sub(tables.hash_log.min(32)), + bt_ok, }; // EXTENT: the tree only over the most recent slice; heads below it. let ext = prime_bt_extent(); @@ -2594,6 +2656,25 @@ pub(crate) fn prime_tables( let _ = iters; return; } + // REFUTED 2026-09-09, recorded so it is not retried: OUTLINING the + // chain-strategy arm of this loop into its own `#[inline(never)]` frame + // with the invariants (`smask`, `cp`, `ca`, `chain_wide`, the plain-head + // test) hoisted to locals and the two checked indexings routed through + // the mask-proven accessors. It reads like bricks 10/12 (the fill loops), + // and it loses here: inside this large frame LLVM had UNSWITCHED the two + // shipping arms into their own loops (dfast 42 instrs / 12 reloads per + // position, lazy 50 / 15); the outlined function is one loop with eight + // invariant tests per position that LLVM no longer unswitches (the + // whole function IS the loop, so the size budget refuses eight + // conditions), and the same arms measured 46 / 9 and 57 / 13 -- + // instructions UP, reloads down, 964 -> 671 + 318 static. Two counters + // disagreeing in sign is not a win. And the path is not on the plain + // `compress()` route at all (`payload_off == 0` returns above); it runs + // with a dictionary/prefix and on streaming slides only. Left as-is. + // BRICK 74: the empty-head link for this producer (see `set_null_tag`). + if !is_fast { + tables.set_null_tag(chain_null_tag(src, mls)); + } let mut p = from; while p <= ilimit && p + 8 <= src.len() { if is_fast { @@ -2615,9 +2696,9 @@ pub(crate) fn prime_tables( (1u64 << (8 * mls)) - 1 }; let (hh, gt) = if tables.chain_wide { - hash_wide_link_tag(src, p, hash_log, smask) + hash_wide_link_tag_b(src, p, 64u32.saturating_sub(hash_log.min(32)), smask, mls) } else { - hash4_link_tag(src, p, hash_log, smask) + hash4_link_tag_b(src, p, 32u32.saturating_sub(hash_log.min(32)), mls) }; if write_chain { let _ = tables.lz_insert(hh, p, gt, cp, ca, chain_mask); @@ -2639,7 +2720,17 @@ pub(crate) fn prime_tables( } let h = hash_mls(src, p, mls, hash_log); if write_chain { - tables.chain[p & chain_mask] = tables.get_h(h).map(|x| x as u32).unwrap_or(0); + // REFUTED, recorded (do not retry): routing this through + // `chain_masked_set` -- whose contract this call satisfies, and + // which every hot finder uses -- retires the bounds check but + // measures **guards -1, instructions +1**. Two deterministic + // counters disagreeing in sign is not a win, and `prime_tables` + // runs once per block, so nothing here justifies trading a + // plainly-safe index for an `unsafe` accessor. Left as-is. + tables.chain[p & chain_mask] = tables + .get_h(h) + .map(|x| x as u32) + .unwrap_or(tables.null_link); } // T1: the Fast branch above learned this the hard way -- prime the // TAG or the filter rejects every primed slot and the priming is @@ -2663,7 +2754,7 @@ pub(crate) fn prime_tables( (1u64 << (8 * sk)) - 1 }; let tv = (load_u64le(src, p) & smask).wrapping_mul(FAST_HASH_PRIME64); - let g = (tv ^ (tv >> 29)) as u8; + let g = (tv >> 56) as u8; // BRICK 52: see `hash4_tag_from` tables.put_h_tag(h, p, g, packed, stag_live); // 1a: prime the LONG tag too, or the filter rejects every // primed long slot -- the exact -59.3% priming-poison class @@ -2877,6 +2968,7 @@ fn encode_block_inner( off_bkt, ); write_block_header(out, last, BlockType::Raw, block.len() as u32); + crate::copies::add(crate::copies::C_RAW_BLOCK_TO_DST, block.len()); out.extend_from_slice(block); // GATE 6 @ L1 -- hand the finder's buffers back to the frame. if finder_scratch_enabled() { @@ -2909,6 +3001,7 @@ fn encode_block_inner( off_bkt, ); write_block_header(out, last, BlockType::Raw, block.len() as u32); + crate::copies::add(crate::copies::C_RAW_BLOCK_TO_DST, block.len()); out.extend_from_slice(block); // GATE 6 @ L1 -- hand the finder's buffers back to the frame. if finder_scratch_enabled() { @@ -2932,22 +3025,26 @@ fn encode_block_inner( // `payload_scratch`). `block.len()` is still a hard upper bound -- a payload // that reaches it is rejected for Raw by `raw_limit` below -- so the first // block sizes the buffer correctly and no later block has to grow it. - let mut payload = core::mem::take(&mut tables.payload_scratch); - payload.clear(); - if payload_reserve_enabled() && payload.capacity() < block.len() { - // REPLACE, do not grow. `payload` was just cleared, so `realloc` would - // memcpy an allocation that holds nothing live. See `opt_ops`. - payload = Vec::with_capacity(block.len()); + // The payload is emitted STRAIGHT INTO `out`, after a three-byte hole for + // the header. `payload_len` below replaces what used to be `payload.len()`. + // If raw wins, `out` is truncated back to `mark` and nothing was lost but + // the writes; if compressed wins, the header is patched in place and the + // whole staging copy is gone. + let mark = out.len(); + out.extend_from_slice(&[0u8; 3]); + let body_at = out.len(); + if payload_reserve_enabled() { + out.reserve(block.len()); } { let _e = crate::prof::scope(crate::prof::Stage::EncodeEntropy); if seqs.is_empty() { - let _ = write_literals(&mut payload, block, entropy)?; - crate::prof::note_emit_lit(payload.len() as u64); - payload.push(0); + let _ = write_literals(&mut *out, block, entropy)?; + crate::prof::note_emit_lit((out.len() - body_at) as u64); + out.push(0); } else { - let lit_reused = write_literals(&mut payload, &literals, entropy)?; - let lit_end = payload.len(); + let lit_reused = write_literals(&mut *out, &literals, entropy)?; + let lit_end = out.len() - body_at; // GATE 19 -- feed the DP its literal price MEASURED, not guessed. // // `find_opt` priced a literal at a flat 6 bits. Real literals cost @@ -2964,10 +3061,11 @@ fn encode_block_inner( tables.opt_lit_price = measured_lit_bits(lit_end, literals.len()); } crate::prof::note_emit_lit(lit_end as u64); - write_sequences(&mut payload, &seqs, reps, entropy, params.strategy, tables)?; - crate::prof::note_emit_seq((payload.len() - lit_end) as u64); + write_sequences(&mut *out, &seqs, reps, entropy, params.strategy, tables)?; + crate::prof::note_emit_seq(((out.len() - body_at) - lit_end) as u64); } } + let payload_len = out.len() - body_at; let raw_limit = if incomp_skip_on(params) { block.len().saturating_sub(mg) } else { @@ -2979,8 +3077,8 @@ fn encode_block_inner( #[cfg(feature = "profile")] { use core::sync::atomic::Ordering::Relaxed; - let ratio = (payload.len() as f64 / raw_limit.max(1) as f64 * 1000.0) as u64; - if payload.len() >= raw_limit { + let ratio = (payload_len as f64 / raw_limit.max(1) as f64 * 1000.0) as u64; + if payload_len >= raw_limit { RAW_MARGIN_SUM.fetch_add(ratio.min(4000), Relaxed); RAW_MARGIN_N.fetch_add(1, Relaxed); // bucket: 1000-1010, 1010-1050, 1050-1200, 1200+ @@ -2993,7 +3091,9 @@ fn encode_block_inner( RAW_MARGIN_HIST[b].fetch_add(1, Relaxed); } } - if payload.len() >= raw_limit { + if payload_len >= raw_limit { + // Rewind the speculative payload, header hole and all. + out.truncate(mark); #[cfg(feature = "profile")] RAW_EXIT[2].fetch_add(1, core::sync::atomic::Ordering::Relaxed); *reps = saved_reps; @@ -3016,8 +3116,8 @@ fn encode_block_inner( off_bkt, ); write_block_header(out, last, BlockType::Raw, block.len() as u32); + crate::copies::add(crate::copies::C_RAW_BLOCK_TO_DST, block.len()); out.extend_from_slice(block); - tables.payload_scratch = payload; // GATE 6 @ L1 -- hand the finder's buffers back to the frame. if finder_scratch_enabled() { tables.seq_scratch = seqs; @@ -3034,16 +3134,14 @@ fn encode_block_inner( peak, params.strategy, false, - payload.len(), + payload_len, tables.rep_yield, off_coll, off_bkt, ); note_raw_outcome(tables, false); - note_step_outcome(tables, payload.len(), block.len()); - write_block_header(out, last, BlockType::Compressed, payload.len() as u32); - out.extend_from_slice(&payload); - tables.payload_scratch = payload; + note_step_outcome(tables, payload_len, block.len()); + patch_block_header(out, mark, last, BlockType::Compressed, payload_len as u32); if finder_scratch_enabled() { tables.seq_scratch = seqs; tables.lit_scratch = literals; @@ -3053,10 +3151,15 @@ fn encode_block_inner( /// Streaming block: `src` is history || current block; sequences only from `block_start`. #[allow(clippy::too_many_arguments)] +/// `block_end` is explicit because the streaming compressor appends caller +/// input straight into its history buffer, so `src` can hold PENDING bytes +/// past this block that must not be coded into it. This was `src.len()`, +/// which is still what the one-shot path passes. pub(crate) fn encode_block_from_scratch( out: &mut Vec, src: &[u8], block_start: usize, + block_end: usize, params: CompressionParameters, tables: &mut MatchTables, reps: &mut [u32; 3], @@ -3068,7 +3171,7 @@ pub(crate) fn encode_block_from_scratch( out, src, block_start, - src.len(), + block_end, window, params, tables, @@ -3264,6 +3367,20 @@ fn note_raw_outcome(tables: &mut MatchTables, raw: bool) { }; } +/// The three-state env resolve of `incomp_skip_on`, cold and outlined -- the +/// same split every other knob got in brick 3, hand-written because this one +/// accepts `off`/`on` as well as `0`/`1`. +#[cfg(feature = "std")] +#[cold] +#[inline(never)] +fn incomp_skip_resolve() -> u8 { + match crate::env_knob("RZSTD_INCOMP_SKIP") { + Ok(x) if x.trim() == "0" || x.trim().eq_ignore_ascii_case("off") => 1, + Ok(x) if x.trim() == "1" || x.trim().eq_ignore_ascii_case("on") => 2, + _ => 3, + } +} + fn incomp_skip_on(params: CompressionParameters) -> bool { #[cfg(test)] { @@ -3280,11 +3397,7 @@ fn incomp_skip_on(params: CompressionParameters) -> bool { // `std::env::var` inside `early_raw_skip`, i.e. an allocation and a // process-environment lookup on every block -- the same shape as // bricks 49/64/77. - v = match std::env::var("RZSTD_INCOMP_SKIP") { - Ok(x) if x.trim() == "0" || x.trim().eq_ignore_ascii_case("off") => 1, - Ok(x) if x.trim() == "1" || x.trim().eq_ignore_ascii_case("on") => 2, - _ => 3, - }; + v = incomp_skip_resolve(); INCOMP_SKIP_ARM.store(v, Ordering::Relaxed); } if v == 1 { @@ -3371,6 +3484,26 @@ fn tap_block( }); } +/// Overwrite a 3-byte block header already reserved at `at`. +/// +/// The block header is FIXED at three bytes, which is what lets the payload be +/// built straight into the frame buffer: reserve the three bytes, emit the +/// payload after them, then come back and fill them in. The alternative -- and +/// what this replaced -- was to build the payload into a scratch `Vec` purely +/// to learn its length, then copy the whole thing into the frame. That copy was +/// 42.2 MB per 208 MB encoded, the largest reducible copy in the encoder. +fn patch_block_header(out: &mut [u8], at: usize, last: bool, ty: BlockType, size: u32) { + let t = match ty { + BlockType::Raw => 0u32, + BlockType::Rle => 1, + BlockType::Compressed => 2, + }; + let n = u32::from(last) | (t << 1) | (size << 3); + out[at] = n as u8; + out[at + 1] = (n >> 8) as u8; + out[at + 2] = (n >> 16) as u8; +} + fn write_block_header(out: &mut Vec, last: bool, ty: BlockType, size: u32) { let t = match ty { BlockType::Raw => 0u32, @@ -3504,18 +3637,18 @@ fn write_literals_inner( entropy: &mut EntropyState, ) -> Result { let _h = crate::prof::scope(crate::prof::Stage::EncodeHuff); - let (sec, upd) = huffman::encode_literals_section(lits, entropy.huff.as_deref())?; + // Writes THROUGH `dst`. The old shape took a `Vec` back, copied it in and + // handed it to the pool; the four arms that decide immediately (empty, RLE, + // tiny, not-worth-Huffman) now emit their bytes once instead of twice, and + // the pool hand-back for the Huffman arm moved inside with the copy that + // still has to happen there. ALLOC-13's loop is still closed -- see the + // `sec_pool_give` at the end of `encode_literals_section_into`. + let upd = huffman::encode_literals_section_into(dst, lits, entropy.huff.as_deref())?; let reused = matches!(upd, HuffUpdate::Unchanged); match upd { HuffUpdate::New(ct) => entropy.huff = Some(alloc::sync::Arc::new(ct)), HuffUpdate::Unchanged => {} } - dst.extend_from_slice(&sec); - // ALLOC-13: close the loop. The winning section is COPIED into `dst` and - // then dropped, so it goes back to the candidate pool -- without this the - // pool starves, every candidate takes from an empty pool, and the pooling - // measures nothing (it did: 24.0/block unchanged until this line existed). - huffman::sec_pool_give(sec); Ok(reused) } @@ -3618,9 +3751,16 @@ fn build_coded_pass( if ofc > 31 { return Err(Error::Corruption); } - ll_count[llc as usize] += 1; + // WIN: the two clamps are NO-OPS and exist only so LLVM can drop a + // bounds check, the same idiom as `rtb[(proba as usize).min(7)]` in + // `fse::normalize`. `llc` and `mlc` come out of a LUT, so their range + // (0..=35 and 0..=52, the lengths of LL_BASE and ML_BASE) is true by + // construction but invisible to the optimiser -- unlike `ofc`, which + // the explicit `ofc > 31` check above already makes provable, which is + // exactly why only these two lines carried a guard branch. + ll_count[(llc as usize).min(ll_count.len() - 1)] += 1; of_count[ofc as usize] += 1; - ml_count[mlc as usize] += 1; + ml_count[(mlc as usize).min(ml_count.len() - 1)] += 1; of_max = of_max.max(ofc); coded.push(CodedSeq { llc, @@ -3662,7 +3802,13 @@ fn write_sequences_inner( // whole pass. Output is identical either way -- the codes are the codes. let (coded, ll_count, of_count, ml_count, of_max) = build_coded_pass(seqs, reps, tables)?; let use_low = strategy.id() >= Strategy::Lazy.id(); - let last_i = coded.len() - 1; + // WIN: fetch the final sequence ONCE, by value (`CodedSeq: Copy`). + // `coded.len() - 1` underflows to `usize::MAX` on an empty `coded`, so + // every one of the NINE `coded[last]` reads below had to carry its own + // bounds check -- LLVM cannot rule out the wrapped index. `.last()` states + // the same intent without the underflow, so all nine checks go, and the + // empty case becomes a clean error instead of a panic. + let last_seq = *coded.last().ok_or(Error::Corruption)?; // REFUTED, recorded: extracting these three `select_seq_table` calls into a // shared non-ISA `select_seq_tables` -- the `build_coded_pass` treatment, // and structurally the same opportunity -- measured **+348**. Each twin did @@ -3685,7 +3831,7 @@ fn write_sequences_inner( entropy.ll.as_deref().map(|r| &**r), use_low, false, - coded[last_i].llc as usize, + last_seq.llc as usize, )?; let of_needs_comp = of_max as usize >= fse::DEFAULT_OF_NORM.len(); let (of_mode, of_t, of_hdr) = select_seq_table( @@ -3697,7 +3843,7 @@ fn write_sequences_inner( entropy.of.as_deref().map(|r| &**r), use_low, of_needs_comp, - coded[last_i].ofc as usize, + last_seq.ofc as usize, )?; let (ml_mode, ml_t, ml_hdr) = select_seq_table( &ml_count, @@ -3708,7 +3854,7 @@ fn write_sequences_inner( entropy.ml.as_deref().map(|r| &**r), use_low, false, - coded[last_i].mlc as usize, + last_seq.mlc as usize, )?; ( ll_mode, ll_t, ll_hdr, of_mode, of_t, of_hdr, ml_mode, ml_t, ml_hdr, @@ -3728,19 +3874,18 @@ fn write_sequences_inner( fse::give_ncount_buf(of_hdr); fse::give_ncount_buf(ml_hdr); - let last = last_i; let _fs = crate::prof::scope(crate::prof::Stage::EncodeFseSeq); - let mut ml_s = ml_t.init_state2(coded[last].mlc as usize); - let mut of_s = of_t.init_state2(coded[last].ofc as usize); - let mut ll_s = ll_t.init_state2(coded[last].llc as usize); + let mut ml_s = ml_t.init_state2(last_seq.mlc as usize); + let mut of_s = of_t.init_state2(last_seq.ofc as usize); + let mut ll_s = ll_t.init_state2(last_seq.llc as usize); let mut bits = BitCStream::from_vec( core::mem::take(&mut tables.bits_scratch), coded.len() * 4 + 16, ); - bits.add_bits(u64::from(coded[last].llx), u32::from(coded[last].llb)); - bits.add_bits(u64::from(coded[last].mlx), u32::from(coded[last].mlb)); - bits.add_bits(u64::from(coded[last].ofx), u32::from(coded[last].ofc)); + bits.add_bits(u64::from(last_seq.llx), u32::from(last_seq.llb)); + bits.add_bits(u64::from(last_seq.mlx), u32::from(last_seq.mlb)); + bits.add_bits(u64::from(last_seq.ofx), u32::from(last_seq.ofc)); bits.flush(); if coded.len() >= 2 { @@ -3807,6 +3952,25 @@ fn ncount_seq_table( ) -> Result<(Vec, FseCTable), Error> { // libzstd ZSTD_buildCTable: last sequence is FSE_initCState2 only, so drop // it from the normalized counts when it still leaves a usable distribution. + // + // This was `counts.to_vec()` -- a fresh heap allocation per call, to copy a + // histogram and decrement ONE entry. It ran three times per block (ll/of/ml) + // and the allocation-site census put `select_seq_table` at HALF of all + // encoder allocations because of it. The sequence tables' symbol counts are + // fixed by the format (LL 36, OF 32, ML 53), so the copy fits on the stack + // and the allocation disappears entirely. + const MAX_SEQ_SYMS: usize = 64; + let n = counts.len(); + if n <= MAX_SEQ_SYMS { + let mut buf = [0u32; MAX_SEQ_SYMS]; + buf[..n].copy_from_slice(counts); + if last_sym < n && buf[last_sym] > 1 { + buf[last_sym] -= 1; + } + return fse::ncount_and_ctable(&buf[..n], max_log, use_low_prob); + } + // Not reachable for the three sequence tables; kept so a future caller with + // a wider alphabet cannot silently truncate. let mut buf = counts.to_vec(); if last_sym < buf.len() && buf[last_sym] > 1 { buf[last_sym] -= 1; @@ -3871,7 +4035,12 @@ fn select_seq_table<'a>( // libzstd ZSTD_selectEncodingType: a single symbol is always RLE. if total > 0 && most == total { let sym = counts.iter().position(|&c| c == total).unwrap_or(0) as u8; - return Ok((1, SeqTable::Own(FseCTable::rle(u16::from(sym))), vec![sym])); + // Pooled, not `vec![sym]`: that was a fresh heap allocation for ONE + // byte, and the caller already returns this buffer through + // `give_ncount_buf`, so the loop closes with no new plumbing. + let mut hdr = fse::take_ncount_buf(); + hdr.push(sym); + return Ok((1, SeqTable::Own(FseCTable::rle(u16::from(sym))), hdr)); } // N9 probe: this rebuilds an RFC-CONSTANT ctable -- three heap allocations, @@ -4220,9 +4389,7 @@ fn fast_lazy_enabled() -> bool { _ => { #[cfg(feature = "std")] { - let on = std::env::var("RZSTD_FASTLAZY") - .map(|v| v.trim() != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_FASTLAZY", true); FAST_LAZY_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -4250,10 +4417,7 @@ fn fast_lazy_threshold() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_FASTLAZY_T") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(0.7); + let v: f32 = crate::env_knob_parse("RZSTD_FASTLAZY_T").unwrap_or(0.7); FASTLAZY_T_CACHE.store(v.to_bits(), Ordering::Relaxed); v } @@ -4314,10 +4478,7 @@ fn rep_len_min() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_REPLEN") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(1.0); + let v: f32 = crate::env_knob_parse("RZSTD_REPLEN").unwrap_or(1.0); REPLEN_CACHE.store(v.to_bits(), Ordering::Relaxed); v } @@ -4347,10 +4508,7 @@ fn rep_decay() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_REP_DECAY") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(0.0); + let v: f32 = crate::env_knob_parse("RZSTD_REP_DECAY").unwrap_or(0.0); REP_DECAY_CACHE.store(v.to_bits(), Ordering::Relaxed); v } @@ -4375,9 +4533,7 @@ fn rep_yield_min_for(strategy: Strategy) -> f32 { use core::sync::atomic::Ordering; let mut c = REPMIN_OVR.load(Ordering::Relaxed); if c == u32::MAX { - c = std::env::var("RZSTD_REPMIN") - .ok() - .and_then(|v| v.trim().parse::().ok()) + c = crate::env_knob_parse::("RZSTD_REPMIN") .map(f32::to_bits) .unwrap_or(u32::MAX - 1); REPMIN_OVR.store(c, Ordering::Relaxed); @@ -4432,10 +4588,7 @@ fn rep_yield_min() -> f32 { ENVHIT[4].fetch_add(1, core::sync::atomic::Ordering::Relaxed); #[cfg(feature = "std")] { - std::env::var("RZSTD_REPMIN") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(REP_YIELD_MIN_DEFAULT) + crate::env_knob_parse("RZSTD_REPMIN").unwrap_or(REP_YIELD_MIN_DEFAULT) } #[cfg(not(feature = "std"))] REP_YIELD_MIN_DEFAULT @@ -4646,6 +4799,7 @@ fn find_fast( #[cfg(all(target_arch = "x86_64", feature = "std"))] #[allow(unsafe_code)] let out = if crate::simd::has_bmi2() { + crate::kreach::hit(crate::kreach::K_FIND_FAST); // SAFETY: runtime CPUID guard, identical body. unsafe { find_fast_impl_bmi2( @@ -4664,6 +4818,7 @@ fn find_fast( ) } } else { + crate::kreach::miss(crate::kreach::K_FIND_FAST); find_fast_impl( $p, $r, @@ -5273,9 +5428,7 @@ fn find_fast_impl_inner< // EXPERIMENT KNOB (profile builds only): bar every block, to test whether // the pre-rep prefix loss is "marginal matches beating cheaper literals". #[cfg(feature = "profile")] - let bar_all = std::env::var("RZSTD_FFBAR_ALL") - .map(|v| v == "1") - .unwrap_or(false); + let bar_all = crate::env_knob_is1("RZSTD_FFBAR_ALL"); #[cfg(not(feature = "profile"))] let bar_all = false; // The bar also covers POST-LATCH fast blocks (refutation #5: the re-seed @@ -5477,7 +5630,6 @@ fn find_fast_impl_inner< // W3, pipelined twin -- see the note in the main loop. let found = ip; ip = emit_fast_seq::( - packed, &ectx, &mut hash_v, &mut tags_v, @@ -5645,7 +5797,6 @@ fn find_fast_impl_inner< // and it drops the only reason this arm touched `seqs` at all. let found = ip; ip = emit_fast_seq::( - packed, &ectx, &mut hash_v, &mut tags_v, @@ -5745,7 +5896,6 @@ fn find_fast_impl_inner< } pair_bytes += ml as u64; ip = emit_fast_seq::( - packed, &ectx, &mut hash_v, &mut tags_v, @@ -6194,9 +6344,7 @@ fn lazy_fill_enabled() -> bool { 1 => false, 2 => true, _ => { - let on = crate::env_knob("RZSTD_LAZY_FILL") - .map(|v| v != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_LAZY_FILL", true); LAZY_FILL_ENABLED_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -6217,10 +6365,7 @@ fn lazy_fill_threshold() -> f32 { if v != u32::MAX { return f32::from_bits(v); } - let t: f32 = crate::env_knob("RZSTD_LAZY_FILL_T") - .ok() - .and_then(|v| v.parse().ok()) - .unwrap_or(0.0); + let t: f32 = crate::env_knob_parse("RZSTD_LAZY_FILL_T").unwrap_or(0.0); LAZY_FILL_T_ARM.store(t.to_bits(), Ordering::Relaxed); t } @@ -6250,9 +6395,7 @@ fn bt_fill_stride() -> usize { } #[cfg(feature = "std")] { - let v = std::env::var("RZSTD_BT_FILL_S") - .ok() - .and_then(|v| v.trim().parse().ok()) + let v = crate::env_knob_parse("RZSTD_BT_FILL_S") .filter(|v| *v >= 1) .unwrap_or(1); BT_FILL_S_C.store(v, Relaxed); @@ -6290,9 +6433,7 @@ fn lazy_fill_stride() -> usize { if v != 0 { return v; } - let s: usize = crate::env_knob("RZSTD_LAZY_FILL_S") - .ok() - .and_then(|v| v.parse().ok()) + let s: usize = crate::env_knob_parse("RZSTD_LAZY_FILL_S") .filter(|&v: &usize| v >= 1) .unwrap_or(1); LAZY_FILL_S_ARM.store(s, Ordering::Relaxed); @@ -6339,9 +6480,7 @@ fn row_fill_stride() -> usize { if v != 0 { return v; } - let s: usize = crate::env_knob("RZSTD_ROW_FILL_S") - .ok() - .and_then(|v| v.parse().ok()) + let s: usize = crate::env_knob_parse("RZSTD_ROW_FILL_S") .filter(|&v: &usize| v >= 1) .unwrap_or(2); ROW_FILL_S_ARM.store(s, Ordering::Relaxed); @@ -6433,11 +6572,12 @@ pub fn set_nl_off_worse_arm(v: f32) { } #[inline(always)] -/// MEASURED INERT (`dispatchaudit.rs`, every level): this bar is UNREACHABLE -/// on the default path. Its only reader is `nl_cut_for`, which opens with -/// `if NL_DISPATCH_ON != 2 { return 8; }` -- and `NL_DISPATCH_ON` initialises -/// to 0, so the function returns before the bar is consulted. Tuning it does -/// nothing until `set_nl_dispatch_arm(true)` is called. +/// WAS MEASURED INERT, AND IS NOW LIVE. Until 2026-09-08 this bar was +/// unreachable on the default path: its only reader is `nl_cut_for`, which +/// opens with `if NL_DISPATCH_ON != 2 { return 8; }`, and `NL_DISPATCH_ON` +/// initialised to 0 -- so the sweep that chose 0.60 was tuning a threshold +/// nothing consulted. `NL_DISPATCH_ON` now initialises to 2 and this bar +/// decides on every DFast block. fn nl_off_worse_max() -> f32 { let v = NL_OFF_WORSE_ARM.load(core::sync::atomic::Ordering::Relaxed); if v == u32::MAX { @@ -6471,7 +6611,9 @@ fn nl_off_worse_max() -> f32 { /// quality cost, so the raise stays OFF; the dispatch, its signal and its arms /// are kept because the SIGNAL is sound (it separates cleanly, see 4.51) and the /// trade may be worth taking at a level where size dominates. -static NL_DISPATCH_ON: core::sync::atomic::AtomicU8 = core::sync::atomic::AtomicU8::new(0); +/// 0 = off, 2 = on. DEFAULTS ON since 2026-09-08 -- see the measurement in +/// `nl_cut_for`. `set_nl_dispatch_arm(false)` restores the old behaviour. +static NL_DISPATCH_ON: core::sync::atomic::AtomicU8 = core::sync::atomic::AtomicU8::new(2); /// Bench hook: enable the next-long raise + its offset-trade dispatch. pub fn set_nl_dispatch_arm(on: bool) { @@ -6498,7 +6640,14 @@ fn nl_cut_for(tables: &MatchTables) -> usize { fn dfast_good_ml_raised() -> usize { let v = DFAST_GOOD_ML_ARM.load(core::sync::atomic::Ordering::Relaxed); if v == 0 { - 24 + // 24 -> 48 (2026-09-08). `mlgrid.rs` sweeps this against + // `dfast_good_ml2` with the dispatch live: 24 is -68,999 B on the + // 18-corpus L3 board, 48 is -82,653 B. The grid's best cell is + // (64, 24) at -82,975 B -- 322 bytes better and at an EDGE, so 48 + // is taken off the plateau instead (everything in 40..64 lands + // within 0.03% of each other, which is the shape of a corpus fit, + // not an optimum). + 48 } else { v } @@ -6611,10 +6760,7 @@ fn dfast_fill_stride() -> usize { if v != usize::MAX { return v; } - let s: usize = crate::env_knob("RZSTD_DFAST_FILL_S") - .ok() - .and_then(|v| v.parse().ok()) - .unwrap_or(0); + let s: usize = crate::env_knob_parse("RZSTD_DFAST_FILL_S").unwrap_or(0); DFAST_FILL_S_ARM.store(s, core::sync::atomic::Ordering::Relaxed); s } @@ -6789,9 +6935,7 @@ fn accel_shift_base() -> u32 { if v != u32::MAX { return v; } - let n: u32 = crate::env_knob("RZSTD_ACCEL") - .ok() - .and_then(|v| v.trim().parse().ok()) + let n: u32 = crate::env_knob_parse("RZSTD_ACCEL") .filter(|&n| (1..=24).contains(&n)) .unwrap_or(0); ACCEL_SHIFT_ARM.store(n, core::sync::atomic::Ordering::Relaxed); @@ -6872,8 +7016,30 @@ fn try_rep1( if back < lowest { return None; } + // BRICK 91 (P22): the width from `ip < ilimit` -- `ilimit` is + // `block_end - 8` at every caller (see above), so this is + // `at + 8 <= block_end` on operands the caller's loop already holds. + debug_assert_eq!(ip < ilimit, at + 8 <= block_end); + rep1_len_w(src, at, back, block_end, ip < ilimit) +} + +/// The compare half of `try_rep1` (BRICK 38): `at` and `back` are already +/// admissible (`at >= rep1 + lowest`, `at + 4 <= block_end`). `find_lazy_impl` +/// calls this directly behind its one-compare `rep_bar` gate. +#[inline(always)] +fn rep1_len(src: &[u8], at: usize, back: usize, block_end: usize) -> Option { + rep1_len_w(src, at, back, block_end, at + 8 <= block_end) +} + +/// `rep1_len` with the width decided by the caller (BRICK 86): inside +/// `while ip <= ilimit`, `at + 8 <= block_end` is `ip < ilimit`, a compare +/// the loop already has the operands for. +#[inline(always)] +fn rep1_len_w(src: &[u8], at: usize, back: usize, block_end: usize, wide: bool) -> Option { + debug_assert!(at + 4 <= block_end && back < at); + debug_assert_eq!(wide, at + 8 <= block_end); // Same fused head as `fast_probe`: one u64 pair gates AND answers 4..7. - if at + 8 <= block_end { + if wide { let x = load_u64le(src, back) ^ load_u64le(src, at); if x as u32 != 0 { return None; @@ -6890,6 +7056,20 @@ fn try_rep1( Some(4 + count_match_fast(src, back + 4, at + 4, block_end)) } +/// BRICK 38 (P2): the first position at which the rep-1 probe is admissible. +/// `try_rep1` admits `ip` iff `rep1 != 0`, `ip + 1 >= rep1` and +/// `ip + 1 - rep1 >= lowest` -- the last implies the second, so the three +/// are `ip >= rep1 + lowest - 1`; a disabled probe is `usize::MAX`, which no +/// `ip <= ilimit` reaches. Recomputed only when `rep1` changes. +#[inline(always)] +fn rep_bar_for(use_rep: bool, rep1: usize, lowest: usize) -> usize { + if use_rep && rep1 != 0 { + rep1 + lowest - 1 + } else { + usize::MAX + } +} + /// Base probe step for the Fast strategy when `target_length == 0`. /// Probe-density arm (gg-matchfind Gate 9). Settable at RUNTIME so the harvest /// can interleave both arms inside ONE process -- a `OnceLock` here made every @@ -7087,9 +7267,7 @@ fn step0_default() -> usize { if v != 0 { return v - 1; } - let on = crate::env_knob("RZSTD_STEP0") - .ok() - .and_then(|v| v.parse().ok()) + let on = crate::env_knob_parse("RZSTD_STEP0") .filter(|&v: &usize| v >= 1) .unwrap_or(2); STEP0_ARM.store(on + 1, Ordering::Relaxed); @@ -7188,7 +7366,8 @@ fn fast_hash_tag( load_u64le_tail(src, pos) } & mask; let hv = v.wrapping_mul(FAST_HASH_PRIME64); - ((hv >> shift) as usize, (hv ^ (hv >> 29)) as u8) + // BRICK 52: the byte under the bucket (the top bits ARE the bucket). + ((hv >> shift) as usize, ((hv << 8) >> shift) as u8) } else { let hv = load_u32le(src, pos).wrapping_mul(HASH4_PRIME); ((hv >> shift) as usize, (hv ^ (hv >> 15)) as u8) @@ -7227,7 +7406,13 @@ fn hash4_tag_mls(src: &[u8], pos: usize, hash_shift: u32, smask: u64) -> (usize, fn hash4_tag_from(v: u64, hash_shift: u32, smask: u64) -> (usize, u8) { let hv = (v as u32).wrapping_mul(HASH4_PRIME); let tv = (v & smask).wrapping_mul(FAST_HASH_PRIME64); - ((hv >> hash_shift) as usize, (tv ^ (tv >> 29)) as u8) + // BRICK 66 (F4, brick 52 retried inlined): the product's TOP byte is the tag -- as well mixed as + // the xor-fold it replaces (every bucket here is a product's top bits) + // and two instructions to seat in the head word instead of four. Every + // producer of a chain/row/short-table tag takes it from here or writes + // the same expression; the wide-chain producers take the byte under + // their bucket instead. + ((hv >> hash_shift) as usize, (tv >> 56) as u8) } /// Brick 39 arm state: 2-way pipelined probe. Runtime-settable so the @@ -7342,9 +7527,7 @@ fn pipe_enabled() -> bool { 1 => false, 2 => true, _ => { - let on = crate::env_knob("RZSTD_MF_PIPE") - .map(|v| v != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_MF_PIPE", true); PIPE_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -7369,9 +7552,7 @@ pub(crate) fn huff_fast_enabled() -> bool { 1 => false, 2 => true, _ => { - let on = crate::env_knob("RZSTD_HUFF_FAST") - .map(|v| v != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_HUFF_FAST", true); HUFF_FAST_ENABLED_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -7395,9 +7576,7 @@ fn payload_reserve_enabled() -> bool { 1 => false, 2 => true, _ => { - let on = crate::env_knob("RZSTD_PAYLOAD_RES") - .map(|v| v != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_PAYLOAD_RES", true); PAYLOAD_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -7451,9 +7630,7 @@ fn lit_push_enabled() -> bool { // nci +2.0%, ooffice +1.8%, mr +0.7%), decompress correctly null. // Its original +5%/z=1.0 was taken cross-process and could not be // resolved; the effect was real all along. - let on = crate::env_knob("RZSTD_LIT_PUSH") - .map(|v| v != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_LIT_PUSH", true); LITPUSH_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -7646,6 +7823,21 @@ pub fn take_lp_guard() -> (u64, u64) { ) } +const _: () = assert!(LIT_PUSH_WIDTH == 16 && LIT_PUSH_WIDTH_WIDE == 32); + +/// The runtime-width arm of `push_literals`' fast path, outlined COLD: no +/// shipping caller passes a width other than 16 or 32, and keeping the +/// `memcpy` here rather than in the finders' loops is the whole point. +/// +/// # Safety +/// `w` readable bytes at `sp`, `w` writable at `dp`, non-overlapping. +#[cold] +#[inline(never)] +#[allow(unsafe_code)] +unsafe fn lit_copy_runtime(sp: *const u8, dp: *mut u8, w: usize) { + unsafe { core::ptr::copy_nonoverlapping(sp, dp, w) } +} + /// Append `src[from..to]` to the literal buffer. /// /// The measured literal run between matches is tiny -- 1.9 bytes/sequence on @@ -7676,6 +7868,15 @@ pub fn take_lp_guard() -> (u64, u64) { /// a fixed-for-the-block flag re-read in the hottest loop. fn push_literals(lits: &mut Vec, src: &[u8], from: usize, to: usize, w: usize) { let n = to - from; + // Counted HERE, at the top, not at the `extend_from_slice` below: the + // tier-1 fast path returns early and serves ~96.7% of appends at L3, so + // a tap further down measures the 3.3% remainder and reads as though + // the encoder barely touches literals. + crate::copies::add(crate::copies::C_LIT_PUSH, n); + // REFUTED 2026-09-09 (brick 15): making `arm` a const generic for the three + // chain finders (whose width is never 0) measured greedy +20 and lazy +6 + // static instructions for bt -3 -- folding the one test re-laid the armed + // monomorphisation. The runtime test stays. let arm = w != 0; #[cfg(feature = "profile")] { @@ -7699,7 +7900,35 @@ fn push_literals(lits: &mut Vec, src: &[u8], from: usize, to: usize, w: usiz // are distinct buffers, so the regions cannot overlap. Exactly // `n <= 16` bytes are published by `set_len`. unsafe { - core::ptr::copy_nonoverlapping(src.as_ptr().add(from), lits.as_mut_ptr().add(len), w); + let sp = src.as_ptr().add(from); + let dp = lits.as_mut_ptr().add(len); + // The whole point of this arm is a FIXED-width copy that inlines to + // one or two vector moves. It was written that way when `w` was the + // constant `LIT_PUSH_WIDTH`; `lit_width_for` then made `w` a per-block + // choice between 16 and 32, and a `copy_nonoverlapping` whose length + // is a runtime value is a `call memcpy` -- the census read one at + // every push site in every finder, with the length coming off the + // stack. Dispatching on the two legal widths restores the constant + // (the branch is on a block constant, predicted); the runtime arm + // remains for any other `w` so the function keeps its contract. + // + // And NOT as three `copy_nonoverlapping` arms with constant lengths: + // LLVM's sink-common pass merged those back into ONE `memcpy` with + // a phi'd length in `find_fast` (the census read 2 -> 2 there while + // the other finders went 2 -> 0). Typed 16-byte loads and stores + // have different SHAPES per arm and cannot be merged into a call; + // the runtime arm is outlined cold so no `memcpy` stays in the loop. + if w == LIT_PUSH_WIDTH_WIDE { + let a = core::ptr::read_unaligned(sp.cast::<[u8; 16]>()); + let b = core::ptr::read_unaligned(sp.add(16).cast::<[u8; 16]>()); + core::ptr::write_unaligned(dp.cast::<[u8; 16]>(), a); + core::ptr::write_unaligned(dp.add(16).cast::<[u8; 16]>(), b); + } else if w == LIT_PUSH_WIDTH { + let a = core::ptr::read_unaligned(sp.cast::<[u8; 16]>()); + core::ptr::write_unaligned(dp.cast::<[u8; 16]>(), a); + } else { + lit_copy_runtime(sp, dp, w); + } lits.set_len(len + n); } return; @@ -8004,10 +8233,8 @@ const FF_NEAR_MAX: usize = 1 << 16; fn ff_anchor_ml() -> usize { #[cfg(feature = "profile")] { - if let Ok(v) = std::env::var("RZSTD_FF_ML") { - if let Ok(n) = v.parse() { - return n; - } + if let Some(n) = crate::env_knob_parse("RZSTD_FF_ML") { + return n; } } 16 @@ -8127,7 +8354,6 @@ fn fill_fast_after_match( /// every match, in all 280 copies. #[inline(never)] fn emit_fast_seq_plain( - packed: bool, ctx: &FastEmitCtx, hash: &mut [u32], tags: &mut [u8], @@ -8138,7 +8364,7 @@ fn emit_fast_seq_plain( m: usize, ml: usize, ) -> usize { - emit_fast_seq_body(packed, ctx, hash, tags, seqs, lits, anchor, found_ip, m, ml) + emit_fast_seq_body(ctx, hash, tags, seqs, lits, anchor, found_ip, m, ml) } /// The ISA twin. See `FastEmitCtx` -- without this the BMI2 `find_fast_impl` @@ -8148,7 +8374,6 @@ fn emit_fast_seq_plain( #[allow(unsafe_code)] #[inline(never)] unsafe fn emit_fast_seq_bmi2( - packed: bool, ctx: &FastEmitCtx, hash: &mut [u32], tags: &mut [u8], @@ -8159,15 +8384,20 @@ unsafe fn emit_fast_seq_bmi2( m: usize, ml: usize, ) -> usize { - emit_fast_seq_body(packed, ctx, hash, tags, seqs, lits, anchor, found_ip, m, ml) + emit_fast_seq_body(ctx, hash, tags, seqs, lits, anchor, found_ip, m, ml) } /// `BMI2` is threaded from the wrapper that already made the CPUID decision /// for the whole block, so this selection is a compile-time fold, not a /// per-match branch. #[inline(always)] +/// BRICK 9: `packed` was a DEAD parameter all the way down -- the body's copy +/// was `_packed`, the layout choice travels in `ctx.pack` -- and it was the +/// FIRST argument, so it held a register while a live scalar went to the +/// stack at every one of the three emit sites, on every sequence at L1/L2. +/// Same defect W3 removed for `mls`; this one survived because it was passed +/// through two dispatch layers before reaching the body that ignored it. fn emit_fast_seq( - packed: bool, ctx: &FastEmitCtx, hash: &mut [u32], tags: &mut [u8], @@ -8180,19 +8410,18 @@ fn emit_fast_seq( ) -> usize { #[cfg(all(target_arch = "x86_64", feature = "std"))] if BMI2 { + crate::kreach::hit(crate::kreach::K_EMIT_FAST_SEQ); // SAFETY: `BMI2` is only ever `true` inside `find_fast_impl_bmi2`, // which the plain wrapper reached under a `has_bmi2()` CPUID guard. #[allow(unsafe_code)] - return unsafe { - emit_fast_seq_bmi2(packed, ctx, hash, tags, seqs, lits, anchor, found_ip, m, ml) - }; + return unsafe { emit_fast_seq_bmi2(ctx, hash, tags, seqs, lits, anchor, found_ip, m, ml) }; } - emit_fast_seq_plain(packed, ctx, hash, tags, seqs, lits, anchor, found_ip, m, ml) + crate::kreach::miss(crate::kreach::K_EMIT_FAST_SEQ); + emit_fast_seq_plain(ctx, hash, tags, seqs, lits, anchor, found_ip, m, ml) } #[inline(always)] fn emit_fast_seq_body( - _packed: bool, ctx: &FastEmitCtx, hash: &mut [u32], tags: &mut [u8], @@ -8558,7 +8787,7 @@ fn find_dfast( // the same win at a different multiplier -- price the copies, not the // pattern. macro_rules! go { - ($h:expr) => {{ + ($h:expr, $p:expr) => {{ // D6: TWIN RETIRED on its ISA density -- 1,287 instructions of // duplicated body converting EIGHTEEN BMI2 ops, 72 per op. Same // test that retired the greedy (123/op), lazy (111/op), chain @@ -8567,8 +8796,15 @@ fn find_dfast( // argument that `shr %cl` and `shrx` are both one uop on any CPU // that HAS BMI2. DFast pays that shift twice per position, which is // exactly why 18 conversions is all a whole duplicate body bought. - let out = - find_dfast_impl::<$h>(src, block_start, block_end, window, params, tables, reps); + let out = find_dfast_impl::<$h, $p>( + src, + block_start, + block_end, + window, + params, + tables, + reps, + ); out }}; } @@ -8598,7 +8834,17 @@ fn find_dfast( // // `dfast_spec_enabled()` selected between the specialised arms and the // generic one; with no specialised arms left there is nothing to select. - go!(0) + // + // BRICK 21: the one axis that IS worth a body -- the tag representation. + // `packed` reaches the probe (`get_h_tag`/`get_hl_tag` per position), the + // insert (`put_h_tag`/`put_hl_tag` per position), `dtag_on`, and the + // after-match fill; the per-position path tested it and kept the + // array-form state live for nothing. Two bodies, chosen once per block. + if tables.pack_tags { + go!(0, true) + } else { + go!(0, false) + } } /// GATE 4/5 EXTENDED TO L3 -- the DEFAULT level's finder. @@ -8615,7 +8861,7 @@ fn find_dfast( /// /// Byte-identical by construction: `HLOG` takes the value the runtime variable /// already held, so every hash index is unchanged. -fn find_dfast_impl( +fn find_dfast_impl( src: &[u8], block_start: usize, block_end: usize, @@ -8626,7 +8872,7 @@ fn find_dfast_impl( ) -> (Vec, Vec) { // W8: the ISA branch now lives once in `find_dfast`'s dispatch, which is // what lets the twin tree drop the HLOG axis. Baseline arm only. - find_dfast_impl_inner::(src, block_start, block_end, window, params, tables, reps) + find_dfast_impl_inner::(src, block_start, block_end, window, params, tables, reps) } /// The shipping per-block epilogue of `find_dfast_impl_inner`, factored out of @@ -8809,6 +9055,10 @@ fn dfast_finder_prologue( Vec::new() }; if lp && seqs.capacity() < seq_guess { + crate::copies::add( + crate::copies::C_SCRATCH_REALLOC, + seq_guess * core::mem::size_of::(), + ); seqs = Vec::with_capacity(seq_guess); } let mut lits = if keep { @@ -8819,10 +9069,15 @@ fn dfast_finder_prologue( Vec::new() }; if lp && lits.capacity() < block_len + LIT_PUSH_WIDTH_MAX { + crate::copies::add( + crate::copies::C_SCRATCH_REALLOC, + block_len + LIT_PUSH_WIDTH_MAX, + ); lits = Vec::with_capacity(block_len + LIT_PUSH_WIDTH_MAX); } let ilimit = block_end.saturating_sub(8); if block_start >= ilimit { + crate::copies::add(crate::copies::C_LIT_PUSH, block_end - block_start); lits.extend_from_slice(&src[block_start..block_end]); return Err((seqs, lits)); } @@ -8839,9 +9094,65 @@ fn dfast_finder_prologue( Ok((seqs, lits, gates)) } +/// The dfast STRIDE fill (`RZSTD_DFAST_FILL_S`), outlined -- see the call site +/// in `find_dfast_impl_inner` for why it left the loop. Body is the former +/// inline loop verbatim: `put_h_tag`/`put_hl_tag` inlined, same representation. +#[inline(never)] +#[allow(clippy::too_many_arguments)] +fn dfast_stride_fill( + tables: &mut MatchTables, + src: &[u8], + from: usize, + stop: usize, + dfs: usize, + hash_shift: u32, + dlong_shift: u32, + smask: u64, + flags: (bool, bool, bool), +) { + let (packed, stag_live, ltag_live) = flags; + let mut p = from; + if p >= stop { + return; + } + let hp = tables.hash.as_mut_ptr(); + let hlp = tables.hash_long.as_mut_ptr(); + let tp = tables.tags.as_mut_ptr(); + let ltp = tables.ltags.as_mut_ptr(); + while p < stop { + let (h, g) = hash4_tag_mls(src, p, hash_shift, smask); + let h8 = hash8_shift(src, p, dlong_shift); + debug_assert!(h < tables.hash.len() && h8 < tables.hash_long.len()); + // SAFETY: `h` and `h8` are the hash shifts' own outputs, bounded by the + // table lengths exactly as the accessors assert; the bases are those + // tables', taken once above and not resized inside the loop. + #[allow(unsafe_code)] + unsafe { + let v = (p as u32) + 1; + if packed { + let w = (v & 0x00FF_FFFF) | (u32::from(g) << 24); + *hp.add(h) = w; + *hlp.add(h8) = w; + } else { + if stag_live { + *tp.add(h) = g; + } + *hp.add(h) = v; + if ltag_live { + *ltp.add(h8) = g; + } + *hlp.add(h8) = v; + } + } + #[cfg(feature = "profile")] + DF_FILL.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + p += dfs; + } +} + #[allow(clippy::too_many_arguments)] #[inline(always)] -fn find_dfast_impl_inner( +fn find_dfast_impl_inner( src: &[u8], block_start: usize, block_end: usize, @@ -9060,7 +9371,9 @@ fn find_dfast_impl_inner( // Read ONCE per block. `hash4_tag`'s index is `(v * HASH4_PRIME) >> shift`, // which is exactly what `hash4` computes, so the tagged path indexes the // same slots as `hash_mls(src, ip, 4, hlog)` did. - let dtag_on = tables.pack_tags || !tables.tags.is_empty(); + // BRICK 21: `PACKED` is this body's representation (see `find_dfast`). + debug_assert_eq!(tables.pack_tags, PACKED); + let dtag_on = PACKED || !tables.tags.is_empty(); let dtag_shift = 32u32.saturating_sub(hlog.min(32)); // 1a: the long-table tag filter. Packed frames only (the representation // needs the 24-bit position proof); the arm gates the compare. @@ -9092,7 +9405,7 @@ fn find_dfast_impl_inner( // tested ELEVEN times per position in one dfast twin. `find_fast_impl` // has hoisted it since ffanat (`let pack = tables.pack_tags`); the whole // dfast path, both fill helpers and the priming pass never did. - let packed = tables.pack_tags; + let packed = PACKED; let stag_live = !tables.tags.is_empty(); let ltag_live = !tables.ltags.is_empty(); // The mls-width short tag's byte mask (min(mls, 8) bytes). @@ -9108,7 +9421,7 @@ fn find_dfast_impl_inner( let fill_ends = dfast_fill_ends(); // Six `&mut MatchTables` field reads per match, hoisted to one each per // block. See `fill_dfast_after_match`. - let fill_packed = tables.pack_tags; + let fill_packed = PACKED; let fill_stag_live = !tables.tags.is_empty(); let fill_ltag_live = !tables.ltags.is_empty(); // W40: the LONG hash shift, once per block. See `dfast_hash_pair`. @@ -9359,7 +9672,7 @@ fn find_dfast_impl_inner( } let mlx = mlx_c; if match_ok(src, m8b, ip + 1, window, block_start, mlx, frame_start_c) { - // Count past match_ok's verified prefix. + // Count past match_ok's verified prefix (fast_probe_wide rule). let ml = mlx + count_match_fast(src, m8b + mlx, ip + 1 + mlx, block_end); if ml >= mls && ml > best_ml { // GATE 14 signal, measured only in the band the raise @@ -9415,7 +9728,7 @@ fn find_dfast_impl_inner( } let mut _acc = false; if match_ok(src, m4, ip, window, block_start, mls, frame_start_c) { - // Count past match_ok's verified prefix. + // Count past match_ok's verified prefix (fast_probe_wide rule). let ml = mls + count_match_fast(src, m4 + mls, ip + mls, block_end); _acc = ml >= mls; if ml >= mls && ml > best_ml { @@ -9525,59 +9838,25 @@ fn find_dfast_impl_inner( // GATE 12 @ L3: the density knob DFast never had. Off by default. let dfs = fill_stride; if dfs != 0 { - // `dtag_shift` IS `32 - tables.hash_log` (hlog mirrors the - // struct field in both dispatch arms); recomputing it here - // from the field kept a variable CL-shift alive in this arm - // while every other hash4 site in the spec copies folded to - // an immediate. - let hash_shift = dtag_shift; - let stop = end.saturating_sub(2).min(ilimit + 1); - let mut p = best_ip + 2 + dfs; - // W9: the accessors reach both tables THROUGH `&mut - // MatchTables`, so this loop reloaded the struct pointer and - // then three field pointers from it on EVERY stored position - // -- four loads per fill. The bases cannot move inside the - // loop (nothing here resizes a table), so take them once. - // The stores below are `put_h_tag`/`put_hl_tag` inlined - // verbatim, same representation and same 190ad8b rule. - if p < stop { - let hp = tables.hash.as_mut_ptr(); - let hlp = tables.hash_long.as_mut_ptr(); - let tp = tables.tags.as_mut_ptr(); - let ltp = tables.ltags.as_mut_ptr(); - while p < stop { - let (h, g) = hash4_tag_mls(src, p, hash_shift, smask); - // W43: resolved shift -- this loop had hoisted its - // four table BASES and still re-derived the hash shift - // on every stored position. - let h8 = hash8_shift(src, p, dlong_shift); - debug_assert!(h < tables.hash.len() && h8 < tables.hash_long.len()); - // SAFETY: `h` and `h8` are the hash shifts' own outputs, - // bounded by the table lengths exactly as the accessors - // assert; the bases are those tables'. - #[allow(unsafe_code)] - unsafe { - let v = (p as u32) + 1; - if packed { - let w = (v & 0x00FF_FFFF) | (u32::from(g) << 24); - *hp.add(h) = w; - *hlp.add(h8) = w; - } else { - if stag_live { - *tp.add(h) = g; - } - *hp.add(h) = v; - if ltag_live { - *ltp.add(h8) = g; - } - *hlp.add(h8) = v; - } - } - #[cfg(feature = "profile")] - DF_FILL.fetch_add(1, core::sync::atomic::Ordering::Relaxed); - p += dfs; - } - } + // BRICK 7: OUTLINED. This stride fill is OFF by default (`dfast_fill_stride` + // resolves to 0), so the loop never ran in production -- yet it sat inline + // in the L3 per-position loop holding four table bases, two shifts, the + // mask and three flags LIVE across the hottest code in the crate. The + // census read that loop at 865 instructions with 201 stack reloads per + // position, the two table bases alone reloaded 12x and 10x. Moving the + // loop into its own frame is pressure relief for the caller; the loop's + // own cost is unchanged and only ever paid when the knob is on. + dfast_stride_fill( + tables, + src, + best_ip + 2 + dfs, + end.saturating_sub(2).min(ilimit + 1), + dfs, + dtag_shift, + dlong_shift, + smask, + (packed, stag_live, ltag_live), + ); } ip = end; anchor = ip; @@ -9651,10 +9930,7 @@ fn dfast_ml_min() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_DFAST_ML") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(14.0); + let v: f32 = crate::env_knob_parse("RZSTD_DFAST_ML").unwrap_or(14.0); DFAST_ML_MIN_CACHE.store(v.to_bits(), Ordering::Relaxed); v } @@ -9670,16 +9946,20 @@ fn dfast_step_forced() -> usize { #[cfg(feature = "std")] { use core::sync::atomic::Ordering; + // OFFSET SENTINEL. This stored the value RAW and treated 0 as "not + // cached" -- but 0 is also the value an UNSET knob resolves to, which is + // the shipping default. So the cache never took, and every call re-read + // the environment: a `std::env::var` allocation and an OS lookup once + // per block, forever, to answer a question fixed for the life of the + // process. Storing `v + 1` makes 0 mean "unread" and nothing else. let c = DFAST_STEP_ARM.load(Ordering::Relaxed); if c != 0 { - return c as usize; + return (c - 1) as usize; } - let v: usize = std::env::var("RZSTD_DFAST_STEP") - .ok() - .and_then(|v| v.trim().parse().ok()) + let v: usize = crate::env_knob_parse("RZSTD_DFAST_STEP") .filter(|v| *v >= 1) .unwrap_or(0); - DFAST_STEP_ARM.store(v as u32, Ordering::Relaxed); + DFAST_STEP_ARM.store(v as u32 + 1, Ordering::Relaxed); v } #[cfg(not(feature = "std"))] @@ -9724,7 +10004,9 @@ static DFAST_STEP_ARM: core::sync::atomic::AtomicU32 = core::sync::atomic::Atomi /// Set the DFast probe density in-process. pub fn set_dfast_step_arm(v: usize) { - DFAST_STEP_ARM.store(v as u32, core::sync::atomic::Ordering::Relaxed); + // `+ 1` to match the reader's offset sentinel: 0 means "never read", + // so a stored value must be biased the same way or it reads back one low. + DFAST_STEP_ARM.store(v as u32 + 1, core::sync::atomic::Ordering::Relaxed); } /// Blocks between forced DFast-pipeline re-probes. @@ -9747,10 +10029,7 @@ fn dfast_spec_min() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_DFAST_SPECMIN") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(0.70); + let v: f32 = crate::env_knob_parse("RZSTD_DFAST_SPECMIN").unwrap_or(0.70); DFAST_SPEC_MIN_ARM.store(v.to_bits(), Ordering::Relaxed); v } @@ -9848,7 +10127,33 @@ fn find_greedy_sel( // shape as `find_fast`'s HLOG (W4/W5) and `find_dfast`'s (W11), and the // same correction applies: killing the const is only half of it -- the // second call site has to go too, or six-or-two inline expansions remain. - find_greedy_impl::<0>(src, block_start, block_end, window, params, tables, reps) + // BRICK 79 (G0): the block's kernel shape as a const of the instance -- + // the lazy finder's brick 58. `walk_cont` is evaluated here exactly as + // the body evaluates it (before the body's `walk_probe` update; asserted + // there); `cp`/`ca` are per-frame facts. + let kind = lazy_kind( + false, + tables.chain_pack, + !tables.ctags.is_empty(), + greedy_walk_cont(tables, search_attempts(params)), + ); + match kind { + 1 => find_greedy_impl::<0, 1>(src, block_start, block_end, window, params, tables, reps), + 2 => find_greedy_impl::<0, 2>(src, block_start, block_end, window, params, tables, reps), + 3 => find_greedy_impl::<0, 3>(src, block_start, block_end, window, params, tables, reps), + 4 => find_greedy_impl::<0, 4>(src, block_start, block_end, window, params, tables, reps), + _ => find_greedy_impl::<0, 7>(src, block_start, block_end, window, params, tables, reps), + } +} + +/// The greedy finder's WALK-CONTINUE dispatch, the one expression the +/// selector and the body both evaluate (BRICK 79). Unlike the lazy +/// finder's it has no `strategy` term. +#[inline(always)] +fn greedy_walk_cont(tables: &MatchTables, attempts: usize) -> bool { + walk_cont_enabled() + && tables.rep_yield <= walk_rep_max() + && (tables.walk_first_share <= walk_first_max(attempts) || tables.walk_probe == 0) } /// Scratch acquisition + the too-short-block exit shared by `find_greedy_impl`, @@ -9861,9 +10166,10 @@ fn chain_finder_prologue( block_start: usize, block_end: usize, tables: &mut MatchTables, + mls: usize, ) -> Result<(Vec, Vec), (Vec, Vec)> { let keep = finder_scratch_enabled(); - let seqs = if keep { + let mut seqs = if keep { let mut v = core::mem::take(&mut tables.seq_scratch); v.clear(); v @@ -9879,14 +10185,375 @@ fn chain_finder_prologue( }; let ilimit = block_end.saturating_sub(8); if block_start >= ilimit { + crate::copies::add(crate::copies::C_LIT_PUSH, block_end - block_start); lits.extend_from_slice(&src[block_start..block_end]); return Err((seqs, lits)); } + // The RESERVE, once, here. `find_greedy` and `find_bt_lazy` each carried + // their own copy of it INLINE after this call -- two `Vec::with_capacity` + // arms, `__rust_alloc`, `handle_error` and the capacity compares, laid + // out inside the hottest function on each of those levels -- and + // `find_lazy` (L6-L12, the levels that carry the most traffic) had NONE: + // its block-0 literals grew from `Vec::new()` by doubling, a chain of + // reallocs and memcpys per frame that the other two never paid. + // + // `block_len + LIT_PUSH_WIDTH_MAX` is the bound `push_literals`' fixed- + // width copy relies on: at most `block_len` literals plus one over-copy. + let block_len = block_end - block_start; + if lits.capacity() < block_len + LIT_PUSH_WIDTH_MAX { + lits = Vec::with_capacity(block_len + LIT_PUSH_WIDTH_MAX); + } + let seq_guess = (tables.last_nseq + tables.last_nseq / 4 + 64).min(block_len / mls + 16); + if seqs.capacity() < seq_guess { + seqs = Vec::with_capacity(seq_guess); + } Ok((seqs, lits)) } +/// C's "jump faster over incompressible sections" step, which this crate's +/// chain ladder never had. +/// +/// `ZSTD_compressBlock_lazy_generic` advances a FAILED position by +/// `((ip - anchor) >> kSearchStrength) + 1`, so the step grows with the literal +/// run: on content that cannot match, C accelerates away while a plain +/// `ip += 1` walks every byte. `find_greedy_impl`, `find_lazy_impl` and +/// `find_bt_lazy` all did the plain thing -- the same "capability present in +/// one finder, absent in its neighbour" shape as the repcode and +/// back-extension defects. `find_fast`/`find_dfast` have had an accel shift +/// for levels. +/// +/// MEASURED (1 MiB of `incomp-32m`, stage profiler, ONE process so box load +/// cancels between the arms): L1 943 us with MatchFind at 11.3%, against L9 +/// 26,918 us with MatchFind at 86.0% -- 28.5x on data where the walk census +/// reads ZERO chain loads. All of it spent proving there is no match, one +/// byte at a time. +/// +/// SWEPT, and the shipped value is 12, not C's 8. The shift trades size for +/// skipped positions and the two do not move together: +/// +/// ```text +/// shift L5 size L7 size L9 size incomp speedup +/// 8 +2,383 +2,597 +2,990 3.2x .. 4.8x +/// 10 -254 -257 +155 3.1x .. 4.2x +/// 12 -235 -216 -15 2.8x .. 3.7x +/// ``` +/// +/// 12 is the only value that is SMALLER on every level and both caps tested +/// (1 MiB and 4 MiB), so it is a strict win rather than a trade. 14 of 18 +/// corpora are BYTE-IDENTICAL under it -- the step only grows on a long +/// literal run, so content that matches never sees it. `x-ray` is untouched +/// at 12 and regresses +1,581 at 10, which is what decided against 10. +/// +/// Position arithmetic behind the speedup: with step `(x >> 12) + 1` a 1 MiB +/// literal run is crossed in ~4,100 positions instead of 1,048,576, and the +/// wall-clock ratio is smaller than that because once search stops dominating +/// the block/literal overhead does. +/// +/// 0 = off (the historical `ip += 1`); otherwise the shift. C's is 8. +static LAZY_ACCEL_ARM: core::sync::atomic::AtomicUsize = + core::sync::atomic::AtomicUsize::new(usize::MAX); + +/// Bench hook: 0 disables, otherwise the shift. +pub fn set_lazy_accel_arm(v: usize) { + LAZY_ACCEL_ARM.store(v, core::sync::atomic::Ordering::Relaxed); +} + +#[inline(always)] +fn lazy_accel() -> usize { + let v = LAZY_ACCEL_ARM.load(core::sync::atomic::Ordering::Relaxed); + if v != usize::MAX { + return v; + } + let n: usize = crate::env_knob_parse("RZSTD_LAZY_ACCEL").unwrap_or(12); + LAZY_ACCEL_ARM.store(n, core::sync::atomic::Ordering::Relaxed); + n +} + +/// The accelerated no-match advance. BRICK 41 (P3): no `sh == 0` arm on the +/// per-position path -- `lazy_step_shift` maps the knob's 0 to 63 once per +/// block, and `(ip - anchor) >> 63` is 0 for every span a block can hold, +/// so the historical step of 1 falls out of the same expression. +#[inline(always)] +fn lazy_step(ip: usize, anchor: usize, sh: usize) -> usize { + debug_assert!((1..64).contains(&sh) && anchor <= ip); + ((ip - anchor) >> sh) + 1 +} + +/// BRICK 95 (P23): `lazy_step` with the `+ 1` folded into the anchor. +/// `anchor_adj` is `anchor - 2^sh` (wrapping), so `(ip - anchor_adj) >> sh` +/// is `(ip - anchor + 2^sh) >> sh == ((ip - anchor) >> sh) + 1` for every +/// span a block can hold (`ip - anchor < 2^63 - 2^sh`). Three instructions +/// per no-match position instead of five, and nothing to increment. +#[inline(always)] +fn lazy_step_adj(ip: usize, anchor_adj: usize, sh: usize) -> usize { + debug_assert!((1..64).contains(&sh)); + ip.wrapping_sub(anchor_adj) >> sh +} + +/// The anchor's folded form for `lazy_step_adj` (BRICK 95). +#[inline(always)] +fn anchor_adj_of(anchor: usize, sh: usize) -> usize { + anchor.wrapping_sub(1usize << sh) +} + +/// The `lazy_accel` knob as a shift `lazy_step` can apply unconditionally +/// (BRICK 41): 0 ("historical step") becomes 63, i.e. always 1; anything +/// above 63 saturates there (the old `>>` would have wrapped its amount). +#[inline(always)] +fn lazy_step_shift(sh: usize) -> usize { + if sh == 0 { + 63 + } else { + sh.min(63) + } +} + +/// The fill loops' block constants (BRICK 19). `lz_fill_range` took twelve +/// parameters, so on Win64 eight rode the stack: the census read 5-6 stack +/// argument stores at every call, and a call happens once per MATCH. Built +/// once per block, passed by reference, read once in the callee. +#[derive(Clone, Copy)] +struct FillCtx { + stride: usize, + shift32: u32, + shift64: u32, + smask: u64, + /// BRICK 100: the tag byte's offset is `mls - 1`. + mls: usize, + chain_mask: usize, + wide_h: bool, + wchain: bool, + cp: bool, + ca: bool, +} +/// The chain-ladder fill loop, outlined (BRICK 10). `ROWS` mirrors the +/// `lz_insert_only` arm each caller used: greedy inserts rows too, lazy's +/// chain arm does not (its row arm is `row_fill_range`). `mode` is +/// `(wide_h, wchain)`, both block constants, resolved ONCE here into one +/// loop per arm exactly as the inline form did. +#[inline(never)] +#[allow(clippy::too_many_arguments)] +#[allow(unsafe_code)] +fn lz_fill_range( + tables: &mut MatchTables, + src: &[u8], + mut p: usize, + stop: usize, + fc: &FillCtx, +) { + let FillCtx { + stride, + shift32, + shift64, + smask, + mls, + chain_mask, + wide_h, + wchain, + cp, + ca, + } = *fc; + // BRICK 26: with `SPEC` the representation is the body's own and every + // per-byte test on it folds; the rows body (`SPEC == false`) keeps the + // runtime flags so the rare shape does not cost three more bodies. + let (cp, ca) = if SPEC { + debug_assert_eq!((cp, ca), (CP, CA)); + (CP, CA) + } else { + (cp, ca) + }; + let src_len = src.len(); + // BRICK 12: the table bases, taken ONCE. `lz_insert_only` reached every + // table through `&mut MatchTables`, and after each store LLVM re-read the + // headers it could not prove the store had left alone -- the census read + // 1-2 stack reloads per matched byte in the chain arms and none in the + // row arm, which already worked from hoisted bases. Same stores, same + // values, same order; only where the bases come from changes. + let hp = tables.hash.as_mut_ptr(); + let chp = tables.chain.as_mut_ptr(); + let tp = tables.tags.as_mut_ptr(); + let ctp = tables.ctags.as_mut_ptr(); + // BRICK 74: the empty-head link (see `set_null_tag`); 0 unless packed. + let null_link = tables.null_link; + macro_rules! body { + ($hash:expr) => {{ + let hash = $hash; + macro_rules! ins { + ($q:expr) => {{ + let p = $q; + #[cfg(feature = "profile")] + if !ROWS { + LF_INSERTS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + } + let (hh, gt) = hash(p); + if ROWS { + // Greedy inserts rows too, and the row insert goes through + // `&mut MatchTables`; measured with the raw form below, that arm + // got WORSE (22 -> 29 instructions, 1 -> 6 reloads per byte) as + // the header re-reads came back. It keeps the method call. + tables.lz_insert_only::(hh, p, gt, cp, ca, chain_mask); + } else { + debug_assert!( + hh < tables.hash.len() && (p & chain_mask) < tables.chain.len() + ); + debug_assert!( + !ca || (hh < tables.tags.len() + && (p & chain_mask) < tables.ctags.len()) + ); + // SAFETY: `hh` is a hash output bounded by the table's own + // length, `p & chain_mask` by the chain's; `tags`/`ctags` are + // only touched when `ca` says they are sized to match. The + // bases were taken above and nothing here resizes a table. + unsafe { + let raw = *hp.add(hh); + let old_tag = if cp { + (raw >> 24) as u8 + } else if ca { + *tp.add(hh) + } else { + 0 + }; + // BRICK 36 (F1): ONE decode for all three representations. + // Packed heads are `(pos + 1) | tag << 24` with + // `pos + 1 < 0x00FF_FFFF` (the `pack_tags` guard, asserted + // at every writer), and the reset writes 0 -- so the low + // 24 bits are zero only when the word is, and for a live + // head `raw - 1` cannot borrow out of the field: + // `(q - 1) | tag << 24 == raw - 1`. The seven-instruction + // field split + guard + cmov was pure decode overhead on + // every inserted byte. + debug_assert!(!cp || raw == 0 || raw & 0x00FF_FFFF != 0); + // BRICK 74: an empty head links to position 0 WITH its tag -- + // a select only where the link carries one (`cp`); otherwise + // the null link is 0 and the decode is the saturating form. + let link = if cp { + if raw == 0 { + null_link + } else { + raw - 1 + } + } else { + debug_assert_eq!(null_link, 0); + raw.saturating_sub(1) + }; + *chp.add(p & chain_mask) = link; + if ca { + *ctp.add(p & chain_mask) = old_tag; + *tp.add(hh) = gt; + } + // BRICK 39 (F2): no field mask. `pack_tags` bounds `p + 1` + // below 0x00FF_FFFF, so the mask was one dead `and` per + // inserted byte; the assertion is the bound it enforced. + debug_assert!(!cp || p + 1 < 0x00FF_FFFF); + *hp.add(hh) = if cp { + ((p as u32) + 1) | (u32::from(gt) << 24) + } else { + (p as u32) + 1 + }; + } + } + }}; + } + if !ROWS && stride == 1 && p < stop { + // BRICK 43 (F3): two positions per trip for the default stride, + // chain arms only -- the rows arm ships at stride 2 and its + // method-call body measured +3 per position with the pair loop + // present. Same inserts in the same order; the loop overhead + // is paid once per pair and the pair's loads overlap. + // BRICK 70 (F5): the bound as a countdown of the remaining + // positions, so the loop test is on the counter and `stop` + // is not a live value the loop has to reload. + let mut left = stop - p; + // BRICK 80 (F7): four per trip while there are four. + while left >= 4 { + ins!(p); + ins!(p + 1); + ins!(p + 2); + ins!(p + 3); + p += 4; + left -= 4; + } + while left >= 2 { + ins!(p); + ins!(p + 1); + p += 2; + left -= 2; + } + if left != 0 { + ins!(p); + } + } else { + while p < stop { + ins!(p); + p += stride; + } + } + }}; + } + // BRICK 88 (F8): no 8-byte-hash arm -- `wide_h` is `mls >= 8`, outside the + // contract (brick 35); the test and three loop bodies were dead weight on + // every call. + debug_assert!(!wide_h); + let _ = src_len; + // BRICK 100 (F9): the byte tag -- see `link_tag`. + if wchain { + body!(|q: usize| hash_wide_link_tag_b(src, q, shift64, smask, mls)); + } else { + body!(|q: usize| hash4_link_tag_b(src, q, shift32, mls)); + } +} + +/// The row-table fill loop, outlined (BRICK 10) -- `find_lazy_impl`'s row arm. +#[inline(never)] +#[allow(clippy::too_many_arguments)] +fn row_fill_range( + rows: &mut crate::rowfind::RowTable, + src: &[u8], + mut p: usize, + stop: usize, + fc: &FillCtx, +) { + let FillCtx { + stride, + shift32, + shift64, + smask, + mls, + wide_h, + wchain, + .. + } = *fc; + let src_len = src.len(); + let rmask = rows.mask(); + macro_rules! body { + ($hash:expr) => {{ + while p < stop { + #[cfg(feature = "profile")] + LF_INSERTS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + let (hh, gt) = $hash; + rows.insert_h(hh, rmask, p as u32, gt); + p += stride; + } + }}; + } + // BRICK 100 (F9): the byte tag -- see `link_tag`. + if wide_h { + body!(if p + 8 <= src_len { + (hash8_shift(src, p, shift64), 0u8) + } else if wchain { + hash_wide_link_tag_b(src, p, shift64, smask, mls) + } else { + hash4_link_tag_b(src, p, shift32, mls) + }); + } else if wchain { + body!(hash_wide_link_tag_b(src, p, shift64, smask, mls)); + } else { + body!(hash4_link_tag_b(src, p, shift32, mls)); + } +} + #[inline(always)] -fn find_greedy_impl( +fn find_greedy_impl( src: &[u8], block_start: usize, block_end: usize, @@ -9895,8 +10562,15 @@ fn find_greedy_impl( tables: &mut MatchTables, reps: [u32; 3], ) -> (Vec, Vec) { + // BRICK 35 (K1): the CONTRACT's bound, both ends. `min_match` is + // documented 3..=7 and `compression_params` / `apply_zstd_kv` both clamp + // it there; only a hand-built `CompressionParameters` could carry more, + // and zstd itself rejects such a value (`ZSTD_MINMATCH_MAX` is 7). With + // the bound stated HERE, `mls_xor` needs no `mls > 8` arm -- which was a + // compare and a branch on EVERY examined candidate in the chain walk, + // and a callee-saved register holding `mls` for the walk's whole life. let mls = if MLS == 0 { - params.min_match.max(3) as usize + params.min_match.clamp(3, 7) as usize } else { MLS }; @@ -9931,7 +10605,8 @@ fn find_greedy_impl( // Scratch + the too-short-block exit, ONE copy for Greedy/Lazy/BtLazy and // their bmi2 twins -- six stamps of the identical idiom become one call // (the `fast_finder_prologue` treatment, chain-finder variant). - let (mut seqs, mut lits) = match chain_finder_prologue(src, block_start, block_end, tables) { + let (mut seqs, mut lits) = match chain_finder_prologue(src, block_start, block_end, tables, mls) + { Ok(t) => t, Err(out) => return out, }; @@ -9941,14 +10616,7 @@ fn find_greedy_impl( // W5: GATE 6 for Greedy. Both output buffers came from the frame but with // NO RESERVE, so they grew by repeated `realloc` with LIVE contents -- // every growth a real memcpy. `find_fast` has had this since brick 38. - let block_len = block_end - block_start; - if lits.capacity() < block_len + LIT_PUSH_WIDTH_MAX { - lits = Vec::with_capacity(block_len + LIT_PUSH_WIDTH_MAX); - } - let seq_guess = (tables.last_nseq + tables.last_nseq / 4 + 64).min(block_len / mls + 16); - if seqs.capacity() < seq_guess { - seqs = Vec::with_capacity(seq_guess); - } + // (reserve moved into `chain_finder_prologue`) // W6: GATE 13 for Greedy. Literals went out through `push_lits_range` -- a // runtime-length `extend_from_slice` -- while find_fast has used the // fixed-width `copy_nonoverlapping` since brick 38. W5 is its @@ -9985,9 +10653,15 @@ fn find_greedy_impl( let fstart_c = tables.frame_start; let lowest_rep = block_start.saturating_sub(window).max(fstart_c); // WALK-CONTINUE dispatch: see `walk_rep_max`. - let walk_cont = walk_cont_enabled() - && tables.rep_yield <= walk_rep_max() - && (tables.walk_first_share <= walk_first_max(attempts) || tables.walk_probe == 0); + // BRICK 79 (G0): the instance's const where the shape is known; the + // expression is still evaluated (and asserted equal) in debug builds. + let walk_cont_rt = greedy_walk_cont(tables, attempts); + let walk_cont = match KIND { + 1 | 3 => true, + 2 | 4 => false, + _ => walk_cont_rt, + }; + debug_assert_eq!(walk_cont, walk_cont_rt); tables.walk_probe = if tables.walk_probe == 0 { WALK_PROBE_PERIOD } else { @@ -9995,8 +10669,21 @@ fn find_greedy_impl( }; let mut wcls = (0u32, 0u32); maybe_latch_wide_chain(tables, src, block_start, window, mls); - let cp = tables.chain_pack; - let ca = !tables.ctags.is_empty(); + // BRICK 79 (G0): the representation as the instance's const (runtime on + // the fallback instance). Packed and tag-array are exclusive by + // construction, asserted here. + let cp = match KIND { + 1 | 2 => true, + 3 | 4 => false, + _ => tables.chain_pack, + }; + let ca = match KIND { + 1 | 2 => false, + 3 | 4 => true, + _ => !tables.ctags.is_empty(), + }; + debug_assert_eq!(cp, tables.chain_pack); + debug_assert_eq!(ca, !tables.ctags.is_empty()); let wchain = tables.chain_wide; let smask = if mls >= 8 { u64::MAX @@ -10006,6 +10693,9 @@ fn find_greedy_impl( // W1: `cp || ca` -- whether ANY link-tag filter is active -- was re-OR'd on // every step of the chain chase. let tag_filter = cp || ca; + // BRICK 78 (G4, brick 65 for L5): the position from which the walk's + // lower bound is `ip - window` rather than `lowest_rep`. + let lowest_w = lowest_rep + window; // W2: `mls >= 8` is the hash-width question, and it was re-asked per // POSITION (the head hash) and per FILLED POSITION, for one per-block // answer. `src.len()` beside it is a slice field re-read the same way. @@ -10017,11 +10707,35 @@ fn find_greedy_impl( let g_shift32 = 32u32.saturating_sub(hash_log.min(32)); let g_shift64 = 64u32.saturating_sub(hash_log.min(32)); let src_len = src.len(); + // BRICK 74: the empty-head link for this block's producer. + tables.set_null_tag(chain_null_tag(src, mls)); // The searches/byte signal feeds the wide latch's second route; greedy // never maintained it, so at L5 the field held its 1.0 INIT and the // route always passed (smallmsg +1.62% leak). let mut searches = 0u64; let mut ip = block_start; + // Hoisted per BLOCK: an atomic load per position would cost more + // than the positions it skips. + let accel_sh = lazy_step_shift(lazy_accel()); + // BRICK 23: the fill loop's shape is a per-block fact. With the row + // table off (every input outside the row band) the `` fill's + // per-byte row test and its live row state buy nothing; the `` + // loop the lazy finder uses inserts the identical head/link/tag words + // at 25-32 instructions per byte instead of 38-42. + let rows_live = !tables.rows.head.is_empty(); + // BRICK 19: the fill's block constants, once, by reference. + let fill_ctx = FillCtx { + stride: 1, + shift32: g_shift32, + shift64: g_shift64, + smask, + mls, + chain_mask, + wide_h, + wchain, + cp, + ca, + }; while ip <= ilimit { if use_rep { if let Some(ml) = try_rep1(src, ip, rep1, lowest_rep, block_end, ilimit) { @@ -10040,30 +10754,48 @@ fn find_greedy_impl( } searches += 1; // W44: resolved shifts, same as the fill below. - let (h, gtag) = if wide_h && ip + 8 <= src_len { - (hash8_shift(src, ip, g_shift64), 0u8) - } else if wchain { - hash_wide_link_tag_shift(src, ip, g_shift64, smask) + // BRICK 82 (G6, brick 68 for L5): no 8-byte-hash arm (`mls >= 8` is + // outside the contract, brick 35). + debug_assert!(!wide_h); + // BRICK 100 (F9): the byte tag -- the LOAD form here; the lazy kernels + // take the shared-word form (`hash4_link_tag_w`), and this finder + // measured 4 fewer per no-match position with the load. + let (h, gtag) = if wchain { + hash_wide_link_tag_b(src, ip, g_shift64, smask, mls) } else { - hash4_tag_mls(src, ip, g_shift32, smask) + hash4_link_tag_b(src, ip, g_shift32, mls) }; let (prev, head_tag) = tables.lz_insert(h, ip, gtag, cp, ca, chain_mask); let mut best_m = 0usize; - let mut best_ml = 0usize; + // BRICK 75 (G1, brick 59 for L5): ONE length -- born `mls - 1`, so + // `ml > best_ml` is the accept test before and after the first + // accept; `pre_eq` at that index is sound on the first candidate. + let mut best_ml = mls - 1; // W3: `best_ml` is 0 or a value that already cleared `mls`, so the // accept pair folds to one compare against a running bar. - let mut bar = mls; if let Some(mut m) = prev { let mut mtag = head_tag; // See `chain_find_best`: the three per-step validity tests fold // to one monotone bound; `m >= ip` is entry-only. - let low = lowest_rep.max(ip.saturating_sub(window)); + let low = if ip >= lowest_w { + ip - window + } else { + lowest_rep + }; + debug_assert_eq!(low, lowest_rep.max(ip.saturating_sub(window))); // W48: `src_len` has been hoisted at block scope since W2; this // walk-entry guard kept re-reading the slice field anyway. - if m < ip && ip + mls <= src_len { - let mut missed_before = false; - for _ in 0..attempts { + // BRICK 82 (brick 49 for L5): `ip <= ilimit = block_end - 8` and + // `mls <= 7` make `ip + mls <= src_len` the loop's own invariant. + debug_assert!(ip + 8 <= src_len && mls <= 8); + if m < ip { + // BRICK 77 (G3, brick 63 for L5): two different non-zero values. + let mut missed_before = 0u8; + // BRICK 76 (G2, brick 62 for L5): an explicit countdown. + let mut left = attempts; + while left != 0 { + left -= 1; if m < low { break; } @@ -10075,7 +10807,9 @@ fn find_greedy_impl( // fabricated tag is 0), and legacy walks probe position 0 // through it -- never tag-filter it (the 2-FALSE-skips // catch on mozilla L5). - if tag_filter && m != 0 && mtag != gtag { + // BRICK 87 (G9, brick 74 for L5): no `m != 0` exemption on the + // packed instances -- their null links carry position 0's tag. + if tag_filter && (cp || m != 0) && mtag != gtag { #[cfg(feature = "profile")] if COUNT { use core::sync::atomic::Ordering::Relaxed; @@ -10084,7 +10818,7 @@ fn find_greedy_impl( LINK_FALSE.fetch_add(1, Relaxed); } } - missed_before = true; + missed_before = 1; if !walk_cont { break; } @@ -10114,26 +10848,25 @@ fn find_greedy_impl( #[cfg(feature = "profile")] WALK_EXAM.fetch_add(1, core::sync::atomic::Ordering::Relaxed); } - if mls_eq(src, m, ip, mls, smask) { + if let Some(x) = mls_xor(src, m, ip, mls, smask) { // C's `match[ml] == ip[ml]` prefilter // (`ZSTD_HcFindBestMatch`): a candidate that DIFFERS at // the current best length cannot exceed it, so the full // `count_match` is provably wasted. The same candidate // still wins, so this is byte-identical. - if best_ml == 0 || pre_eq(src, m, ip, best_ml) { + if pre_eq(src, m, ip, best_ml) { // Count past mls_eq's verified prefix (see // `chain_find_best`). - let ml = mls + count_match_fast(src, m + mls, ip + mls, block_end); - if ml >= bar { - if missed_before { - if best_ml == 0 { + let ml = fused_ml(x, src, m, ip, block_end); // BRICK 11: see `mls_xor` + if ml > best_ml { + if missed_before != 0 { + if best_ml < mls { wcls.0 += 1; } else { wcls.1 += 1; } } best_ml = ml; - bar = ml + 1; best_m = m; // Reaches the block end -- nothing can be longer. if ip + best_ml >= block_end { @@ -10142,7 +10875,7 @@ fn find_greedy_impl( } } } else { - missed_before = true; + missed_before = 2; #[cfg(feature = "profile")] if COUNT { WALK_BYTEMISS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); @@ -10210,40 +10943,21 @@ fn find_greedy_impl( // W7: `end` and `ilimit` are both fixed for this fill, so the // two bounds it tested on every inserted position fold to one. let stop = end.min(ilimit + 1); - let mut p = ip + 1; - // W37: the hash MODE is a block constant; it was re-asked on every - // inserted position. Hoisted, so each arm's body is one hash and - // one insert -- and the two non-wide arms shed the - // `p + 8 <= src_len` test that only the 8-byte hash needs. - // - // W10 stands: `lz_insert_only` is the entry for callers that - // discard the result. - macro_rules! g_fill { - ($hash:expr) => {{ - while p < stop { - let (hh, gt) = $hash; - tables.lz_insert_only::(hh, p, gt, cp, ca, chain_mask); - p += 1; - } - }}; - } - if wide_h { - g_fill!(if p + 8 <= src_len { - (hash8_shift(src, p, g_shift64), 0u8) - } else if wchain { - hash_wide_link_tag_shift(src, p, g_shift64, smask) - } else { - hash4_tag_mls(src, p, g_shift32, smask) - }); - } else if wchain { - g_fill!(hash_wide_link_tag_shift(src, p, g_shift64, smask)); + // BRICK 10: outlined, see `lz_fill_range` and the note in `find_lazy_impl`. + if rows_live { + lz_fill_range::(tables, src, ip + 1, stop, &fill_ctx); + } else if cp { + lz_fill_range::(tables, src, ip + 1, stop, &fill_ctx); + } else if ca { + lz_fill_range::(tables, src, ip + 1, stop, &fill_ctx); } else { - g_fill!(hash4_tag_mls(src, p, g_shift32, smask)); + lz_fill_range::(tables, src, ip + 1, stop, &fill_ctx); } ip = end; anchor = ip; } else { - ip += 1; + // C: `ip += ((ip-anchor) >> kSearchStrength) + 1`. + ip += lazy_step(ip, anchor, accel_sh); } } greedy_finder_epilogue( @@ -10348,13 +11062,26 @@ pub(crate) struct ChainCtx<'a> { /// saturating sub, a max and a struct load, rebuilt on every call for a /// value the caller already computes as `lowest_rep`. lowest: usize, + /// BRICK 65 (P17): `lowest + window`, the position from which the walk's + /// lower bound is `ip - window` rather than `lowest` -- one compare per + /// walk instead of a saturating subtract and a max. + lowest_w: usize, + /// BRICK 71 (P19): whether the row table exists (`!rows.head.is_empty()`), + /// a per-block fact the walk's insert re-read through the tables pointer + /// on every call to decide the row mirror. + rows_live: bool, /// W5: `cp || ca` -- whether ANY link-tag filter is active. Both terms are /// per block, but the walk re-OR'd them on every LINK STEP. tag_filter: bool, + /// BRICK 14: a per-BLOCK bool that was the kernel's THIRD argument, so + /// `tables` -- the fifth -- went to the stack at every call (one store at + /// each of the two call sites per position, one load in the callee) and + /// the callee spilled the bool on entry. Here it is one field of a + /// context the callee already dereferences. + walk_cont: bool, } -type ChainFn = - for<'a> fn(&ChainCtx<'a>, usize, bool, &mut (u32, u32), &mut MatchTables) -> (usize, usize); +type ChainFn = for<'a> fn(&ChainCtx<'a>, usize, &mut MatchTables) -> (usize, usize); /// E1: the ROW walk -- one dependent load per ROW instead of per CANDIDATE. /// @@ -10374,8 +11101,6 @@ type ChainFn = fn row_find_best( ctx: &ChainCtx, ip: usize, - _walk_cont: bool, - _cls: &mut (u32, u32), tables: &mut MatchTables, ) -> (usize, usize) { let ChainCtx { @@ -10407,9 +11132,9 @@ fn row_find_best( let (h, gtag) = if hash_mode & 2 != 0 && ip + 8 <= src_len { (hash8_shift(src, ip, hash_shift64), 0u8) } else if hash_mode & 1 != 0 { - hash_wide_link_tag_shift(src, ip, hash_shift64, smask) + hash_wide_link_tag_b(src, ip, hash_shift64, smask, mls) } else { - hash4_tag_mls(src, ip, hash_shift32, smask) + hash4_link_tag_w(src, ip, hash_shift32, mls) }; // W11: probe returns the WALK STATE, not a collected array. The row is // still read strictly before `ip` is inserted -- the insert now sits below @@ -10491,9 +11216,9 @@ fn row_find_best( let hm = if hash_mode & 2 != 0 && m + 8 <= src_len { hash8_shift(src, m, hash_shift64) } else if hash_mode & 1 != 0 { - hash_wide_link_tag_shift(src, m, hash_shift64, smask).0 + hash_wide_link_tag_b(src, m, hash_shift64, smask, mls).0 } else { - hash4_tag_mls(src, m, hash_shift32, smask).0 + hash4_link_tag_b(src, m, hash_shift32, mls).0 }; if hm == h { ROW_BUCKET[1].fetch_add(1, Relaxed); @@ -10503,10 +11228,10 @@ fn row_find_best( ROW_BUCKET[2].fetch_add(1, Relaxed); } } - if mls_eq(src, m, ip, mls, smask) { + if let Some(x) = mls_xor(src, m, ip, mls, smask) { // C's `match[ml] == ip[ml]` prefilter, same as the chain walk. if best_ml == 0 || pre_eq(src, m, ip, best_ml) { - let ml = mls + count_match_fast(src, m + mls, ip + mls, block_end); + let ml = fused_ml(x, src, m, ip, block_end); // BRICK 11: see `mls_xor` if ml >= bar { best_ml = ml; best_m = m; @@ -10529,24 +11254,31 @@ fn row_find_best( (best_m, best_ml) } +/// BRICK 20: one instantiation per TAG REPRESENTATION -- `CP` (packed +/// 24-bit link + 8-bit tag), `CA` (tag array), or neither. Both are +/// per-block constants that the walk re-tested on every candidate (two +/// `test`s and a `cmov` on `cp`, a stack-reloaded `tag_filter` compare), +/// holding a register and two stack slots across the hottest loop in the +/// L6-L12 encoder. The block selects the instantiation once, through the +/// fn pointer `find_lazy_impl` already dispatches on. `CP` and `CA` are +/// never both true (`ctags` is only allocated when `chain_pack` is off, +/// and the kernel consults `ca` only when `cp` is false), so three of the +/// four shapes exist. #[inline(never)] -fn chain_find_best( +fn chain_find_best( ctx: &ChainCtx, ip: usize, - walk_cont: bool, - cls: &mut (u32, u32), tables: &mut MatchTables, ) -> (usize, usize) { - chain_find_best_inner::(ctx, ip, walk_cont, cls, tables) + chain_find_best_inner::(ctx, ip, tables) } #[allow(clippy::too_many_arguments)] #[inline(always)] -fn chain_find_best_inner( +#[allow(unsafe_code)] +fn chain_find_best_inner( ctx: &ChainCtx, ip: usize, - walk_cont: bool, - cls: &mut (u32, u32), tables: &mut MatchTables, ) -> (usize, usize) { // BRICK 52, COMPLETED: the AUTHORITATIVE clamped value, never `params`. @@ -10573,13 +11305,27 @@ fn chain_find_best_inner( wchain, wide_hash, lowest, + lowest_w, + rows_live, tag_filter, // W45: both shifts, resolved by `ChainCtx` since 14.9's W20. hash_shift32, hash_shift64, + walk_cont, .. } = *ctx; debug_assert_eq!(tag_filter, cp || ca); + // BRICK 20: the representation is the instantiation's; the ctx copies + // are checked against it and then shadowed so every test below folds. + debug_assert_eq!(cp, CP); + debug_assert_eq!(ca, CA); + let cp = CP; + let ca = CA; + let tag_filter = CP || CA; + // BRICK 24: and the walk-continue decision, the last per-block flag the + // mismatch path reloaded and tested per candidate. + debug_assert_eq!(walk_cont, WC); + let walk_cont = WC; let mls = if MLS == 0 { mls } else { MLS }; debug_assert_eq!(hash_log, tables.hash_log); debug_assert_eq!(chain_mask, tables.chain.len() - 1); @@ -10601,23 +11347,92 @@ fn chain_find_best_inner( // W49: and `src.len()` twice more, for the same reason the row finder // hoisted it (W9). let src_len = src.len(); - let (h, gtag) = if wide_hash && ip + 8 <= src_len { - (hash8_shift(src, ip, hash_shift64), 0u8) - } else if wchain { - hash_wide_link_tag_shift(src, ip, hash_shift64, smask) + // BRICK 68 (P11, brick 54 retried inlined): no 8-byte-hash arm. `wide_hash` is `mls >= 8`, and the + // finders bound `mls` to 3..=7 (brick 35), so the arm's flag test, add + // and compare ran on every call for a case that cannot arrive. The row + // finder still reads `wide_hash` through `hash_mode`; this kernel does + // not. + debug_assert!(!wide_hash, "chain kernel: mls >= 8 is outside the contract"); + // BRICK 100b: the hash4 arm's tag from the word `mls_xor` hoists (see + // `link_tag_from`); the wide arm keeps the byte load -- sharing the + // word there moved the tag-array shapes' dominant paths +1. + let (h, gtag) = if wchain { + hash_wide_link_tag_b(src, ip, hash_shift64, smask, mls) } else { - hash4_tag_mls(src, ip, hash_shift32, smask) + hash4_link_tag_w(src, ip, hash_shift32, mls) + }; + // BRICK 69 (P18): the insert on raw bases taken ONCE per call -- the + // fill's brick 12 for the walk. `lz_insert` re-derived each base from + // the tables pointer (three dependent loads per call) and the loop + // derived the chain base again. Same writes as `lz_insert`: the old + // head becomes the link (`raw - 1`, brick 36's identity), the tag array + // is mirrored when live, the head takes `ip + 1 | tag << 24` (no mask, + // brick 39's bound), and the rows are mirrored through the method as + // before. + let hp = tables.hash.as_mut_ptr(); + let chp = tables.chain.as_mut_ptr(); + let tp = tables.tags.as_mut_ptr(); + let ctp = tables.ctags.as_mut_ptr(); + debug_assert!(h < tables.hash.len() && chain_mask < tables.chain.len()); + debug_assert!(!ca || (h < tables.tags.len() && chain_mask < tables.ctags.len())); + debug_assert!(!cp || ip + 1 < 0x00FF_FFFF); + // SAFETY: `h` is the hash's own output, bounded by the table length; the + // chain and tag-array indices are masked by `chain_mask`; `tags`/`ctags` + // are touched only when `ca` says they are sized with the tables. The + // bases were taken above and nothing here resizes a table. + let (prev, head_tag) = unsafe { + let raw = *hp.add(h); + let old_tag = if cp { + (raw >> 24) as u8 + } else if ca { + *tp.add(h) + } else { + 0 + }; + debug_assert!(!cp || raw == 0 || raw & 0x00FF_FFFF != 0); + // BRICK 74: an empty head links to position 0 WITH its tag (packed). + *chp.add(ip & chain_mask) = if cp { + if raw == 0 { + tables.null_link + } else { + raw - 1 + } + } else { + raw.saturating_sub(1) + }; + if ca { + *ctp.add(ip & chain_mask) = old_tag; + *tp.add(h) = gtag; + } + *hp.add(h) = if cp { + ((ip as u32) + 1) | (u32::from(gtag) << 24) + } else { + (ip as u32) + 1 + }; + (MatchTables::lz_head_pos(raw, cp), old_tag) }; - let (prev, head_tag) = tables.lz_insert(h, ip, gtag, cp, ca, chain_mask); + // BRICK 71 (P19): the row mirror behind the block's own bool. + debug_assert_eq!(rows_live, !tables.rows.head.is_empty()); + if rows_live { + let r = tables.rows.row_of(h); + tables.rows.insert(r, ip as u32, gtag); + } // P0/gg-matchfind: candidate examinations are the WORK COUNTER, the primary // evidence under the Great Gate 2026-08-06 law. Compiled out entirely when // the profile feature is off. const COUNT: bool = cfg!(feature = "profile"); let mut probes = 0u64; + // BRICK 64 (P14): the walk_cont classification is written straight to + // `tables.wcls` on the rare accept (brick 50's locals, right for the + // standalone kernel, cost nine instructions per walk once the walk was + // inlined: duplicated zero stores at entry and a two-load test at exit). let mut best_m = 0usize; - let mut best_ml = 0usize; - // W7: the acceptance bar -- see the accept test. - let mut bar = mls; + // BRICK 59 (K8): ONE length. `best_ml` is born `mls - 1`, so `ml > + // best_ml` is the accept test before and after the first accept (W7's + // bar was `best_ml + 1`, seeded with `mls`), `pre_eq` at that index is + // sound on the first candidate (the first-word compare just verified + // byte `mls - 1`), and "no match yet" is `best_ml < mls`. + let mut best_ml = mls - 1; let Some(mut m) = prev else { #[cfg(feature = "profile")] WALK_EXIT[0].fetch_add(1, core::sync::atomic::Ordering::Relaxed); @@ -10633,13 +11448,38 @@ fn chain_find_best_inner( // only fire on ENTRY (afterwards m strictly decreases below ip), and the // window and lowest checks are both lower bounds on m, merged into a // per-walk constant. `ip - m > window <=> m < ip - window` for m < ip. - let low = lowest.max(ip.saturating_sub(window)); - let mut missed_before = false; - if m < ip && ip + mls <= src_len { + // BRICK 65 (P17): one compare. `lowest_w = lowest + window`, so below it + // the bound is `lowest`; at or above it `ip - window >= lowest`. + debug_assert_eq!(lowest_w, lowest + window); + let low = if ip >= lowest_w { ip - window } else { lowest }; + debug_assert_eq!(low, lowest.max(ip.saturating_sub(window))); + // BRICK 63 (K12): a small integer, not a bool -- the two miss arms + // write DIFFERENT values so LLVM cannot hoist one constant store above + // the tag test and pay it (plus the restore) on the paths that never + // miss. Readers test `!= 0`. + let mut missed_before = 0u8; + // BRICK 49 (P9): `ip + mls <= src_len` is the caller's invariant, not a + // per-call question -- `find_lazy_impl` holds `ip <= ilimit = block_end - 8` + // at both call sites and `mls <= 7` (brick 35). It was an add, a compare + // and a branch per call, with both operands reloaded from the stack. + debug_assert!(ip + 8 <= src_len && mls <= 8); + if m < ip { // 5 = ran the full depth; each `break` below overwrites it. + // BRICK 61 (K10): the chain and tag-array bases, once. Through + // `&mut MatchTables` the inlined walk re-derived the chain base from + // the tables pointer on every candidate (two dependent loads). + // Nothing in the loop resizes a table; `m & chain_mask` is in bounds + // by the mask (brick 50's argument, restated at each read). + // (BRICK 69: `chp` / `ctp` are the entry's bases.) #[cfg(feature = "profile")] let mut exit_why = 5usize; - for _ in 0..attempts { + // BRICK 62 (K11): an explicit countdown that nothing else reads. + // `for _ in 0..attempts` is an up-counter against `attempts`, which + // in the inlined finder is a frame slot reloaded on every candidate; + // the countdown is `dec`/`je` with nothing to load. + let mut left = attempts; + while left != 0 { + left -= 1; // Monotone: m only decreases, so one bound test per step. if m < low { #[cfg(feature = "profile")] @@ -10663,13 +11503,19 @@ fn chain_find_best_inner( // // Byte-identical: `chain_masked` is a pure read and nothing in the // body writes `chain` (the insert happens before the loop). - let link = tables.chain_masked(m & chain_mask); + // SAFETY: `m & chain_mask <= chain_mask < chain.len()` (asserted + // above); the base was taken above and nothing here resizes. + let link = unsafe { *chp.add(m & chain_mask) }; // Link-tag reject: skip `mls_eq`'s src[m] load on a tag byte the // link load already delivered. Sound: mls_eq true => 4 bytes // equal => tags equal. // See the greedy walk: position 0 is sentinel-ambiguous, never // tag-filtered. - if tag_filter && m != 0 && mtag != gtag { + // BRICK 74 (K14): no `m != 0` exemption for the PACKED shape -- its + // null links carry position 0's own tag (see `set_null_tag`), so the + // phantom candidate is tag-tested like any other. The tag-array + // shape keeps the exemption (its links carry no tag byte). + if tag_filter && (cp || m != 0) && mtag != gtag { #[cfg(feature = "profile")] if COUNT { use core::sync::atomic::Ordering::Relaxed; @@ -10678,7 +11524,7 @@ fn chain_find_best_inner( LINK_FALSE.fetch_add(1, Relaxed); } } - missed_before = true; + missed_before = 1; if !walk_cont { break; } @@ -10693,14 +11539,28 @@ fn chain_find_best_inner( probes += 1; #[cfg(feature = "profile")] WALK_EXAM.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + // BRICK 46: the phantom position-0 candidate (see + // `take_walk_phantom`). + #[cfg(feature = "profile")] + if m == 0 { + WALK_M0.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + } } - if mls_eq(src, m, ip, mls, smask) { + if let Some(x) = mls_xor(src, m, ip, mls, smask) { // C's `match[ml] == ip[ml]` prefilter -- see `find_greedy`. - if best_ml == 0 || pre_eq(src, m, ip, best_ml) { + if pre_eq(src, m, ip, best_ml) { // Count from the byte AFTER what mls_eq just verified -- // restarting at 0 re-compared the first word of every // candidate (the fast_probe_wide rule, applied here). - let ml = mls + count_match_fast(src, m + mls, ip + mls, block_end); + // BRICK 11: see `mls_xor`; BRICK 56: the long + // continuation is outlined behind `ctx`. + let ml = if x != 0 { + #[cfg(feature = "profile")] + FUSED_SHORT.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + (x.trailing_zeros() as usize) >> 3 + } else { + walk_count8(ctx, m, ip) + }; // offset_ok and the frame_start floor are GUARANTEED by // the walk bound (m >= low >= lowest >= frame_start, // m >= ip - window, m < ip); re-checking per accept was @@ -10713,26 +11573,29 @@ fn chain_find_best_inner( // a running bar. (The same fold REGRESSED in the Bt walk, // where the extra live value spilled `best_m`; this loop // carries fewer, so it is re-measured here, not assumed.) - if ml >= bar { - if missed_before { - if best_ml == 0 { - cls.0 += 1; + if ml > best_ml { + if missed_before != 0 { + if best_ml < mls { + tables.wcls.0 += 1; } else { - cls.1 += 1; + tables.wcls.1 += 1; } #[cfg(feature = "profile")] if COUNT { use core::sync::atomic::Ordering::Relaxed; - if best_ml == 0 { + if best_ml < mls { WALK_CONT_FIRST.fetch_add(1, Relaxed); } else { WALK_CONT_UPGRADE.fetch_add(1, Relaxed); } } } + #[cfg(feature = "profile")] + if m == 0 { + WALK_M0_ACCEPT.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + } best_ml = ml; best_m = m; - bar = ml + 1; if ip + best_ml >= block_end { #[cfg(feature = "profile")] { @@ -10743,7 +11606,7 @@ fn chain_find_best_inner( } } } else { - missed_before = true; + missed_before = 2; #[cfg(feature = "profile")] if COUNT { WALK_BYTEMISS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); @@ -10770,7 +11633,9 @@ fn chain_find_best_inner( mtag = if cp { (link >> 24) as u8 } else if ca { - tables.ctags_masked(m & chain_mask) + // SAFETY: as the chain read; `ctags` is sized with `chain` when + // `ca` (asserted above). + unsafe { *ctp.add(m & chain_mask) } } else { 0 }; @@ -10785,6 +11650,11 @@ fn chain_find_best_inner( if COUNT { crate::prof::note_probes(probes); } + // BRICK 59: `best_ml < mls` is "nothing accepted" -- an accept needs + // `ml > mls - 1`. Same `(0, 0)` as before. + if best_ml < mls { + return (0, 0); + } (best_m, best_ml) } @@ -10835,21 +11705,91 @@ fn find_lazy_sel( // kernel monomorphisation (`chain_find_best::` as a fn pointer), so // this collapse takes those generic too -- `mls` becomes a runtime compare // in the walk instead of an immediate. Measured, not assumed. - find_lazy_impl::<0>( - src, - block_start, - block_end, - window, - params, - tables, - depth, - reps, - ) + // + // BRICK 58 (P13b): the block's kernel SHAPE is a const of the finder so + // the walk is inlined at its two call sites (see `lazy_search`). The + // shape is derived here exactly as the body derives it (asserted there); + // the row finder and the tags-off shapes keep the pointer (`KIND == 7`). + let kind = lazy_kind( + row_find_enabled() && !tables.rows.head.is_empty(), + tables.chain_pack, + !tables.ctags.is_empty(), + lazy_walk_cont(params, tables, search_attempts(params)), + ); + macro_rules! go { + ($k:expr) => { + find_lazy_impl::<0, $k>( + src, + block_start, + block_end, + window, + params, + tables, + depth, + reps, + ) + }; + } + match kind { + 1 => go!(1), + 2 => go!(2), + 3 => go!(3), + 4 => go!(4), + _ => go!(7), + } +} + +/// BRICK 58: the lazy finder's kernel shape as a const. 1..=4 are the +/// shipping chain shapes (packed / tag-array, each with and without +/// walk_cont) and are inlined; 7 is "through the pointer" (rows, tags off). +#[inline(always)] +fn lazy_kind(use_rows: bool, cp: bool, ca: bool, walk_cont: bool) -> u8 { + match (use_rows, cp, ca, walk_cont) { + (false, true, _, true) => 1, + (false, true, _, false) => 2, + (false, false, true, true) => 3, + (false, false, true, false) => 4, + _ => 7, + } +} + +/// The WALK-CONTINUE dispatch (see `walk_rep_max`), as the one expression +/// both `find_lazy_sel` and the finder body evaluate -- it reads block +/// state the body updates AFTER deciding, so the two must agree on order. +#[inline(always)] +fn lazy_walk_cont(params: CompressionParameters, tables: &MatchTables, attempts: usize) -> bool { + walk_cont_enabled() + // GATE 3's rule for the L1-routed case: `find_lazy` reachable with + // `strategy == Fast` is the Gate 1 dispatch, and the C-parity walk + // must not change the Fast ladder's bytes. + && params.strategy != Strategy::Fast + && tables.rep_yield <= walk_rep_max() + && (tables.walk_first_share <= walk_first_max(attempts) || tables.walk_probe == 0) +} + +/// BRICK 58: the search, resolved by the finder's `KIND`. For the four +/// shipping chain shapes this is `chain_find_best_inner` -- `inline(always)`, +/// so the walk lands here, in the finder's own frame; otherwise the block's +/// pointer, as before. +#[inline(always)] +fn lazy_search( + cfb: ChainFn, + ctx: &ChainCtx, + ip: usize, + tables: &mut MatchTables, +) -> (usize, usize) { + match KIND { + 1 => chain_find_best_inner::(ctx, ip, tables), + 2 => chain_find_best_inner::(ctx, ip, tables), + 3 => chain_find_best_inner::(ctx, ip, tables), + 4 => chain_find_best_inner::(ctx, ip, tables), + _ => cfb(ctx, ip, tables), + } } #[allow(clippy::too_many_arguments)] #[inline(always)] -fn find_lazy_impl( +fn find_lazy_impl( src: &[u8], block_start: usize, block_end: usize, @@ -10859,8 +11799,15 @@ fn find_lazy_impl( depth: usize, reps: [u32; 3], ) -> (Vec, Vec) { + // BRICK 35 (K1): the CONTRACT's bound, both ends. `min_match` is + // documented 3..=7 and `compression_params` / `apply_zstd_kv` both clamp + // it there; only a hand-built `CompressionParameters` could carry more, + // and zstd itself rejects such a value (`ZSTD_MINMATCH_MAX` is 7). With + // the bound stated HERE, `mls_xor` needs no `mls > 8` arm -- which was a + // compare and a branch on EVERY examined candidate in the chain walk, + // and a callee-saved register holding `mls` for the walk's whole life. let mls = if MLS == 0 { - params.min_match.max(3) as usize + params.min_match.clamp(3, 7) as usize } else { MLS }; @@ -10887,18 +11834,6 @@ fn find_lazy_impl( // D4: the BMI2 chain twin is retired -- 457 instructions of duplicated // walk converting THREE BMI2 ops, 152 per op, the worst ratio in the // crate. Same reasoning as W4/W5/W6. - #[cfg(all(target_arch = "x86_64", feature = "std"))] - let cfb: ChainFn = if use_rows { - row_find_best:: - } else { - chain_find_best:: - }; - #[cfg(not(all(target_arch = "x86_64", feature = "std")))] - let cfb: ChainFn = if use_rows { - row_find_best:: - } else { - chain_find_best:: - }; // GATE 6 family, fourth instance: take the finder buffers from the FRAME. // // `find_fast_impl` was wired to `MatchTables::seq_scratch`/`lit_scratch` @@ -10913,7 +11848,8 @@ fn find_lazy_impl( // Scratch + the too-short-block exit, ONE copy for Greedy/Lazy/BtLazy and // their bmi2 twins -- six stamps of the identical idiom become one call // (the `fast_finder_prologue` treatment, chain-finder variant). - let (mut seqs, mut lits) = match chain_finder_prologue(src, block_start, block_end, tables) { + let (mut seqs, mut lits) = match chain_finder_prologue(src, block_start, block_end, tables, mls) + { Ok(t) => t, Err(out) => return out, }; @@ -10978,20 +11914,22 @@ fn find_lazy_impl( } else { lazy_fill_stride() }; - // WALK-CONTINUE dispatch: see `walk_rep_max`. - let walk_cont = walk_cont_enabled() - // GATE 3's rule for the L1-routed case: `find_lazy` reachable with - // `strategy == Fast` is the Gate 1 dispatch, and the C-parity walk - // must not change the Fast ladder's bytes. - && params.strategy != Strategy::Fast - && tables.rep_yield <= walk_rep_max() - && (tables.walk_first_share <= walk_first_max(attempts) || tables.walk_probe == 0); + // WALK-CONTINUE dispatch: see `walk_rep_max`. BRICK 58: for the inlined + // shapes it is the finder's const; the expression is still evaluated + // (and asserted equal) in debug builds, dead in release. + let walk_cont_rt = lazy_walk_cont(params, tables, attempts); + let walk_cont = match KIND { + 1 | 3 => true, + 2 | 4 => false, + _ => walk_cont_rt, + }; + debug_assert_eq!(walk_cont, walk_cont_rt); tables.walk_probe = if tables.walk_probe == 0 { WALK_PROBE_PERIOD } else { tables.walk_probe - 1 }; - let mut wcls = (0u32, 0u32); + tables.wcls = (0, 0); // ORDER IS LOAD-BEARING: `maybe_latch_wide_chain` can flip // `tables.chain_wide` for the REST of the frame, so every value below it // must be read AFTER it. Building the context any earlier captured the @@ -10999,6 +11937,39 @@ fn find_lazy_impl( maybe_latch_wide_chain(tables, src, block_start, window, mls); let cp = tables.chain_pack; let ca = !tables.ctags.is_empty(); + debug_assert!( + KIND == 7 || lazy_kind(use_rows, cp, ca, walk_cont) == KIND, + "find_lazy_impl: KIND disagrees with the block's shape" + ); + // The kernel is selected ONCE per block, as a FUNCTION POINTER, and that + // is the right shape -- REFUTED 2026-09-09, both alternatives, on the + // emitted-asm count so it is not retried: + // * a direct branch `if use_rows { row(..) } else { chain(..) }` at + // each call site took the indirect calls 2 -> 0 but DUPLICATED the + // five-argument marshalling in both arms: per-position loop +18 + // instructions, look-ahead loop +70, whole function 1472 -> 1470; + // * inlining `chain_find_best_inner` into the loop instead landed the + // 331-instruction walk TWICE (one per call site): 1472 -> 1982, and + // the per-position loop went 458 instrs / 10 spills -> 464 / 20. + // One indirect call with one marshalling sequence is the cheapest form + // LLVM produces here. The two cfg arms this used to carry were identical + // (the BMI2 twin they selected between is retired, D4); one is kept. + // + // BRICK 20: the chain kernel comes in three tag-representation shapes + // (see `chain_find_best`); the block picks its own here, once. + let cfb: ChainFn = if use_rows { + row_find_best:: + } else { + // BRICK 24: `walk_cont` is the third axis (six kernels). + match (cp, ca, walk_cont) { + (true, _, true) => chain_find_best::, + (true, _, false) => chain_find_best::, + (false, true, true) => chain_find_best::, + (false, true, false) => chain_find_best::, + (false, false, true) => chain_find_best::, + (false, false, false) => chain_find_best::, + } + }; let wchain = tables.chain_wide; let smask = if mls >= 8 { u64::MAX @@ -11007,7 +11978,8 @@ fn find_lazy_impl( }; // W6: the same two facts the fill loop re-derived per inserted position. let wide_h = mls >= 8; - let src_len = src.len(); + // BRICK 74: the empty-head link for this block's producer. + tables.set_null_tag(chain_null_tag(src, mls)); // W1/W2: the walk's prologue, hoisted -- see `ChainCtx`. let chain_ctx = ChainCtx { src, @@ -11028,7 +12000,10 @@ fn find_lazy_impl( hash_shift64: 64u32.saturating_sub(tables.hash_log.min(32)), lowest1: lowest_rep.max(1), lowest: lowest_rep, + lowest_w: lowest_rep + window, + rows_live: !tables.rows.head.is_empty(), tag_filter: cp || ca, + walk_cont, }; // GATE 13, which this finder never received. Every other finder resolves // the literal-copy width once per block and emits through `push_literals`; @@ -11051,9 +12026,37 @@ fn find_lazy_impl( // moves the bitstream with no edit here to explain why. let lp_copy = lit_width_for(tables); let gain_cmp = lazy_gain_enabled(); + // Hoisted per BLOCK: an atomic load per position would cost more + // than the positions it skips. + let accel_sh = lazy_step_shift(lazy_accel()); + // BRICK 95 (P23): the anchor in its folded form for the no-match step. + let mut anchor_adj = anchor_adj_of(anchor, accel_sh); + // BRICK 19: the fill's block constants, once, by reference. + let fill_ctx = FillCtx { + stride: fill_stride, + shift32: f_shift32, + shift64: f_shift64, + smask, + mls, + chain_mask, + wide_h, + wchain, + cp, + ca, + }; + // BRICK 38 (P2): the rep probe's four admission tests, as one bound on + // `ip` -- see `rep_bar_for`. Refreshed where `rep1` changes. + let mut rep_bar = rep_bar_for(use_rep, rep1, lowest_rep); while ip <= ilimit { - if use_rep { - if let Some(ml) = try_rep1(src, ip, rep1, lowest_rep, block_end, ilimit) { + if ip >= rep_bar { + debug_assert!(use_rep && rep1 != 0 && ip + 1 >= rep1 + lowest_rep); + debug_assert_eq!( + rep1_len(src, ip + 1, ip + 1 - rep1, block_end), + try_rep1(src, ip, rep1, lowest_rep, block_end, ilimit) + ); + // BRICK 86 (P21): the probe's width from `ip < ilimit` -- the same + // question as `ip + 9 <= block_end`, on operands the loop holds. + if let Some(ml) = rep1_len_w(src, ip + 1, ip + 1 - rep1, block_end, ip < ilimit) { rep_hits += 1; let mstart = ip + 1; push_literals(&mut lits, src, anchor, mstart, lp_copy); @@ -11064,19 +12067,28 @@ fn find_lazy_impl( }); ip = mstart + ml; anchor = ip; + anchor_adj = anchor_adj_of(anchor, accel_sh); continue; } } searches += 1; - let (mut best_m, mut best_ml) = cfb(&chain_ctx, ip, walk_cont, &mut wcls, tables); - let mut best_ip = ip; - let mut look_hi = ip; // PROBE: highest position the look-ahead inserted - if best_ml >= mls { - // W3: the in-hand match's gain, carried with it. MOVED INSIDE this - // guard -- its only two readers are in this block, and computing it - // above cost a multiply plus a `leading_zeros` on every position - // where the walk found NOTHING, which is the common case at L9 - // (chain hit rate 3-10%). + let (mut best_m, mut best_ml) = lazy_search::(cfb, &chain_ctx, ip, tables); + // BRICK 37 (P1): ONE test per position. `cfb` returns `(0, 0)` or a + // length that already cleared `mls` (W9), the look-ahead below only + // ever raises `best_ml`, and the emit used to re-test `best_ml != 0` + // after the look-ahead's `best_ml >= mls` -- the same predicate, so + // the second `test`/`je` and the `mls` reload were pure overhead on + // every position, and `best_ip`/`look_hi` were spilled across the + // join on the no-match path, where nothing reads them. + if best_ml != 0 { + debug_assert!(best_ml >= mls); + let mut best_ip = ip; + let mut look_hi = ip; // PROBE: highest position the look-ahead inserted + // W3: the in-hand match's gain, carried with it. MOVED INSIDE this + // guard -- its only two readers are in this block, and computing it + // above cost a multiply plus a `leading_zeros` on every position + // where the walk found NOTHING, which is the common case at L9 + // (chain hit rate 3-10%). let mut best_gain = if gain_cmp { lazy_gain(best_ml, ip - best_m) } else { @@ -11088,7 +12100,7 @@ fn find_lazy_impl( break; } look_hi = ip2; - let (m, ml) = cfb(&chain_ctx, ip2, walk_cont, &mut wcls, tables); + let (m, ml) = lazy_search::(cfb, &chain_ctx, ip2, tables); // W3: `lazy_gain(best_ml, best_ip - best_m)` describes the // match ALREADY IN HAND, so it changes only when that match // does -- but it was recomputed on every look-ahead step (a @@ -11126,10 +12138,10 @@ fn find_lazy_impl( best_ip = ip2; } } - } - // W10: same identity as W9 -- `best_ml` is 0 or already past `mls`. - debug_assert!(best_ml == 0 || best_ml >= mls); - if best_ml != 0 { + // W10: same identity as W9 -- `best_ml` is 0 or already past `mls`, + // and the look-ahead never lowers it. BRICK 37 (P1) folded the emit + // into the guard above on exactly that identity. + debug_assert!(best_ml >= mls); // DEFECT B3 FIX: back-extend the match -- see `find_greedy`. let mut s = best_ip; let mut mm = best_m; @@ -11156,6 +12168,22 @@ fn find_lazy_impl( // The repcode must track the offset ACTUALLY EMITTED. Lazy // commits at `best_ip` (the look-ahead winner), not `ip`. rep1 = best_ip - best_m; + // BRICK 85 (P20): `rep1` is a match offset here, never 0, so the + // helper's `rep1 != 0` arm is dead on this path. + debug_assert!(rep1 != 0); + debug_assert_eq!( + if use_rep { + rep1 + lowest_rep - 1 + } else { + usize::MAX + }, + rep_bar_for(use_rep, rep1, lowest_rep) + ); + rep_bar = if use_rep { + rep1 + lowest_rep - 1 + } else { + usize::MAX + }; // DEFECT B1 FIX: back-fill every position the match covers. // `find_greedy` already did this; lazy/lazy2 jumped straight to // `best_ip + best_ml`, so every byte inside a match was absent @@ -11169,7 +12197,6 @@ fn find_lazy_impl( // Stride the back-fill. `1` = every position (C's behaviour). // Larger strides thin the chain: the cost of the back-fill is // the chain DENSITY it creates, not the inserts themselves. - let stride = fill_stride; // DEFECT B2 FIX: never insert a position TWICE. The look-ahead // already inserted `ip+1 ..= look_hi` via `chain_find_best`, and // re-inserting `p` stores `chain[p] = get_h(h)` when the head IS @@ -11181,7 +12208,7 @@ fn find_lazy_impl( // than the cheaper dfast below them. C cannot hit this: its // `nextToUpdate` cursor is monotone, so every position is inserted // exactly once. - let mut p = (best_ip + 1).max(look_hi + 1); + let p = (best_ip + 1).max(look_hi + 1); // Consumers are `take_lazy_fill` gate harnesses only; in // shipping LF_INSERTS was one lock-prefixed RMW PER COVERED // POSITION -- the pair-tail class (959e0ae), on the matchiest @@ -11198,65 +12225,35 @@ fn find_lazy_impl( // the fold `find_greedy_impl`'s fill already had (its W7) and // this one never received. let stop = end.min(ilimit + 1); - // W30/W31/W32: the hash MODE and the table CHOICE are BLOCK - // constants, and this loop re-asked both on every inserted - // position. Hoisting them leaves each arm with one hash and - // one insert in its body -- and the two non-wide arms shed the - // `p + 8 <= src_len` test entirely, since only the 8-byte hash - // needs it. - // - // W33/W34 (row arm): the row mask and the table borrow are - // hoisted out, and `insert_h` folds `row_of` into the insert, - // so a position costs one call rather than two plus a struct - // load for the mask. - // - // W26/W27 stand: the row arm writes ONLY the row table (14.8 - // proved the rest dead), and the chain arm takes - // `lz_insert_only` rather than discarding a built return. - macro_rules! fill_body { - ($hash:expr, $ins:expr) => {{ - while p < stop { - #[cfg(feature = "profile")] - LF_INSERTS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); - let (hh, gt) = $hash; - $ins(hh, gt, p); - p += stride; - } - }}; - } - macro_rules! fill_arms { - ($ins:expr) => {{ - if wide_h { - fill_body!( - if p + 8 <= src_len { - (hash8_shift(src, p, f_shift64), 0u8) - } else if wchain { - hash_wide_link_tag_shift(src, p, f_shift64, smask) - } else { - hash4_tag_mls(src, p, f_shift32, smask) - }, - $ins - ); - } else if wchain { - fill_body!(hash_wide_link_tag_shift(src, p, f_shift64, smask), $ins); - } else { - fill_body!(hash4_tag_mls(src, p, f_shift32, smask), $ins); - } - }}; - } + // BRICK 10: OUTLINED. This is the per-MATCHED-BYTE loop -- it runs once per + // byte of every match at L6-L12 -- and it lived inline here in six copies + // (three hash arms x two inserters), each reloading the chain mask, the + // chain base and its bounds from spill slots on every byte: the census read + // 22 instructions and 4 stack reloads per inserted position. In its own + // frame those invariants are register-resident for the loop's whole life; + // the caller pays one call per match, amortised over the match's length. if use_rows { - let rows = &mut tables.rows; - let rmask = rows.mask(); - fill_arms!(|hh: usize, gt: u8, q: usize| rows.insert_h(hh, rmask, q as u32, gt)); + row_fill_range(&mut tables.rows, src, p, stop, &fill_ctx); } else { - fill_arms!(|hh: usize, gt: u8, q: usize| tables - .lz_insert_only::(hh, q, gt, cp, ca, chain_mask)); + if cp { + lz_fill_range::(tables, src, p, stop, &fill_ctx); + } else if ca { + lz_fill_range::(tables, src, p, stop, &fill_ctx); + } else { + lz_fill_range::(tables, src, p, stop, &fill_ctx); + } } } ip = end; anchor = ip; + anchor_adj = anchor_adj_of(anchor, accel_sh); } else { - ip += 1; + // C: `ip += ((ip-anchor) >> kSearchStrength) + 1`. + debug_assert_eq!( + lazy_step_adj(ip, anchor_adj, accel_sh), + lazy_step(ip, anchor, accel_sh) + ); + ip += lazy_step_adj(ip, anchor_adj, accel_sh); } } // Same shipping tail as `find_greedy_impl`, so it is the SAME helper -- @@ -11266,6 +12263,7 @@ fn find_lazy_impl( // stores move BELOW the call: they read the post-update EWMAs, which the // helper has written by the time it returns, and they publish to // independent statics, so order against `note_finder_work` is immaterial. + let wcls = tables.wcls; greedy_finder_epilogue( tables, src, @@ -11466,9 +12464,7 @@ fn bt_depth_target() -> usize { } #[cfg(feature = "std")] { - let v = std::env::var("RZSTD_BT_DEPTH_TARGET") - .ok() - .and_then(|v| v.trim().parse().ok()) + let v = crate::env_knob_parse("RZSTD_BT_DEPTH_TARGET") .filter(|v| *v >= 1) .unwrap_or(32); BT_DEPTH_T_C.store(v, Relaxed); @@ -11512,10 +12508,7 @@ fn bt_depth_rep_max() -> f32 { } #[cfg(feature = "std")] { - let v: f32 = std::env::var("RZSTD_BT_DEPTH_REP") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(50.0); + let v: f32 = crate::env_knob_parse("RZSTD_BT_DEPTH_REP").unwrap_or(50.0); BT_DEPTH_REP_C.store(v.to_bits(), Relaxed); v } @@ -11534,10 +12527,7 @@ fn bt_depth_min_slog() -> u32 { } #[cfg(feature = "std")] { - let v = std::env::var("RZSTD_BT_DEPTH_SLOG") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(7); + let v = crate::env_knob_parse("RZSTD_BT_DEPTH_SLOG").unwrap_or(7); BT_DEPTH_SLOG_C.store(v, Relaxed); v } @@ -11553,582 +12543,136 @@ fn bt_depth_steps() -> u32 { return c; } #[cfg(feature = "std")] - { - let v = std::env::var("RZSTD_BT_DEPTH") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(1); - BT_DEPTH_STEPS_C.store(v, Relaxed); - v - } - #[cfg(not(feature = "std"))] - 1 -} - -pub static BT_WALKS2: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); -pub static BT_ITERS: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); -pub static BT_FULL: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); - -/// `(walks, total_iterations, walks_that_used_ALL attempts)` -pub fn take_bt_iters() -> (u64, u64, u64) { - use core::sync::atomic::Ordering::Relaxed; - ( - BT_WALKS2.swap(0, Relaxed), - BT_ITERS.swap(0, Relaxed), - BT_FULL.swap(0, Relaxed), - ) -} - -fn search_attempts(params: CompressionParameters) -> usize { - let v = SEARCH_LOG_ARM.load(core::sync::atomic::Ordering::Relaxed); - let base = params.search_log.min(12) as i32; - let d = if v == 0 { 0 } else { v as i32 - 8 }; - 1usize << base.saturating_add(d).clamp(0, 12) -} - -/// The `(hash_log, chain_log)` pairs the binary-tree specialisation covers. -/// -/// ONE list, two consumers: the dispatch arms in `bt_find_best` and the public -/// `BT_SPEC_PAIRS` the coverage test asserts against. They were previously -/// independent, so a pair could be dropped from the dispatch while every test -/// still passed -- which is exactly how 24 of 64 (size, level) cells came to run -/// the slow runtime body unnoticed. -macro_rules! bt_spec_list { - ($cb:ident) => { - $cb! { - // DEAD-COPY CENSUS 2026-08-21 (`deadcopy.rs`): every clevel x - // every input-size decade x the streaming case produces exactly - // 20 (hash_log, chain_log) pairs across the four Bt strategies. - // (18, 18) was shipped and is in NONE of them -- no input can - // reach it. Culled: it was 4 symbols (SEARCH x plain/BMI2) of - // code no frame can execute. The other 20 are all reachable, so - // this list is now exactly the reachable set. - (11, 11) (12, 12) (13, 13) (14, 14) (14, 15) (15, 15) (16, 16) - (17, 17) (17, 18) (19, 18) (19, 19) (20, 20) (21, 21) - (22, 22) (22, 23) (22, 24) (23, 22) (23, 23) (23, 24) (24, 24) - } - }; -} - -macro_rules! bt_spec_pairs_const { - ($( ($h:literal, $c:literal) )*) => { - /// Every `(hash_log, chain_log)` pair served by the specialised body. - /// Anything else falls to `bt_find_best_runtime`. - pub const BT_SPEC_PAIRS: &[(u32, u32)] = &[$( ($h, $c) ),*]; - }; -} -bt_spec_list!(bt_spec_pairs_const); - -/// The dispatch, RESOLVED ONCE PER BLOCK: `(hash_log, chain_log)` is -/// loop-invariant in every caller, yet `bt_find_best` re-ran a jump-table -/// dispatch (plus re-reading both fields) on every call -- per position, -/// per look-ahead, per fill insert and per DP edge. Callers hoist a fn -/// pointer instead; one predictable indirect call replaces the dance. -/// Same arms, same runtime fallback, same bt_spec parity gate. -/// The per-block-constant arguments of every bt call, packed: the fn -/// pointer previously re-marshaled NINE scalars per position, per -/// look-ahead step, per fill insert and per DP edge. -pub(crate) struct BtCtx<'a> { - src: &'a [u8], - block_start: usize, - block_end: usize, - window: usize, - mls: usize, - attempts: usize, - chain_log: u32, - /// W1/W2/W3: three values the walk's PROLOGUE recomputed on every call -- - /// and this function is called per position, per look-ahead step AND per - /// fill insert (61.9% of all tree work at L13-L15), so "per call" is the - /// hottest unit in the Bt ladder. - /// - /// `bt_lowest` is `block_start.saturating_sub(window).max(frame_start)`: a - /// saturating sub, a max, and a struct load through `&mut MatchTables` - /// that LLVM must re-prove after every `chain` write. `chain_len` served - /// the entry guard, another struct load. Both are fixed for the block. - bt_lowest: usize, - chain_len: usize, - /// W6: `hash_mls`'s `mls >= 8` question, answered once per BLOCK. The walk - /// loaded `mls` from the context and compared it on EVERY call. Kept as a - /// flag rather than deleted: the advanced API can set `min_match` to 8, - /// which other guards in this file already respect, even though every - /// shipping Bt row uses 3..=5. - wide_hash: bool, -} - -type BtFn = for<'a> fn(&BtCtx<'a>, usize, &mut MatchTables) -> (usize, usize); - -/// The INSERT dispatch's own type. Insert callers discard the result -- both -/// fills and the priming pass -- but the `BtFn` signature forced every insert -/// trampoline to MATERIALISE one: the emitted wrapper built a 40-byte frame, -/// made a real call, then zeroed `rax`/`rdx` to return `(0, 0)`, on 61.9% of -/// all tree work at L13-L15. Returning `()` lets the same wrapper compile to -/// a bare tail `jmp`, which is what the SEARCH side already gets. -type BtInsFn = for<'a> fn(&BtCtx<'a>, usize, &mut MatchTables); - -fn bt_rt_search(ctx: &BtCtx, ip: usize, t: &mut MatchTables) -> (usize, usize) { - bt_find_best_runtime(true, ctx, ip, t) -} - -fn bt_rt_insert(ctx: &BtCtx, ip: usize, t: &mut MatchTables) -> (usize, usize) { - bt_find_best_runtime(false, ctx, ip, t) -} - -/// `bt_resolve` for the insert side -- same table, `BtInsFn` shape. -fn bt_resolve_ins(_hash_log: u32, _chain_log: u32) -> BtInsFn { - #[cfg(all(target_arch = "x86_64", feature = "std"))] - let bmi2 = crate::simd::has_bmi2(); - #[cfg(not(all(target_arch = "x86_64", feature = "std")))] - let bmi2 = false; - // D11: completes D5. That win retired the bt-runtime SEARCH twins - // (`bt_rt_search_bmi2`/`bt_rt_insert_bmi2`) on their ISA density -- 291 - // instructions converting three BMI2 ops -- and missed this INSERT - // selector, which kept `bt_find_best_runtime_bmi2` (316 instrs) alive - // through `bt_rt_ins_bmi2`. Same body, same three ops, same verdict. - #[cfg(all(target_arch = "x86_64", feature = "std"))] - let _ = bmi2; - #[cfg(all(target_arch = "x86_64", feature = "std"))] - let rt: BtInsFn = bt_rt_ins_plain; - #[cfg(not(all(target_arch = "x86_64", feature = "std")))] - let rt: BtInsFn = bt_rt_ins_plain; - if !bt_spec_enabled() { - return rt; - } - // W9: the (hash_log, chain_log) SPEC LIST IS BMI2-REDUNDANT. - // - // The spec copies exist to fold the hash shift and the chain mask to - // immediates. On the twins both are already free: `shrx` takes its count - // from any GPR, and the mask is one `and` whose operand costs the same in a - // register as in an immediate. `BtCtx` (brick 48's successor) already - // holds both in registers for the whole walk, so the runtime arm's operands - // are register-resident before the walk starts. - // - // The list was buying nothing on the twins and costing 40 monomorphisations - // of the search body plus 20 of the insert body. Byte-identical: the consts - // took the values the ctx fields already held. - #[cfg(all(target_arch = "x86_64", feature = "std"))] - if bmi2 { - return rt; - } - // W6, insert-only twin -- see `bt_resolve` above for the full argument. - // - // The 2026-08-21 census proved all 20 pairs REACHABLE, and that is the - // wrong test -- HLOG's six values in `find_fast` were all reachable too - // (W4). The right test is what the consts BUY, and here they reach exactly - // two places: `HLOG` feeds `hash8`/`hash4` (a shift immediate) and `CLOG` - // feeds `btlog` -> `bt_mask` (an AND mask that is loop-invariant and sits - // in a register either way). On aarch64/wasm32 neither is worth anything - // -- register shifts and register ANDs cost what the immediate forms cost. - // On baseline x86 `shr %cl` is 1 uop. And BMI2 hosts never came here at - // all: the `if bmi2 { return rt }` above already sent them to `rt`. - // - // So this table only ever served pre-BMI2 x86 and the non-x86 targets, and - // charged them 11,283 instructions of I-cache to fold two immediates. - rt -} -fn bt_resolve(_hash_log: u32, _chain_log: u32) -> BtFn { - // ISA selection happens HERE, once per block, so the per-position bt - // calls carry no dispatch of their own. - #[cfg(all(target_arch = "x86_64", feature = "std"))] - let bmi2 = crate::simd::has_bmi2(); - #[cfg(not(all(target_arch = "x86_64", feature = "std")))] - let bmi2 = false; - #[cfg(all(target_arch = "x86_64", feature = "std"))] - // D5: the BMI2 bt-runtime twins are retired -- 291 instructions converting - // THREE BMI2 ops. `bmi2` is still read above for the specialisation guard - // this function keeps; only the twin selection goes. - let _ = bmi2; - let rt: BtFn = if SEARCH { bt_rt_search } else { bt_rt_insert }; - #[cfg(not(all(target_arch = "x86_64", feature = "std")))] - let rt: BtFn = if SEARCH { bt_rt_search } else { bt_rt_insert }; - if !bt_spec_enabled() { - return rt; - } - // W9: the (hash_log, chain_log) SPEC LIST IS BMI2-REDUNDANT. - // - // The spec copies exist to fold the hash shift and the chain mask to - // immediates. On the twins both are already free: `shrx` takes its count - // from any GPR, and the mask is one `and` whose operand costs the same in a - // register as in an immediate. `BtCtx` (brick 48's successor) already - // holds both in registers for the whole walk, so the runtime arm's operands - // are register-resident before the walk starts. - // - // The list was buying nothing on the twins and costing 40 monomorphisations - // of the search body plus 20 of the insert body. Byte-identical: the consts - // took the values the ctx fields already held. - #[cfg(all(target_arch = "x86_64", feature = "std"))] - if bmi2 { - return rt; - } - // W6: THE (hash_log, chain_log) SPECIALISATION IS RETIRED -- 20 copies of - // `bt_find_best_impl` (6,003 instructions) and 20 of `bt_ins_spec` (5,280) - // become zero, and every caller takes the runtime-generic `rt` above. - // - // The 2026-08-21 census proved all 20 pairs REACHABLE, and that is the - // wrong test -- HLOG's six values in `find_fast` were all reachable too - // (W4). The right test is what the consts BUY, and here they reach exactly - // two places: `HLOG` feeds `hash8`/`hash4` (a shift immediate) and `CLOG` - // feeds `btlog` -> `bt_mask` (an AND mask that is loop-invariant and sits - // in a register either way). On aarch64/wasm32 neither is worth anything - // -- register shifts and register ANDs cost what the immediate forms cost. - // On baseline x86 `shr %cl` is 1 uop. And BMI2 hosts never came here at - // all: the `if bmi2 { return rt }` above already sent them to `rt`. - // - // So this table only ever served pre-BMI2 x86 and the non-x86 targets, and - // charged them 11,283 instructions of I-cache to fold two immediates. - rt -} - -/// Safe `BtFn`-shaped wrapper for the BMI2 twin; `bt_resolve` hands this out -/// only after its own `has_bmi2()` check, once per block. -/// Insert-only twin of `bt_find_best_spec_bmi2`, returning `()` -- see -/// `BtInsFn`. -#[cfg(all(target_arch = "x86_64", feature = "std"))] -#[allow(dead_code)] -fn bt_ins_spec_bmi2( - ctx: &BtCtx, - ip: usize, - tables: &mut MatchTables, -) { - // SAFETY: only reachable through `bt_resolve_ins`'s CPUID guard. - #[allow(unsafe_code)] - unsafe { - bt_find_best_impl_bmi2::(ctx, ip, tables); - } -} - -fn bt_rt_ins_plain(ctx: &BtCtx, ip: usize, t: &mut MatchTables) { - bt_find_best_runtime(false, ctx, ip, t); -} - -#[cfg(all(target_arch = "x86_64", feature = "std"))] -#[allow(dead_code)] -fn bt_find_best_spec_bmi2( - ctx: &BtCtx, - ip: usize, - tables: &mut MatchTables, -) -> (usize, usize) { - // SAFETY: only reachable through `bt_resolve`'s CPUID guard. - #[allow(unsafe_code)] - unsafe { - bt_find_best_impl_bmi2::(ctx, ip, tables) - } -} - -#[cfg(all(target_arch = "x86_64", feature = "std"))] -#[target_feature(enable = "bmi2,lzcnt")] -#[allow(unsafe_code)] -#[inline(never)] -unsafe fn bt_find_best_impl_bmi2( - ctx: &BtCtx, - ip: usize, - tables: &mut MatchTables, -) -> (usize, usize) { - bt_find_best_impl_inner::(ctx, ip, tables) -} - -#[inline(always)] -fn bt_find_best_impl_inner( - ctx: &BtCtx, - ip: usize, - tables: &mut MatchTables, -) -> (usize, usize) { - let BtCtx { - src, - block_start, - block_end, - window, - mls, - attempts, - chain_log, - bt_lowest, - chain_len, - wide_hash, - } = *ctx; - debug_assert_eq!(wide_hash, mls >= 8); - debug_assert_eq!(chain_len, tables.chain.len()); - debug_assert_eq!( - bt_lowest, - block_start.saturating_sub(window).max(tables.frame_start) - ); - // Diagnostic ONLY -- gated. Unguarded this was one atomic read-modify-write - // per `bt_find_best` CALL, i.e. per POSITION across the whole L13-L22 - // ladder (~15.7M per level per corpus set). Same defect class as the two - // per-probe atomics removed from `fast_probe`, which were worth +6.97%. - // `take_bt_calls` therefore needs `--features rusty_zstd/profile`. - if cfg!(feature = "profile") { - BT_SPEC_CALLS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); - } - const fn btlog(c: u32) -> u32 { - let c = if c > 24 { 24 } else { c }; - let c = c.saturating_sub(1); - if c < 1 { - 1 - } else { - c - } - } - let _ = chain_log; - let bt_log = btlog(CLOG); - let bt_mask = (1usize << bt_log) - 1; - // T2: guard the WORST CASE, not this `ip`. - // - // The tree addresses `(x & bt_mask) << 1` and that `+ 1`, so the largest - // index it can ever form is `(bt_mask << 1) | 1` -- and `x` is `m`, a match - // position, not `ip`. The old pair of guards (`len < 2`, then `larger >= - // len` for this one `ip`) therefore bounded nothing inside the walk, which - // is why every `chain[..]` access needed its own bounds check. - // - // It also closes a real edge. `bt_log` comes from `CLOG`/`params.chain_log` - // rather than from the table, and `btlog` floors at 1, so `bt_mask >= 1` and - // the tree needs `chain.len() >= 4` -- with `chain_log = 1`, reachable - // through the advanced API, it addressed index 3 of a 2-entry table. - if (bt_mask << 1) | 1 >= chain_len { - return (0, 0); - } - // W6: `hash_mls`'s own `mls >= 8` test, answered per block instead. - // W50: `src.len()` hoisted. The shifts here are already free -- `HLOG` is - // a const generic, so both hashes fold their shift at compile time; the - // slice field read was the only per-position cost left on this line. - let spec_src_len = src.len(); - let h = if wide_hash && ip + 8 <= spec_src_len { - hash8(src, ip, HLOG) - } else { - hash4(load_u32le(src, ip), HLOG) - }; - // SPEC arm: `h < 2^HLOG` by the hash shift, and the resolve dispatch - // guarantees tables.hash_log == HLOG, so hash.len() == 1 << HLOG. - // `larger <= (bt_mask << 1) | 1` is the T2 entry guard's bound. Both - // per-call checks were provably dead here (the runtime arm keeps its - // own). - debug_assert!(h < tables.hash.len()); - let mut match_idx = tables.get_h(h); - tables.put_h(h, ip); - let mut smaller = (ip & bt_mask) << 1; - let mut larger = smaller + 1; - debug_assert!(larger < tables.chain.len()); - // Loop-INVARIANT, recomputed on every node of every walk: a saturating_sub, - // a max and a field load through `&mut MatchTables`, on a loop that runs - // ~30M times per level across the corpus. The `tables.chain[..]` writes in - // this same loop are what stop LLVM proving `frame_start` cannot change. - // W3: hoisted into `BtCtx` -- see its definition. - // Hoisted: the per-node window test `ip - m > window` is `m < ip - window` - // (m < ip is tested first), one cmp against a per-call constant instead - // of sub+cmp per node. - let win_low = ip.saturating_sub(window); - // W4: the single hot-path lower bound (see the walk's break). - let low = if win_low > bt_lowest { - win_low - } else { - bt_lowest - }; - // W1: the count head's only non-`m` precondition, hoisted out of the walk. - // See the head itself for why the other two tests are implied. - debug_assert!(block_end <= src.len()); - let head_ok = ip + 8 <= block_end; - // GATE 14 DISPATCH -- the chain-walk depth. - // - // 4.33's "82-84% of walks end by exhausting `attempts`" is REFUTED and this - // comment used to repeat it. That flag was set at the BOTTOM of the loop, so - // it measured "did at least one iteration", not "used all attempts". - // - // The walk is NOT depth-bound. Measured with `take_bt_iters` (walks, - // iterations, walks that consumed ALL attempts), 15 corpora at 512 KiB: - // - // L13 13.5% full depth, mean 6.8 iterations - // L19 2.9% full depth, mean 8.4 - // L22 2.6% full depth, mean 8.6 - // - // 97-98% of walks at L19/L22 end on their own guards, an order of magnitude - // under a 128- or 512-attempt budget. That is why raising the depth arm by - // +1 or +2 moves output on 0 of 18 corpora at L22: nothing wants more depth, - // and the probes live in the TAIL rather than at the cap. - // - // Priced at L19 (deterministic probe counts, 18 corpora): - // searchLog +1 +8.6% probes -0.002% size -- deeper buys nothing - // searchLog -1 -9.2% probes +0.001% size -- one step is nearly free - // searchLog -2 -16.9% probes +0.014% size - // - // One step shallower is free in aggregate and loses on exactly ONE corpus: - // versions-16m, +4.00%. That is the constant-stride content Gates 1, 2 and 6 - // all veto on `rep_yield`, and the same veto serves here -- a near-copy file - // needs the depth to walk past its many equal-prefix candidates. - // P0/gg-matchfind: work counter -- see `chain_find_best`. - const COUNT: bool = cfg!(feature = "profile"); - let mut probes = 0u64; - let mut best_ml = 0usize; - let mut best_m = 0usize; - let mut iters = 0u32; - for _ in 0..attempts { - iters += 1; - let Some(m) = match_idx else { - tables.chain_set(smaller, 0); - tables.chain_set(larger, 0); - break; - }; - // W4 RETRIED: the walk tested TWO lower bounds per node, and both were - // SPILLED -- two stack reloads and two compares on the hottest path in - // the Bt ladder. They collapse to one compare against their max, with - // the disambiguation moved into the break (taken once per walk). - // - // This was tried once before and REVERTED: it destabilised the - // register allocator and the node path came back at 60 instructions. - // The blocker was live-set pressure, and the prologue hoist above has - // since removed `chain_len` and `frame_start` from it -- so the trade - // is re-measured, not re-assumed. - if m >= ip || m < low { - if m >= ip || m < win_low { - tables.chain_set(smaller, 0); - tables.chain_set(larger, 0); - } - break; - } - // The T2 ENTRY guard already proves the worst case: - // bt_idx + 1 <= (bt_mask << 1) | 1 < chain.len(). The per-node - // re-check it replaced had survived it as a dead branch. - let bt_idx = (m & bt_mask) << 1; - debug_assert!(bt_idx + 1 < tables.chain.len()); - if COUNT { - probes += 1; - } - // GATE 8 ON THE Bt LADDER -- the gate is DEAD at L13-L22 (`pipe_enabled` - // has no caller there: find_fast 0 calls, find_opt 272), so this BUILDS - // the capability rather than tuning it. - // - // Both children of this node live at `bt_idx` and `bt_idx + 1` -- one - // cache line -- and NEITHER depends on `count_match`. In program order - // the descent load was issued only after `count_match` had walked `src`, - // so the chain miss serialised behind the src misses instead of - // overlapping them. `chain` is far larger than LLC at these levels, so - // that load misses on essentially every node. - // - // Applied to BOTH bt bodies -- keeping two hand-written copies in step - // is exactly what `find_dfast_runtime` failed to do until Gate 6 - // silently broke Gate 4's byte-identity. - let c_lo = tables.chain_at(bt_idx); - let c_hi = tables.chain_at(bt_idx + 1); - // REFUTED (2026-08-21): C's commonLengthSmaller/Larger floor - // (count from the BST-invariant shared prefix instead of 0). - // Corrupted the ROUNDTRIP on the first board: our tree tolerates - // stale and aliased structure (bt slots alias at chain_log-1, and - // the early breaks leave dangling subtree links) PRECISELY BECAUSE - // this count re-verifies every byte from 0. The floor inherits C's - // sort invariant only with C's full insert discipline; counting - // from it here emitted matches longer than the data. The from-zero - // count is load-bearing -- it is the tree's validity check. - // The count head OPEN-CODED (count_match_fast's shape) because the - // descent bytes ride in it: on a first-word mismatch, mb and ib are - // bytes OF the two words already in registers -- the separate - // `src.get(m + ml)` / `src.get(ip + ml)` loads and their two bounds - // branches vanish for that (majority) case. Value-exact: in the head - // case m + ml < m + 8 <= src.len(), so get() returns exactly the - // byte the word holds; the long path keeps the get()-based loads - // (bytes BEYOND block_end legitimately participate in routing). - // W1 GUARD COLLAPSE: the three-test head was two loop-INVARIANT - // tests plus one redundant one. `block_end <= src.len()` (it is a - // position in `src`) makes `ip + 8 <= src.len()` follow from - // `ip + 8 <= block_end`, and `m < ip` -- proven by the break above -- - // makes `m + 8 <= src.len()` follow too. What is left does not depend - // on `m`, so it leaves the loop entirely: `head_ok`, computed once - // per walk. - // - // W2 DIRECTION BY BSWAP: the descent needs the ORDER of the two byte - // strings, and `mb < ib` at the first differing byte IS lexicographic - // order -- which big-endian u64 comparison gives directly. Two - // `bswap`+`cmp` replace `and`+two `shrx`+`cmp`, and, more importantly, - // the branch no longer waits on `bsf`: direction and length are now - // INDEPENDENT chains instead of one serial dependency. - // - // W3 INSERT-ONLY LENGTH ELISION falls out of W2: with direction no - // longer derived from `ml`, the SEARCH = false copies (both fills and - // the priming pass -- 61.9% of all tree work at L13-L15) have no - // reader for the head path's `ml` at all, so the whole - // `bsf`/`shr` chain dead-codes away in those monomorphisations. - // - // Byte-identical on every path: same `ml` where `ml` is read, and the - // same direction bit. - let (ml, go_smaller) = if head_ok { - let a = load_u64le(src, m); - let b = load_u64le(src, ip); - if a != b { - ( - ((a ^ b).trailing_zeros() as usize) >> 3, - a.swap_bytes() < b.swap_bytes(), - ) - } else { - let ml = 8 + count_match_fast(src, m + 8, ip + 8, block_end); - let mb = src.get(m + ml).copied().unwrap_or(0); - let ib = src.get(ip + ml).copied().unwrap_or(0); - (ml, mb < ib) - } - } else { - let ml = count_match(src, m, ip, block_end); - let mb = src.get(m + ml).copied().unwrap_or(0); - let ib = src.get(ip + ml).copied().unwrap_or(0); - (ml, mb < ib) - }; - #[cfg(feature = "profile")] - { - BT_PROBE.fetch_add(1, core::sync::atomic::Ordering::Relaxed); - if ml < mls { - BT_SHORT.fetch_add(1, core::sync::atomic::Ordering::Relaxed); - } - if ml <= best_ml { - BT_NOGAIN.fetch_add(1, core::sync::atomic::Ordering::Relaxed); - } - } - // offset_ok and the frame_start floor are GUARANTEED by the node - // validity above (m >= win_low => ip - m <= window; m >= bt_lowest >= - // frame_start); re-checking per node was pure redundancy. - // - // INSERT-ONLY copies (SEARCH = false) serve the three callers that - // DISCARD the return -- both fills (61.9% of all tree work at - // L13-L15) and the priming pass. The descent and every tree write - // are identical (the bt walk has NO best_ml-dependent break), so - // skipping the tracking is byte-identical for a discarded result. - if SEARCH && ml >= mls && ml > best_ml { - best_ml = ml; - best_m = m; - } - if go_smaller { - tables.chain_set(smaller, m as u32); - // BYTE-IDENTICAL: if the store above targeted the slot we - // pre-loaded, forward the stored value by hand -- the original read - // happened AFTER the write and would have observed it. - let v = if smaller == bt_idx + 1 { - m as u32 - } else { - c_hi - }; - smaller = bt_idx + 1; - match_idx = if v == 0 { None } else { Some(v as usize) }; - } else { - tables.chain_set(larger, m as u32); - let v = if larger == bt_idx { m as u32 } else { c_lo }; - larger = bt_idx; - match_idx = if v == 0 { None } else { Some(v as usize) }; - } - // smaller/larger are bt_idx or bt_idx + 1: covered by the entry - // guard, same as above. - debug_assert!(smaller < tables.chain.len() && larger < tables.chain.len()); - } - // Consumers are the g14/btdepth gate harnesses only; unguarded this was - // THREE lock-prefixed RMWs per walk -- per POSITION across L13-L22 (the - // 959e0ae class, fourth sighting, in both bt bodies). - #[cfg(feature = "profile")] - { - use core::sync::atomic::Ordering::Relaxed; - BT_WALKS2.fetch_add(1, Relaxed); - BT_ITERS.fetch_add(iters as u64, Relaxed); - if iters as usize >= attempts { - BT_FULL.fetch_add(1, Relaxed); - } + { + let v = crate::env_knob_parse("RZSTD_BT_DEPTH").unwrap_or(1); + BT_DEPTH_STEPS_C.store(v, Relaxed); + v } - #[cfg(not(feature = "profile"))] - let _ = iters; - if COUNT { - crate::prof::note_probes(probes); + #[cfg(not(feature = "std"))] + 1 +} + +pub static BT_WALKS2: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +pub static BT_ITERS: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +pub static BT_FULL: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); + +/// `(walks, total_iterations, walks_that_used_ALL attempts)` +pub fn take_bt_iters() -> (u64, u64, u64) { + use core::sync::atomic::Ordering::Relaxed; + ( + BT_WALKS2.swap(0, Relaxed), + BT_ITERS.swap(0, Relaxed), + BT_FULL.swap(0, Relaxed), + ) +} + +fn search_attempts(params: CompressionParameters) -> usize { + let v = SEARCH_LOG_ARM.load(core::sync::atomic::Ordering::Relaxed); + let base = params.search_log.min(12) as i32; + let d = if v == 0 { 0 } else { v as i32 - 8 }; + 1usize << base.saturating_add(d).clamp(0, 12) +} + +// The `(hash_log, chain_log)` specialisation of the binary-tree walk is +// RETIRED. `bt_resolve` had returned the runtime body on every path since +// the spec copies were culled for I-cache density (6,003 + 5,280 +// instructions of monomorphs), but the pairs list, the dead `_spec` / +// `_impl` bodies, the `RZSTD_BT_SPEC` knob and a coverage test that asserted +// against the list all outlived the dispatch they described -- the test +// passed while selecting nothing. Brick 8 removed them together. + +/// The dispatch, RESOLVED ONCE PER BLOCK: `(hash_log, chain_log)` is +/// loop-invariant in every caller, yet `bt_find_best` re-ran a jump-table +/// dispatch (plus re-reading both fields) on every call -- per position, +/// per look-ahead, per fill insert and per DP edge. Callers hoist a fn +/// pointer instead; one predictable indirect call replaces the dance. +/// Same arms, same runtime fallback, same bt_spec parity gate. +/// The per-block-constant arguments of every bt call, packed: the fn +/// pointer previously re-marshaled NINE scalars per position, per +/// look-ahead step, per fill insert and per DP edge. +/// The per-block tree geometry: the node mask, and whether the tree fits the +/// chain table at all (BRICK 34). `bt_log` floors at 1, so the largest index +/// the walk can form is `(bt_mask << 1) | 1` -- the worst-case guard the +/// kernel used to re-derive on every call. +#[inline] +fn bt_geom(chain_log: u32, chain_len: usize) -> (usize, bool) { + let bt_log = chain_log.min(24).saturating_sub(1).max(1); + let bt_mask = (1usize << bt_log) - 1; + (bt_mask, ((bt_mask << 1) | 1) < chain_len) +} + +pub(crate) struct BtCtx<'a> { + src: &'a [u8], + /// BRICK 34: the tree geometry and both hash shifts, derived ONCE per + /// block instead of on every call -- and this kernel is called per + /// position, per look-ahead step and per fill insert, so its prologue + /// is the hottest per-call unit in the Bt ladder (123 instructions + /// against a 133-instruction walk loop). See `bt_geom`. + bt_mask: usize, + bt_shift32: u32, + bt_shift64: u32, + bt_ok: bool, + block_start: usize, + block_end: usize, + window: usize, + mls: usize, + attempts: usize, + chain_log: u32, + /// W1/W2/W3: three values the walk's PROLOGUE recomputed on every call -- + /// and this function is called per position, per look-ahead step AND per + /// fill insert (61.9% of all tree work at L13-L15), so "per call" is the + /// hottest unit in the Bt ladder. + /// + /// `bt_lowest` is `block_start.saturating_sub(window).max(frame_start)`: a + /// saturating sub, a max, and a struct load through `&mut MatchTables` + /// that LLVM must re-prove after every `chain` write. `chain_len` served + /// the entry guard, another struct load. Both are fixed for the block. + bt_lowest: usize, + chain_len: usize, + /// W6: `hash_mls`'s `mls >= 8` question, answered once per BLOCK. The walk + /// loaded `mls` from the context and compared it on EVERY call. Kept as a + /// flag rather than deleted: the advanced API can set `min_match` to 8, + /// which other guards in this file already respect, even though every + /// shipping Bt row uses 3..=5. + wide_hash: bool, +} + +type BtFn = for<'a> fn(&BtCtx<'a>, usize, &mut MatchTables) -> (usize, usize); + +/// The INSERT dispatch's own type. Insert callers discard the result -- both +/// fills and the priming pass -- but the `BtFn` signature forced every insert +/// trampoline to MATERIALISE one: the emitted wrapper built a 40-byte frame, +/// made a real call, then zeroed `rax`/`rdx` to return `(0, 0)`, on 61.9% of +/// all tree work at L13-L15. Returning `()` lets the same wrapper compile to +/// a bare tail `jmp`, which is what the SEARCH side already gets. +type BtInsFn = for<'a> fn(&BtCtx<'a>, usize, &mut MatchTables); + +fn bt_rt_search(ctx: &BtCtx, ip: usize, t: &mut MatchTables) -> (usize, usize) { + bt_find_best_runtime(true, ctx, ip, t) +} + +fn bt_rt_insert(ctx: &BtCtx, ip: usize, t: &mut MatchTables) -> (usize, usize) { + bt_find_best_runtime(false, ctx, ip, t) +} + +/// `bt_resolve` for the insert side -- same table, `BtInsFn` shape. +fn bt_resolve_ins(_hash_log: u32, _chain_log: u32) -> BtInsFn { + // Runtime insert only -- see `bt_resolve`. + bt_rt_ins_plain +} +fn bt_resolve(_hash_log: u32, _chain_log: u32) -> BtFn { + // Runtime body only; the specialisation and its BMI2 twins are retired + // (see the note where `BT_SPEC_PAIRS` used to live). The two parameters + // are kept so the call sites read as the dispatch they once were. + if SEARCH { + bt_rt_search + } else { + bt_rt_insert } - (best_m, best_ml) +} + +fn bt_rt_ins_plain(ctx: &BtCtx, ip: usize, t: &mut MatchTables) { + bt_find_best_runtime(false, ctx, ip, t); } #[inline(never)] @@ -12159,6 +12703,10 @@ fn bt_find_best_runtime_inner( bt_lowest, chain_len, wide_hash, + bt_mask, + bt_shift32, + bt_shift64, + bt_ok, } = *ctx; debug_assert_eq!(wide_hash, mls >= 8); debug_assert_eq!(chain_len, tables.chain.len()); @@ -12174,37 +12722,32 @@ fn bt_find_best_runtime_inner( if cfg!(feature = "profile") { BT_RUNTIME_CALLS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); } - let hash_log = tables.hash_log; - let bt_log = chain_log.min(24).saturating_sub(1).max(1); - let bt_mask = (1usize << bt_log) - 1; - // T2: guard the WORST CASE, not this `ip`. - // - // The tree addresses `(x & bt_mask) << 1` and that `+ 1`, so the largest - // index it can ever form is `(bt_mask << 1) | 1` -- and `x` is `m`, a match - // position, not `ip`. The old pair of guards (`len < 2`, then `larger >= - // len` for this one `ip`) therefore bounded nothing inside the walk, which - // is why every `chain[..]` access needed its own bounds check. - // - // It also closes a real edge. `bt_log` comes from `CLOG`/`params.chain_log` - // rather than from the table, and `btlog` floors at 1, so `bt_mask >= 1` and - // the tree needs `chain.len() >= 4` -- with `chain_log = 1`, reachable - // through the advanced API, it addressed index 3 of a 2-entry table. - if (bt_mask << 1) | 1 >= chain_len { + // BRICK 34: the geometry and both shifts are BLOCK constants, built once + // in `BtCtx` (see `bt_geom`). They were derived on every call, and the + // call count here is per position + per look-ahead + per fill insert. + // The assertions restate the derivations the context now owns; the + // worst-case guard (`bt_log` floors at 1, so `chain.len() >= 4`) is + // `bt_ok`, and it still closes the `chain_log = 1` edge the advanced API + // can reach. + debug_assert_eq!( + (bt_mask, bt_ok), + bt_geom(chain_log, chain_len), + "BtCtx geometry disagrees with its own chain_log/chain_len" + ); + debug_assert_eq!(bt_shift32, 32u32.saturating_sub(tables.hash_log.min(32))); + debug_assert_eq!(bt_shift64, 64u32.saturating_sub(tables.hash_log.min(32))); + let _ = chain_log; + if !bt_ok { return (0, 0); } - // W6: see the spec impl. - // W46: the SPEC impl gets both shifts folded for free -- it hashes with the - // `HLOG` const generic. The RUNTIME twin, which is the arm that actually - // executes whenever the (hash_log, chain_log) pair is off the spec list, - // re-derived `min` + `saturating_sub` on every searched position. // W47: `src.len()` is a slice field re-read on the same line. let bt_src_len = src.len(); - let bt_shift32 = 32u32.saturating_sub(hash_log.min(32)); - let h = if wide_hash && ip + 8 <= bt_src_len { - hash8_shift(src, ip, 64u32.saturating_sub(hash_log.min(32))) - } else { - hash4_shift(load_u32le(src, ip), bt_shift32) - }; + // BRICK 99 (K18): no 8-byte-hash arm -- `mls >= 8` is outside the contract + // (the three `BtCtx` builders clamp it), so the flag test, the add and the + // compare against `src_len` ran on every call for a case that cannot arrive. + debug_assert!(!wide_hash); + let _ = (bt_shift64, bt_src_len); + let h = hash4_shift(load_u32le(src, ip), bt_shift32); if h >= tables.hash.len() { return (0, 0); } @@ -12313,8 +12856,9 @@ fn bt_find_best_runtime_inner( // Applied to BOTH bt bodies -- keeping two hand-written copies in step // is exactly what `find_dfast_runtime` failed to do until Gate 6 // silently broke Gate 4's byte-identity. - let c_lo = tables.chain_at(bt_idx); - let c_hi = tables.chain_at(bt_idx + 1); + // BRICK 27: the children are read AFTER the write below, one per node + // (see the `go_smaller` arms). The eager pair that lived here spilled + // both words to the stack and reloaded them on the same path. // REFUTED (2026-08-21): C's commonLengthSmaller/Larger floor // (count from the BST-invariant shared prefix instead of 0). // Corrupted the ROUNDTRIP on the first board: our tree tolerates @@ -12394,19 +12938,16 @@ fn bt_find_best_runtime_inner( } if go_smaller { tables.chain_set(smaller, m as u32); - // BYTE-IDENTICAL: if the store above targeted the slot we - // pre-loaded, forward the stored value by hand -- the original read - // happened AFTER the write and would have observed it. - let v = if smaller == bt_idx + 1 { - m as u32 - } else { - c_hi - }; + // BYTE-IDENTICAL (BRICK 27): read after the write. If the store + // above targeted this slot the read returns `m` -- exactly what the + // forwarding compare used to select -- and the untouched word + // otherwise; nothing else writes the tree between the two. + let v = tables.chain_at(bt_idx + 1); smaller = bt_idx + 1; match_idx = if v == 0 { None } else { Some(v as usize) }; } else { tables.chain_set(larger, m as u32); - let v = if larger == bt_idx { m as u32 } else { c_lo }; + let v = tables.chain_at(bt_idx); larger = bt_idx; match_idx = if v == 0 { None } else { Some(v as usize) }; } @@ -12447,7 +12988,9 @@ fn find_bt_lazy( depth: usize, reps: [u32; 3], ) -> (Vec, Vec) { - let mls = params.min_match.max(3) as usize; + // BRICK 99 (K18): the contract's bound (brick 35) -- `wide_hash` below is + // then provably false and the tree kernel's 8-byte-hash arm is gone. + let mls = params.min_match.clamp(3, 7) as usize; // GATE 6 family, fourth instance: take the finder buffers from the FRAME. // // `find_fast_impl` was wired to `MatchTables::seq_scratch`/`lit_scratch` @@ -12464,7 +13007,8 @@ fn find_bt_lazy( // Scratch + the too-short-block exit, ONE copy for Greedy/Lazy/BtLazy and // their bmi2 twins -- six stamps of the identical idiom become one call // (the `fast_finder_prologue` treatment, chain-finder variant). - let (mut seqs, mut lits) = match chain_finder_prologue(src, block_start, block_end, tables) { + let (mut seqs, mut lits) = match chain_finder_prologue(src, block_start, block_end, tables, mls) + { Ok(t) => t, Err(out) => return out, }; @@ -12473,14 +13017,7 @@ fn find_bt_lazy( // W8: GATE 6 for BtLazy2 -- every other finder takes its output buffers // from the frame WITH A RESERVE; this one grew them by repeated `realloc` // with LIVE contents, so every growth is a real memcpy. - let block_len = block_end - block_start; - if lits.capacity() < block_len + LIT_PUSH_WIDTH_MAX { - lits = Vec::with_capacity(block_len + LIT_PUSH_WIDTH_MAX); - } - let seq_guess = (tables.last_nseq + tables.last_nseq / 4 + 64).min(block_len / mls + 16); - if seqs.capacity() < seq_guess { - seqs = Vec::with_capacity(seq_guess); - } + // (reserve moved into `chain_finder_prologue`) // W9: GATE 13 for BtLazy2. `push_lits_range` appends through a // runtime-length `extend_from_slice`; `push_literals` takes the // fixed-width `copy_nonoverlapping` path when the run fits and the spare @@ -12516,6 +13053,8 @@ fn find_bt_lazy( // repcode's. One value now, and the two cannot drift apart. let fstart_c = tables.frame_start; let lowest_rep = block_start.saturating_sub(window).max(fstart_c); + // BRICK 34: the block's tree geometry, once. + let (bt_mask, bt_ok) = bt_geom(clog, tables.chain.len()); let bt_ctx = BtCtx { src, block_start, @@ -12527,6 +13066,10 @@ fn find_bt_lazy( bt_lowest: lowest_rep, chain_len: tables.chain.len(), wide_hash: mls >= 8, + bt_mask, + bt_shift32: 32u32.saturating_sub(tables.hash_log.min(32)), + bt_shift64: 64u32.saturating_sub(tables.hash_log.min(32)), + bt_ok, }; let gain_cmp = lazy_gain_enabled_bt(); let fill_on = lazy_fill_enabled(); @@ -12535,6 +13078,9 @@ fn find_bt_lazy( let mut rep1 = reps[0] as usize; let mut rep_hits = 0u64; let mut ip = block_start; + // Hoisted per BLOCK: an atomic load per position would cost more + // than the positions it skips. + let accel_sh = lazy_step_shift(lazy_accel()); while ip <= ilimit { if use_rep { if let Some(ml) = try_rep1(src, ip, rep1, lowest_rep, block_end, ilimit) { @@ -12659,7 +13205,8 @@ fn find_bt_lazy( ip = end; anchor = ip; } else { - ip += 1; + // C: `ip += ((ip-anchor) >> kSearchStrength) + 1`. + ip += lazy_step(ip, anchor, accel_sh); } } tables.rep_yield = if seqs.is_empty() { @@ -12708,10 +13255,7 @@ fn opt_lit_cost(tables: &MatchTables) -> u32 { const NO_OVERRIDE: u32 = u32::MAX - 1; let mut e = OPT_LIT_ARM.load(Ordering::Relaxed); if e == UNCHECKED { - e = std::env::var("RZSTD_OPT_LIT") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(NO_OVERRIDE); + e = crate::env_knob_parse("RZSTD_OPT_LIT").unwrap_or(NO_OVERRIDE); OPT_LIT_ARM.store(e, Ordering::Relaxed); } if e != NO_OVERRIDE { @@ -12778,10 +13322,7 @@ fn opt_rep_min() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_OPT_REP_MIN") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(50.0); + let v: f32 = crate::env_knob_parse("RZSTD_OPT_REP_MIN").unwrap_or(50.0); OPT_REP_MIN_C.store(v.to_bits(), Ordering::Relaxed); v } @@ -12868,9 +13409,7 @@ fn opt_fill_enabled() -> bool { if c != 0 { return c == 2; } - let v = std::env::var("RZSTD_OPT_FILL") - .map(|v| v.trim() != "0") - .unwrap_or(true); + let v = crate::env_knob_not0("RZSTD_OPT_FILL", true); OPT_FILL_C.store(if v { 2 } else { 1 }, Ordering::Relaxed); v } @@ -12892,10 +13431,7 @@ fn opt_fill_rep_max() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_OPT_FILL_REP") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(50.0); + let v: f32 = crate::env_knob_parse("RZSTD_OPT_FILL_REP").unwrap_or(50.0); OPT_FILL_REP_C.store(v.to_bits(), Ordering::Relaxed); v } @@ -12916,10 +13452,7 @@ fn opt_fill_max() -> usize { } #[cfg(feature = "std")] { - std::env::var("RZSTD_OPT_FILL_MAX") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(usize::MAX) + crate::env_knob_parse("RZSTD_OPT_FILL_MAX").unwrap_or(usize::MAX) } #[cfg(not(feature = "std"))] usize::MAX @@ -12952,17 +13485,9 @@ pub fn take_opt_fill_ins() -> u64 { /// GATE 12 @ L19 defect arm: `false` restores the per-jump `std::env::var` /// lookups the back-fill guard used to perform inside the DP loop, so the fix /// can be A/B'd in one process instead of across two binaries. -static OPT_HOIST_ARM: core::sync::atomic::AtomicU8 = core::sync::atomic::AtomicU8::new(0); - -/// Bench hook: `false` reads the four back-fill knobs per jumped position again. -pub fn set_opt_hoist_arm(hoisted: bool) { - OPT_HOIST_ARM.store(u8::from(hoisted) + 1, core::sync::atomic::Ordering::Relaxed); -} - -#[inline] -fn opt_hoisted() -> bool { - OPT_HOIST_ARM.load(core::sync::atomic::Ordering::Relaxed) != 1 -} +/// Bench hook, now a NO-OP (BRICK 17): the per-jump re-read arm it selected +/// was retired from `find_opt`'s DP loop. Kept so the arm tables link. +pub fn set_opt_hoist_arm(_hoisted: bool) {} fn opt_fill_stride() -> usize { #[cfg(feature = "profile")] @@ -12973,9 +13498,7 @@ fn opt_fill_stride() -> usize { } #[cfg(feature = "std")] { - std::env::var("RZSTD_OPT_FILL_S") - .ok() - .and_then(|v| v.trim().parse().ok()) + crate::env_knob_parse("RZSTD_OPT_FILL_S") .filter(|v| *v >= 1) .unwrap_or(1) } @@ -13009,7 +13532,9 @@ fn find_opt( #[cfg(feature = "profile")] OPT_CALLS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); let n = block_end - block_start; - let mls = params.min_match.max(3) as usize; + // BRICK 99 (K18): the contract's bound (brick 35) -- `wide_hash` below is + // then provably false and the tree kernel's 8-byte-hash arm is gone. + let mls = params.min_match.clamp(3, 7) as usize; if n < 8 { return (Vec::new(), src[block_start..block_end].to_vec()); } @@ -13063,6 +13588,8 @@ fn find_opt( let clog = params.chain_log.min(24); let btf = bt_resolve::(tables.hash_log, clog); let btf_ins = bt_resolve_ins(tables.hash_log, clog); + // BRICK 34: the block's tree geometry, once. + let (bt_mask, bt_ok) = bt_geom(clog, tables.chain.len()); let bt_ctx = BtCtx { src, block_start, @@ -13074,6 +13601,10 @@ fn find_opt( bt_lowest: block_start.saturating_sub(window).max(tables.frame_start), chain_len: tables.chain.len(), wide_hash: mls >= 8, + bt_mask, + bt_shift32: 32u32.saturating_sub(tables.hash_log.min(32)), + bt_shift64: 64u32.saturating_sub(tables.hash_log.min(32)), + bt_ok, }; let extra = match params.strategy { Strategy::BtUltra2 => 2u32, @@ -13171,9 +13702,7 @@ fn find_opt( // (an lzcnt, a sub and two cmovs) never enters the loop's dependency // chain. One compare replaces compare + compare + cmov. let mlb_over = if mlb_on { 34usize } else { usize::MAX }; - // Per-JUMP arm read hoisted (the OFF arm's deliberate env re-reads stay - // inside; only the selector atomic moves). - let hoisted_arm = opt_hoisted(); + // (The per-jump re-read arm and its selector were retired in BRICK 17.) while i < n { // T2/T4 SAFETY, for the literal edge below -- the ONLY part of this loop // that runs at EVERY position. @@ -13410,39 +13939,26 @@ fn find_opt( // only seen the 0. // The OFF arm re-reads the environment here, per jumped position, // exactly as the shipped code did before the hoist. - let hoisted = hoisted_arm; - let (g_on, g_rep) = if hoisted { - (fill_on, fill_rep_max) - } else { - (opt_fill_enabled(), opt_fill_rep_max()) - }; + // BRICK 17: the four knobs are block constants, read once above. + // The OFF arm that re-read them per jumped position (an A/B hook + // for GATE 12's hoist) is retired: with `hoisted_arm` a runtime + // bool the DP loop carried BOTH arms -- nine rip-relative static + // loads and four selector tests per jump, on the shipping path + // that never took them. `set_opt_hoist_arm` is a no-op now. // W9: `opt_rep_meas` and `opt_rep_peak` are per-BLOCK signals, but // they were read from the struct on every JUMP -- and on // match-dense content the DP jumps constantly. Hoisted for the // shipped (hoisted) arm; the measurement arm keeps its deliberate // per-jump re-reads. - let gate_ok = if hoisted { - fill_gate_hoisted - } else { - g_on && tables.opt_rep_meas >= 2 && tables.opt_rep_peak < g_rep - }; - if gate_ok { - let step = if hoisted { - fill_step - } else { - opt_fill_stride() - }; + if fill_gate_hoisted { + let step = fill_step; // Cap the span. text-32m and versions-16m hold 93% of ALL jumped // positions (3.58M of 3.85M) and contribute -15 and +54 bytes; // dickens, samba, nci, ooffice and xml hold 6% and contribute // -381. An enormous jump means one huge repeat, and filling its // interior buys nothing -- those positions are reachable through // the repeat itself. - let span = bml.min(if hoisted { - fill_span_max - } else { - opt_fill_max() - }); + let span = bml.min(fill_span_max); // W14: the fill walked POSITIONS but addressed BYTES, so each // inserted position paid `block_start + q` and `qp + 8 > // block_end` -- two adds and a compare for a walk whose stride @@ -13754,6 +14270,9 @@ fn find_opt( /// byte mismatch is just a hash collision, and C's `ZSTD_HcFindBestMatch` /// steps past it to the next link. Our walk broke on it, amputating the /// remaining chain at the first collision. +// Since BRICK 11 the walks use `mls_xor`; the boolean form serves only the +// profile-build census sites. +#[cfg_attr(not(feature = "profile"), allow(dead_code))] #[inline(always)] fn mls_eq(src: &[u8], m: usize, ip: usize, mls: usize, smask: u64) -> bool { // The census found the tail slice-eq compiled to a LIBC MEMCMP CALL per @@ -13775,12 +14294,103 @@ fn mls_eq(src: &[u8], m: usize, ip: usize, mls: usize, smask: u64) -> bool { ); return (load_u64le(src, m) ^ load_u64le(src, ip)) & smask == 0; } + mls_eq_wide(src, m, ip, mls) +} + +/// The `mls > 8` arm of `mls_eq`, OUTLINED AND COLD. +/// +/// No shipping row has `min_match` above 7 (the tables pin 3..=7; only the +/// advanced API can ask for 8+), so this arm never runs in production -- yet +/// it was inlined into every walk that calls `mls_eq`: the greedy walk, the +/// chain walk and the row walk, six call sites. Each copy carried a slice +/// construction, TWO bounds-check guards (the `src[m + 4..m + mls]` slicing, +/// encode.rs:14004 by the panic-Location census) and a `call memcmp`, sitting +/// in the hot walk's cache lines. That is where every one of `find_greedy`'s +/// guard branches lived, and the only `memcmp` in the matchfind symbols. +/// +/// Deterministic verdict: guards on the walk paths 6 -> 0, `memcmp` sites +/// 6 -> 1, byte-identical by construction (same predicate, same bytes). +#[cfg_attr(not(feature = "profile"), allow(dead_code))] +#[cold] +#[inline(never)] +fn mls_eq_wide(src: &[u8], m: usize, ip: usize, mls: usize) -> bool { if load_u32le(src, m) != load_u32le(src, ip) { return false; } src[m + 4..m + mls] == src[ip + 4..ip + mls] } +/// `mls_eq` that RETURNS THE XOR it computed (BRICK 11) -- the fused head +/// that `fast_probe_wide` has had since W2 and the chain walks never got. +/// +/// The walks tested `(load8(m) ^ load8(ip)) & smask == 0`, threw the xor +/// away, and then `count_match_fast(m + mls, ip + mls)` LOADED BOTH WORDS +/// AGAIN and xor'd them again to find the first differing byte. But when the +/// first xor is non-zero, its lowest set byte IS the match length: bytes +/// below `mls` are equal by the mask, so the difference sits at index +/// `>= mls`, and every walk holds `ip <= ilimit = block_end - 8`, so that +/// index is inside the block without a clamp. Only a zero xor -- all eight +/// bytes equal -- needs the counter, and it can start at 8. Identical to +/// `mls + count_match_fast(src, m + mls, ip + mls, block_end)` on every arm. +/// +/// BRICK 35 (K1) removed the wide (`mls > 8`) arm: the chain-ladder finders +/// bound `mls` to the 3..=7 contract at their derivation, so the arm select +/// was a compare and a branch per examined candidate for a case that cannot +/// arrive. +#[inline(always)] +fn mls_xor(src: &[u8], m: usize, ip: usize, mls: usize, smask: u64) -> Option { + // BRICK 35 (K1): no wide arm. Every caller derives `mls` through the + // finders' `clamp(3, 7)`, so `mls <= 8` is not a per-candidate question; + // the `mls_eq_wide` route stays available to the profile census's + // `mls_eq` only. + debug_assert!(mls <= 8, "mls_xor: min_match above the 3..=7 contract"); + debug_assert!(m < ip && ip + 8 <= src.len()); + let x = load_u64le(src, m) ^ load_u64le(src, ip); + if x & smask == 0 { + Some(x) + } else { + None + } +} + +/// BRICK 56 (K7): `fused_ml`'s long continuation (`x == 0`, the first eight +/// bytes matched), OUTLINED behind the walk context so the chain walk's +/// loop carries nothing for it -- `ip + 8` and `ip + 16` were hoisted call +/// arguments, spilled at every kernel entry, in a loop already one register +/// short. Called on `FUSED_LONG` only (~0.04 per byte at L9). +#[inline(never)] +fn walk_count8(ctx: &ChainCtx, m: usize, ip: usize) -> usize { + #[cfg(feature = "profile")] + FUSED_LONG.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + 8 + count_match_fast(ctx.src, m + 8, ip + 8, ctx.block_end) +} + +/// The length that goes with `mls_xor`'s `Some(x)`. +#[inline(always)] +fn fused_ml(x: u64, src: &[u8], m: usize, ip: usize, block_end: usize) -> usize { + if x != 0 { + #[cfg(feature = "profile")] + FUSED_SHORT.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + (x.trailing_zeros() as usize) >> 3 + } else { + #[cfg(feature = "profile")] + FUSED_LONG.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + 8 + count_match_fast(src, m + 8, ip + 8, block_end) + } +} + +#[cfg(feature = "profile")] +static FUSED_SHORT: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +#[cfg(feature = "profile")] +static FUSED_LONG: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); + +/// (short, long) fused-head resolutions since the last call -- BRICK 11's verdict. +#[cfg(feature = "profile")] +pub fn take_fused() -> (u64, u64) { + use core::sync::atomic::Ordering::Relaxed; + (FUSED_SHORT.swap(0, Relaxed), FUSED_LONG.swap(0, Relaxed)) +} + /// WALK-CONTINUE arm: C-parity chain walk (step past byte mismatches). /// Byte-CHANGING (finds matches the amputated walk missed), so it ships on /// the adjudication board in `chainwalk`, not on byte-identity. @@ -13890,10 +14500,7 @@ fn walk_first_max(attempts: usize) -> f32 { // `set_walk_first_max_arm` does -- the `attempts` scaling is what the // unset path provides. if WALK_FIRST_ENV.swap(1, Relaxed) == 0 { - if let Some(v) = crate::env_knob("RZSTD_WALK_FIRST_MAX") - .ok() - .and_then(|s| s.parse::().ok()) - { + if let Some(v) = crate::env_knob_parse::("RZSTD_WALK_FIRST_MAX") { WALK_FIRST_ARM.store(v.to_bits(), Relaxed); return v; } @@ -13995,16 +14602,69 @@ static CHAIN_TAG_ARM: core::sync::atomic::AtomicU8 = core::sync::atomic::AtomicU /// Only the LAZY ladder is wired: `find_greedy_impl` carries its own hand-copied /// walk rather than going through `ChainFn`. Lazy is where the loads are anyway /// -- 139M at L7, 221M at L9, 674M at L12, against greedy's 43M at L5. +/// Restore the row arm to AUTO (the shipped default): size-gated by +/// `row_auto_ok`. `set_row_arm` FORCES and cannot express this, which is what +/// made a single-process arm board impossible to baseline correctly. +pub fn set_row_arm_auto() { + ROW_ARM.store(0, core::sync::atomic::Ordering::Relaxed); +} + pub fn set_row_arm(on: bool) { ROW_ARM.store( if on { 2 } else { 1 }, core::sync::atomic::Ordering::Relaxed, ); } -static ROW_ARM: core::sync::atomic::AtomicU8 = core::sync::atomic::AtomicU8::new(1); +/// 0 = AUTO (size-gated, see `row_auto_ok`), 1 = forced off, 2 = forced on. +static ROW_ARM: core::sync::atomic::AtomicU8 = core::sync::atomic::AtomicU8::new(0); #[inline(always)] pub(crate) fn row_find_enabled() -> bool { - ROW_ARM.load(core::sync::atomic::Ordering::Relaxed) == 2 + // AUTO and forced-on both permit; the ALLOCATION decides for AUTO, and + // `use_rows` is this AND `!rows.head.is_empty()`, so an unallocated + // table keeps the chain regardless. + ROW_ARM.load(core::sync::atomic::Ordering::Relaxed) != 1 +} + +/// The measured AUTO band for the row match finder. +/// +/// A row holds the last 16 positions for its bucket where the chain held +/// all of them, trading DEPTH for RECENCY -- and recent means SMALL +/// OFFSETS, which cost fewer bits. While the window is not yet full the row +/// gives up almost no depth and banks the offset saving; once the chain is +/// deep it finds matches the row cannot. So the verdict is monotone in +/// SOURCE LENGTH, and `rowcross.rs` measures the crossover (14 corpora, +/// every cell round-tripped): +/// +/// ```text +/// L9 256K 1.0059 | 512K 0.9882 | 1M 0.9882 | 2M 0.9894 | 4M 0.9944 | 6M 1.0018 +/// L7 256K 1.0078 | 512K 0.9866 | 1M 0.9880 | 2M 0.9895 | 4M 0.9936 | 6M 1.0002 +/// L12 --- | 512K 0.9959 | 1M 0.9968 | 2M 0.9992 | 4M 1.0070 | 6M 1.0163 +/// ``` +/// +/// 512 KiB..2 MiB is the band that wins at EVERY level measured, so that is +/// the band taken; 4 MiB would still pay at L7/L9 but costs at L12, and the +/// strategy enum cannot separate L9 from L12. Below 512 KiB the row loses +/// (the chain is shallow there too, so recency buys nothing). +/// +/// In the band this is a DOUBLE win: 1.1-1.3% smaller AND 2.5-8.5x fewer +/// dependent loads (`ROW_LOADS` vs `WALK_EXAM`). +/// +/// NOT content-dispatched: literal share, mean match length and +/// sequences/KiB were each tested against the per-corpus win/loss split and +/// all three OVERLAP, so no content threshold separates them (`rowsig.rs`). +const ROW_AUTO_MIN: u64 = 512 << 10; +const ROW_AUTO_MAX: u64 = 2 << 20; + +#[inline] +fn row_auto_ok(params: CompressionParameters, src_len: Option) -> bool { + match ROW_ARM.load(core::sync::atomic::Ordering::Relaxed) { + 1 => false, + 2 => true, + _ => { + matches!(params.strategy, Strategy::Lazy | Strategy::Lazy2) + && matches!(src_len, Some(n) if (ROW_AUTO_MIN..=ROW_AUTO_MAX).contains(&n)) + } + } } /// WIDE-CHAIN LATCH census: `[events, positions_rescanned]`. The latch does a /// full O(window) chain rebuild when it fires; this is what that costs. @@ -14108,9 +14768,7 @@ pub(crate) fn dfast_bext_enabled() -> bool { 1 => false, 2 => true, _ => { - let on = crate::env_knob("RZSTD_DFAST_BEXT") - .map(|v| v != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_DFAST_BEXT", true); DFAST_BEXT_ARM.store(if on { 2 } else { 1 }, Relaxed); on } @@ -14185,18 +14843,65 @@ fn dfast_hash_pair( let hv4 = (v as u32).wrapping_mul(HASH4_PRIME); let tv = (v & smask).wrapping_mul(FAST_HASH_PRIME64); let h8 = (v.wrapping_mul(0xCF1B_BCDC_B7A5_6463) >> lshift) as usize; - ((hv4 >> dtag_shift) as usize, (tv ^ (tv >> 29)) as u8, h8) + ((hv4 >> dtag_shift) as usize, (tv >> 56) as u8, h8) // BRICK 52: see `hash4_tag_from` +} + +/// BRICK 100 (F9): the chain ladder's link tag is the LAST BYTE of the +/// `mls`-byte gram, `src[pos + mls - 1]`. +/// +/// Sound: an accept needs the first `mls` bytes equal, so a tag mismatch +/// can only reject what the compare would reject (`taggate`'s argument, +/// unchanged). What it filters: chain buckets are keyed by the 4-byte gram, +/// so the mates a walk meets mostly SHARE those 4 bytes and die at byte +/// `mls` (the census that chose the mls-width product tag over the 4-byte +/// one: 2.4M of L12's 169M bytemiss steps caught by 4 bytes, 1.4%) -- and +/// THIS tag is that byte, so it rejects every one of them where the +/// product's top byte rejected 255 in 256. The producer is one byte load +/// and one shift into the head word instead of a mask, a 64-bit multiply +/// and a shift-and-mask; the walk's goal tag loses the same three per call. +/// +/// Contract: every caller holds `pos + 8 <= src.len()` (the fill's +/// `ilimit`, the walk's brick-49 invariant, the primer's and the wide +/// re-insert's own guards) and `mls <= 7` (brick 35's clamp; the wide +/// latch returns on `mls >= 8`). +#[inline(always)] +#[allow(unsafe_code)] +fn link_tag(src: &[u8], pos: usize, mls: usize) -> u8 { + debug_assert!((3..=8).contains(&mls) && pos + mls <= src.len()); + // SAFETY: the contract above -- `pos + mls - 1 < pos + 8 <= src.len()`. + unsafe { *src.get_unchecked(pos + mls - 1) } +} + +/// hash4 index + the lazy ladder's link tag (BRICK 100: `link_tag`). Index +/// bit-identical to `hash4`; `hash_shift` arrives resolved. +#[inline(always)] +fn hash4_link_tag_b(src: &[u8], pos: usize, hash_shift: u32, mls: usize) -> (usize, u8) { + ( + hash4_shift(load_u32le(src, pos), hash_shift), + link_tag(src, pos, mls), + ) +} + +/// `link_tag` from the little-endian word at `pos`: byte `mls - 1` of `v`. +/// The WALK takes its goal tag this way (BRICK 100b): `mls_xor` hoists +/// `load_u64le(src, ip)` for the first-word compare, and deriving the tag +/// from that same word keeps it ONE frame-resident value -- with a +/// separate byte load LLVM rematerialised the goal word on every candidate +/// (a load and a copy: dominant path 28 -> 29 / 25 -> 27). For the +/// const-MLS kernels the shift is a constant. +#[inline(always)] +fn link_tag_from(v: u64, mls: usize) -> u8 { + debug_assert!((3..=8).contains(&mls)); + (v >> (8 * (mls - 1))) as u8 } -/// hash4 index + the lazy ladder's link tag. The tag is MLS-WIDTH -/// (`hash4_tag_mls`), not 4-byte: chain buckets are keyed by the 4-byte -/// gram, so colliding candidates mostly SHARE those 4 bytes and die at byte -/// 5 -- the short table's structure, not the long table's. Measured with the -/// 4-byte tag first: only 2.4M of L12's 169M bytemiss steps caught (1.4%); -/// the byte-5 class is the whole game here. Index bit-identical to `hash4`. +/// `hash4_link_tag_b` for the walk: index and tag from one u64 load, the +/// word `mls_xor` compares with (see `link_tag_from`). #[inline(always)] -fn hash4_link_tag(src: &[u8], pos: usize, hash_log: u32, smask: u64) -> (usize, u8) { - hash4_tag_mls(src, pos, 32u32.saturating_sub(hash_log.min(32)), smask) +fn hash4_link_tag_w(src: &[u8], pos: usize, hash_shift: u32, mls: usize) -> (usize, u8) { + let v = load_u64le(src, pos); + debug_assert_eq!(link_tag_from(v, mls), link_tag(src, pos, mls)); + (hash4_shift(v as u32, hash_shift), link_tag_from(v, mls)) } /// WIDE-CHAIN arm: key the lazy ladder's buckets on the mls-byte gram @@ -14314,8 +15019,11 @@ fn maybe_latch_wide_chain( WIDE_LATCH[1].fetch_add(to.saturating_sub(from) as u64, Relaxed); } let mut p = from; + // BRICK 74: the links re-inserted below carry the WIDE producer's null tag. + tables.set_null_tag(chain_null_tag(src, mls)); + let wshift = 64u32.saturating_sub(hash_log.min(32)); while p <= to && p + 8 <= src.len() { - let (h, g) = hash_wide_link_tag(src, p, hash_log, smask); + let (h, g) = hash_wide_link_tag_b(src, p, wshift, smask, mls); // FULL insert, not heads-only: heads-only reseeding left every // wide bucket one deep with stale narrow-epoch links below it -- // the latched frame walked chains of length ~1 over its whole @@ -14327,20 +15035,26 @@ fn maybe_latch_wide_chain( tables.chain_wide = true; } -/// Wide bucket key + tag from one u64 load and ONE multiply (tag and index -/// take disjoint bit ranges of the same product, the fast-hash shape). +/// Wide bucket key from one u64 load and one multiply, with the ladder's +/// link tag (BRICK 100: `link_tag`); `shift` arrives resolved (W22). #[inline(always)] -fn hash_wide_link_tag(src: &[u8], pos: usize, hash_log: u32, smask: u64) -> (usize, u8) { - hash_wide_link_tag_shift(src, pos, 64u32.saturating_sub(hash_log.min(32)), smask) +fn hash_wide_link_tag_b(src: &[u8], pos: usize, shift: u32, smask: u64, mls: usize) -> (usize, u8) { + let hv = (load_u64le(src, pos) & smask).wrapping_mul(FAST_HASH_PRIME64); + ((hv >> shift) as usize, link_tag(src, pos, mls)) } -/// W22: `hash_wide_link_tag` with the shift resolved. Third and last of the -/// three hash entries that re-derived a BLOCK constant per position. +/// BRICK 74 (K14): position 0's tag under the block's producer -- the tag an +/// EMPTY head's packed link carries (`MatchTables::set_null_tag`). The same +/// function the fill and the walk tag with (BRICK 100: `link_tag`), at +/// position 0; 0 when there is no first word (no walk reaches position 0 +/// then either). #[inline(always)] -fn hash_wide_link_tag_shift(src: &[u8], pos: usize, shift: u32, smask: u64) -> (usize, u8) { - let v = load_u64le(src, pos) & smask; - let hv = v.wrapping_mul(FAST_HASH_PRIME64); - ((hv >> shift) as usize, (hv ^ (hv >> 29)) as u8) +fn chain_null_tag(src: &[u8], mls: usize) -> u8 { + if src.len() < 8 { + 0 + } else { + link_tag(src, 0, mls) + } } /// Chain-walk census: src loads the link tag skipped, and (COUNT) the @@ -14371,6 +15085,7 @@ fn push_lits_range(lits: &mut Vec, src: &[u8], from: usize, to: usize) { // `push_literals` at all; fixing that gives L9 the full 16/32/64 tiering // instead of a second copy of tier 1. This helper is now what its name // says: the per-block tail flush, a few hundred calls per corpus. + crate::copies::add(crate::copies::C_LIT_PUSH, to - from); lits.extend_from_slice(unsafe { src.get_unchecked(from..to) }); } @@ -14500,6 +15215,30 @@ pub fn take_walk_census() -> (u64, u64) { (WALK_EXAM.swap(0, Relaxed), WALK_BYTEMISS.swap(0, Relaxed)) } +/// BRICK 46: candidates examined AT POSITION 0 by the chain walk, and how +/// many of them were accepted. A link of 0 is both "no link" and position 0, +/// so every chain that ends inside the first window is followed to m = 0 and +/// examined there -- a phantom candidate that was never in the chain. The +/// accept count is what a representation with an unambiguous null would +/// change. +#[cfg(feature = "profile")] +pub static WALK_M0: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +#[cfg(feature = "profile")] +pub static WALK_M0_ACCEPT: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +#[cfg(feature = "profile")] +pub fn take_walk_phantom() -> (u64, u64) { + use core::sync::atomic::Ordering::Relaxed; + (WALK_M0.swap(0, Relaxed), WALK_M0_ACCEPT.swap(0, Relaxed)) +} + +/// REFUTED 2026-09-09, recorded so it is not retried: the FUSED HEAD that paid +/// in the chain walks (brick 11) loses HERE. `match_xor` returned this xor and +/// the caller took the length from it; the deterministic counter said dfast's +/// candidates resolve inside the first word only 37% of the time (L3) -- the +/// long-hash candidates match eight bytes BY CONSTRUCTION -- so the modelled +/// net was +43,877 instructions at L3 and +103,109 at L4 over the 16 MiB +/// corpus, and the static count +141. The same idea is right where the first +/// word usually decides and wrong where it usually does not. #[inline(always)] fn match_ok( src: &[u8], @@ -14517,15 +15256,17 @@ fn match_ok( if m < lowest { return false; } - if ip + mls > src.len() || m + mls > src.len() { - return false; - } // The tail slice-eq compiled to a LIBC MEMCMP CALL per candidate (for // mls = 5, comparing ONE byte) -- the mls_eq lesson, applied to the // shared validity helper. Self-proving: the u64 path runs only when its // own 8-byte reads are in bounds (m < ip from the order check above). + // + // BRICK 33: the length tests `ip + mls > len || m + mls > len` used to + // run BEFORE this arm, per candidate. Inside it they are implied -- + // `mls <= 8`, `ip + 8 <= len`, `m < ip` -- so they only guard the cold + // tail, and that is where they live now. if mls <= 8 && ip + 8 <= src.len() { - debug_assert!(m + 8 <= src.len()); + debug_assert!(m + 8 <= src.len() && ip + mls <= src.len() && m + mls <= src.len()); let mask = if mls == 8 { u64::MAX } else { @@ -14533,6 +15274,9 @@ fn match_ok( }; return (load_u64le(src, m) ^ load_u64le(src, ip)) & mask == 0; } + if ip + mls > src.len() || m + mls > src.len() { + return false; + } match_ok_cold_tail(src, m, ip, mls) } @@ -14561,22 +15305,20 @@ fn match_ok_cold_tail(src: &[u8], m: usize, ip: usize, mls: usize) -> bool { /// the true frame edge. #[cold] #[inline(never)] -fn count_match_sub8(src: &[u8], m: usize, ip: usize, max: usize) -> usize { - if ip + 8 <= src.len() { - let x = load_u64le(src, m) ^ load_u64le(src, ip); - let n = if x == 0 { - max - } else { - ((x.trailing_zeros() as usize) >> 3).min(max) - }; - #[cfg(feature = "profile")] - crate::simd::note_eqlen(n); - return n; - } - let a = &src[m..m + max]; - let b = &src[ip..ip + max]; +/// The sub-8 tail, on raw pointers. The old form tried one masked 8-byte +/// compare when the FRAME had room past `ip`; that needed `src.len()`, which +/// would have been a fifth argument on the stack at every hot call site. +/// This arm runs on ~1 call in 2000 and never more than seven compares, so +/// the byte ladder bounded by `max` is the right trade. +/// +/// # Safety +/// Same contract as `count_match_raw`: `m <= ip`, `ip + max <= src.len()`. +#[allow(unsafe_code)] +unsafe fn count_match_sub8_raw(base: *const u8, m: usize, ip: usize, max: usize) -> usize { + debug_assert!(m <= ip && max < 8); let mut n = 0usize; - while n < max && a[n] == b[n] { + // SAFETY: `m + n <= ip + n < ip + max <= src.len()` for every `n < max`. + while n < max && unsafe { *base.add(m + n) == *base.add(ip + n) } { n += 1; } #[cfg(feature = "profile")] @@ -14631,32 +15373,54 @@ pub(crate) fn count_match(src: &[u8], m: usize, ip: usize, limit: usize) -> usiz // src.len()`, `len - m >= len - ip >= limit - ip`, so `max` is `limit - // ip` either way. The oracle test exercises `m == ip` directly. debug_assert!(limit <= src.len() && m <= ip); + // SAFETY: the two debug-asserted invariants are the whole contract of + // `count_match_raw`. Every caller in this crate passes `limit = block_end` + // (<= src.len() by construction) and a candidate `m` at or below `ip`; + // `ldm` clamps `limit` to `src.len()` at its call site. + #[allow(unsafe_code)] + unsafe { + count_match_raw(src.as_ptr(), m, ip, limit) + } +} + +/// The match-length kernel entry the finders actually pay for. +/// +/// The safe form above takes `src: &[u8]` -- a FAT pointer -- so with `m`, +/// `ip` and `limit` it was FIVE machine arguments, and the Win64 ABI put the +/// fifth on the stack: one store at every call site (9-16 per finder) and +/// one load here. It then built two slices, `&src[m..m + max]` and +/// `&src[ip..limit]`, whose bounds LLVM cannot prove from debug-asserts in +/// release, and turned them straight back into pointers for the kernel. +/// +/// This is NOT the experiment `count_eq_len_ge8`'s doc refutes. That one +/// KEPT the bounds proof (moved into `simd`), still built subslices on the +/// sub-8 branch, and added an `assert!` -- a third panic path -- to make a +/// raw call sound from safe code; 209 -> 244. This one has no proof to +/// relocate, no slice on any path, no assert, and four register arguments. +/// The instruction count is the verdict either way (see the changelog). +/// +/// # Safety +/// `m <= ip` and `limit <= src.len()` for the `src` that `base` points into. +/// Then `max = limit - ip`, and `base[m..m + max]` and `base[ip..limit]` are +/// both in bounds. +#[inline(never)] +#[allow(unsafe_code)] +unsafe fn count_match_raw(base: *const u8, m: usize, ip: usize, limit: usize) -> usize { + debug_assert!(m <= ip); if ip >= limit { return 0; } let max = limit - ip; - let a = &src[m..m + max]; - let b = &src[ip..limit]; - // Sub-8 boundary tails answer HERE, without the dispatch or the call -- - // and as ONE masked compare when the frame has 8-byte room past `ip` - // (`m + 8 <= ip + 8 <= len` via `m < ip`); the byte loop survives only - // at the true frame edge. + // Sub-8 boundary tails: OUTLINED AND COLD. `max` is the room left in the + // BLOCK, so it drops under 8 only at the very last bytes of one -- the + // `eqwidth` counter reads `max >= 64` on 99.956% of calls. if max < 8 { - // OUTLINED AND COLD. `max` is the room left in the BLOCK, so it drops - // under 8 only at the very last bytes of one: the `eqwidth` counter - // reads `max >= 64` on 99.956% of calls, which puts this whole arm -- - // a masked compare plus a SEVEN-step unrolled byte ladder -- at under - // one call in 2000. It was sitting inline in the encoder's hottest - // function, which runs once per match CANDIDATE. - return count_match_sub8(src, m, ip, max); - } - // The slices have PROVEN equal length `max >= 8`; the known-length inner - // skips the re-min / zero-test / sub-8 re-branch the public entry does. - // - // These two subslices are NOT removable: passing `(src, m, ip, max)` and - // proving the bound inside `simd` measured WORSE (209 -> 244 instructions - // in this function) -- see `count_eq_len_ge8`'s doc for the receipt. - let n = crate::simd::count_eq_len_ge8(a, b, max); + // SAFETY: same contract, `max < 8` proven just above. + return unsafe { count_match_sub8_raw(base, m, ip, max) }; + } + // SAFETY: `m <= ip < limit <= src.len()` per the contract; both pointers + // address readable bytes and `max` bytes follow each. + let n = unsafe { crate::simd::count_eq_len_ge8_raw(base.add(m), base.add(ip), max) }; #[cfg(feature = "profile")] crate::simd::note_eqlen(n); n @@ -15029,28 +15793,11 @@ pub fn take_bt_calls() -> (u64, u64) { /// /// The `find_dfast` specialisation is NOT affected -- tested the same way it /// came out 6 stable-spec / 0 stable-generic and remains on. -static BT_SPEC_ARM: core::sync::atomic::AtomicU8 = core::sync::atomic::AtomicU8::new(0); - /// Bench hook for in-process ABBA. -pub fn set_bt_spec_arm(on: bool) { - BT_SPEC_ARM.store(u8::from(on) + 1, core::sync::atomic::Ordering::Relaxed); -} - -#[inline] -fn bt_spec_enabled() -> bool { - use core::sync::atomic::Ordering; - match BT_SPEC_ARM.load(Ordering::Relaxed) { - 1 => false, - 2 => true, - _ => { - let on = crate::env_knob("RZSTD_BT_SPEC") - .map(|v| v.trim() != "0") - .unwrap_or(true); - BT_SPEC_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); - on - } - } -} +/// No-op since brick 8: the binary-tree specialisation this selected is +/// retired (`bt_resolve` returns the runtime body unconditionally). Kept so +/// the bench arms that name it still build; they measure nothing. +pub fn set_bt_spec_arm(_on: bool) {} /// GATE 6 @ L3 arm: C's `_search_next_long` ip+1 long-hash probe in DFast. /// Default OFF until measured, so enabling it differs from the default. @@ -15068,9 +15815,7 @@ fn next_long_enabled() -> bool { 1 => false, 2 => true, _ => { - let on = crate::env_knob("RZSTD_NEXT_LONG") - .map(|v| v.trim() != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_NEXT_LONG", true); NEXT_LONG_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -15090,10 +15835,7 @@ fn next_long_min() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_NEXT_LONG_T") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(0.10); + let v: f32 = crate::env_knob_parse("RZSTD_NEXT_LONG_T").unwrap_or(0.10); NEXT_LONG_MIN_CACHE.store(v.to_bits(), Ordering::Relaxed); v } @@ -15119,9 +15861,7 @@ fn pair_enabled() -> bool { 1 => false, 2 => true, _ => { - let on = crate::env_knob("RZSTD_PAIR") - .map(|v| v.trim() != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_PAIR", true); PAIR_ON_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -15168,10 +15908,7 @@ fn pair_gain_lo() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_PAIR_LO") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(0.71); + let v: f32 = crate::env_knob_parse("RZSTD_PAIR_LO").unwrap_or(0.71); PAIR_LO_ARM.store(v.to_bits(), Ordering::Relaxed); v } @@ -15203,10 +15940,7 @@ fn pair_rep_max() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_PAIR_T") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(0.7); + let v: f32 = crate::env_knob_parse("RZSTD_PAIR_T").unwrap_or(0.7); PAIR_T_CACHE.store(v.to_bits(), Ordering::Relaxed); v } @@ -15357,9 +16091,7 @@ fn tag_enabled() -> bool { 1 => false, 2 => true, _ => { - let on = crate::env_knob("RZSTD_TAG") - .map(|v| v.trim() != "0") - .unwrap_or(true); + let on = crate::env_knob_not0("RZSTD_TAG", true); TAG_ARM.store(if on { 2 } else { 1 }, Ordering::Relaxed); on } @@ -15401,10 +16133,7 @@ fn tag_min() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_TAG_T") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(0.0); + let v: f32 = crate::env_knob_parse("RZSTD_TAG_T").unwrap_or(0.0); TAG_MIN_ARM.store(v.to_bits(), Ordering::Relaxed); v } @@ -15455,10 +16184,7 @@ fn pair_rate_hi() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_PAIR_HI") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(1.0); + let v: f32 = crate::env_knob_parse("RZSTD_PAIR_HI").unwrap_or(1.0); PAIR_HI_ARM.store(v.to_bits(), Ordering::Relaxed); v } @@ -15483,10 +16209,7 @@ fn pair_gain_min() -> f32 { if c != u32::MAX { return f32::from_bits(c); } - let v: f32 = std::env::var("RZSTD_PAIR_G") - .ok() - .and_then(|v| v.trim().parse().ok()) - .unwrap_or(0.20); + let v: f32 = crate::env_knob_parse("RZSTD_PAIR_G").unwrap_or(0.20); PAIR_GAIN_ARM.store(v.to_bits(), Ordering::Relaxed); v } @@ -16107,10 +16830,23 @@ mod tests { /// the opposite event from the one this gate exists to catch, and suppressing /// a real improvement to preserve the ladder would be backwards. /// - /// On the FULL osdb this test reads, the margin is +0.074% (3,517,111 at L3 + /// On the FULL osdb this test reads, the margin was +0.074% (3,517,111 at L3 /// against 3,519,696 at L5); the 0.012% figure above is the 8 MiB prefix the /// boards use. The tolerance below is set from the full-file number. /// + /// WIDENED 2026-09-08, same event again. The next-long offset-trade + /// dispatch (`nl_dispatch` defaulted ON, raised cut 24 -> 48) is another + /// pure size win on the DFast ladder, and it takes L3 from 3,517,111 to + /// **3,514,780** on this file. L5 is **3,519,696 -- unchanged, the exact + /// value recorded above**, which is the proof that Greedy did not move + /// and the inversion is once more the cheaper level GAINING. The margin + /// goes +0.074% -> +0.140%, so the bar goes 0.1% -> 0.2%. + /// + /// The gate keeps its teeth: the historical DEFECT inversions on this + /// pair were +1.25% and +0.33%, both still far above 0.2%, and + /// `L5_CEILING` is untouched -- L5 sits at 3,519,696 against a 3,530,000 + /// ceiling, so a real Greedy regression still fires it. + /// /// The exception is deliberately narrow: this pair only, and a ceiling on L5 /// itself so the gate keeps its teeth. If Greedy ever loses a capability its /// size grows, `L5_CEILING` fires, and the exception cannot hide it -- which @@ -16127,10 +16863,10 @@ mod tests { for lvl in [1, 3, 5, 7, 9, 13, 16, 19] { let n = crate::compress(&src, lvl).unwrap().len(); // The one adjudicated inversion: L3 -> L5, and only as a near-tie. - // The bar is 0.1%: the measured tie is +0.074%, and the historical + // The bar is 0.2%: the measured tie is +0.140%, and the historical // DEFECT inversions on this pair were +1.25% and +0.33% -- both far // above it, so the gate still catches every defect it ever caught. - let tie = prev_lvl == 3 && lvl == 5 && n <= prev + prev / 1000; + let tie = prev_lvl == 3 && lvl == 5 && n <= prev + prev / 500; assert!( n <= prev || tie, "level {lvl} emitted {n} bytes, more than the previous level's {prev}" diff --git a/crates/rusty_zstd/src/fse.rs b/crates/rusty_zstd/src/fse.rs index 3c79b02..9bee1cc 100644 --- a/crates/rusty_zstd/src/fse.rs +++ b/crates/rusty_zstd/src/fse.rs @@ -621,21 +621,25 @@ mod ct_pool { static DELTA: RefCell>> = const { RefCell::new(Vec::new()) }; } pub(super) fn take_state(n: usize) -> Vec { - let mut v = STATE + let got = STATE .try_with(|c| c.try_borrow_mut().ok().and_then(|mut p| p.pop())) .ok() - .flatten() - .unwrap_or_default(); + .flatten(); + #[cfg(feature = "profile")] + crate::scratch::note_pool(got.is_some()); + let mut v = got.unwrap_or_default(); v.clear(); v.resize(n, 0u16); v } pub(super) fn take_delta(n: usize) -> Vec { - let mut v = DELTA + let got = DELTA .try_with(|c| c.try_borrow_mut().ok().and_then(|mut p| p.pop())) .ok() - .flatten() - .unwrap_or_default(); + .flatten(); + #[cfg(feature = "profile")] + crate::scratch::note_pool(got.is_some()); + let mut v = got.unwrap_or_default(); v.clear(); v.resize(n, FseCDelta { nb: 0, find: 0 }); v @@ -1010,17 +1014,17 @@ pub(crate) fn normalize_count( let low_threshold = total >> table_log; let mut largest = 0usize; let mut largest_p: i16 = 0; - for s in 0..=max_sv { - // SAFETY: `max_sv == count.len() - 1` with `count` non-empty (checked at - // entry), and `norm` is built `max_sv + 1` long just above. - debug_assert!(s < count.len() && s < norm.len()); - #[allow(unsafe_code)] - let c = *unsafe { count.get_unchecked(s) }; + // `norm` was just resized to `count.len()`, so zipping the two makes the + // iteration bounded by construction: LLVM proves both accesses in range + // from one length, which retires the bounds checks on `norm[s]` and lets + // the `get_unchecked` that used to be needed for `count[s]` go with them. + // Strictly safer than what it replaces, and one fewer `unsafe` island. + for (s, (&c, n)) in count.iter().zip(norm.iter_mut()).enumerate() { if c == 0 { continue; } if c <= low_threshold { - norm[s] = low_prob; + *n = low_prob; still -= 1; continue; } @@ -1039,7 +1043,7 @@ pub(crate) fn normalize_count( largest_p = proba; largest = s; } - norm[s] = proba; + *n = proba; still -= i32::from(proba); } // SAFETY for the `largest` accesses here and below: `largest` starts at 0 @@ -1054,12 +1058,14 @@ pub(crate) fn normalize_count( let mut n2 = crate::scratch::pool_take(&SC_NORM); n2.resize(max_sv + 1, 0i16); let mut dist = 0i32; - for s in 0..=max_sv { - if count[s] == 0 { + // Same bounded-by-construction zip as the main loop above: `n2` is + // resized to `count.len()`, so neither index needs a runtime check. + for (&c, w_out) in count.iter().zip(n2.iter_mut()) { + if c == 0 { continue; } - let w = ((u64::from(count[s]) << table_log) / u64::from(total)).max(1) as i16; - n2[s] = w; + let w = ((u64::from(c) << table_log) / u64::from(total)).max(1) as i16; + *w_out = w; dist += i32::from(w); } let leftover = (1i32 << table_log) - dist; @@ -1072,6 +1078,10 @@ pub(crate) fn normalize_count( *v = 1; } } + // `norm` was taken from the pool at the top and this branch returns + // `n2` instead, so without this the buffer is DROPPED and the pool + // drains -- which is what held the hit rate at 78%. + crate::scratch::pool_give(&SC_NORM, norm); return Ok(n2); } #[allow(unsafe_code)] @@ -1092,6 +1102,24 @@ pub(crate) fn give_ncount_buf(v: alloc::vec::Vec) { crate::scratch::pool_give(&SC_NCOUNT, v); } +/// Take an ncount-sized buffer from the pool. +/// +/// Exposed so callers that build a one-byte RLE header by hand get a POOLED +/// buffer instead of a fresh `vec![sym]`. The caller already returns these +/// through `give_ncount_buf`, so the loop closes without any new plumbing. +pub(crate) fn take_ncount_buf() -> alloc::vec::Vec { + crate::scratch::pool_take(&SC_NCOUNT) +} + +/// Hand a `normalize_count` result back to the pool. +/// +/// `ncount_and_ctable` already does this at its own death site; a caller that +/// uses `normalize_count` DIRECTLY owns the buffer and must close the loop +/// itself, or the pool drains and every later take allocates. +pub(crate) fn give_norm_buf(v: alloc::vec::Vec) { + crate::scratch::pool_give(&SC_NORM, v); +} + pub(crate) fn write_ncount(norm: &[i16], table_log: u8) -> Result, Error> { // ALLOC-4: `Vec::new()` grown by `push` reallocated on every doubling -- // 1, 2, 4, 8 ... which is why the attribution sampler kept landing in @@ -1193,10 +1221,12 @@ pub(crate) fn compress_using_ctable(src: &[u8], table: &FseCTable) -> Result Result<(usi /// re-generate this body under its own feature set. #[inline(always)] fn weights_into_body(dst: &mut [u8], src: &[u8], max_out: usize) -> Result<(usize, usize), Error> { + // Narrow to the caller's cap ONCE, up front. Every write below is then + // bounded by ONE length the compiler can see, so the explicit + // `n_out >= max_out` guards and the implicit `dst[n_out]` bounds checks + // become the same test and merge -- four guard branches instead of eight. + // It also turns a would-be PANIC into a clean `Corruption` if a caller ever + // passes a buffer shorter than the cap it asked for; both existing callers + // pass 255 with a 255-byte buffer, so this is unreachable today. + let dst = dst.get_mut(..max_out).ok_or(Error::Corruption)?; #[cfg(feature = "std")] let recycled = WEIGHT_TBL.with(|c| c.borrow_mut().take()); #[cfg(not(feature = "std"))] @@ -1428,7 +1468,7 @@ fn weights_into_body(dst: &mut [u8], src: &[u8], max_out: usize) -> Result<(usiz let mut s2 = table.init_state(&mut br); let mut n_out = 0usize; loop { - if n_out >= max_out { + if n_out >= dst.len() { return Err(Error::Corruption); } dst[n_out] = table.entry(s1).symbol; @@ -1436,13 +1476,13 @@ fn weights_into_body(dst: &mut [u8], src: &[u8], max_out: usize) -> Result<(usiz s1 = table.update(s1, &mut br)?; let _ = br.reload(); if br.overflowed() { - if n_out < max_out { + if n_out < dst.len() { dst[n_out] = table.entry(s2).symbol; n_out += 1; } break; } - if n_out >= max_out { + if n_out >= dst.len() { return Err(Error::Corruption); } dst[n_out] = table.entry(s2).symbol; @@ -1450,7 +1490,7 @@ fn weights_into_body(dst: &mut [u8], src: &[u8], max_out: usize) -> Result<(usiz s2 = table.update(s2, &mut br)?; let _ = br.reload(); if br.overflowed() { - if n_out < max_out { + if n_out < dst.len() { dst[n_out] = table.entry(s1).symbol; n_out += 1; } diff --git a/crates/rusty_zstd/src/huffman.rs b/crates/rusty_zstd/src/huffman.rs index 3d5f75b..b6538fc 100644 --- a/crates/rusty_zstd/src/huffman.rs +++ b/crates/rusty_zstd/src/huffman.rs @@ -340,10 +340,12 @@ impl HuffmanTable { // off. With the arm gone that hazard goes with it. #[cfg(all(target_arch = "x86_64", feature = "std"))] if crate::simd::has_bmi2() { + crate::kreach::hit(crate::kreach::K_HUF_DEC4X); // SAFETY: guarded by runtime CPUID; the body is identical. #[allow(unsafe_code)] return unsafe { self.decode_4x_bmi2(s0, s1, s2, s3, d0, d1, d2, d3) }; } + crate::kreach::miss(crate::kreach::K_HUF_DEC4X); self.decode_4x_inner::(s0, s1, s2, s3, d0, d1, d2, d3) } @@ -410,12 +412,14 @@ impl HuffmanTable { X4_X1_CALLS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); #[cfg(all(target_arch = "x86_64", feature = "std"))] if BMI2 { + crate::kreach::hit(crate::kreach::K_HUF_DEC4X1); // SAFETY: `BMI2 == true` is reached only from `decode_4x_bmi2`, // which is itself entered under the `has_bmi2()` CPUID guard and // carries the same `#[target_feature]` set. #[allow(unsafe_code)] return unsafe { self.decode_4x_x1_bmi2(s0, s1, s2, s3, d0, d1, d2, d3) }; } + crate::kreach::miss(crate::kreach::K_HUF_DEC4X1); return self.decode_4x_x1(s0, s1, s2, s3, d0, d1, d2, d3); } // N2: the 4-stream X2 use. Instrumenting only the 1-stream site read @@ -1474,12 +1478,15 @@ impl HuffCTable { if crate::encode::huff_fast_enabled() { #[cfg(all(target_arch = "x86_64", feature = "std"))] if crate::simd::has_bmi2() { + crate::kreach::hit(crate::kreach::K_HUF_ENC); // SAFETY: guarded by runtime CPUID; the body is identical. #[allow(unsafe_code)] return unsafe { self.encode_stream_unrolled_bmi2_into(src, buf) }; } + crate::kreach::miss(crate::kreach::K_HUF_ENC); self.encode_stream_unrolled_into(src, buf) } else { + crate::kreach::miss(crate::kreach::K_HUF_ENC); self.encode_stream_scalar_into(src, buf) } } @@ -1909,27 +1916,33 @@ fn huffman_nbits(freq: &[u32; 256]) -> Result<[u8; 256], Error> { internal: &[usize], ii: &mut usize, ) -> Option { - let lc = leaves.get(*li).and_then(|&i| nodes.get(i)).map(|n| n.count); + // WIN: carry the node index OUT of the `get`, instead of re-indexing. + // Each arm below used to do `leaves[*li]` / `internal[*ii]` after the + // `.get()` above had already proven that exact index valid and fetched + // it -- so the same element was located twice and the second lookup + // paid a bounds check the first had already discharged. Threading the + // index through the `Option` removes both checks and their panic pads. + // Byte-identical by construction: same values, same tie rule, same + // order -- and the tie rule is what the bitstream depends on. + let lc = leaves + .get(*li) + .and_then(|&i| nodes.get(i).map(|n| (n.count, i))); let ic = internal .get(*ii) - .and_then(|&i| nodes.get(i)) - .map(|n| n.count); + .and_then(|&i| nodes.get(i).map(|n| (n.count, i))); match (lc, ic) { // `<=`: the leaf wins a tie. See the tie-rule note above. - (Some(l), Some(x)) if l <= x => { - let r = leaves[*li]; + (Some((l, leaf)), Some((x, _))) if l <= x => { *li += 1; - Some(r) + Some(leaf) } - (Some(_), Some(_)) | (None, Some(_)) => { - let r = internal[*ii]; + (Some(_), Some((_, node))) | (None, Some((_, node))) => { *ii += 1; - Some(r) + Some(node) } - (Some(_), None) => { - let r = leaves[*li]; + (Some((_, leaf)), None) => { *li += 1; - Some(r) + Some(leaf) } (None, None) => None, } @@ -2392,6 +2405,11 @@ fn write_tree_fse(weights: &[u8]) -> Result, Error> { let norm = fse::normalize_count(&count[..=max_sv], table_log, total, false)?; let ncount = fse::write_ncount(&norm, table_log)?; let ct = fse::FseCTable::from_norm(&norm, table_log)?; + // `normalize_count` hands out a POOLED buffer. `ncount_and_ctable` closes + // that loop at its own death site; this caller uses `normalize_count` + // directly, so it has to. Without it every call here drained the pool by + // one and the next take allocated. + fse::give_norm_buf(norm); let payload = fse::compress_using_ctable(weights, &ct)?; let csize = ncount.len() + payload.len(); if csize == 0 || csize >= 128 { @@ -2401,6 +2419,12 @@ fn write_tree_fse(weights: &[u8]) -> Result, Error> { out.push(csize as u8); out.extend_from_slice(&ncount); out.extend_from_slice(&payload); + // Both of these are POOLED buffers that die here, and neither loop was + // closed: `write_ncount` takes from `SC_NCOUNT` and + // `compress_using_ctable` allocates its payload. Same defect as the `norm` + // buffer above -- a caller that uses the low-level builders directly owns + // the give-back that `ncount_and_ctable` performs for its own callers. + fse::give_ncount_buf(ncount); Ok(out) } @@ -2480,6 +2504,20 @@ fn write_lit_huff_header_into( let mut h = outbuf; h.clear(); let mut b = [0u8; 5]; + let n = lit_huff_header_bytes(lit_type, n_streams, regen, csize, &mut b)?; + h.extend_from_slice(&b[..n]); + Ok(h) +} + +/// The header bytes themselves, shared by the `Vec` and append forms so the +/// format arithmetic cannot drift between them. +fn lit_huff_header_bytes( + lit_type: u8, + n_streams: u32, + regen: u32, + csize: u32, + b: &mut [u8; 5], +) -> Result { let n: usize = if n_streams == 1 { if regen > 0x3FF || csize > 0x3FF { return Err(Error::Corruption); @@ -2507,8 +2545,7 @@ fn write_lit_huff_header_into( } else { return Err(Error::Corruption); }; - h.extend_from_slice(&b[..n]); - Ok(h) + Ok(n) } #[cfg(feature = "alloc")] @@ -2702,6 +2739,31 @@ fn pack_huff_section( pack_huff_section_into(lit_type, n_streams, regen, tree, body, Vec::new()) } +/// Append the packed section to `dst` and return its byte length. +/// +/// The header needs `csize`, and `csize` is `tree.len() + body.len()` -- both +/// known here, because the body has already been encoded. So there is nothing +/// circular about writing this straight into the frame; the only reason the +/// `_into` twin below stages into its own buffer is that CANDIDATES compete on +/// size and a loser has to be discardable. The caller resolves that by +/// appending the candidate that usually wins and truncating on the rare loss. +fn pack_huff_section_append( + dst: &mut Vec, + lit_type: u8, + n_streams: u32, + regen: u32, + tree: &[u8], + body: &[u8], +) -> Result { + let csize = (tree.len() + body.len()) as u32; + let mut h = [0u8; 5]; + let hn = lit_huff_header_bytes(lit_type, n_streams, regen, csize, &mut h)?; + dst.extend_from_slice(&h[..hn]); + dst.extend_from_slice(tree); + dst.extend_from_slice(body); + Ok(hn + tree.len() + body.len()) +} + fn pack_huff_section_into( lit_type: u8, n_streams: u32, @@ -2831,17 +2893,26 @@ pub(crate) fn lit_sample_peak(lits: &[u8]) -> u32 { /// should be remembered for later treeless blocks. #[cfg(feature = "alloc")] #[inline(always)] -pub(crate) fn encode_literals_section( +/// Append the literals section for `lits` to `dst`. +/// +/// Takes `dst` rather than returning a `Vec` so the four decided-immediately +/// arms (empty, RLE, tiny, not-worth-Huffman) can write their bytes ONCE. Only +/// the Huffman arm needs a staging buffer, because its candidates compete on +/// encoded size and the winner is not known until they are all built. +pub(crate) fn encode_literals_section_into( + dst: &mut Vec, lits: &[u8], prev: Option<&HuffCTable>, -) -> Result<(Vec, HuffUpdate), Error> { +) -> Result { let n = lits.len() as u32; if n == 0 { - return Ok((vec![0], HuffUpdate::Unchanged)); + dst.push(0); + return Ok(HuffUpdate::Unchanged); } let all_same = n >= 2 && lits.iter().all(|&b| b == lits[0]); if all_same { - return Ok((write_raw_or_rle(lits, true), HuffUpdate::Unchanged)); + write_raw_or_rle_into(dst, lits, true); + return Ok(HuffUpdate::Unchanged); } // BRICK 60: do NOT materialize the raw section just to hold a baseline // LENGTH. It is a full copy of every literal byte, and on Huffman-friendly @@ -2849,10 +2920,12 @@ pub(crate) fn encode_literals_section( // away every time. Its size is exact arithmetic -- `hdr + n` -- so carry the // NUMBER and build the bytes only if raw actually wins. if n < 8 { - return Ok((write_raw_or_rle(lits, false), HuffUpdate::Unchanged)); + write_raw_or_rle_into(dst, lits, false); + return Ok(HuffUpdate::Unchanged); } if n >= 64 && !literals_worth_huffman(lits) { - return Ok((write_raw_or_rle(lits, false), HuffUpdate::Unchanged)); + write_raw_or_rle_into(dst, lits, false); + return Ok(HuffUpdate::Unchanged); } crate::prof::note_lit_try(0); @@ -2965,42 +3038,59 @@ pub(crate) fn encode_literals_section( // ALLOC-15: `new_tbl`'s tree is consumed by `try_huff_section` (which copies // it into the section) and then dropped -- give it back on the way out. + // The new table is Huffman-OPTIMAL for these frequencies, so `body_new <= + // body_prev` always and this candidate is the one that usually wins. Append + // it STRAIGHT INTO `dst` and truncate on the rare loss, instead of packing + // every candidate into a staging buffer and copying the winner out. + let mark = dst.len(); + let mut in_dst = 0usize; if let Some((ct, tree)) = new_tbl { { crate::prof::note_lit_try(3); - if let Some(sec) = try_huff_section(2, preferred, n, &tree, &ct, lits) { - if sec.len() < best_len { + let appended = + try_huff_section_append(dst, 2, preferred, n, &tree, &ct, lits).or_else(|| { + if preferred == 4 { + dst.truncate(mark); + try_huff_section_append(dst, 2, 1, n, &tree, &ct, lits) + } else { + None + } + }); + match appended { + Some(len) if len < best_len => { crate::prof::note_lit_try(4); - if let Some(old) = best.replace(sec) { + // `best_len` is not updated: this is the LAST candidate, so + // nothing compares against it again, and the emitted length + // travels in `in_dst`. + in_dst = len; + if let Some(old) = best.take() { sec_pool_give(old); } - // ALLOC-11: MOVE, don't clone. The `else if` below is the - // only other user and the two arms are exclusive, so the - // borrow checker accepts the move -- the clone was copying - // a 12 KiB table (4 KiB x1 + 8 KiB x2) for nothing. + // ALLOC-11: MOVE, don't clone -- the clone was copying a + // 12 KiB table for nothing. update = HuffUpdate::New(ct); } - } else if preferred == 4 { - if let Some(sec) = try_huff_section(2, 1, n, &tree, &ct, lits) { - if sec.len() < best_len { - if let Some(old) = best.replace(sec) { - sec_pool_give(old); - } - update = HuffUpdate::New(ct); - } - } + // Lost (or failed): rewind, leaving whatever `best` holds. + _ => dst.truncate(mark), } } give_tree_buf(tree); } - // Raw only gets built if nothing beat it. - let best = match best { - Some(sec) => sec, - None => { - crate::prof::note_lit_try(5); - write_raw_or_rle(lits, false) - } + // Raw only gets built if nothing beat it -- and now it is never BUILT at + // all, it is written straight out. + let Some(best) = best else { + if in_dst > 0 { + // The winner is already in `dst`; nothing to copy and nothing to + // pool. This is the zero-copy path. + crate::prof::note_lit_margin(raw_len, in_dst); + return Ok(update); + } + crate::prof::note_lit_try(5); + let raw_bytes = raw_section_len(n); + write_raw_or_rle_into(dst, lits, false); + crate::prof::note_lit_margin(raw_len, raw_bytes); + return Ok(update); }; // PROMETHEUS margin tap. Measured against `best.len()`, the section ACTUALLY // emitted -- NOT against `best_len`, which the new-table branch above leaves @@ -3008,10 +3098,55 @@ pub(crate) fn encode_literals_section( // comparison). Tapping `best_len` reported a perfect hole across four // buckets, which is what a stale variable looks like, not a distribution. crate::prof::note_lit_margin(raw_len, best.len()); - Ok((best, update)) + // The previous-table candidate won, so it is in a staging buffer and still + // has to be copied. When the NEW-table candidate wins -- the common case -- + // this is skipped entirely because it is already in `dst`. + crate::copies::add(crate::copies::C_SECTION_TO_DST, best.len()); + dst.extend_from_slice(&best); + sec_pool_give(best); + Ok(update) +} + +/// Allocating wrapper. Tests assert on the section bytes; production uses the +/// `_into` form so the bytes are written once. +#[cfg(test)] +pub(crate) fn encode_literals_section( + lits: &[u8], + prev: Option<&HuffCTable>, +) -> Result<(Vec, HuffUpdate), Error> { + let mut v = Vec::new(); + let u = encode_literals_section_into(&mut v, lits, prev)?; + Ok((v, u)) } #[cfg(feature = "alloc")] +/// `try_huff_section`, appending onto `dst` instead of returning a `Vec`. +/// +/// Returns the number of bytes appended, or `None` (having appended nothing) if +/// the encode failed. The body still needs its own buffer -- it is what the +/// header's `csize` is measured from -- but the SECTION no longer does, which +/// is the copy this removes. +fn try_huff_section_append( + dst: &mut Vec, + lit_type: u8, + n_streams: u32, + regen: u32, + tree: &[u8], + ct: &HuffCTable, + lits: &[u8], +) -> Option { + let buf = body_pool_take(); + let body = if n_streams == 1 { + ct.encode_stream_into(lits, buf).ok()? + } else { + encode_4_streams_into(ct, lits, buf).ok()? + }; + crate::copies::add(crate::copies::C_HUFF_EMIT, body.len()); + let r = pack_huff_section_append(dst, lit_type, n_streams, regen, tree, &body).ok(); + body_pool_give(body); + r +} + fn try_huff_section( lit_type: u8, n_streams: u32, @@ -3032,6 +3167,11 @@ fn try_huff_section( } else { encode_4_streams_into(ct, lits, buf).ok()? }; + // Census: every CANDIDATE built, and the body bytes `pack_huff_section_into` + // copies into it. Compared against sections emitted, this says whether the + // winner could have been written straight into `dst` -- a ratio near 1 means + // the staging buffer usually serves a single uncontested candidate. + crate::copies::add(crate::copies::C_HUFF_EMIT, body.len()); let sec = pack_huff_section_into(lit_type, n_streams, regen, tree, &body, sec_pool_take()).ok(); body_pool_give(body); sec @@ -3203,7 +3343,24 @@ fn raw_section_len(n: u32) -> usize { hdr + n as usize } -fn write_raw_or_rle(lits: &[u8], rle: bool) -> Vec { +/// Append the raw/RLE literals section straight to `dst`. +/// +/// COPY ELIMINATION: the `Vec`-returning twin below built the section into a +/// fresh allocation which the caller then copied into `dst` and dropped -- so +/// every raw literal byte was moved TWICE after already being staged out of +/// `src`, three touches for a byte the format says to store verbatim. Writing +/// through `dst` removes the allocation and one full traversal of the literals. +fn write_raw_or_rle_into(dst: &mut Vec, lits: &[u8], rle: bool) { + let (hdr, hn, body) = raw_or_rle_parts(lits, rle); + crate::copies::add(crate::copies::C_SECTION_TO_DST, hn + body.len()); + dst.extend_from_slice(&hdr[..hn]); + dst.extend_from_slice(body); +} + +/// The header bytes and payload slice, shared by both forms so they cannot +/// drift -- this is a format-visible layout. +#[inline] +fn raw_or_rle_parts(lits: &[u8], rle: bool) -> ([u8; 3], usize, &[u8]) { // C12: eight `Vec` plumbing sites became two. The header is at most three // bytes across three size classes, and each `push` inlined its own // capacity test and grow path -- the same shape as C5, C7 and C11. Staging @@ -3235,10 +3392,7 @@ fn write_raw_or_rle(lits: &[u8], rle: bool) -> Vec { } else { lits }; - let mut dst = Vec::with_capacity(hn + body.len()); - dst.extend_from_slice(&hdr[..hn]); - dst.extend_from_slice(body); - dst + (hdr, hn, body) } #[cfg(all(test, feature = "alloc"))] diff --git a/crates/rusty_zstd/src/kreach.rs b/crates/rusty_zstd/src/kreach.rs new file mode 100644 index 0000000..38fc3b6 --- /dev/null +++ b/crates/rusty_zstd/src/kreach.rs @@ -0,0 +1,175 @@ +//! KERNEL REACH CENSUS -- does the shipping path actually call the kernel? +//! +//! Every other gate in this crate is blind to the one defect this module +//! exists to find. A kernel that is written, tested, benchmarked and NOT +//! CALLED passes byte-identity (the two paths agree by design), passes the +//! round-trip, passes the conformance suite, and reads FLAT under an +//! arm-toggle A/B -- which looks exactly like "this kernel does not help" +//! and gets recorded as a refutation that nothing ever revisits. +//! +//! The only instrument that separates "the kernel does not help" from "the +//! arm is not wired to anything" is a COUNT of how much work goes down each +//! path. It is deterministic: same number on any machine, at any load, with +//! no pinning, no ABBA, no noise floor and no z-score. One run is the answer. +//! +//! ## The tap must not become the thing it measures +//! +//! `count_eq_len` runs ~247M times at L19 and `emit_fast_seq` once per +//! sequence. An `AtomicU64::fetch_add` lowers to `lock xaddq` on x86-64 at +//! every ordering -- a bus-locked full-barrier RMW -- so a per-call atomic +//! there would be the instrument dominating the measurement (this is exactly +//! what already inflated every pre-existing `EQ_OPS` share in this crate). +//! So the per-call counters are thread-local `Cell` bumps (load/add/store), +//! folded into the process totals when the thread ends or on an explicit +//! flush. Per-block sites could afford atomics but use the same path anyway, +//! because one shape is easier to trust than two. +//! +//! ## The label is part of the instrument +//! +//! A bucket printed as "scalar" that actually counts calls INTO a kernel +//! manufactures a finding that does not exist. Each slot below names one +//! dispatch site, and `hit` is bumped on the side that reaches the kernel, +//! `miss` on the side that does not -- both AT the dispatch, never inferred +//! from an eligibility test upstream of it. In particular `simd::eq_call`'s +//! existing `wide_eligible` counter is NOT kernel reach: it counts calls +//! where `max >= 64`, which is the vector arm's ELIGIBILITY, and most of +//! those are resolved by the 32-byte word ladder before any kernel runs. + +/// One slot per shipping dispatch site. +/// +/// ENCODE side. +pub const K_COUNT_EQ_WIDE: usize = 0; +/// `find_fast_impl` -- BMI2 twin vs baseline, once per block. +pub const K_FIND_FAST: usize = 1; +/// `emit_fast_seq` -- BMI2 twin vs baseline, once per emitted sequence. +pub const K_EMIT_FAST_SEQ: usize = 2; +/// `fse::compress_using_ctable` -- BMI2 twin vs baseline. +pub const K_FSE_CTABLE: usize = 3; +/// `fse::weights_into` -- BMI2 twin vs baseline. +pub const K_FSE_WEIGHTS: usize = 4; +/// `huffman::encode_stream_unrolled` -- BMI2 twin vs baseline. +pub const K_HUF_ENC: usize = 5; +/// DECODE side. `decode_sequences` -- the duplicated-loop twin vs baseline. +pub const K_DEC_SEQ: usize = 6; +/// `huffman::decode_4x` -- BMI2 twin vs baseline. +pub const K_HUF_DEC4X: usize = 7; +/// `huffman::decode_4x_x1` -- BMI2 twin vs baseline. +pub const K_HUF_DEC4X1: usize = 8; +/// BOTH sides. `xxh64` stripe loop -- AVX2/NEON kernel vs scalar stripes. +pub const K_XXH_STRIPE: usize = 9; + +/// Number of census slots. +pub const N_SLOTS: usize = 10; + +/// Human names, index-aligned with the `K_*` constants above. `(name, side)`. +pub const SLOT_NAMES: [(&str, &str); N_SLOTS] = [ + ("count_eq_len wide", "enc"), + ("find_fast_impl", "enc"), + ("emit_fast_seq", "enc"), + ("fse compress_ctable", "enc"), + ("fse weights_into", "enc"), + ("huffman encode_stream", "enc"), + ("decode_sequences", "dec"), + ("huffman decode_4x", "dec"), + ("huffman decode_4x_x1", "dec"), + ("xxh64 stripes", "both"), +]; + +#[cfg(not(feature = "profile"))] +mod imp { + /// Shipping build: every tap folds to nothing. + #[inline(always)] + pub fn hit(_slot: usize) {} + /// Shipping build: every tap folds to nothing. + #[inline(always)] + pub fn miss(_slot: usize) {} + /// Shipping build: every tap folds to nothing. + #[inline(always)] + pub fn flush_this_thread() {} +} + +#[cfg(feature = "profile")] +mod imp { + use super::N_SLOTS; + use core::cell::Cell; + use core::sync::atomic::{AtomicU64, Ordering::Relaxed}; + + pub(super) static G_HIT: [AtomicU64; N_SLOTS] = [const { AtomicU64::new(0) }; N_SLOTS]; + pub(super) static G_MISS: [AtomicU64; N_SLOTS] = [const { AtomicU64::new(0) }; N_SLOTS]; + + struct Tls { + hit: [Cell; N_SLOTS], + miss: [Cell; N_SLOTS], + } + + fn fold(c: &Cell, g: &AtomicU64) { + let v = c.replace(0); + if v != 0 { + g.fetch_add(v, Relaxed); + } + } + + impl Tls { + const fn new() -> Self { + Tls { + hit: [const { Cell::new(0) }; N_SLOTS], + miss: [const { Cell::new(0) }; N_SLOTS], + } + } + fn flush(&self) { + for (c, g) in self.hit.iter().zip(G_HIT.iter()) { + fold(c, g); + } + for (c, g) in self.miss.iter().zip(G_MISS.iter()) { + fold(c, g); + } + } + } + + impl Drop for Tls { + fn drop(&mut self) { + self.flush(); + } + } + + std::thread_local! { + static TLS: Tls = const { Tls::new() }; + } + + /// Count one call that REACHED the kernel at `slot`. + #[inline(always)] + pub fn hit(slot: usize) { + let _ = TLS.try_with(|t| t.hit[slot].set(t.hit[slot].get() + 1)); + } + + /// Count one call that did NOT reach the kernel at `slot`. + #[inline(always)] + pub fn miss(slot: usize) { + let _ = TLS.try_with(|t| t.miss[slot].set(t.miss[slot].get() + 1)); + } + + /// Fold this thread's cells into the process totals. + pub fn flush_this_thread() { + let _ = TLS.try_with(|t| t.flush()); + } +} + +pub use imp::{flush_this_thread, hit, miss}; + +/// Read and clear the whole census: `[(hit, miss); N_SLOTS]`. +/// +/// Flushes the calling thread first. Worker threads fold on their own `Drop`, +/// so a multi-threaded run must be joined before this is read. +#[cfg(feature = "profile")] +pub fn take() -> [(u64, u64); N_SLOTS] { + use core::sync::atomic::Ordering::Relaxed; + imp::flush_this_thread(); + let mut out = [(0u64, 0u64); N_SLOTS]; + for (i, o) in out.iter_mut().enumerate() { + *o = ( + imp::G_HIT[i].swap(0, Relaxed), + imp::G_MISS[i].swap(0, Relaxed), + ); + } + out +} diff --git a/crates/rusty_zstd/src/ldm.rs b/crates/rusty_zstd/src/ldm.rs index 9236203..2e31e62 100644 --- a/crates/rusty_zstd/src/ldm.rs +++ b/crates/rusty_zstd/src/ldm.rs @@ -95,9 +95,16 @@ pub(crate) fn prime_ldm( let mls = p.min_match as usize; let from = payload_off.saturating_sub(window); let mut pos = from + (step - from % step) % step; + debug_assert!(tables.hash.len() == 1usize << p.hash_log.min(20)); while pos + mls <= payload_off && pos + 8 <= src.len() { let h = ldm_hash(src, pos, p.hash_log); - tables.hash[h] = pos as u32; + // BRICK 31: `ldm_hash` masks to `hash_log` bits and the table is + // exactly that size (`LdmTables::new`), as in `collect_ldm`. + debug_assert!(h < tables.hash.len()); + #[allow(unsafe_code)] + { + *unsafe { tables.hash.get_unchecked_mut(h) } = pos as u32; + } pos += step; } } @@ -122,16 +129,45 @@ pub(crate) fn collect_ldm( let mut ip = block_start; let align = (step - (ip % step)) % step; ip = ip.saturating_add(align); + // BRICK 18: the head test's byte mask -- the first `min(mls, 8)` bytes. + let smask: u64 = if mls >= 8 { + u64::MAX + } else { + (1u64 << (8 * mls)) - 1 + }; + debug_assert!(tables.hash.len() == 1usize << p.hash_log.min(20)); while ip <= ilimit && ip + 8 <= src.len() { let h = ldm_hash(src, ip, p.hash_log); - let m = tables.hash[h] as usize; - tables.hash[h] = ip as u32; + // `ldm_hash` masks to `hash_log` bits and the table is exactly that + // size (see `LdmTables::new`), so the index is proven; the checked + // form cost a guard on each of the two accesses per position. + debug_assert!(h < tables.hash.len()); + #[allow(unsafe_code)] + let m = *unsafe { tables.hash.get_unchecked(h) } as usize; + #[allow(unsafe_code)] + { + *unsafe { tables.hash.get_unchecked_mut(h) } = ip as u32; + } + // The candidate check used to be `src[m..m + mls] == src[ip..ip + mls]` + // -- a libc `memcmp` of `mls` (64 by default) bytes on EVERY candidate + // that passed the window tests, followed by `count_eq`, which reads + // the same bytes again and decides the same thing (`ml >= mls` holds + // exactly when the first `mls` bytes are equal; `ip + mls <= block_end` + // by `ilimit`, so the count's limit covers them). One masked 8-byte + // xor rejects the hash collisions, and the count settles the rest. + // `m < ip` and `ip + 8 <= src.len()` put both words in bounds. + #[cfg(feature = "profile")] + if m < ip && m >= frame_start && ip - m <= window && m + mls <= src.len() { + LDM_CANDS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + } if m < ip && m >= frame_start && ip - m <= window && m + mls <= src.len() - && src[m..m + mls] == src[ip..ip + mls] + && (crate::simd::load_u64_le(src, m) ^ crate::simd::load_u64_le(src, ip)) & smask == 0 { + #[cfg(feature = "profile")] + LDM_COUNTS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); let ml = count_eq(src, m, ip, block_end); if ml >= mls { let offset = (ip - m) as u32; @@ -217,6 +253,21 @@ fn ldm_hash(src: &[u8], ip: usize, hash_log: u32) -> usize { /// is here because it is free, and because the oversight CLASS -- a hand-rolled /// loop beside a better kernel nobody wired in -- is the same one that left the /// xxh64 vector kernel unreachable (V1/D8a). +/// BRICK 18 verdict counters: candidates that passed the window tests (the +/// population the old `memcmp` ran on) and those the 8-byte head let through +/// to `count_eq`. +#[cfg(feature = "profile")] +pub static LDM_CANDS: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +#[cfg(feature = "profile")] +pub static LDM_COUNTS: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); + +/// `(candidates, counted)` since the last call. +#[cfg(feature = "profile")] +pub fn take_ldm_stats() -> (u64, u64) { + use core::sync::atomic::Ordering::Relaxed; + (LDM_CANDS.swap(0, Relaxed), LDM_COUNTS.swap(0, Relaxed)) +} + #[inline] fn count_eq(src: &[u8], m: usize, ip: usize, limit: usize) -> usize { crate::encode::count_match(src, m, ip, limit.min(src.len())) diff --git a/crates/rusty_zstd/src/lib.rs b/crates/rusty_zstd/src/lib.rs index 8eddc1a..8592d4d 100644 --- a/crates/rusty_zstd/src/lib.rs +++ b/crates/rusty_zstd/src/lib.rs @@ -57,9 +57,58 @@ compile_error!( #[cfg(all(feature = "alloc", feature = "std"))] #[inline] pub(crate) fn env_knob(name: &str) -> Result { + // Every read is an OS lookup AND a `String` allocation, for a value fixed + // for the life of the process. A knob read more than once per process has + // a broken cache; this counter is how that is detected rather than + // grepped for. + #[cfg(feature = "profile")] + ENV_READS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); std::env::var(name).map_err(|_| ()) } +/// Cold, outlined: read a knob and PARSE it (trimmed), or `None`. +/// +/// Every knob reader used to spell this chain out at its own call site -- +/// `env_knob(..).ok().and_then(|x| x.trim().parse().ok())` -- and LLVM +/// inlined it, so `std::env::var`, the `String` drop, `trim`'s +/// `is_whitespace` walk and `from_str` were laid out inside the encoder's +/// hottest functions: `find_lazy` carried FIVE `env::var` call sites and +/// THIRTEEN `__rust_dealloc` call sites for values fixed for the life of the +/// process. The hot path of a knob is one atomic load and a compare; this +/// is everything else, behind one call the hot path never takes. +#[cold] +#[inline(never)] +pub(crate) fn env_knob_parse(name: &str) -> Option { + env_knob(name).ok().and_then(|x| x.trim().parse().ok()) +} + +/// Cold, outlined: a boolean knob that is ON unless set to `"0"`. +#[cold] +#[inline(never)] +pub(crate) fn env_knob_not0(name: &str, default: bool) -> bool { + match env_knob(name) { + Ok(v) => v.trim() != "0", + Err(()) => default, + } +} + +/// Cold, outlined: a boolean knob that is ON only when set to `"1"`. +#[cold] +#[inline(never)] +pub(crate) fn env_knob_is1(name: &str) -> bool { + env_knob(name).map(|v| v.trim() == "1").unwrap_or(false) +} + +/// Count of `env_knob` reads -- see the note there. +#[cfg(feature = "profile")] +pub static ENV_READS: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); + +/// Read and clear the env-read counter. +#[cfg(feature = "profile")] +pub fn take_env_reads() -> u64 { + ENV_READS.swap(0, core::sync::atomic::Ordering::Relaxed) +} + /// No-std twin: every knob reads as unset, so every call site takes its /// shipping default. #[cfg(all(feature = "alloc", not(feature = "std")))] @@ -71,6 +120,8 @@ pub(crate) fn env_knob(_name: &str) -> Result { mod bit; mod block; mod compressed; +/// Copy census: how many times does the encoder move each input byte? +pub mod copies; mod decode; #[cfg(feature = "alloc")] mod dict; @@ -82,6 +133,8 @@ mod fse; mod huffman; #[cfg(all(feature = "alloc", feature = "std"))] mod in_bench; +/// Kernel-reach census: does the shipping path actually call each kernel? +pub mod kreach; #[cfg(feature = "alloc")] mod ldm; #[cfg(feature = "std")] @@ -133,6 +186,8 @@ pub use dict::{ public_dict_id, Dictionary, DICT_ID_PUBLIC_MAX, DICT_ID_PUBLIC_MIN, MAGIC_DICTIONARY, }; #[cfg(feature = "profile")] +pub use encode::take_fused; +#[cfg(feature = "profile")] pub use encode::take_row_bucket; #[cfg(feature = "alloc")] pub use encode::{ @@ -145,6 +200,8 @@ pub use in_bench::{ bench_roundtrip, bench_roundtrip_clocked, mbps, mbps_best, time_loops, InProcessBench, LoopTiming, }; +#[cfg(feature = "profile")] +pub use ldm::take_ldm_stats; #[cfg(feature = "alloc")] pub use ldm::{LdmParams, DEFAULT_LONG_WINDOW_LOG}; #[cfg(feature = "std")] @@ -153,9 +210,11 @@ pub use mt::{ JOB_SIZE_MIN, NB_WORKERS_MAX, }; #[cfg(feature = "alloc")] -pub use params::{compression_params, CompressionParameters, Strategy}; +pub use params::{compression_params, set_hash_tight_arm, CompressionParameters, Strategy}; #[cfg(feature = "profile")] pub use rowfind::take_row_walk; +#[cfg(feature = "profile")] +pub use scratch::take_pool_census; #[cfg(feature = "alloc")] pub use seekable::{ compress_seekable, compress_seekable_adv, decompress_frame_at, parse_seek_table, SeekEntry, @@ -240,7 +299,7 @@ pub use encode::{ take_bext, take_envhits, take_ff_arms, take_ff_waste, take_link_tag, take_long_tag, take_long_tag_residual, take_raw_exits, take_raw_margin, take_row_census, take_short_tag_residual, take_step_forfeit, take_tag_reads, take_walk_census, - take_walk_classes, take_walk_signals, FF_LATCH, FF_LAZY_FIRES, + take_walk_classes, take_walk_phantom, take_walk_signals, FF_LATCH, FF_LAZY_FIRES, }; #[doc(hidden)] pub use encode::{take_ent_save, take_n9_basic}; @@ -293,15 +352,16 @@ pub use encode::{ set_dfast_spec_min_arm, set_dfast_step_arm, set_dfast_tag_arm, set_fast_lazy_arm, set_fast_spec_arm, set_finder_scratch_arm, set_g5_arms, set_g5_band_arm, set_g5_fast_arms, set_g5_fast_len_arm, set_g5_opt_arms, set_g5_tiny_arm, set_huff_fast_arm, set_incomp_skip_arm, - set_lazy_fill_arm, set_lazy_fill_stride_arm, set_lazy_fill_threshold_arm, set_lazy_gain_arm, - set_lit_short_arm, set_litpush_arm, set_litpush_hoist_arm, set_long_tag_arm, set_next_long_arm, - set_nl_dispatch_arm, set_nl_off_worse_arm, set_opt_fill_max_arm, set_opt_fill_stride_arm, - set_opt_hoist_arm, set_opt_lit_arm, set_opt_mlbits_arm, set_opt_ops_arm, set_opt_rep_arm, - set_pair_gain_arm, set_pair_hi_arm, set_pair_lo_arm, set_pair_on_arm, set_payload_arm, - set_pipe_arm, set_pipe_rep1_arm, set_prefix_bound_arm, set_prefix_window_arm, set_prime_bt_arm, - set_prime_bt_depth_arm, set_prime_bt_extent_arm, set_prime_bt_tree_arm, set_prime_stride_arm, - set_raw_probe_arm, set_raw_run_min_arm, set_raw_skip_arm, set_rep1_mode, set_rep_reprobe_arm, - set_replen_pipe_arm, set_row_arm, set_row_fill_stride_arm, set_search_log_delta, set_step0_arm, + set_lazy_accel_arm, set_lazy_fill_arm, set_lazy_fill_stride_arm, set_lazy_fill_threshold_arm, + set_lazy_gain_arm, set_lit_short_arm, set_litpush_arm, set_litpush_hoist_arm, set_long_tag_arm, + set_next_long_arm, set_nl_dispatch_arm, set_nl_off_worse_arm, set_opt_fill_max_arm, + set_opt_fill_stride_arm, set_opt_hoist_arm, set_opt_lit_arm, set_opt_mlbits_arm, + set_opt_ops_arm, set_opt_rep_arm, set_pair_gain_arm, set_pair_hi_arm, set_pair_lo_arm, + set_pair_on_arm, set_payload_arm, set_pipe_arm, set_pipe_rep1_arm, set_prefix_bound_arm, + set_prefix_window_arm, set_prime_bt_arm, set_prime_bt_depth_arm, set_prime_bt_extent_arm, + set_prime_bt_tree_arm, set_prime_stride_arm, set_raw_probe_arm, set_raw_run_min_arm, + set_raw_skip_arm, set_rep1_mode, set_rep_reprobe_arm, set_replen_pipe_arm, set_row_arm, + set_row_arm_auto, set_row_fill_stride_arm, set_search_log_delta, set_step0_arm, set_step_forfeit_arm, set_step_probe_arm, set_tag_alloc_arm, set_tag_arm, set_walk_cont_arm, set_walk_first_max_arm, set_walk_rep_max_arm, set_wide_chain_arm, set_wide_first_max_arm, set_wide_spb_min_arm, take_bt_calls, take_bt_iters, take_bt_probe_stats, take_content_signals, @@ -316,7 +376,7 @@ pub use encode::{ pub use encode::{ set_bt_deep_arm, set_bt_deep_min_arm, set_bt_depth_cached_arm, set_bt_depth_target_arm, set_dfast_litpush_arm, set_lit_push_tiers_arm, take_lit_hist, take_lit_push, take_lit_tiers, - take_opt_signals, BT_SPEC_PAIRS, + take_opt_signals, }; #[doc(hidden)] #[cfg(feature = "alloc")] diff --git a/crates/rusty_zstd/src/mt.rs b/crates/rusty_zstd/src/mt.rs index 057b64f..c963e52 100644 --- a/crates/rusty_zstd/src/mt.rs +++ b/crates/rusty_zstd/src/mt.rs @@ -124,7 +124,15 @@ pub fn compress_mt( }, &mut parts, )?; - let mut out = Vec::new(); + // RESERVE the exact total before concatenating. This was `Vec::new()`, so + // the buffer grew to the whole compressed stream by doubling -- and a Vec + // grown to N by doubling copies ~N bytes in reallocs, meaning an + // unreserved concat pays for the compressed output roughly TWICE. The + // total is known: the jobs have already finished and their lengths are + // right here. + let total: usize = parts.iter().map(alloc::vec::Vec::len).sum(); + crate::copies::add(crate::copies::C_MT_CONCAT, total); + let mut out = Vec::with_capacity(total); for p in parts { out.extend_from_slice(&p); } @@ -179,10 +187,16 @@ where let mut done = Vec::new(); loop { let idx = next.fetch_add(1, Ordering::Relaxed); - if idx >= n { + // WIN: `.get` is the SAME test as `idx >= n` -- `n` is a + // copy of `ranges.len()` -- but it also discharges the + // bounds check that followed it. The copy travels into + // this thread closure, and LLVM loses the relation + // between it and the slice's own length across that + // boundary, so the index was tested twice per work item. + let Some(&range) = ranges.get(idx) else { break; - } - done.push((idx, f(idx, ranges[idx])?)); + }; + done.push((idx, f(idx, range)?)); } Ok(done) })); diff --git a/crates/rusty_zstd/src/params.rs b/crates/rusty_zstd/src/params.rs index a97eb78..4f18de5 100644 --- a/crates/rusty_zstd/src/params.rs +++ b/crates/rusty_zstd/src/params.rs @@ -307,6 +307,34 @@ fn row_to_params(row: Row) -> CompressionParameters { } /// Parameters C would pick at `level` for an optional size hint (`None` = unknown / large). +/// How much smaller than C's `windowLog + 1` the hash may be, in bits, when +/// the source length is known. 0 = C's sizing (two buckets per position). +/// DEFAULTS TO 1 (one bucket per position) and applies only to BtLazy2 and +/// above -- see the gate and its measurements at the clamp site. +static HASH_TIGHT_ARM: core::sync::atomic::AtomicU32 = core::sync::atomic::AtomicU32::new(u32::MAX); + +/// Bench hook for the source-sized hash. 0 restores C's sizing. +pub fn set_hash_tight_arm(v: u32) { + HASH_TIGHT_ARM.store(v, core::sync::atomic::Ordering::Relaxed); +} + +#[inline] +fn hash_tight_log() -> u32 { + let v = HASH_TIGHT_ARM.load(core::sync::atomic::Ordering::Relaxed); + if v != u32::MAX { + return v; + } + #[cfg(feature = "std")] + let n: u32 = crate::env_knob("RZSTD_HASH_TIGHT") + .ok() + .and_then(|x| x.trim().parse().ok()) + .unwrap_or(1); + #[cfg(not(feature = "std"))] + let n: u32 = 1; + HASH_TIGHT_ARM.store(n, core::sync::atomic::Ordering::Relaxed); + n +} + pub fn compression_params( level: i32, src_hint: Option, @@ -356,6 +384,57 @@ pub fn compression_params( if p.hash_log > p.window_log + 1 { p.hash_log = p.window_log + 1; } + // SIZE THE HASH FROM THE SOURCE, not just from the window. + // + // C stops at `hashLog <= windowLog + 1`, i.e. TWO hash buckets per + // window position, and we matched that. But once the window has been + // reduced to the source, two buckets per position is two buckets per + // BYTE OF INPUT -- 8 bytes of hash on top of the chain's inherent 4, + // which is exactly the measured 12 bytes of table per input byte. For + // a source that cannot fill those buckets it is memory zeroed and + // never read. + // + // `hash_tight_log()` is the shift off C's sizing: 0 keeps C exactly, + // 1 gives one bucket per position, 2 one per two positions. + // APPLIED TO EVERY STRATEGY. The cost is not uniform, and the + // measurement is what licensed taking it everywhere rather than only + // on the tree ladder: + // + // ```text + // 64K 256K 1M 4M tables + // L1..L3 Fast/DFast +0 +0 +0 +0 0% never bites + // L4 DFast +469 B +0 +0 +0 -50% (64K only) + // L5 Greedy +384 B +0 +0 +0 -33% + // L7 Lazy +393 B +1453 B +0 +0 -33% + // L9 Lazy2 +402 B +1207 B -2522 B +0 -33% + // L13 BtLazy2 +1 B +144 B +0 +0 -25..-33% + // L16 BtOpt +0 +0 +0 +0 -25% + // L19/L22 +0 +0 +0 +0 -25% + // ``` + // + // Fast and DFast are untouched BY CONSTRUCTION -- their `hash_log` is + // already at or below `src_log`, so the clamp never fires. Everything + // that does move costs at most +0.11%, only at 64K-256K, and is zero + // or NEGATIVE from 1 MiB up. Deliberate trade: at most a tenth of a + // percent of ratio for a third of the table. + // + // What it buys: table allocation -25% to -50%, and peak RSS -4.9% to + // -12.5% (L16 at 1 MiB: 32.8 -> 28.7 MB), sampled live. + // + // NOT a speed win, measured and recorded: cutting the table 33% moved + // encode time -1.8%, inside the noise. `vec![0; n]` for a large n takes + // zero pages from the OS rather than memsetting, so the cost scales + // with pages TOUCHED, not pages allocated. + if let Some(n) = src_hint { + let t = hash_tight_log(); + if n > 0 && t > 0 { + let src_log = (n.max(64) - 1).ilog2() + 1; + let want = (src_log + 1).saturating_sub(t).max(6); + if p.hash_log > want { + p.hash_log = want; + } + } + } // `ZSTD_cycleLog`: bt strategies address two slots per position. let bt_scale = u32::from(p.strategy as u32 >= Strategy::BtLazy2 as u32); let cycle_log = p.chain_log.saturating_sub(bt_scale); diff --git a/crates/rusty_zstd/src/prof.rs b/crates/rusty_zstd/src/prof.rs index 1a14855..a15e7bc 100644 --- a/crates/rusty_zstd/src/prof.rs +++ b/crates/rusty_zstd/src/prof.rs @@ -39,9 +39,22 @@ pub enum Stage { DecSeqLoop = 17, /// The trailing literal run after the last sequence. DecSeqTail = 18, + /// STREAMING DECODE wrapper anatomy. These partition `Decompressor:: + /// stream` and exist because the scoped decode stages account for only + /// ~1.09x of a 1.5-1.8x streaming-vs-one-shot gap -- the rest is the + /// wrapper, and nothing was measuring it. Scoped once per `stream()` + /// call (a few hundred per frame), never per block or per byte. + /// `input.extend_from_slice` of the caller's chunk. + StreamInAcc = 19, + /// The decode-until-output-fillable loop (contains the block stages). + StreamProgress = 20, + /// `output.copy_from_slice` out of the decoded window. + StreamOutCopy = 21, + /// `compact_input` + `compact` -- the two reclaim paths. + StreamCompact = 22, } -pub const N_STAGES: usize = 19; +pub const N_STAGES: usize = 23; const NAMES: [&str; N_STAGES] = [ "EncodeTotal", @@ -63,6 +76,10 @@ const NAMES: [&str; N_STAGES] = [ "DecSeqTables", "DecSeqLoop", "DecSeqTail", + "StreamInAcc", + "StreamProgress", + "StreamOutCopy", + "StreamCompact", ]; /// Per-block Z1 harvest row (profile builds only). @@ -108,7 +125,34 @@ pub struct BlockTap { /// Deterministic encode work counts (`codec-six-whys-unknowns`: count before time). #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)] pub struct EncodeCounts { + /// SCOPE WARNING -- this field does NOT mean the same thing in every + /// finder, and a table that divides it by input bytes across levels is + /// comparing two different quantities: + /// + /// * `find_fast_impl_inner` bumps it at the TOP of the scan loop, before + /// the hash is computed -- so at L1 it counts POSITIONS SCANNED. + /// * `find_dfast_impl_inner` bumps it inside `if let Some(m8)`, i.e. + /// only once a tag filter has already returned a candidate -- so at L3 + /// it counts SURVIVORS. + /// + /// So a `probe_hits / hash_probes` "hit rate" reads ~12% at L1 and ~94% + /// at L3 for reasons that are entirely about the DENOMINATOR. For a + /// cross-finder comparison use `encode::take_mm`, whose `MM_TOTAL` is + /// bumped at the loop top in both. See `mfsplit.rs`. pub hash_probes: u64, + /// SCOPE WARNING -- instrumented on the Fast and DFast paths ONLY. + /// + /// `note_hash_fill` is called from `fill_fast_after_match` and + /// `fill_dfast_after_match`. The chain/row inserters that Greedy, Lazy, + /// Lazy2 and BtLazy2 fill through (`MatchTables::lz_insert` and + /// `lz_insert_only`) do NOT report, so this field reads a FALSE ZERO at + /// L5 and above -- not "those finders perform no fills". + /// + /// Deliberately not wired there: `lazyfill.rs` measures 41,742,765 fill + /// inserts at L9, and a `lock xaddq` on each would be the instrument + /// dominating what it measures (the EQ_OPS lesson in `simd::counters`). + /// Wiring it needs a per-block local accumulator flushed once, the shape + /// the DFast fills already use -- not a counter in `lz_insert`. pub hash_fills: u64, pub probe_hits: u64, pub seqs: u64, diff --git a/crates/rusty_zstd/src/scratch.rs b/crates/rusty_zstd/src/scratch.rs index d53a49c..eff6f1f 100644 --- a/crates/rusty_zstd/src/scratch.rs +++ b/crates/rusty_zstd/src/scratch.rs @@ -234,16 +234,85 @@ pub(crate) use scratch_slot; pub(crate) fn pool_take( slot: &'static std::thread::LocalKey>>>, ) -> Vec { - let mut v = slot + let got = slot .try_with(|c| c.try_borrow_mut().ok().and_then(|mut p| p.pop())) .ok() - .flatten() - .unwrap_or_default(); + .flatten(); + // A pool that MISSES allocates, so its hit rate is the whole question: + // a `pool_take` that returns `None` is indistinguishable at the call site + // from never having pooled at all. + #[cfg(feature = "profile")] + { + use core::sync::atomic::Ordering::Relaxed; + if got.is_some() { + POOL_HIT.fetch_add(1, Relaxed); + } else { + POOL_MISS.fetch_add(1, Relaxed); + } + } + let mut v = got.unwrap_or_default(); v.clear(); v } -/// Return a buffer to a bounded thread-local free list (cap 6). +/// Record a take on a pool that keeps its OWN free list (`fse::ct_pool`), +/// so one census covers every pool in the crate rather than just this one. +#[cfg(feature = "profile")] +#[inline] +pub(crate) fn note_pool(hit: bool) { + use core::sync::atomic::Ordering::Relaxed; + if hit { + POOL_HIT.fetch_add(1, Relaxed); + } else { + POOL_MISS.fetch_add(1, Relaxed); + } +} + +/// Pool hit/miss census. A miss is an allocation. +#[cfg(feature = "profile")] +pub static POOL_HIT: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +/// Pool misses -- each one is a fresh allocation. +#[cfg(feature = "profile")] +pub static POOL_MISS: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +/// Buffers handed back with real capacity. +#[cfg(feature = "profile")] +pub static POOL_GIVE: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +/// Buffers handed back with ZERO capacity -- never pooled, so the matching +/// take must allocate. A take/give imbalance shows up here first. +#[cfg(feature = "profile")] +pub static POOL_GIVE_EMPTY: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); +/// Buffers DROPPED because the free list was full. +#[cfg(feature = "profile")] +pub static POOL_DROP: core::sync::atomic::AtomicU64 = core::sync::atomic::AtomicU64::new(0); + +/// Read and clear the pool census: `(hits, misses, drops, gives, give_empty)`. +#[cfg(feature = "profile")] +pub fn take_pool_census() -> (u64, u64, u64, u64, u64) { + use core::sync::atomic::Ordering::Relaxed; + ( + POOL_HIT.swap(0, Relaxed), + POOL_MISS.swap(0, Relaxed), + POOL_DROP.swap(0, Relaxed), + POOL_GIVE.swap(0, Relaxed), + POOL_GIVE_EMPTY.swap(0, Relaxed), + ) +} + +/// How many buffers one slot's free list holds. +/// +/// This was a bare `6` and it was STARVING the pool: a block hands back three +/// ncount headers plus their losing candidates, and anything past the cap is +/// dropped -- freed, so the next `pool_take` that wants it allocates. Measured +/// at 6: **78.2% hit rate, 1,437 misses and 708 drops** over four corpora. +/// +/// REFUTED TWICE, recorded. Raising it to 32 changed hits and misses NOT AT +/// ALL -- first at a 78.2% hit rate (5,167 / 1,437 both ways), and again after +/// two `SC_NORM` leaks were fixed and the rate rose to 89.1% (5,885 / 719 at +/// caps 6, 12 and 32 alike). Only drops move. The misses are first-use per +/// slot and genuine concurrent liveness, not capacity. +pub(crate) const POOL_CAP: usize = 6; + +/// Return a buffer to a bounded thread-local free list. #[cfg(all(feature = "std", feature = "alloc"))] #[inline] pub(crate) fn pool_give( @@ -251,12 +320,23 @@ pub(crate) fn pool_give( v: Vec, ) { if v.capacity() == 0 { + // A zero-capacity vec is not a buffer -- returning it would put an + // empty shell in the pool that the next take has to grow anyway. + #[cfg(feature = "profile")] + POOL_GIVE_EMPTY.fetch_add(1, core::sync::atomic::Ordering::Relaxed); return; } + #[cfg(feature = "profile")] + POOL_GIVE.fetch_add(1, core::sync::atomic::Ordering::Relaxed); let _ = slot.try_with(|c| { if let Ok(mut p) = c.try_borrow_mut() { - if p.len() < 6 { + if p.len() < POOL_CAP { p.push(v); + } else { + // Dropped: the free list is full, so this buffer is freed and + // the next `pool_take` that wants it will allocate. + #[cfg(feature = "profile")] + POOL_DROP.fetch_add(1, core::sync::atomic::Ordering::Relaxed); } } }); diff --git a/crates/rusty_zstd/src/seekable.rs b/crates/rusty_zstd/src/seekable.rs index 416914c..1374408 100644 --- a/crates/rusty_zstd/src/seekable.rs +++ b/crates/rusty_zstd/src/seekable.rs @@ -85,8 +85,13 @@ pub fn compress_seekable_adv( adv: AdvancedOptions, ) -> Result, Error> { let max_frame = max_frame_size.max(1); + // Both of these grew by doubling. The FRAME COUNT is known here, so + // `entries` can be exact; `out` cannot be, because the frames have not been + // compressed yet -- so it is reserved from the FIRST frame's measured size + // in the loop below rather than from a guessed ratio. + let nframes = src.len().div_ceil(max_frame).max(1); let mut out = Vec::new(); - let mut entries: Vec = Vec::new(); + let mut entries: Vec = Vec::with_capacity(nframes); // C6: THE EMPTY-INPUT SPECIAL CASE IS DELETED. It was a full copy of the // loop body below -- `encode_oneshot`, an entry push, an `extend_from_slice` // and its own `append_seek_table` + return -- for a case that IS exactly @@ -122,6 +127,16 @@ pub fn compress_seekable_adv( None }, }); + if out.is_empty() { + // Extrapolate the whole output from what the first frame actually + // compressed to. `saturating_mul` because `nframes` is derived + // from a caller-supplied frame size. + crate::copies::add( + crate::copies::C_MT_REGROW, + zst.len().saturating_mul(nframes), + ); + out.reserve(zst.len().saturating_mul(nframes)); + } out.extend_from_slice(&zst); off = end; if off >= src.len() { diff --git a/crates/rusty_zstd/src/simd.rs b/crates/rusty_zstd/src/simd.rs index 16a3a37..4d06ed5 100644 --- a/crates/rusty_zstd/src/simd.rs +++ b/crates/rusty_zstd/src/simd.rs @@ -132,7 +132,9 @@ pub fn bench_eq_words(a: &[u8], b: &[u8]) -> usize { } /// GATE 15 arm. 0 = shipped (AVX2 where available), 1 = force the word loop, -/// 2 = peek the first 8 bytes before going wide. +/// 2 = peek the first 8 bytes before going wide, 3 = census poison: take +/// the wide dispatch's SCALAR arm -- what a non-AVX2 CPU takes -- so the +/// kernel-reach census can prove its MISS branch actually fires. /// /// The question the CPU-capability dispatch does not answer: AVX2's first loop /// reads 64 bytes per side before it can return, and at L3 the mean match is @@ -186,7 +188,8 @@ mod counters { /// Compare operations executed: wide (32B cmpeq), word (8B), byte. pub(super) static G_OPS: [AtomicU64; 3] = [AtomicU64::new(0), AtomicU64::new(0), AtomicU64::new(0)]; - pub(super) static G_HIST: [AtomicU64; 5] = [ + pub(super) static G_HIST: [AtomicU64; 6] = [ + AtomicU64::new(0), AtomicU64::new(0), AtomicU64::new(0), AtomicU64::new(0), @@ -198,7 +201,7 @@ mod counters { pub(super) calls: Cell, pub(super) wide: Cell, pub(super) ops: [Cell; 3], - pub(super) hist: [Cell; 5], + pub(super) hist: [Cell; 6], } fn fold(c: &Cell, g: &AtomicU64) { @@ -220,6 +223,7 @@ mod counters { Cell::new(0), Cell::new(0), Cell::new(0), + Cell::new(0), ], } } @@ -312,12 +316,12 @@ pub fn take_eq_ops() -> (u64, u64, u64) { ) } -/// Read and clear `(calls, wide_eligible, [<8, 8-31, 32-63, 64-255, 256+])`. +/// Read and clear `(calls, wide_eligible, [<3, 3-7, 8-31, 32-63, 64-255, 256+])`. #[cfg(feature = "profile")] -pub fn take_eqlen_stats() -> (u64, u64, [u64; 5]) { +pub fn take_eqlen_stats() -> (u64, u64, [u64; 6]) { use core::sync::atomic::Ordering::Relaxed; counters::flush_this_thread(); - let mut h = [0u64; 5]; + let mut h = [0u64; 6]; for (i, v) in counters::G_HIST.iter().enumerate() { h[i] = v.swap(0, Relaxed); } @@ -474,6 +478,9 @@ unsafe fn finish_words(a: *const u8, b: *const u8, mut n: usize, max: usize) -> /// This is the "bounds-check tax is ~0" law landing again: LLVM had already /// folded both range checks into six instructions shared by every path. #[inline(always)] +/// No production caller since `count_match` went to raw pointers; kept as +/// the SAFE oracle entry for the kernel tests. +#[allow(dead_code)] pub(crate) fn count_eq_len_ge8(a: &[u8], b: &[u8], max: usize) -> usize { debug_assert!(max >= 8 && a.len() >= max && b.len() >= max); // SAFETY: `max <= a.len()` and `max <= b.len()` are the caller's contract, @@ -559,9 +566,25 @@ pub(crate) unsafe fn count_eq_len_ge8_raw(a: *const u8, b: *const u8, max: usize // one of ~71M calls at L19, to serve a branch taken once per // process. Branching on the raw cache state instead means // nothing is live across anything. + // Arm 3 exists ONLY so the kernel-reach census can prove its + // MISS branch fires. Arm 1 short-circuits above this dispatch, + // so it can show the hit counter going to zero but never + // exercises the scalar side of the tap -- and a counter whose + // failure branch has never run is not yet evidence. This routes + // through the same site a non-AVX2 CPU would take. + if arm == 3 { + crate::kreach::miss(crate::kreach::K_COUNT_EQ_WIDE); + return count_eq_len_words_raw(a, b, 32, max); + } match AVX2_CACHE.load(core::sync::atomic::Ordering::Relaxed) { - 1 => return count_eq_len_avx2(a, b, max), - 2 => return count_eq_len_words_raw(a, b, 32, max), + 1 => { + crate::kreach::hit(crate::kreach::K_COUNT_EQ_WIDE); + return count_eq_len_avx2(a, b, max); + } + 2 => { + crate::kreach::miss(crate::kreach::K_COUNT_EQ_WIDE); + return count_eq_len_words_raw(a, b, 32, max); + } _ => return avx2_first_call(a, b, max), } } @@ -569,15 +592,18 @@ pub(crate) unsafe fn count_eq_len_ge8_raw(a: *const u8, b: *const u8, max: usize { // No `std` means no runtime probe: the ISA is proven at compile // time and there is nothing to dispatch on. + crate::kreach::hit(crate::kreach::K_COUNT_EQ_WIDE); return count_eq_len_avx2(a, b, max); } #[cfg(target_arch = "aarch64")] { // NEON is baseline aarch64. + crate::kreach::hit(crate::kreach::K_COUNT_EQ_WIDE); return count_eq_len_neon(a, b, max); } #[allow(unreachable_code)] { + crate::kreach::miss(crate::kreach::K_COUNT_EQ_WIDE); return count_eq_len_words_raw(a, b, 32, max); } } @@ -601,8 +627,10 @@ unsafe fn avx2_first_call(a: *const u8, b: *const u8, max: usize) -> usize { // SAFETY: contract forwarded unchanged to whichever arm wins. unsafe { if avx2_detect() { + crate::kreach::hit(crate::kreach::K_COUNT_EQ_WIDE); count_eq_len_avx2(a, b, max) } else { + crate::kreach::miss(crate::kreach::K_COUNT_EQ_WIDE); count_eq_len_words_raw(a, b, 32, max) } } @@ -634,22 +662,27 @@ unsafe fn count_eq_len_small(a: *const u8, b: *const u8, max: usize) -> usize { #[cfg(feature = "profile")] #[inline] pub(crate) fn note_eqlen(n: usize) { - // bits = 0..=64; bucket = [<8, 8-31, 32-63, 64-255, 256+]. - // bits<=3 -> 0 | 4..=5 -> 1 | 6 -> 2 | 7..=8 -> 3 | >=9 -> 4 + // bits = 0..=64; bucket = [<3, 3-7, 8-31, 32-63, 64-255, 256+]. + // bits<=2 -> 0 | 3 -> 1 | 4..=5 -> 2 | 6 -> 3 | 7..=8 -> 4 | >=9 -> 5 + // The `<3` split exists for one question: at the FAST finder (mls 5) + // a fused 8-byte head resolves a candidate without the count call + // exactly when n <= 2 (5 + n < 8). Read it with `eqshare`. const BUCKET: [u8; 65] = { - let mut t = [4u8; 65]; + let mut t = [5u8; 65]; let mut i = 0; while i <= 64 { - t[i] = if i <= 3 { + t[i] = if i <= 2 { 0 - } else if i <= 5 { + } else if i == 3 { 1 - } else if i == 6 { + } else if i <= 5 { 2 - } else if i <= 8 { + } else if i == 6 { 3 - } else { + } else if i <= 8 { 4 + } else { + 5 }; i += 1; } diff --git a/crates/rusty_zstd/src/stream.rs b/crates/rusty_zstd/src/stream.rs index 14c1dc3..d392913 100644 --- a/crates/rusty_zstd/src/stream.rs +++ b/crates/rusty_zstd/src/stream.rs @@ -39,6 +39,58 @@ pub static ENC_SLIDE: [core::sync::atomic::AtomicU64; 2] = [ core::sync::atomic::AtomicU64::new(0), core::sync::atomic::AtomicU64::new(0), ]; +/// History multiplier at which the encoder slides its window. +/// +/// `k` means: hold up to `k` windows of history, and on overflow drop back to +/// one. A slide then costs the same as ever but fires every `(k - 1) * window` +/// bytes, so the slide's whole overhead -- memmove, six table clears and the +/// re-prime -- scales as `1 / (k - 1)`. Default 2 (the Section 20 value). +fn enc_slide_mul() -> usize { + match crate::env_knob("RZSTD_ENC_SLIDE_MUL") + .ok() + .and_then(|v| v.parse::().ok()) + { + Some(k) if (2..=8).contains(&k) => k, + _ => 3, + } +} + +/// Ceiling on the EXTRA history held beyond two windows. +/// +/// The slide's cost is per-slide and its frequency is `1 / ((k - 1) * window)`, +/// so the win from raising `k` is large exactly where the window is SMALL and +/// slides are constant, and negligible where the window is huge -- at L22 a +/// 128 MiB window does not slide until 128 MiB of input, which most streams +/// never reach. The memory cost runs the other way: it is `(k - 2) * window`, +/// so a flat multiplier would spend +128 MiB at L22 to remove slides that +/// mostly do not happen. Capping the extra in ABSOLUTE bytes keeps the whole +/// win at every level that slides often and bounds the worst case at +8 MiB. +const SLIDE_EXTRA_MAX: usize = 8 << 20; + +/// Ablation: the decoded-buffer reserve cap. Shipping value 8 MiB; the probe +/// lifts it so `decoded` can be reserved to the full content size, making the +/// streaming buffer structurally identical to the one-shot output buffer. +#[cfg(feature = "std")] +fn dec_reserve_cap() -> u64 { + static C: std::sync::OnceLock = std::sync::OnceLock::new(); + *C.get_or_init(|| { + crate::env_knob("RZSTD_DEC_RESERVE_CAP") + .ok() + .and_then(|v| v.parse::().ok()) + .unwrap_or(8 << 20) + }) +} +#[cfg(not(feature = "std"))] +fn dec_reserve_cap() -> u64 { + 8 << 20 +} + +/// History length at which the window slides, for this `window`. +fn slide_threshold(mul: usize, window: usize) -> usize { + let extra = mul.saturating_sub(2).saturating_mul(window); + 2 * window + extra.min(SLIDE_EXTRA_MAX) +} + /// Read and clear the encoder window-slide census. #[cfg(feature = "profile")] pub fn take_enc_slide() -> [u64; 2] { @@ -96,6 +148,8 @@ pub fn decompress_stream_out_size() -> usize { /// Reusable compressor (one frame at a time). pub struct Compressor { + /// History multiplier at which the window slides; see `set_slide_mul`. + slide_mul: usize, params: CompressionParameters, checksum: bool, pledged: Option, @@ -106,9 +160,15 @@ pub struct Compressor { tables: MatchTables, entropy: EntropyState, hist: Vec, - in_acc: Vec, - /// Consumed prefix of `in_acc`; compacted once per `stream` call. - in_off: usize, + /// End of the ENCODED prefix of `hist`; everything after it is pending + /// input that no block has coded yet. + /// + /// There used to be a separate `in_acc` staging buffer, so every input + /// byte was copied TWICE before encoding began -- once from the caller + /// into `in_acc`, once from `in_acc` into `hist` -- measured at exactly + /// 1.000 + 1.000 bytes per input byte. `hist` was always the buffer the + /// finders read, so staging bought nothing that a cursor does not. + hist_done: usize, out_acc: Vec, /// DECSEQ-II CUT 7 -- read cursor into `out_acc`, same shape as the /// decoder's `in_off` (CUT 5): the per-call `out_acc.drain(..n)` was an @@ -141,6 +201,8 @@ impl Compressor { // `MatchTables::new` no longer allocates it (see ffanat), so do it here. tables.alloc_fast_tags(params); Ok(Self { + // Defaults to the env knob, which defaults to the shipping 2. + slide_mul: enc_slide_mul(), tables, params, checksum: opts.checksum, @@ -151,8 +213,7 @@ impl Compressor { reps: [1, 4, 8], entropy: EntropyState::default(), hist: Vec::new(), - in_acc: Vec::new(), - in_off: 0, + hist_done: 0, out_acc: Vec::new(), out_off: 0, produced_in: 0, @@ -182,6 +243,7 @@ impl Compressor { self.write_dict_id = self.dict_id.is_some(); self.hist.clear(); self.hist.extend_from_slice(dict.content()); + self.hist_done = self.hist.len(); let window = 1usize << self.params.window_log.min(31); crate::encode::prime_tables( &mut self.tables, @@ -206,6 +268,7 @@ impl Compressor { self.write_dict_id = false; self.hist.clear(); self.hist.extend_from_slice(prefix); + self.hist_done = self.hist.len(); let window = 1usize << self.params.window_log.min(31); crate::encode::prime_tables( &mut self.tables, @@ -218,6 +281,18 @@ impl Compressor { } /// Omit Dictionary_ID from the frame header (`--no-dictID`). + /// Override the history multiplier at which the window slides. + /// + /// `k` windows of history are held and a slide drops back to one, so the + /// slide's whole cost -- memmove, six table clears, and the re-prime that + /// dominates it -- scales as `1 / (k - 1)`. It is a MEMORY-for-work trade + /// and it also perturbs compressed size, because the re-prime inserts every + /// position of the retained window and is therefore acting as a table + /// densification pass. Present so both arms can be priced in one process. + pub fn set_slide_mul(&mut self, k: usize) { + self.slide_mul = k.clamp(2, 8); + } + pub fn set_write_dict_id(&mut self, write: bool) { if !self.started { self.write_dict_id = write; @@ -239,7 +314,8 @@ impl Compressor { done: self.out_pending() == 0, }); } - self.in_acc.extend_from_slice(input); + crate::copies::add(crate::copies::C_ENC_IN_ACC, input.len()); + self.hist.extend_from_slice(input); if !self.started { write_frame_header( &mut self.out_acc, @@ -270,7 +346,9 @@ impl Compressor { break; } } - self.compact_in(); + // `compact_in` is gone with `in_acc`: there is no staging buffer to + // reclaim any more. The history buffer's own reclaim is the window + // slide in `emit_block`, which now measures the ENCODED prefix. if flush == Flush::End && !self.ended { if self.pending() == 0 { @@ -302,12 +380,17 @@ impl Compressor { /// 64 KiB -- never a per-call memmove of the unread remainder. fn take_output(&mut self, output: &mut [u8]) -> usize { let n = self.out_pending().min(output.len()); + crate::copies::add(crate::copies::C_ENC_OUT, n); output[..n].copy_from_slice(&self.out_acc[self.out_off..self.out_off + n]); self.out_off += n; if self.out_off == self.out_acc.len() { self.out_acc.clear(); self.out_off = 0; } else if self.out_off >= 64 * 1024 { + crate::copies::add( + crate::copies::C_ENC_OUT_COMPACT, + self.out_acc.len() - self.out_off, + ); self.out_acc.drain(..self.out_off); self.out_off = 0; } @@ -315,24 +398,7 @@ impl Compressor { } fn pending(&self) -> usize { - self.in_acc.len().saturating_sub(self.in_off) - } - - /// CUT 7's input half: this drained on EVERY `stream` call, memmoving the - /// unconsumed remainder each time. Reclaim is now free when everything is - /// consumed and amortised (64 KiB threshold) otherwise; `pending()` and - /// `emit_block` are already offset-aware. - fn compact_in(&mut self) { - if self.in_off == 0 { - return; - } - if self.in_off == self.in_acc.len() { - self.in_acc.clear(); - self.in_off = 0; - } else if self.in_off >= 64 * 1024 { - self.in_acc.drain(..self.in_off); - self.in_off = 0; - } + self.hist.len().saturating_sub(self.hist_done) } fn emit_empty_last_if_needed(&mut self) -> Result<(), Error> { @@ -346,18 +412,22 @@ impl Compressor { } fn emit_block(&mut self, take: usize, last: bool) -> Result<(), Error> { - let block_start = self.hist.len(); + // No copy here any more: the bytes are already in `hist`, appended + // by `stream`. This advances a cursor instead, and the checksum is + // taken over exactly the block rather than "to the end of hist", + // which now has pending bytes past it. + let block_start = self.hist_done; + let block_end = block_start + take; if take > 0 { - let end = self.in_off + take; - self.hist.extend_from_slice(&self.in_acc[self.in_off..end]); - self.xxh.update(&self.hist[block_start..]); - self.in_off = end; + self.xxh.update(&self.hist[block_start..block_end]); + self.hist_done = block_end; } let window = 1usize << self.params.window_log.min(31); encode_block_from_scratch( &mut self.out_acc, &self.hist, block_start, + block_end, self.params, &mut self.tables, &mut self.reps, @@ -382,8 +452,23 @@ impl Compressor { // valid frames; the round-trip, the external decoder and the size are // the gate). One-shot output is untouched -- `emit_block` is // streaming-only. - if self.hist.len() >= 2 * window { - let drop = self.hist.len() - window; + // SECTION 20b -- the same trade, one notch further, made MEASURABLE. + // Section 20 moved the trigger from `hist > window` (a slide on every + // block) to `hist >= 2 * window`, which cut webster from 240 slides and + // 503 MB memmoved to 15 slides and 31 MB. The cost per slide is + // unchanged -- memmove the window, zero six tables, re-prime the whole + // window -- so the ONLY remaining lever on it is how often it fires, + // and that is linear in this multiplier: at `k * window` a slide + // happens every `(k - 1) * window` bytes. + // + // It is a MEMORY trade, not a free win: `k` windows of history are held + // instead of two. So it is a knob with a shipping default rather than a + // constant, and `streamcopies.rs` prices both arms. + // Measured on `hist_done`, not `hist.len()`: the tail past the cursor + // is pending input that has not been coded, and dropping any of it + // would silently lose caller bytes. + if self.hist_done >= slide_threshold(self.slide_mul, window) { + let drop = self.hist_done - window; #[cfg(feature = "profile")] { ENC_SLIDE[0].fetch_add(1, core::sync::atomic::Ordering::Relaxed); @@ -392,12 +477,14 @@ impl Compressor { core::sync::atomic::Ordering::Relaxed, ); } + crate::copies::add(crate::copies::C_HIST_SLIDE, self.hist.len() - drop); self.hist.drain(..drop); + self.hist_done -= drop; self.tables.reset(); crate::encode::prime_tables( &mut self.tables, &self.hist, - self.hist.len(), + self.hist_done, window, self.params, ); @@ -484,7 +571,11 @@ impl Decompressor { output: &mut [u8], end: bool, ) -> Result { - self.input.extend_from_slice(input); + crate::copies::add(crate::copies::C_DEC_IN_ACC, input.len()); + { + let _s = crate::prof::scope(crate::prof::Stage::StreamInAcc); + self.input.extend_from_slice(input); + } // SECTION 19 BRICK A -- decode no further than the caller can drink. // The old exit only fired when `output` was EMPTY, so a caller feeding // a whole frame in one call had ALL of it decoded into `decoded` @@ -493,21 +584,34 @@ impl Decompressor { // once the pending bytes can fill `output` bounds `decoded` at // ~output + window + one block, and later calls resume from `input` // exactly where this one stopped. - loop { - let have = self.decoded.len() - self.decoded_off; - if have > 0 && have >= output.len() { - break; - } - if !self.progress()? { - break; + { + let _s = crate::prof::scope(crate::prof::Stage::StreamProgress); + loop { + let have = self.decoded.len() - self.decoded_off; + if have > 0 && have >= output.len() { + break; + } + if !self.progress()? { + break; + } } } - self.compact_input(); + { + let _s = crate::prof::scope(crate::prof::Stage::StreamCompact); + self.compact_input(); + } let avail = self.decoded.len() - self.decoded_off; let n = avail.min(output.len()); - output[..n].copy_from_slice(&self.decoded[self.decoded_off..self.decoded_off + n]); + crate::copies::add(crate::copies::C_DEC_OUT, n); + { + let _s = crate::prof::scope(crate::prof::Stage::StreamOutCopy); + output[..n].copy_from_slice(&self.decoded[self.decoded_off..self.decoded_off + n]); + } self.decoded_off += n; - self.compact(); + { + let _s = crate::prof::scope(crate::prof::Stage::StreamCompact); + self.compact(); + } if end && self.in_avail() != 0 && self.header.is_none() && n == 0 && avail == 0 { return Err(Error::UnexpectedEof); } @@ -537,10 +641,45 @@ impl Decompressor { &self.input[self.in_off..] } + /// STREAMING-VS-ONE-SHOT GAP, measured and still OPEN. Streaming decode + /// runs at 0.703-0.776x of `decompress_into` on identical bytes (ABBA + /// interleaved, null arm 0.95-1.08x, z = -1.67 to -3.00). Eight causes + /// have been eliminated by measurement, so none of these is worth + /// re-testing without new information: + /// + /// 1. copy traffic -- cut 74% (9.87 -> 2.53 B/output), ratio unchanged + /// 2. structural re-entry -- stage call counts are IDENTICAL (256/256) + /// 3. a single hot stage -- scoped stages grow only 1.09x + /// 4. the decoded-window compaction -- ablated, no change + /// 5. per-call overhead -- 32x fewer `stream` calls, no change + /// 6. buffer reallocation -- the header-time reserve already exists + /// 7. buffer SHAPE -- made structurally one-shot-like, gap persists + /// 8. the content checksum -- disabled, no change + /// + /// A ninth, the benchmark itself, WAS real and is why the figure above is + /// lower than first reported: a harness that fed a chunk and read once + /// under-drained and inflated the gap to ~1.8x. The next instrument is a + /// sampling profiler on the two binaries; the stage profiler cannot + /// resolve it (its rdtsc tax is 27-29% of wall and compresses the + /// measured 1.4x into 1.04x). + /// /// CUT 5's amortiser: reclaim consumed input only when it is all consumed /// (a `clear`, no memmove) or the dead prefix has grown past 64 KiB -- so /// the per-unit O(remaining) drains become O(1) cursor bumps and the total - /// moved is bounded by the bytes fed, not units x remaining. + /// moved is genuinely bounded by the bytes fed. + /// + /// `2 * in_off >= len` is what makes that claim true, and it was missing. + /// The trigger fired on an ABSOLUTE dead prefix (64 KiB) while the drain + /// memmoves the LIVE remainder -- and Brick A deliberately stops decoding + /// the moment the caller's buffer can be filled, so that remainder grows + /// against a fixed trigger. Measured before the fix, 32 MiB streamed with + /// a 64 KiB feed: **244 MB memmoved on webster, 7.63 bytes per OUTPUT + /// byte** -- the O(n^2) front-drain this module's own header warns about, + /// one level below where CUT 5 removed it. + /// + /// Requiring the reclaim to cover the move also bounds the buffer: the + /// live tail is never more than half, so `input` holds at most ~2x what + /// the caller has fed ahead of consumption. fn compact_input(&mut self) { if self.in_off == 0 { return; @@ -548,7 +687,23 @@ impl Decompressor { if self.in_off == self.input.len() { self.input.clear(); self.in_off = 0; - } else if self.in_off >= 64 * 1024 { + // `3 * dead >= 2 * total` means the dead prefix is at least TWICE the + // live tail, so each compaction reclaims twice what it moves rather + // than merely matching it -- the same frequency lever as the decoded + // window above, and it halves this traffic again for one more buffer's + // worth of held input. The bound stays real: the live tail is never + // more than a third, so `input` holds at most ~1.5x what the caller has + // fed ahead. + } else if self.in_off >= 64 * 1024 && 3 * self.in_off >= 2 * self.input.len() { + // Counted AT the drain, so it records bytes actually memmoved. An + // earlier version of this tap sat in `stream()` and recorded + // `input.len() - in_off` once per call -- the standing unconsumed + // input, a LEVEL summed as though it were a FLOW. It read 15.27 + // "bytes per output byte" and meant nothing. + crate::copies::add( + crate::copies::C_DEC_IN_COMPACT, + self.input.len() - self.in_off, + ); self.input.drain(..self.in_off); self.in_off = 0; } @@ -647,7 +802,7 @@ impl Decompressor { .content_size .map(|cs| cs.saturating_add(u64::from(h.block_size_max())).min(keep)) .unwrap_or(keep) - .min(8 << 20) as usize; + .min(dec_reserve_cap()) as usize; self.decoded.reserve(want); } self.header = Some(h); @@ -763,7 +918,21 @@ impl Decompressor { // compaction reclaim at least as much as it moves, so total traffic is // bounded by ~1x the decoded bytes, for at most one extra window of // memory held. - if drop >= window.max(64 * 1024) { + // SECTION 19c -- the same frequency lever the ENCODER slide took, and + // strictly cheaper here. Brick B made each compaction reclaim at least + // as much as it moves, bounding traffic at ~1x the decoded bytes. + // Waiting for TWO windows of dead prefix halves how often it fires and + // so halves that bound, for one more window of memory. + // + // Unlike the encoder's slide this has NO ratio cost: the encoder's + // slide re-primes the match tables, so sliding less often changes which + // matches are found and costs 0.06-0.14% size. Decode output is fixed + // by the bitstream -- the only thing that changes is when the buffer is + // reclaimed. The extra is capped in ABSOLUTE bytes for the same reason + // as the encoder's: the win scales with compaction FREQUENCY (high when + // the window is small) and the memory cost with window SIZE. + let extra = window.min(SLIDE_EXTRA_MAX); + if drop >= (window + extra).max(64 * 1024) { #[cfg(feature = "profile")] { DEC_COMPACT[0].fetch_add(1, core::sync::atomic::Ordering::Relaxed); @@ -772,6 +941,7 @@ impl Decompressor { core::sync::atomic::Ordering::Relaxed, ); } + crate::copies::add(crate::copies::C_DEC_COMPACT, self.decoded.len() - drop); self.decoded.drain(..drop); self.decoded_off -= drop; if drop <= self.frame_start { @@ -792,6 +962,38 @@ impl Default for Decompressor { #[cfg(test)] mod tests { + /// The slide threshold must hold the extra history where slides are + /// FREQUENT and refuse to at high levels, where the window is huge and + /// slides are rare. A flat multiplier costs +128 MiB at L22 to remove + /// slides a 128 MiB window mostly never performs. + #[test] + fn slide_threshold_caps_the_extra_history() { + // Small windows: the full extra window is held. + for wlog in 19..=23u32 { + let w = 1usize << wlog; + let t = super::slide_threshold(3, w); + let extra = t - 2 * w; + assert!( + extra <= super::SLIDE_EXTRA_MAX, + "wlog {wlog}: extra {extra} exceeds the cap" + ); + assert_eq!(extra, w.min(super::SLIDE_EXTRA_MAX)); + } + // L22-class window: capped, NOT 3x. + let w = 1usize << 27; + let t = super::slide_threshold(3, w); + assert_eq!(t, 2 * w + super::SLIDE_EXTRA_MAX); + assert!( + t < 3 * w, + "a flat 3x would cost a whole extra 128 MiB window" + ); + // k=2 reproduces the pre-change threshold exactly, at every size. + for wlog in 10..=27u32 { + let w = 1usize << wlog; + assert_eq!(super::slide_threshold(2, w), 2 * w); + } + } + use super::*; use crate::compress; diff --git a/crates/rusty_zstd/src/train.rs b/crates/rusty_zstd/src/train.rs index 041acfe..32f391f 100644 --- a/crates/rusty_zstd/src/train.rs +++ b/crates/rusty_zstd/src/train.rs @@ -143,15 +143,31 @@ fn k_candidates(k: u32, d: usize, steps: u32, max_dict: usize) -> Vec { } fn fallback_content(samples: &[&[u8]], max_dict: usize) -> Vec { - let mut cat = Vec::new(); + // Two copies became one. `Vec::new()` grew to the whole sample set by + // doubling (~1x the samples in realloc traffic), and the tail slice was + // then copied into a SECOND allocation. The total is known from the slice + // lengths, and only the last `max_dict` bytes are ever kept -- so reserve + // exactly what is needed and drop the head in place. + let total: usize = samples.iter().map(|s| s.len()).sum(); + let mut cat = Vec::with_capacity( + total + .min(max_dict.saturating_mul(2)) + .max(total.min(1 << 20)), + ); for s in samples { cat.extend_from_slice(s); + // Keeping only the tail bounds the buffer at ~2x `max_dict` instead of + // the whole sample set, which is the real memory win here. + if cat.len() > max_dict.saturating_mul(2) { + let drop = cat.len() - max_dict; + cat.drain(..drop); + } } if cat.len() > max_dict { - cat[cat.len() - max_dict..].to_vec() - } else { - cat + let drop = cat.len() - max_dict; + cat.drain(..drop); } + cat } fn hash_dmer(src: &[u8], pos: usize, d: usize, f: u32) -> usize { @@ -171,15 +187,24 @@ fn hash_dmer(src: &[u8], pos: usize, d: usize, f: u32) -> usize { // runtime-length subslice does not, by either spelling.** The array turns a // dynamic bound into a static one. A subslice just moves the dynamic bound. // Every remaining pad in this crate is the second shape. + // WIN: walk the tail as an ITERATOR instead of indexing `src[pos + i]`. + // The note above records that a runtime-length SUBSLICE does not retire + // these pads -- it only moves the dynamic bound -- and that is still true. + // An iterator is a different construction: it carries no index to prove, so + // the bounds checks and their panic pads have nothing to guard. `take` and + // `skip` reproduce the old loop ranges exactly: + // `take(d.min(8))` == `0..d.min(8).min(tail.len())` + // `take(d).skip(8)` == `8..d.min(tail.len())` + // and `tail.len() == src.len().saturating_sub(pos)` for every `pos`. + let tail = src.get(pos..).unwrap_or(&[]); let mut v = 0u64; - let n = d.min(8).min(src.len().saturating_sub(pos)); - for i in 0..n { - v |= u64::from(src[pos + i]) << (8 * i); + for (i, &b) in tail.iter().take(d.min(8)).enumerate() { + v |= u64::from(b) << (8 * i); } if d > 8 { let mut acc = 0u64; - for i in 8..d.min(src.len().saturating_sub(pos)) { - acc = acc.wrapping_mul(131).wrapping_add(u64::from(src[pos + i])); + for &b in tail.iter().take(d).skip(8) { + acc = acc.wrapping_mul(131).wrapping_add(u64::from(b)); } v ^= acc; } @@ -188,15 +213,24 @@ fn hash_dmer(src: &[u8], pos: usize, d: usize, f: u32) -> usize { } fn packed_dmer(src: &[u8], pos: usize, d: usize) -> u64 { + // WIN: walk the tail as an ITERATOR instead of indexing `src[pos + i]`. + // The note above records that a runtime-length SUBSLICE does not retire + // these pads -- it only moves the dynamic bound -- and that is still true. + // An iterator is a different construction: it carries no index to prove, so + // the bounds checks and their panic pads have nothing to guard. `take` and + // `skip` reproduce the old loop ranges exactly: + // `take(d.min(8))` == `0..d.min(8).min(tail.len())` + // `take(d).skip(8)` == `8..d.min(tail.len())` + // and `tail.len() == src.len().saturating_sub(pos)` for every `pos`. + let tail = src.get(pos..).unwrap_or(&[]); let mut v = 0u64; - let n = d.min(8).min(src.len().saturating_sub(pos)); - for i in 0..n { - v |= u64::from(src[pos + i]) << (8 * i); + for (i, &b) in tail.iter().take(d.min(8)).enumerate() { + v |= u64::from(b) << (8 * i); } if d > 8 { let mut acc = 0u64; - for i in 8..d.min(src.len().saturating_sub(pos)) { - acc = acc.wrapping_mul(131).wrapping_add(u64::from(src[pos + i])); + for &b in tail.iter().take(d).skip(8) { + acc = acc.wrapping_mul(131).wrapping_add(u64::from(b)); } v ^= acc; } @@ -340,15 +374,18 @@ where break; } } - let mut content = Vec::new(); + // Same shape as `fallback_content`: an unreserved concat followed by a + // second full copy of the tail. The segment lengths are already known. + let total: usize = segments.iter().map(alloc::vec::Vec::len).sum(); + let mut content = Vec::with_capacity(total.min(max_dict).max(total.min(1 << 20))); for seg in segments.iter().rev() { content.extend_from_slice(seg); } if content.len() > max_dict { - content[content.len() - max_dict..].to_vec() - } else { - content + let drop = content.len() - max_dict; + content.drain(..drop); } + content } fn finalize_dictionary( @@ -373,7 +410,11 @@ fn finalize_dictionary( } let cap = max_dict - header_len; if content.len() > cap { - content = content[content.len() - cap..].to_vec(); + // Was `content[content.len() - cap..].to_vec()` -- a fresh allocation + // and a full copy to discard a prefix. `drain` moves the tail down in + // place and keeps the allocation. + let drop = content.len() - cap; + content.drain(..drop); } let clen = content.len() as u32; let mut reps = harvested.reps; diff --git a/crates/rusty_zstd/src/xxh64.rs b/crates/rusty_zstd/src/xxh64.rs index 412041c..9521840 100644 --- a/crates/rusty_zstd/src/xxh64.rs +++ b/crates/rusty_zstd/src/xxh64.rs @@ -261,6 +261,13 @@ where { census::HYBRID_BYTES.fetch_add(n as u64, core::sync::atomic::Ordering::Relaxed); census::HYBRID_CALLS.fetch_add(1, core::sync::atomic::Ordering::Relaxed); + // Only a call that actually consumed a tile reached the kernel. A + // sub-tile input declines here and is served by the scalar remainder + // walk BY DESIGN -- scoring that as a kernel hit would inflate the + // share with zero-byte calls. + if n > 0 { + crate::kreach::hit(crate::kreach::K_XXH_STRIPE); + } } n } @@ -304,6 +311,12 @@ fn stripes_hybrid(input: &[u8], v: &mut [u64; 4]) -> usize { }); } } + // Reached only when NO vector arm exists for this build/CPU (or the bench + // knob forced it off). That is a genuine routing miss, unlike the sub-tile + // decline above -- but only when there was a whole tile's work to do. + if input.len() >= PRE_TILE { + crate::kreach::miss(crate::kreach::K_XXH_STRIPE); + } let _ = (input, v); 0 } diff --git a/crates/rusty_zstd/tests/c_cross.rs b/crates/rusty_zstd/tests/c_cross.rs index 078e9fe..0104ab1 100644 --- a/crates/rusty_zstd/tests/c_cross.rs +++ b/crates/rusty_zstd/tests/c_cross.rs @@ -249,55 +249,12 @@ fn compression_is_independent_of_call_history() { } } -/// REGRESSION (2026-08-19): the binary-tree finder dispatches to a const-generic -/// specialisation keyed on `(hash_log, chain_log)`, falling back to a slower -/// hand-written runtime body (279 instructions / 4 variable shifts against the -/// specialisation's 260 / 1). Both parameters are DERIVED FROM THE INPUT SIZE, -/// and the original coverage proof varied only the level -- at one size, the -/// 2 MiB corpus prefix. Measured across the size axis, 24 of 64 (size, level) -/// cells fell through: every input at 64 KiB, 512 KiB and 1 MiB, at every bt -/// level, ran the slow body. -/// -/// Asserted against `BT_SPEC_PAIRS`, which is generated from the SAME macro list -/// as the dispatch arms, so this cannot pass while a pair is missing from the -/// dispatch. It deliberately does NOT use the call counters: those are gated -/// behind `--features profile`, so a counter-based version of this test passed -/// vacuously with a pair removed. -#[test] -fn bt_specialisation_covers_every_input_size() { - let mut uncovered = Vec::new(); - let mut n: u64 = 1024; - while n <= (64 << 20) { - for lvl in [13i32, 14, 15, 16, 17, 18, 19, 20, 21, 22] { - let p = rusty_zstd::compression_params(lvl, Some(n)).unwrap(); - let pair = (p.hash_log.min(24), p.chain_log.min(24)); - if !rusty_zstd::BT_SPEC_PAIRS.contains(&pair) { - uncovered.push((n >> 10, lvl, pair)); - } - } - n += (n / 4).max(1024); - } - assert!( - uncovered.is_empty(), - "bt specialisation misses (KiB, level, (hash_log, chain_log)): {uncovered:?}" - ); - - // and the bytes must not depend on which body served the call - let big: Vec = (0..(3 << 20) as u32) - .map(|i| (i.wrapping_mul(2_654_435_761) >> 13) as u8) - .collect(); - for &sz in &[64 << 10, 512 << 10, 1 << 20, 3 << 20] { - let src = &big[..sz.min(big.len())]; - for lvl in [13i32, 17, 19, 22] { - rusty_zstd::set_bt_spec_arm(false); - let a = rusty_zstd::compress(src, lvl).unwrap(); - rusty_zstd::set_bt_spec_arm(true); - let b = rusty_zstd::compress(src, lvl).unwrap(); - assert_eq!(a, b, "specialised body differs from runtime at {sz} L{lvl}"); - assert_eq!(rusty_zstd::decompress(&b).unwrap(), src); - } - } -} +// `bt_specialisation_covers_every_input_size` was removed in brick 8. It +// asserted every reachable `(hash_log, chain_log)` pair against +// `BT_SPEC_PAIRS`, but the dispatch that list fed had already been retired +// (`bt_resolve` returned the runtime body on every path), so the test was +// guarding a phantom: it passed while selecting nothing. The runtime body is +// exercised by every other bt-level test in this file. /// REGRESSION (2026-08-19, GATE 18 step 3): `compress_with_params` accepts a /// `CompressionParameters` struct and applies NO validation of its own. Every diff --git a/crates/rusty_zstd/tests/env_reads_gate.rs b/crates/rusty_zstd/tests/env_reads_gate.rs new file mode 100644 index 0000000..63f1109 --- /dev/null +++ b/crates/rusty_zstd/tests/env_reads_gate.rs @@ -0,0 +1,39 @@ +//! A knob must be read from the environment ONCE PER PROCESS, not per block. +//! +//! Every read is an OS lookup and a `String` allocation for a value fixed for +//! the life of the process. This crate has been bitten by the per-call shape +//! repeatedly -- one instance is recorded as having cost 60% of L19 encode -- +//! and the newest one hid behind a cache whose sentinel COLLIDED with the value +//! it cached: `dfast_step_forced` stored 0 for "cached" while 0 was also what an +//! unset knob resolves to, so the cache never took. +//! +//! Grepping cannot catch that. Counting can: a correctly cached knob costs a +//! fixed number of reads no matter how much data is compressed, so if the count +//! SCALES WITH INPUT SIZE something is re-reading per block. +#![cfg(feature = "profile")] + +#[test] +fn env_knob_reads_do_not_scale_with_input() { + let base: Vec = (0..(1u32 << 20)) + .map(|i| (i as u8) ^ (i >> 5) as u8) + .collect(); + + // Warm every cache first: the first compress legitimately reads each knob. + let _ = rusty_zstd::compress(&base[..1 << 16], 3).expect("warm"); + let _ = rusty_zstd::take_env_reads(); + + let small = rusty_zstd::compress(&base[..1 << 17], 3).expect("small"); + let n_small = rusty_zstd::take_env_reads(); + let big = rusty_zstd::compress(&base, 3).expect("big"); + let n_big = rusty_zstd::take_env_reads(); + assert!(!small.is_empty() && !big.is_empty()); + + // 8x the input must not cost meaningfully more reads. A per-block read + // would scale with the block count, i.e. ~8x here. + assert!( + n_big <= n_small + 2, + "env reads scale with input: {n_small} for 128 KiB, {n_big} for 1 MiB -- \ + a knob is being re-read per block. Check for a cache whose sentinel \ + collides with the knob's default value." + ); +} diff --git a/crates/rusty_zstd/tests/kreach_gate.rs b/crates/rusty_zstd/tests/kreach_gate.rs new file mode 100644 index 0000000..006a375 --- /dev/null +++ b/crates/rusty_zstd/tests/kreach_gate.rs @@ -0,0 +1,260 @@ +//! STANDING GATE: every shipping dispatch site must ROUTE to its kernel. +//! +//! This is the gate whose absence let a real defect live for months. The AVX2 +//! xxh64 kernel in this crate was reachable only from a free function whose +//! callers were one unit test and one benchmark; the encoder, decoder and +//! streaming API all took the scalar route, and the DECODE side ran the +//! kernel on 0% of its bytes. Every other gate passed the whole time -- +//! byte-identity passes because the two paths agree BY DESIGN, the round-trip +//! passes, conformance passes, and an arm-toggle A/B reads FLAT, which looks +//! exactly like "this kernel does not help" and gets written down as a +//! refutation nobody revisits. +//! +//! A count is the only instrument that separates "the kernel does not help" +//! from "the arm is not wired to anything". So this test counts. +//! +//! ONE `#[test]` IN THIS FILE, DELIBERATELY. The census counters are +//! process-global; cargo runs the tests inside one binary in parallel, so a +//! second test here would interleave its compressions with this one's and +//! corrupt both counts. Separate test binaries are separate processes and do +//! not interfere. +//! +//! The gate SKIPS a slot whose ISA the host CPU does not have, rather than +//! failing it -- a runner without AVX2 is not a routing defect. What it must +//! never do is pass silently because nothing ran, so it also asserts that the +//! sites it does check were actually exercised. +#![cfg(feature = "profile")] + +use rusty_zstd::kreach::{self, N_SLOTS, SLOT_NAMES}; + +/// Slots that need BMI2 on the host to be reachable. +const NEEDS_BMI2: [usize; 8] = [ + kreach::K_FIND_FAST, + kreach::K_EMIT_FAST_SEQ, + kreach::K_FSE_CTABLE, + kreach::K_FSE_WEIGHTS, + kreach::K_HUF_ENC, + kreach::K_DEC_SEQ, + kreach::K_HUF_DEC4X, + kreach::K_HUF_DEC4X1, +]; + +/// Slots that need AVX2 (x86) or NEON (aarch64). +const NEEDS_VEC: [usize; 2] = [kreach::K_COUNT_EQ_WIDE, kreach::K_XXH_STRIPE]; + +fn have_bmi2() -> bool { + #[cfg(all(target_arch = "x86_64", feature = "std"))] + { + std::is_x86_feature_detected!("bmi2") && std::is_x86_feature_detected!("lzcnt") + } + #[cfg(not(all(target_arch = "x86_64", feature = "std")))] + { + false + } +} + +fn have_vec() -> bool { + #[cfg(all(target_arch = "x86_64", feature = "std"))] + { + std::is_x86_feature_detected!("avx2") + } + #[cfg(target_arch = "aarch64")] + { + true // NEON is baseline in ARMv8-A. + } + #[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))] + { + false + } +} + +/// Content that actually reaches the sites under test: long repeats so the +/// match finder runs its wide common-prefix arm, a skewed literal alphabet so +/// Huffman and FSE both build and code real tables, and enough bytes to clear +/// the xxh64 tile threshold several times over. +fn corpus() -> Vec { + let mut v = Vec::with_capacity(4 << 20); + let words: [&str; 8] = [ + "the ", "quick ", "brown ", "fox ", "jumps ", "over ", "lazy ", "dog ", + ]; + let mut x: u64 = 0x9E37_79B9_7F4A_7C15; + while v.len() < (4 << 20) { + x = x + .wrapping_mul(6364136223846793005) + .wrapping_add(1442695040888963407); + let pick = (x >> 33) as usize % words.len(); + v.extend_from_slice(words[pick].as_bytes()); + // Periodic long repeats: these are what drive matches past 64 bytes, + // which is the only way the wide `count_eq_len` arm is entered at all. + if (x >> 60) & 7 == 0 { + let take = v.len().min(4096); + let start = v.len() - take; + v.extend_from_within(start..start + take); + } + } + v +} + +#[test] +fn every_dispatch_site_routes_to_its_kernel() { + let src = corpus(); + // SELF-VERIFICATION. An assertion that has never fired is not evidence: + // a detached tap and a perfectly-routed kernel both print 100%. Setting + // RZSTD_KREACH_POISON=1 forces every arm with a knob onto its scalar + // side, and this test MUST then fail. Run it that way after touching any + // dispatch site -- see CONTRIBUTING/CHANGELOG for the one-liner. + if std::env::var_os("RZSTD_KREACH_POISON").is_some() { + eprintln!("POISON: arms forced scalar; this test is EXPECTED to fail"); + rusty_zstd::set_xxh_avx2_arm(false); + rusty_zstd::set_seqloop_avx2_arm(false); + rusty_zstd::set_eqlen_arm(3); + } + let bmi2 = have_bmi2(); + let vec = have_vec(); + eprintln!( + "host ISA: bmi2={bmi2} vec(avx2/neon)={vec}, corpus {} B", + src.len() + ); + + let mut enc = [(0u64, 0u64); N_SLOTS]; + let mut dec = [(0u64, 0u64); N_SLOTS]; + + // ONE LEVEL PER MATCH-FINDER STRATEGY, and asserted to be so. + // + // This was `[1, 3, 9]` under a comment claiming it covered "the distinct + // match-finder strategies". It resolves to Fast, DFast and Lazy2 -- three + // of eight. Greedy (L5), Lazy (L7), BtLazy2 (L13), BtOpt (L16) and + // BtUltra2 (L19) were never compressed here, so any kernel reached only + // from `find_greedy`, `find_lazy`, `find_bt_lazy` or `find_opt` scored + // (0 kernel, 0 scalar) -- and the loop below SKIPS a slot with `h + m == + // 0` as "not exercised on this side". A dispatch that never took its twin + // in those finders would have passed this gate on silence, which is + // exactly the failure the poison self-check exists to prevent elsewhere. + // + // The high levels take a smaller prefix: BtOpt and BtUltra2 are orders of + // magnitude slower per byte, and reach is a RATIO -- it does not need the + // full corpus to be measured, only enough traffic to be non-zero. + const LEVELS: &[(i32, usize)] = &[ + (1, 4 << 20), + (3, 4 << 20), + (5, 4 << 20), + (7, 4 << 20), + (9, 4 << 20), + (13, 2 << 20), + (16, 1 << 20), + (18, 1 << 20), + (19, 1 << 20), + ]; + { + let mut seen: Vec = LEVELS + .iter() + .filter_map(|&(l, _)| rusty_zstd::compression_params(l, None).ok()) + .map(|p| format!("{:?}", p.strategy)) + .collect(); + seen.sort(); + seen.dedup(); + const WANT: &[&str] = &[ + "Fast", "DFast", "Greedy", "Lazy", "Lazy2", "BtLazy2", "BtOpt", "BtUltra", "BtUltra2", + ]; + let missing: Vec<&str> = WANT + .iter() + .copied() + .filter(|w| !seen.iter().any(|x| x == w)) + .collect(); + assert!( + missing.is_empty(), + "kreach_gate LEVELS no longer cover every match finder: missing \ + {missing:?} (covered: {seen:?}). A kernel reached only from a \ + missing finder would score 0/0 and be SKIPPED, so this gate would \ + pass on silence." + ); + eprintln!("strategies exercised: {}", seen.join(", ")); + } + for &(lvl, cap) in LEVELS { + let s = &src[..src.len().min(cap)]; + let _ = kreach::take(); + let z = rusty_zstd::compress(s, lvl).expect("compress"); + let e = kreach::take(); + let out = rusty_zstd::decompress(&z).expect("decompress"); + let d = kreach::take(); + assert_eq!(out, s, "L{lvl} roundtrip"); + for i in 0..N_SLOTS { + enc[i].0 += e[i].0; + enc[i].1 += e[i].1; + dec[i].0 += d[i].0; + dec[i].1 += d[i].1; + } + } + + let mut checked = 0usize; + let mut failures = Vec::new(); + for (side, t) in [("encode", &enc), ("decode", &dec)] { + for i in 0..N_SLOTS { + let needed = if NEEDS_VEC.contains(&i) { + vec + } else if NEEDS_BMI2.contains(&i) { + bmi2 + } else { + true + }; + let (h, m) = t[i]; + if h + m == 0 { + continue; // not exercised on this side; other sides cover it + } + if !needed { + eprintln!( + " {side}/{}: SKIPPED, host lacks the ISA ({h} kernel, {m} scalar)", + SLOT_NAMES[i].0 + ); + continue; + } + checked += 1; + let pct = 100.0 * h as f64 / (h + m) as f64; + eprintln!( + " {side}/{:<22} {h:>12} kernel {m:>10} scalar {pct:>7.2}%", + SLOT_NAMES[i].0 + ); + if pct < 95.0 { + failures.push(format!( + "{side}/{} routed only {pct:.2}% of calls to its kernel \ + ({h} kernel, {m} scalar) -- the twin exists but the \ + shipping path is not taking it", + SLOT_NAMES[i].0 + )); + } + } + } + + // A gate that checks nothing must fail, not pass. This is the failure mode + // that let the original defect survive: silence read as success. + // + // The floor is HOST-DERIVED, not the constant 6 it started as. Eight of the + // ten slots need BMI2, which no aarch64 host has -- and macOS runners are + // aarch64 -- so they are SKIPPED by design there and a constant 6 failed a + // perfectly-routed build. The floor still exists (silence must not pass); it + // just tracks what this CPU can actually route. + // + // The poison self-check still bites on aarch64: `set_xxh_avx2_arm(false)` + // gates the NEON stripe path too, so `xxh64 stripes` goes scalar and the + // routing assertion below fires. (`count_eq_len`'s NEON arm is chosen at + // compile time and cannot be poisoned -- one poisonable slot is enough.) + let floor = if bmi2 { + 6 + } else if vec { + 2 + } else { + 1 + }; + assert!( + checked >= floor, + "kernel-reach gate exercised only {checked} sites (floor {floor} for \ + bmi2={bmi2} vec={vec}) -- it is not measuring what it claims. Either \ + the corpus stopped reaching the dispatch sites or the census taps \ + were detached from them." + ); + assert!( + failures.is_empty(), + "kernel routing regressed:\n{}", + failures.join("\n") + ); +} diff --git a/crates/rzstd-alloc/Cargo.toml b/crates/rzstd-alloc/Cargo.toml index 4e05fdc..a7dc4b7 100644 --- a/crates/rzstd-alloc/Cargo.toml +++ b/crates/rzstd-alloc/Cargo.toml @@ -11,7 +11,7 @@ description = "rusty_alloc seam for rusty_zstd deliverables — never depend on publish = false [dependencies] -rusty_alloc-api = { version = "=1.1.4" } +rusty_alloc-api = { version = "=2.0.5" } [lints] workspace = true diff --git a/crates/rzstd-alloc/src/lib.rs b/crates/rzstd-alloc/src/lib.rs index c2eff3c..2d4d667 100644 --- a/crates/rzstd-alloc/src/lib.rs +++ b/crates/rzstd-alloc/src/lib.rs @@ -2,7 +2,19 @@ //! //! House law: `#[global_allocator]` lives in the *deliverable* (`main.rs`), //! never in a shared library. This crate holds the exact `rusty_alloc-api` -//! pin (`=1.1.0`) so feature code never names that crate. +//! pin so feature code never names that crate. +//! +//! PIN: `=2.0.5` (was `=2.0.0`, and `=1.1.4` before that). The doc here once +//! said `=1.1.0` while the manifest said `=1.1.4` -- a stale comment beside +//! the thing it documents, which is the one place a pin must not drift. Read +//! the version from `Cargo.toml`. +//! +//! KNOWN SPLIT, deliberate: `rusty_zstd`'s optional `rusty-alloc` feature goes +//! through `rusty_alloc_default`, which as of 0.1.2 still tracks the 1.x line +//! (1.1.6). So the CLI and bench binaries run rusty_alloc 2.0.5 through THIS +//! seam while that feature would install 1.1.6. No single binary links both -- +//! `cargo tree` on the CLI shows only 2.0.5 -- but the two paths are on +//! different majors until `rusty_alloc_default` publishes a 2.x. #![no_std] diff --git a/tools/asmcensus/README.md b/tools/asmcensus/README.md new file mode 100644 index 0000000..9858e98 --- /dev/null +++ b/tools/asmcensus/README.md @@ -0,0 +1,65 @@ +# asmcensus -- deterministic loop verdicts from the emitted assembly + +Built 2026-09-09 for the matchfind campaign, when the box's CPU load made every +clock inadmissible. All of it reads `target/release/deps/rusty_zstd-*.s` from + + cargo rustc --release -p rusty_zstd -- --emit asm + +- `cfg.py` -- shared: regions -> real CFG (every jump inside a region is an + edge; jump tables resolved), dominators, NATURAL loops. +- `loops2.py` -- per symbol: each natural loop's instrs / spill stores / stack + reads / rip-relative static loads / calls. +- `paths2.py` -- the TRUE shortest header->latch path of one loop (Dijkstra on + executed instructions), `nocall` to isolate the no-match path, + `-v` to print it. This is the per-candidate / per-position cost. +- `pathdump.py` -- print an explicit block path with its stack reads marked. +- `hotslots2.py` -- hot stack slots of one loop with provenance (spill / hoisted + invariant / incoming argument). +- `loopsig.py` -- loops with a content signature (constants, stores) to match + them across two builds. +- `riploads.py` -- which statics (knob arms) a loop reads, and how often. + +Verdict discipline: compare PATHS, not loop totals -- a loop total is the union of +its arms. See CHANGELOG "matchfind" for the bricks these decided. + +## The three-target board (2026-09-09, bricks 35-71) + +Four more scripts, written for the lazy ladder's candidate / insert / position +campaign. They price PATHS (Dijkstra over executed instructions, header to latch) +selected by the FEATURES a path must execute -- bit 0 an indirect call, bit 1 an +`xor` (the first-word compare), bit 2 a register byte compare (the tag test), bit +3 `shrq %cl` (the lazy step), bit 4 `bsf` (the fused short count), bit 5 a +memory-operand `cmpb` (the `pre_eq` byte test) -- because the shortest cycle of a +loop is almost never the common one. + +- `verdict3.py [ ...]` -- the board: per chain kernel the prologue, + the walk loop, and the tag-skip / first-word-miss / **pre_eq-fail** (the 83% + path at L9) / fused-short paths; per fill body its per-byte loops; per finder + the no-match position cycle with and without the rep probe, the look-ahead + step, and the INLINED walk loops. `verdict3.py 'K cp.wc' 38` dumps one + path (the number is the feature mask). +- `score.py ...` -- ONE number per state: the modelled instructions per + input byte at L9 (`mfbudget`'s unit rates: 0.297 walks, 1.725 candidates, + 0.147 tag skips, 0.087 fused resolutions per byte) summed over the four + shipping kernel shapes, for both the pointer-dispatched and the inlined form. + A brick that moves two arms in opposite directions is decided here. +- `pathdump2.py
[nocall]` -- any loop's + shortest cycle executing the mask's features, segment by segment. +- `poscycle.py ` -- the lazy finder's per-position cycles: plain no-match, + through the walk (one tag test), and through an examined candidate. + +What they found, in order: the candidate path priced for twenty bricks was the +0.6% one; the per-walk CALL frame was second only to the real candidate path; +inlining the walk (`find_lazy_impl::`) cut the model 396 -> 339, and +eleven bricks on the inlined form took it to 285. Full record in CHANGELOG.md. + +- `gwalk.py ` -- the greedy (L5) finder's inline walk instances: dominant, + tag-skip and fused paths, and each position loop's cycle through the walk. +- `reppath.py ` -- the lazy finder's inlined position loops: the no-match + cycle with and without the rep probe executed. + +- `fillloops.py ...` -- every fill body's loops (each `lz_fill_range` + instantiation and `row_fill_range`): size, mnemonics and the per-call + prologue to each. The board's one `F` row folds a body's arms together; this + is where a producer change that drops the shipping quad 68 -> 56 while a + cold arm grows +12 is told apart. \ No newline at end of file diff --git a/tools/asmcensus/__pycache__/cfg.cpython-311.pyc b/tools/asmcensus/__pycache__/cfg.cpython-311.pyc new file mode 100644 index 0000000..efaba5e Binary files /dev/null and b/tools/asmcensus/__pycache__/cfg.cpython-311.pyc differ diff --git a/tools/asmcensus/__pycache__/verdict3.cpython-311.pyc b/tools/asmcensus/__pycache__/verdict3.cpython-311.pyc new file mode 100644 index 0000000..14411ac Binary files /dev/null and b/tools/asmcensus/__pycache__/verdict3.cpython-311.pyc differ diff --git a/tools/asmcensus/btpos.py b/tools/asmcensus/btpos.py new file mode 100644 index 0000000..ab581de --- /dev/null +++ b/tools/asmcensus/btpos.py @@ -0,0 +1,18 @@ +"""btpos.py : the bt-lazy finder's position loops, no-match cycle with +the kernel call allowed (its search is a call).""" +import sys, re, os +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +import verdict3 as V +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg, loop_body +b = symbol_bodies(sys.argv[1], [re.compile(r'encode\d+find_bt_lazy\b')]) +for sym, body in b.items(): + ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) + lab = {i: l for i, (l, _) in enumerate(blocks)} + out = [f"{os.path.basename(sys.argv[1])} find_bt_lazy {len(ins)}"] + for h, bs in sorted(loops.items(), key=lambda kv: len(kv[1])): + lb = loop_body(blocks, bs) + if not any(re.match(r'^shrq\s+%cl', t) for t in lb): + continue + r = V.shortest(blocks, succ, lab, h, bs, need=8) + out.append(f" position {lab[h]} L{len(lb)} no-match {r[0]}/{r[1]}r{r[2]}s" if r else f" position {lab[h]} L{len(lb)} -") + print("\n".join(out)) diff --git a/tools/asmcensus/cfg.py b/tools/asmcensus/cfg.py new file mode 100644 index 0000000..373aec8 --- /dev/null +++ b/tools/asmcensus/cfg.py @@ -0,0 +1,156 @@ +"""Shared: parse one symbol's body into basic blocks and find its NATURAL loops +using dominators (a back edge u->h counts only when h dominates u), so a jump +to an earlier-laid-out block that is not a loop header no longer creates a +phantom loop spanning the prologue.""" +import re, collections + +JCC = re.compile(r'^j(mp|e|ne|a|ae|b|be|g|ge|l|le|s|ns|z|nz|o|no|p|np|c|nc)\s+(\.LBB\d+_\d+)') + + +JUMP_TABLES = {} + + +def symbol_bodies(path, pats, skip_bmi2=True): + """also harvests every jump table (.LJTIn_m: .long .LBBn_x-.LJTIn_m) so + `jmpq *reg` blocks get their real successors""" + L = open(path, encoding='utf-8', errors='replace').read().split('\n') + cur = None + bodies = collections.OrderedDict() + jt = None + for l in L: + t = l.strip() + mj = re.match(r'^(\.LJTI\d+_\d+):', t) + if mj: + jt = mj.group(1) + JUMP_TABLES[jt] = [] + continue + if jt: + me = re.match(r'^\.(?:long|quad|rva)\s+(\.LBB\d+_\d+)', t) + if me: + JUMP_TABLES[jt].append(me.group(1)) + continue + jt = None + # a function label: Rust v0 (`_R...`) or a plain C symbol; never `.LBB`/`.L` + m = re.match(r'^([A-Za-z_][A-Za-z0-9_$.]*):', l) + if m and not m.group(1).startswith(('.', 'Lfunc', 'Ltmp', 'Lexception')): + cur = m.group(1) + continue + if cur and any(p.search(cur) for p in pats) and not (skip_bmi2 and 'bmi2' in cur): + bodies.setdefault(cur, []).append(t) + return bodies + + +def merged(bodies): + """the bodies of every matched symbol as ONE instruction list, each behind a + synthetic entry label so it starts its own block (BRICK 103 outlined the + lazy finder's five KIND shapes into five symbols; the loop metrics are + per loop, so a union is what the board wants)""" + out = [] + for k, body in enumerate(bodies.values()): + out.append(f'.LBB9999_{k}:') + out.extend(body) + return out + + +def instrs(body): + return [t for t in body if t and not t.startswith('#') and (not t.startswith('.') or re.match(r'^\.LBB\d+_\d+:', t))] + + +def blocks_of(ins): + blocks = [] + lab = 'ENTRY' + curb = [] + for t in ins: + m = re.match(r'^(\.LBB\d+_\d+):', t) + if m: + blocks.append((lab, curb)) + lab = m.group(1) + curb = [] + continue + curb.append(t) + blocks.append((lab, curb)) + return blocks + + +def cfg(blocks): + idx = {l: i for i, (l, _) in enumerate(blocks)} + succ = collections.defaultdict(set) + # A label-delimited region can hold SEVERAL conditional jumps (LLVM emits a + # label only where something jumps to), so every jump in the region is an + # edge; the fall-through edge exists unless the region ends unconditionally. + for i, (l, b) in enumerate(blocks): + for j, t in enumerate(b): + m = JCC.match(t) + if m: + if m.group(2) in idx: + succ[i].add(idx[m.group(2)]) + elif re.match(r'^jmp\w*\s+\*', t): + tbl = None + for x in reversed(b[max(0, j - 8):j]): + mt = re.search(r'(\.LJTI\d+_\d+)', x) + if mt: + tbl = mt.group(1) + break + for tgt in JUMP_TABLES.get(tbl, []): + if tgt in idx: + succ[i].add(idx[tgt]) + last = b[-1] if b else '' + ends = last.startswith(('ret', 'ud2')) or re.match(r'^jmp\w*\s', last) + if not ends and i + 1 < len(blocks): + succ[i].add(i + 1) + pred = collections.defaultdict(set) + for u, vs in succ.items(): + for v in vs: + pred[v].add(u) + return succ, pred + + +def dominators(n, succ, pred): + # iterative data-flow: dom[v] = {v} U intersect(dom[p] for p in pred[v]); entry = 0 + full = set(range(n)) + dom = [full.copy() for _ in range(n)] + dom[0] = {0} + changed = True + while changed: + changed = False + for v in range(1, n): + ps = [dom[p] for p in pred[v]] + new = ({v} | set.intersection(*ps)) if ps else {v} + if new != dom[v]: + dom[v] = new + changed = True + return dom + + +def natural_loops(blocks): + """returns {header_index: set(block indices)} for real back edges only""" + succ, pred = cfg(blocks) + dom = dominators(len(blocks), succ, pred) + loops = {} + for u, vs in succ.items(): + for h in vs: + if h in dom[u]: # h dominates u: a real back edge + bs = {h, u} + st = [] if u == h else [u] + while st: + x = st.pop() + for q in pred[x]: + if q not in bs: + bs.add(q) + if q != h: # never walk past the header + st.append(q) + loops[h] = loops.get(h, set()) | bs + return loops + + +def loop_body(blocks, bs): + return [t for i in sorted(bs) for t in blocks[i][1]] + + +STORE = re.compile(r'^mov\w*\s+[^,]+,\s*(-?\d+)\(%r([sb])p\)$') + + +def spill_stats(lb): + sp = sum(1 for t in lb if STORE.match(t)) + rl = sum(len(re.findall(r'-?\d+\(%r[sb]p\)', t)) for t in lb if not STORE.match(t)) + return sp, rl diff --git a/tools/asmcensus/fillloops.py b/tools/asmcensus/fillloops.py new file mode 100644 index 0000000..0f83887 --- /dev/null +++ b/tools/asmcensus/fillloops.py @@ -0,0 +1,63 @@ +"""fillloops.py [ ...]: the fill bodies' loops -- every +`lz_fill_range` instantiation and `row_fill_range`, each loop's size, its +mnemonics, and the per-call prologue (shortest entry->loop-header path) to +the packed hash4 quad loop. Reads the wins and the leaks the board's one-line +`F` row folds together (a producer change can move a cold arm by +12 while +the shipping quad drops 12).""" +import sys, re, heapq +import verdict3 as V +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg, loop_body + +PATS = [ + (r'lz_fill_rangeKb0_Kb1_KBR_KBV_', 'fill packed'), + (r'lz_fill_rangeKb0_Kb0_Kb1_Kb1_', 'fill tag-array'), + (r'lz_fill_rangeKb0_Kb0_Kb0_Kb1_', 'fill no-tags'), + (r'lz_fill_rangeKb1_', 'fill rows'), + (r'row_fill_range', 'row fill'), +] + + +def prologue(blocks, succ, lab, h): + dist = {0: 0} + pq = [(0, 0)] + while pq: + d, u = heapq.heappop(pq) + if d > dist.get(u, 1e18): + continue + if u == h: + return d + bl = blocks[u][1] + for v in succ[u]: + cut = len(bl) + for j, t in enumerate(bl): + m = V.JCC.match(t) + if m and m.group(2) == lab[v]: + cut = j + 1 + break + if any(t.startswith('ret') for t in bl[:cut]): + continue + c = d + cut + if c < dist.get(v, 1e18): + dist[v] = c + heapq.heappush(pq, (c, v)) + return None + + +for path in sys.argv[1:]: + print(f"=== {path}") + for pat, name in PATS: + b = symbol_bodies(path, [re.compile(pat)]) + if not b: + continue + for sym, body in b.items(): + ins = instrs(body) + blocks = blocks_of(ins) + loops = natural_loops(blocks) + succ, _ = cfg(blocks) + lab = {i: l for i, (l, _) in enumerate(blocks)} + rows = sorted((len(loop_body(blocks, bs)), lab[h], h) for h, bs in loops.items()) + print(f" {name:14} {len(ins):4} instrs | loops {[n for n, _, _ in rows]}") + for n, l, h in rows: + mn = ' '.join(t.split()[0] for t in loop_body(blocks, loops[h])) + pro = prologue(blocks, succ, lab, h) + print(f" {l:12} n={n:3} prologue={pro} :: {mn[:150]}") diff --git a/tools/asmcensus/gwalk.py b/tools/asmcensus/gwalk.py new file mode 100644 index 0000000..5d2e08d --- /dev/null +++ b/tools/asmcensus/gwalk.py @@ -0,0 +1,24 @@ +"""gwalk.py [...]: the greedy finder's inline walk and frame -- the +dominant (pre_eq-fail) path, the tag-skip path, and the position cycle +through the walk -- for the L5 ports of the lazy walk's bricks.""" +import sys, re, os +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +import verdict3 as V +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg, loop_body, spill_stats, merged +for path in sys.argv[1:]: + b = symbol_bodies(path, [re.compile(r'encode\d+find_greedy(\b|_impl)')]); body = merged(b) + ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) + lab = {i: l for i, (l, _) in enumerate(blocks)} + out = [f"{os.path.basename(path)} find_greedy {len(ins)}"] + for h, bs in sorted(loops.items(), key=lambda kv: len(kv[1])): + lb = loop_body(blocks, bs); sp, rl = spill_stats(lb) + feats = set(i for t in lb for i, r in enumerate(V.FEAT) if r.match(t)) + f = lambda q: f"{q[0]}/{q[1]}r{q[2]}s" if q else "-" + if 1 in feats and 2 in feats and 3 not in feats: + skip = V.shortest(blocks, succ, lab, h, bs, need=4); pre = V.shortest(blocks, succ, lab, h, bs, need=38); fused = V.shortest(blocks, succ, lab, h, bs, need=22) + out.append(f" walk {lab[h]} L{len(lb)} sp{sp} rd{rl} | skip {f(skip)} pre {f(pre)} fused {f(fused)}") + elif 3 in feats: + r = V.shortest(blocks, succ, lab, h, bs, need=8, nocall=True); rw = V.shortest(blocks, succ, lab, h, bs, need=12, nocall=True) + if rw: + out.append(f" position {lab[h]} L{len(lb)} | no-match {f(r)} | through walk {f(rw)}") + print("\n".join(out)) diff --git a/tools/asmcensus/hotslots2.py b/tools/asmcensus/hotslots2.py new file mode 100644 index 0000000..8ebfaea --- /dev/null +++ b/tools/asmcensus/hotslots2.py @@ -0,0 +1,62 @@ +"""Hot stack slots of ONE natural loop (dominance-based), with provenance. +usage: hotslots2.py [top-n] +`auto` = the smallest natural loop (>= 60 instrs) that calls count_match_raw.""" +import re, sys, collections, os +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, loop_body, STORE, cfg, dominators + +bodies = symbol_bodies(sys.argv[1], [re.compile(sys.argv[2])]) +sym, body = next(iter(bodies.items())) +want = sys.argv[3] +top = int(sys.argv[4]) if len(sys.argv) > 4 else 24 +ins = instrs(body) +blocks = blocks_of(ins) +loops = natural_loops(blocks) +lab_of = {i: l for i, (l, _) in enumerate(blocks)} +if want == 'auto': + cands = [] + for h, bs in loops.items(): + lb = loop_body(blocks, bs) + if len(lb) >= 60 and any(t.startswith('call') and 'count_match_raw' in t for t in lb): + cands.append((len(lb), h)) + cands.sort() + h = cands[0][1] +else: + h = next(i for i, l in lab_of.items() if l == want) +bs = loops[h] +lb = loop_body(blocks, bs) +# latches: blocks in the loop with an edge to h +succ, pred = cfg(blocks) +latches = [u for u in bs if h in succ[u]] +reads = collections.Counter() +writes_in = collections.Counter() +for t in lb: + ms = STORE.match(t) + if ms: + writes_in[ms.group(1) + '(%r' + ms.group(2) + 'p)'] += 1 + continue + for mm in re.finditer(r'(-?\d+)\(%r([sb])p\)', t): + reads[mm.group(1) + '(%r' + mm.group(2) + 'p)'] += 1 +first_store = {} +for j, t in enumerate(ins): + ms = STORE.match(t) + if ms: + k = ms.group(1) + '(%r' + ms.group(2) + 'p)' + if k not in first_store: + ctx = [x for x in ins[max(0, j - 3):j] if not x.startswith('.LBB')] + first_store[k] = ' | '.join(ctx + [t]) +in_store = {} +for t in lb: + ms = STORE.match(t) + if ms: + k = ms.group(1) + '(%r' + ms.group(2) + 'p)' + in_store.setdefault(k, t) +name = re.sub(r'^_R.*?(encode|rowfind)\d+', '', sym)[:40] +nsp = sum(writes_in.values()) +nrd = sum(reads.values()) +print(f"### {name} loop {lab_of[h]}: {len(lb)} instrs, {len(bs)} blocks, latches={[lab_of[u] for u in latches]}, {nsp} spill stores, {nrd} stack reads, {len(reads)} distinct slots") +print(f"{'slot':<12}{'reads':>6}{'w-in':>5} kind provenance") +for k in sorted(set(list(reads) + list(writes_in)), key=lambda k: -(reads[k] + writes_in[k]))[:top]: + kind = 'SPILL' if writes_in[k] else ('HOISTED' if k in first_store else 'INCOMING') + prov = in_store.get(k, first_store.get(k, '-')) if writes_in[k] else first_store.get(k, '-') + print(f"{k:<12}{reads[k]:>6}{writes_in[k]:>5} {kind:<9} {prov[:140]}") diff --git a/tools/asmcensus/loops2.py b/tools/asmcensus/loops2.py new file mode 100644 index 0000000..ba93267 --- /dev/null +++ b/tools/asmcensus/loops2.py @@ -0,0 +1,35 @@ +"""Dominance-based natural-loop census per symbol: instrs / spill stores / +stack reads / rip-relative static loads / calls, plus the statics named. +usage: loops2.py [...]""" +import re, sys, collections, os +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, loop_body, spill_stats + +bodies = symbol_bodies(sys.argv[1], [re.compile(p) for p in sys.argv[2:]]) +RIP = re.compile(r'_R[A-Za-z0-9_]*?(?:encode|lib|prof|rowfind|ldm|simd)\d+([A-Za-z0-9_]+?)(?:\.0)?\(%rip\)') +for sym, b in bodies.items(): + ins = instrs(b) + blocks = blocks_of(ins) + loops = natural_loops(blocks) + name = re.sub(r'^_R.*?(encode|rowfind|ldm)\d+', '', sym)[:38] + n_all = sum(len(x) for _, x in blocks) + print(f"##### {name}: {n_all} instrs, {len(blocks)} blocks, {len(loops)} natural loops") + rows = [] + for h, bs in loops.items(): + lb = loop_body(blocks, bs) + sp, rl = spill_stats(lb) + rips = collections.Counter(m.group(1)[:24] for t in lb for m in RIP.finditer(t)) + calls = collections.Counter() + for t in lb: + if t.startswith('call'): + c = re.sub(r'^call\w*\s+', '', t) + c = 'INDIRECT' if c.startswith('*') else re.sub(r'.*?(encode|rowfind|simd|ldm|alloc|core|std)\d+', '', c)[:22] + calls[c] += 1 + rows.append((len(lb), blocks[h][0], len(bs), sp, rl, rips, calls)) + rows.sort(key=lambda r: -r[0]) + print(f" {'header':<12}{'instrs':>7}{'blks':>5}{'spills':>7}{'reads':>6}{'rip':>4} calls") + for n, lab, nb, sp, rl, rips, calls in rows[:10]: + cs = ' '.join(f"{k}x{v}" if v > 1 else k for k, v in calls.most_common(5)) + print(f" {lab:<12}{n:>7}{nb:>5}{sp:>7}{rl:>6}{sum(rips.values()):>4} {cs[:80]}") + if rips: + print(" statics: " + ', '.join(f"{k} x{v}" for k, v in rips.most_common(10))) diff --git a/tools/asmcensus/loopsig.py b/tools/asmcensus/loopsig.py new file mode 100644 index 0000000..b297a8a --- /dev/null +++ b/tools/asmcensus/loopsig.py @@ -0,0 +1,47 @@ +"""Per-loop census with a CONTENT signature, so loops can be matched across builds. +usage: loopsig.py [ ...]""" +import re, sys, collections + +L = open(sys.argv[1], encoding='utf-8', errors='replace').read().split('\n') +pats = [re.compile(p) for p in sys.argv[2:]] +cur = None +bodies = collections.OrderedDict() +for l in L: + m = re.match(r'^(_R[A-Za-z0-9_]+):', l) + if m: + cur = m.group(1) + continue + if cur and any(p.search(cur) for p in pats): + bodies.setdefault(cur, []).append(l.strip()) +JT = re.compile(r'^j\w+\s+(\.LBB\d+_\d+)') +for sym, b in bodies.items(): + ins = [t for t in b if t and not t.startswith('#') and (not t.startswith('.') or re.match(r'^\.LBB\d+_\d+:', t))] + labels = {} + flat = [] + for t in ins: + m = re.match(r'^(\.LBB\d+_\d+):', t) + if m: + labels[m.group(1)] = len(flat) + continue + flat.append(t) + short = re.sub(r'^_R.*?(encode|rowfind)\d+', '', sym)[:40] + print(f"##### {short}: {len(flat)} instrs") + rows = [] + for i, t in enumerate(flat): + m = JT.match(t) + if m and m.group(1) in labels and labels[m.group(1)] <= i: + a = labels[m.group(1)] + seg = flat[a:i + 1] + if any(x.startswith('ret') for x in seg): + continue + rl = sum(len(re.findall(r'-?\d+\(%r[sb]p\)', x)) for x in seg) + sp = sum(1 for x in seg if re.match(r'^mov\w*\s+%\w+,\s*-?\d+\(%r[sb]p\)', x)) + inner = sum(1 for x in seg[:-1] if JT.match(x) and JT.match(x).group(1) in labels and a <= labels[JT.match(x).group(1)] < i) + calls = [re.sub(r'^call\w*\s+', '', x) for x in seg if x.startswith('call')] + calls = [re.sub(r'.*?(encode|rowfind|simd)\d+', '', c)[:18] if not c.startswith('*') else 'INDIRECT' for c in calls] + consts = collections.Counter(re.findall(r'\$(-?\d{6,})', ' '.join(seg))) + stores = sum(1 for x in seg if re.match(r'^mov[bwlq]\s+%\w+,\s*\(', x)) + rows.append((len(seg), sp, rl - sp, inner, m.group(1), ','.join(calls[:4]), ' '.join(f"{k[:6]}x{v}" for k, v in consts.most_common(3)), stores)) + rows.sort() + for n, sp, rl, inner, lab, calls, consts, st in rows: + print(f" {lab:<12} {n:>4}i {sp:>2}s {rl:>3}r inner={inner:<2} stores={st:<2} calls=[{calls}] consts={consts}") diff --git a/tools/asmcensus/pathdump.py b/tools/asmcensus/pathdump.py new file mode 100644 index 0000000..85b8aa0 --- /dev/null +++ b/tools/asmcensus/pathdump.py @@ -0,0 +1,43 @@ +"""Print the instructions executed along an explicit block path through a loop +(each region up to the jump that is TAKEN to reach the next block), and tally +its stack reads by slot and the byte-flag tests on it. +usage: pathdump.py
...""" +import re, sys, os, collections +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +from cfg import symbol_bodies, instrs, blocks_of, STORE + +bodies = symbol_bodies(sys.argv[1], [re.compile(sys.argv[2])]) +sym, body = next(iter(bodies.items())) +ins = instrs(body) +blocks = blocks_of(ins) +idx = {l: i for i, (l, _) in enumerate(blocks)} +path = [idx[x] for x in sys.argv[3:]] +JCC = re.compile(r'^j(mp|e|ne|a|ae|b|be|g|ge|l|le|s|ns|z|nz|o|no|p|np|c|nc)\s+(\.LBB\d+_\d+)') +h = path[0] +tot = 0 +reads = collections.Counter() +flags = 0 +for k, i in enumerate(path): + b = blocks[i][1] + nxt = path[k + 1] if k + 1 < len(path) else h + cut = len(b) + for j, t in enumerate(b): + m = JCC.match(t) + if m and m.group(2) == blocks[nxt][0]: + cut = j + 1 + break + seg = b[:cut] + print(f"{blocks[i][0]}:") + for t in seg: + mark = '' + if not STORE.match(t): + for mm in re.finditer(r'(-?\d+)\(%r([sb])p\)', t): + reads[mm.group(1) + '(%r' + mm.group(2) + 'p)'] += 1 + mark = ' <-- stack read' + if re.match(r'^(cmpb|testb)\s+\$?\d*,?\s*-?\d+\(%r[sb]p\)', t) or re.match(r'^cmpb\s+\$0,\s*-?\d+\(%r[sb]p\)', t): + flags += 1 + mark = ' <-- FLAG test' + print(f" {t}{mark}") + tot += len(seg) +print(f"=== path: {tot} instrs, {sum(reads.values())} stack reads over {len(reads)} slots, {flags} byte-flag tests") +print(" slots: " + ', '.join(f"{k} x{v}" for k, v in reads.most_common())) diff --git a/tools/asmcensus/pathdump2.py b/tools/asmcensus/pathdump2.py new file mode 100644 index 0000000..fa2c301 --- /dev/null +++ b/tools/asmcensus/pathdump2.py @@ -0,0 +1,20 @@ +"""pathdump2.py
[nocall]: the shortest +header->latch cycle of that loop executing the `need` features (bit0 indirect +call, bit1 xor, bit2 tag byte-compare, bit3 lazy_step shift, bit4 fused bsf, +bit5 pre_eq memory cmpb), printed segment by segment.""" +import sys, re, os +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +import verdict3 as V +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg +b = symbol_bodies(sys.argv[1], [re.compile(sys.argv[2])]); sym, body = next(iter(b.items())) +ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) +lab = {i: l for i, (l, _) in enumerate(blocks)} +h = next(i for i, l in lab.items() if l == sys.argv[3]) +r = V.shortest(blocks, succ, lab, h, loops[h], need=int(sys.argv[4]), nocall='nocall' in sys.argv) +if not r: + sys.exit("no path") +print(f"### {sys.argv[3]} need={sys.argv[4]}: {r[0]} instrs, {r[1]} reads, {r[2]} stores") +for sg in r[4]: + print(" --") + for t in sg: + print(" " + t) diff --git a/tools/asmcensus/paths2.py b/tools/asmcensus/paths2.py new file mode 100644 index 0000000..0a303ac --- /dev/null +++ b/tools/asmcensus/paths2.py @@ -0,0 +1,101 @@ +"""TRUE shortest header->latch path of one natural loop (Dijkstra on executed +instructions), optionally forbidding blocks that contain calls or that write +memory to a given base register, so the per-position NO-MATCH path can be +isolated. Prints the path with its stack reads and flag tests. +usage: paths2.py
[nocall] [avoid=.LBBx,.LBBy]""" +import re, sys, os, collections, heapq +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg, STORE + +bodies = symbol_bodies(sys.argv[1], [re.compile(sys.argv[2])]) +sym, body = next(iter(bodies.items())) +hdr = sys.argv[3] +nocall = 'nocall' in sys.argv[4:] +avoid = set() +for a in sys.argv[4:]: + if a.startswith('avoid='): + avoid = set(a[6:].split(',')) +ins = instrs(body) +blocks = blocks_of(ins) +loops = natural_loops(blocks) +succ, pred = cfg(blocks) +lab = {i: l for i, (l, _) in enumerate(blocks)} +h = next(i for i, l in lab.items() if l == hdr) +bs = loops[h] +latches = {u for u in bs if h in succ[u]} +JCC = re.compile(r'^j(mp|e|ne|a|ae|b|be|g|ge|l|le|s|ns|z|nz|o|no|p|np|c|nc)\s+(\.LBB\d+_\d+)') + + +def seg(u, v): + """instructions of region u executed when control goes to v next""" + b = blocks[u][1] + cut = len(b) + for j, t in enumerate(b): + m = JCC.match(t) + if m and m.group(2) == lab[v]: + cut = j + 1 + break + return b[:cut] + + +def ok_seg(u, v): + """the executed segment of u on the way to v: no call if nocall""" + if lab[v] in avoid: + return False + if nocall and any(t.startswith('call') for t in seg(u, v)): + return False + return True + + +# Dijkstra from h over loop blocks; goal = reaching h again via a latch +dist = {h: 0} +prev = {} +pq = [(0, h)] +best = None +while pq: + d, u = heapq.heappop(pq) + if d > dist.get(u, 1e18): + continue + for v in succ[u]: + if v == h: + if u in latches and ok_seg(u, h): + c = d + len(seg(u, h)) + if best is None or c < best[0]: + best = (c, u) + continue + if v not in bs or not ok_seg(u, v): + continue + c = d + len(seg(u, v)) + if c < dist.get(v, 1e18): + dist[v] = c + prev[v] = u + heapq.heappush(pq, (c, v)) +if best is None: + sys.exit("no path under the constraints") +path = [best[1]] +while path[-1] != h: + path.append(prev[path[-1]]) +path.reverse() +name = re.sub(r'^_R.*?(encode|rowfind)\d+', '', sym)[:40] +print(f"### {name} loop {hdr} shortest{' no-call' if nocall else ''} path: {best[0]} instrs over {len(path)} blocks") +reads = collections.Counter() +flags = 0 +stores = 0 +for k, u in enumerate(path): + v = path[k + 1] if k + 1 < len(path) else h + for t in seg(u, v): + if STORE.match(t): + stores += 1 + else: + for mm in re.finditer(r'(-?\d+)\(%r([sb])p\)', t): + reads[mm.group(1) + '(%r' + mm.group(2) + 'p)'] += 1 + if re.match(r'^(cmpb|testb)\s+.*-?\d+\(%r[sb]p\)', t): + flags += 1 +print(f" stack reads {sum(reads.values())} over {len(reads)} slots, stack stores {stores}, byte-flag tests {flags}") +print(" blocks: " + ' '.join(lab[u] for u in path)) +if '-v' in sys.argv: + for k, u in enumerate(path): + v = path[k + 1] if k + 1 < len(path) else h + print(f"{lab[u]}:") + for t in seg(u, v): + print(" " + t) diff --git a/tools/asmcensus/poscycle.py b/tools/asmcensus/poscycle.py new file mode 100644 index 0000000..49d6801 --- /dev/null +++ b/tools/asmcensus/poscycle.py @@ -0,0 +1,30 @@ +"""poscycle.py : the lazy finder's per-POSITION cycles, priced two ways: +the plain no-match cycle (need: the lazy_step shift; no direct call) and the +cycle THROUGH THE WALK (also executes a tag compare, i.e. at least one +candidate) -- for an inlined finder the second is position + walk entry + +one candidate + walk exit, which for the pointer-dispatched finder is +position (18) + kernel prologue + candidate + kernel exit.""" +import sys, re, os +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +import verdict3 as V +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg, loop_body, spill_stats, merged +path = sys.argv[1] +b = symbol_bodies(path, [re.compile(r'encode\d+find_lazy(\b|_impl)')]); body = merged(b) +ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) +lab = {i: l for i, (l, _) in enumerate(blocks)} +rows = [] +for h, bs in loops.items(): + lb = loop_body(blocks, bs) + if not any(re.match(r'^shrq\s+%cl', t) for t in lb): + continue + has_ind = any(t.startswith('callq\t*') for t in lb) + r = V.shortest(blocks, succ, lab, h, bs, need=8, nocall=True) + rw = V.shortest(blocks, succ, lab, h, bs, need=12, nocall=True) + rwx = V.shortest(blocks, succ, lab, h, bs, need=14, nocall=True) # + the first-word xor: through a candidate that is examined + rows.append((len(lb), lab[h], 'ptr' if has_ind else 'inl', r, rw, rwx)) +rows.sort() +print(os.path.basename(path), "find_lazy", len(ins), "instrs") +print(" loop-size header kind | no-match cycle | cycle through the walk (>=1 tag test) | ... and an examined candidate") +for n, l, k, r, rw, rwx in rows: + f = lambda q: f"{q[0]}/{q[1]}r{q[2]}s" if q else "-" + print(f" {n:>4} {l:<12} {k} | {f(r):>10} | {f(rw):>10} | {f(rwx):>10}") diff --git a/tools/asmcensus/reppath.py b/tools/asmcensus/reppath.py new file mode 100644 index 0000000..85fad3d --- /dev/null +++ b/tools/asmcensus/reppath.py @@ -0,0 +1,23 @@ +"""reppath.py : the lazy finder's inlined position loops -- the no-match +cycle with the rep probe executed (need: shift + xor, no direct call).""" +import sys, re, os +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +import verdict3 as V +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg, loop_body, merged +b = symbol_bodies(sys.argv[1], [re.compile(r'encode\d+find_lazy(\b|_impl)')]); body = merged(b) +ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) +lab = {i: l for i, (l, _) in enumerate(blocks)} +rows = [] +for h, bs in loops.items(): + lb = loop_body(blocks, bs) + if not any(re.match(r'^shrq\s+%cl', t) for t in lb) or any(t.startswith('callq\t*') for t in lb): + continue + r = V.shortest(blocks, succ, lab, h, bs, need=8, nocall=True) + rr = V.shortest(blocks, succ, lab, h, bs, need=10, nocall=True) + if r and rr: + rows.append((len(lb), lab[h], r, rr)) +rows.sort() +f = lambda q: f"{q[0]}/{q[1]}r{q[2]}s" +print(os.path.basename(sys.argv[1]), "inlined position loops: no-match | with the rep probe") +for n, l, r, rr in rows[:6]: + print(f" L{n:<4} {l:<12} {f(r):>10} | {f(rr):>10}") diff --git a/tools/asmcensus/riploads.py b/tools/asmcensus/riploads.py new file mode 100644 index 0000000..8dbcb6f --- /dev/null +++ b/tools/asmcensus/riploads.py @@ -0,0 +1,86 @@ +"""rip-relative (static / knob-arm) loads inside each finder's natural loops: +which statics, how many times, in which loop (size).""" +import re, sys, collections + +L = open(sys.argv[1], encoding='utf-8', errors='replace').read().split('\n') +pats = [re.compile(p) for p in sys.argv[2:]] +cur = None +bodies = collections.OrderedDict() +for l in L: + m = re.match(r'^(_R[A-Za-z0-9_]+):', l) + if m: + cur = m.group(1) + continue + if cur and any(p.search(cur) for p in pats) and 'bmi2' not in cur: + bodies.setdefault(cur, []).append(l.strip()) +JCC = re.compile(r'^j(mp|e|ne|a|ae|b|be|g|ge|l|le|s|ns|z|nz|o|no|p|np|c|nc)\s+(\.LBB\d+_\d+)') + + +def natloops(ins): + blocks = [] + lab = 'ENTRY' + curb = [] + for t in ins: + m = re.match(r'^(\.LBB\d+_\d+):', t) + if m: + blocks.append((lab, curb)) + lab = m.group(1) + curb = [] + continue + curb.append(t) + blocks.append((lab, curb)) + idx = {l: i for i, (l, _) in enumerate(blocks)} + succ = collections.defaultdict(set) + for i, (l, b) in enumerate(blocks): + last = b[-1] if b else '' + m = JCC.match(last) + if m: + if m.group(2) in idx: + succ[i].add(idx[m.group(2)]) + if m.group(1) != 'mp' and i + 1 < len(blocks): + succ[i].add(i + 1) + elif last.startswith(('ret', 'ud2', 'jmp')): + pass + elif i + 1 < len(blocks): + succ[i].add(i + 1) + pred = collections.defaultdict(set) + for u, vs in succ.items(): + for v in vs: + pred[v].add(u) + loops = {} + for u, vs in succ.items(): + for h in vs: + if h <= u: + bs = {h, u} + st = [u] + while st: + x = st.pop() + for q in pred[x]: + if q not in bs: + bs.add(q) + st.append(q) + loops[h] = loops.get(h, set()) | bs + return blocks, loops + + +for sym, b in bodies.items(): + ins = [t for t in b if t and not t.startswith('#') and (not t.startswith('.') or re.match(r'^\.LBB\d+_\d+:', t))] + blocks, loops = natloops(ins) + name = re.sub(r'^_R.*?(encode|rowfind)\d+', '', sym)[:36] + rows = [] + for h, bs in loops.items(): + lb = [t for i in sorted(bs) for t in blocks[i][1]] + rips = collections.Counter() + for t in lb: + for mm in re.finditer(r'_R[A-Za-z0-9_]*?encode\d+([A-Za-z0-9_]+?)\.0\(%rip\)|_R[A-Za-z0-9_]*?(?:encode|lib|prof|rowfind|ldm)\d+([A-Za-z0-9_]+)\(%rip\)', t): + rips[(mm.group(1) or mm.group(2))[:28]] += 1 + calls = sum(1 for t in lb if t.startswith('call')) + rows.append((len(lb), blocks[h][0], sum(rips.values()), rips, calls, any('count_match_raw' in t or 'call\t*' in t or 'callq\t*' in t for t in lb))) + rows.sort(key=lambda r: -r[0]) + print(f"##### {name}: {len(loops)} natural loops") + for n, lab, nr, rips, calls, hot in rows[:8]: + if nr == 0: + print(f" {lab:<12} {n:>5} instrs rip-loads=0") + continue + print(f" {lab:<12} {n:>5} instrs rip-loads={nr:<3} calls={calls:<3} {'[per-position]' if hot else ''}") + print(" " + ', '.join(f"{k} x{v}" for k, v in rips.most_common(14))) diff --git a/tools/asmcensus/score.py b/tools/asmcensus/score.py new file mode 100644 index 0000000..6efad5f --- /dev/null +++ b/tools/asmcensus/score.py @@ -0,0 +1,164 @@ +"""score.py [...]: the MODELLED instructions per input byte at L9 for +the lazy ladder's search, per kernel shape, from the emitted assembly and the +`mfbudget` unit rates (0.297 walks, 1.725 examined candidates, 0.147 tag +skips, 0.087 fused-head resolutions per byte). Handles both forms: + pointer -- the walk is a separate symbol: frame = position no-match (18) + + kernel prologue + kernel exit; paths from the kernel's loop + inlined -- the walk loops live inside `find_lazy`: frame = the position + cycle through the walk (one tag test) minus the skip path +Per shape: cost = walks*frame + exams*pre + skips*skip + fused*(fused-pre). +Reads are reported beside instructions, never summed with them.""" +import sys, re, os, heapq +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +import verdict3 as V +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg, loop_body, spill_stats, STORE, merged + +WALKS, EXAMS, SKIPS, FUSED = 0.297, 1.725, 0.147, 0.087 +JCC = V.JCC + + +def prologue_len(blocks, succ, lab, h): + dist = {0: 0}; pq = [(0, 0)] + while pq: + d, u = heapq.heappop(pq) + if d > dist.get(u, 1e18): + continue + if u == h: + return d + b = blocks[u][1] + for v in succ[u]: + cut = len(b) + for j, t in enumerate(b): + m = JCC.match(t) + if m and m.group(2) == lab[v]: + cut = j + 1 + break + if any(t.startswith('ret') for t in b[:cut]): + continue + c = d + cut + if c < dist.get(v, 1e18): + dist[v] = c; heapq.heappush(pq, (c, v)) + return None + + +def exit_len(blocks, succ, lab, h, bs): + def seg(u, v): + bl = blocks[u][1]; cut = len(bl) + for j, t in enumerate(bl): + m = JCC.match(t) + if m and m.group(2) == lab[v]: + cut = j + 1; break + return bl[:cut] + best = None + for u in bs: + for v in succ[u]: + if v in bs: + continue + dist = {v: 0}; pq = [(0, v)] + while pq: + d, x = heapq.heappop(pq) + if d > dist.get(x, 1e18): + continue + bl = blocks[x][1] + if any(t.startswith('ret') for t in bl): + c = d + bl.index(next(t for t in bl if t.startswith('ret'))) + 1 + if best is None or c < best: + best = c + break + for w in succ[x]: + c = d + len(seg(x, w)) + if c < dist.get(w, 1e18): + dist[w] = c; heapq.heappush(pq, (c, w)) + return best + + +def walk_paths(blocks, succ, lab, h, bs): + lb = loop_body(blocks, bs) + packed = any('$16777215' in t for t in lb) + skip = V.shortest(blocks, succ, lab, h, bs, need=4) + miss = V.shortest(blocks, succ, lab, h, bs, need=6) + pre = V.shortest(blocks, succ, lab, h, bs, need=38) + fused = V.shortest(blocks, succ, lab, h, bs, need=22) + if not (skip and miss and pre): + return None + wc = skip[0] < miss[0] + return dict(packed=packed, wc=wc, skip=skip, miss=miss, pre=pre, fused=fused or pre, size=len(lb), spills=spill_stats(lb)) + + +def shape(p): + return ('cp' if p['packed'] else 'ca') + ('.wc' if p['wc'] else '') + + +def score_pointer(path): + out = {} + for name, pat in (('cp.wc', r'chain_find_bestKj0_Kb1_Kb0_KBX_'), ('cp', r'chain_find_bestKj0_Kb1_Kb0_KB11_'), + ('ca.wc', r'chain_find_bestKj0_Kb0_Kb1_KB11_'), ('ca', r'chain_find_bestKj0_Kb0_Kb1_KBX_')): + b = symbol_bodies(path, [re.compile(pat)]) + if not b: + continue + sym, body = next(iter(b.items())) + ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) + lab = {i: l for i, (l, _) in enumerate(blocks)} + h, bs = max(loops.items(), key=lambda kv: len(loop_body(blocks, kv[1]))) + p = walk_paths(blocks, succ, lab, h, bs) + if not p: + continue + frame = 18 + prologue_len(blocks, succ, lab, h) + (exit_len(blocks, succ, lab, h, bs) or 0) + out[name] = (frame, p) + return out + + +def score_inlined(path): + b = symbol_bodies(path, [re.compile(r'encode\d+find_lazy(\b|_impl)')]); body = merged(b) + ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) + lab = {i: l for i, (l, _) in enumerate(blocks)} + walks = [] + for h, bs in loops.items(): + lb = loop_body(blocks, bs) + if any(re.match(r'^shrq\s+%cl', t) for t in lb): + continue + p = walk_paths(blocks, succ, lab, h, bs) + if p: + walks.append((h, bs, p)) + out = {} + for h, bs, p in walks: + # the smallest position loop (has the step shift) containing this walk's header + cands = [(len(pbs), ph, pbs) for ph, pbs in loops.items() if h in pbs and any(re.match(r'^shrq\s+%cl', t) for t in loop_body(blocks, pbs))] + if not cands: + continue + _, ph, pbs = min(cands) + cyc = V.shortest(blocks, succ, lab, ph, pbs, need=12, nocall=True) + if not cyc: + continue + frame = cyc[0] - p['skip'][0] + key = shape(p) + # two inlined sites per instance: keep the cheaper frame per shape, note both + out.setdefault(key, []).append((frame, p, cyc, lab[h])) + return {k: sorted(v, key=lambda t: t[0]) for k, v in out.items()} + + +def cost(frame, p): + return WALKS * frame + EXAMS * p['pre'][0] + SKIPS * p['skip'][0] + FUSED * (p['fused'][0] - p['pre'][0]) + + +for path in sys.argv[1:]: + print(f"##### {os.path.basename(path)}") + ptr = score_pointer(path) + total = 0.0 + for k in ('cp.wc', 'cp', 'ca.wc', 'ca'): + if k in ptr: + frame, p = ptr[k] + c = cost(frame, p) + total += c + print(f" ptr {k:<6} frame {frame:>4} | skip {p['skip'][0]:>3}/{p['skip'][1]}r pre {p['pre'][0]:>3}/{p['pre'][1]}r{p['pre'][2]}s fused {p['fused'][0]:>3} | loop {p['size']:>4} sp{p['spills'][0]:>2} rd{p['spills'][1]:>3} | cost {c:6.1f}/byte") + print(f" ptr sum of the four shipping shapes: {total:.1f} instrs/byte (L9 model)") + inl = score_inlined(path) + if inl: + total = 0.0 + for k in ('cp.wc', 'cp', 'ca.wc', 'ca'): + for frame, p, cyc, hdr in inl.get(k, []): + c = cost(frame, p) + print(f" inl {k:<6} frame {frame:>4} ({cyc[0]}/{cyc[1]}r{cyc[2]}s cycle) | skip {p['skip'][0]:>3}/{p['skip'][1]}r pre {p['pre'][0]:>3}/{p['pre'][1]}r{p['pre'][2]}s fused {p['fused'][0]:>3} | loop {p['size']:>4} sp{p['spills'][0]:>2} rd{p['spills'][1]:>3} | cost {c:6.1f}/byte {hdr}") + if inl.get(k): + total += cost(inl[k][0][0], inl[k][0][1]) + print(f" inl sum (cheapest site per shape): {total:.1f} instrs/byte (L9 model)") diff --git a/tools/asmcensus/verdict3.py b/tools/asmcensus/verdict3.py new file mode 100644 index 0000000..5f32a30 --- /dev/null +++ b/tools/asmcensus/verdict3.py @@ -0,0 +1,237 @@ +"""The three-target verdict board: for one .s, the six chain kernels' walk +loop (shortest header->latch path = the first-word candidate path), the four +fill bodies' per-byte loops, and the lazy finder's per-position no-match loop. +usage: verdict3.py [ ...] (columns per file)""" +import re, sys, os, collections, heapq +sys.path.insert(0, os.path.dirname(os.path.abspath(__file__))) +from cfg import symbol_bodies, instrs, blocks_of, natural_loops, cfg, STORE, loop_body, spill_stats, merged +JCC = re.compile(r'^j(mp|e|ne|a|ae|b|be|g|ge|l|le|s|ns|z|nz|o|no|p|np|c|nc)\s+(\.LBB\d+_\d+)') + + +FEAT = [re.compile(r'^callq \*'), re.compile(r'^xorq\s'), re.compile(r'^(cmpb\s+[^$(]|cmpl\s+\$1677721[56],)'), re.compile(r'^shrq\s+%cl'), re.compile(r'^(rep\s+bsf|tzcnt|bsf)'), re.compile(r'^(cmpb\s+\(|movzbl\s+\()'), re.compile(r'^callq _R')] # bit4 fused-short, bit5 pre_eq, bit6 direct call # bit3: shrq %cl (lazy_step) bit0: indirect call, bit1: an xor (first-word / rep compare), bit2: a byte compare (the tag test) + + +DIRECT_CALL = re.compile(r'^callq _R') + + +def shortest(blocks, succ, lab, h, bs, avoid=(), need=0, nocall=False): + """Dijkstra over (block, features-seen) from the header back to it; every + jump to v inside u is its own edge (a region can reach v by several jumps, + each executing a different prefix), so a path that must execute the xor + is found even when the region's FIRST jump to the same target precedes it.""" + latches = {u for u in bs if h in succ[u]} + + def segs(u, v): + b = blocks[u][1] + out = [] + for j, t in enumerate(b): + m = JCC.match(t) + if m and m.group(2) == lab[v]: + out.append(b[:j + 1]) + last = b[-1] if b else '' + ends = last.startswith(('ret', 'ud2')) or re.match(r'^jmp\w*\s', last) + if not ends and v == u + 1: + out.append(b) + return out + + def feats(sg, f): + for t in sg: + for i, r in enumerate(FEAT): + if r.match(t): + f |= 1 << i + return f + dist = {(h, 0): 0}; prev = {}; pq = [(0, h, 0)]; best = None + while pq: + d, u, f = heapq.heappop(pq) + if d > dist.get((u, f), 1e18): + continue + for v in succ[u]: + if lab[v] in avoid and v != h: + continue + for sg in segs(u, v): + if nocall and any(DIRECT_CALL.match(t) for t in sg): + continue + f2 = feats(sg, f) + c = d + len(sg) + if v == h: + if u in latches and (f2 & need) == need: + if best is None or c < best[0]: + best = (c, (u, f), sg) + continue + if v not in bs: + continue + if c < dist.get((v, f2), 1e18): + dist[(v, f2)] = c; prev[(v, f2)] = ((u, f), sg); heapq.heappush(pq, (c, v, f2)) + if best is None: + return None + segs_out = [best[2]] + st = best[1] + while st != (h, 0): + pst, sg = prev[st] + segs_out.append(sg); st = pst + segs_out.reverse() + reads = 0; stores = 0 + for sg in segs_out: + for t in sg: + if STORE.match(t): + stores += 1 + else: + reads += len(re.findall(r'-?\d+\(%r[sb]p\)', t)) + return best[0], reads, stores, len(segs_out), segs_out + + +TARGETS = [ + ('K cp.wc', r'chain_find_bestKj0_Kb1_Kb0_KBX_'), + ('K cp', r'chain_find_bestKj0_Kb1_Kb0_KB11_'), + ('K ca.wc', r'chain_find_bestKj0_Kb0_Kb1_KB11_'), + ('K ca', r'chain_find_bestKj0_Kb0_Kb1_KBX_'), + ('K none.wc', r'chain_find_bestKj0_Kb0_KBX_Kb1_'), + ('K none', r'chain_find_bestKj0_Kb0_KBX_KBX_'), + ('F cp', r'lz_fill_rangeKb0_Kb1_KBR_KBV_'), + ('F ca', r'lz_fill_rangeKb0_KBR_Kb1_KBZ_'), + ('F none', r'lz_fill_rangeKb0_KBR_KBR_Kb1_'), + ('F rows', r'lz_fill_rangeKb1_Kb0_KBV_KBV_'), + ('P lazy', r'encode\d+find_lazy(\b|_impl)'), + ('P greedy', r'encode\d+find_greedy(\b|_impl)'), +] + + +def one(path): + out = {} + for name, pat in TARGETS: + b = symbol_bodies(path, [re.compile(pat)]) + if not b: + out[name] = None; continue + body = merged(b) + ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) + lab = {i: l for i, (l, _) in enumerate(blocks)} + rows = [] + for h, bs in loops.items(): + lb = loop_body(blocks, bs); sp, rl = spill_stats(lb) + rows.append((len(lb), h, bs, sp, rl)) + if name.startswith('K'): + # the walk loop: the largest loop + n, h, bs, sp, rl = max(rows) + r = shortest(blocks, succ, lab, h, bs) + tagged = 'none' not in name + # prologue: Dijkstra from block 0 to the loop header over non-loop blocks + pro = None + dist = {0: 0}; pq = [(0, 0)] + import heapq as _hq + while pq: + d, u = _hq.heappop(pq) + if d > dist.get(u, 1e18): + continue + if u == h: + pro = d; break + b = blocks[u][1] + for v in succ[u]: + # executed prefix of u up to the jump to v (or whole block on fall-through) + cut = len(b) + for j, t in enumerate(b): + m_ = JCC.match(t) + if m_ and m_.group(2) == lab[v]: + cut = j + 1; break + if any(t.startswith('ret') for t in b[:cut]): + continue + c = d + cut + if c < dist.get(v, 1e18): + dist[v] = c; _hq.heappush(pq, (c, v)) + base = 4 if tagged else 0 + r = shortest(blocks, succ, lab, h, bs, need=base) + rx = shortest(blocks, succ, lab, h, bs, need=base | 2) + rp = shortest(blocks, succ, lab, h, bs, need=base | 2 | 32) + rf = shortest(blocks, succ, lab, h, bs, need=base | 2 | 16) + out[name] = (len(ins), lab[h], n, sp, rl, r, rx, pro, rp, rf) + elif name.startswith('F'): + # every per-byte loop, smallest first: (loop instrs, path) + rows.sort() + out[name] = (len(ins), [(lab[h], n, sp, rl, shortest(blocks, succ, lab, h, bs)) for n, h, bs, sp, rl in rows]) + else: + # the per-position loop: the loop whose header holds the kernel indirect call... + # take every loop containing an indirect call and report the smallest path + best = None + for n, h, bs, sp, rl in rows: + lb = loop_body(blocks, bs) + if not any(t.startswith('callq\t*') for t in lb): + continue + # avoid the emit blocks: those calling push_literals / grow / fill + r = shortest(blocks, succ, lab, h, bs, need=8, nocall=True) + r3 = shortest(blocks, succ, lab, h, bs, need=10, nocall=True) + if r and (best is None or r[0] < best[1][0]): + best = (lab[h], r, n, sp, rl, r3) + # inlined walk loops (brick 58+): loops with the tag test and the first-word xor, no shift + walks = [] + for n, h, bs, sp, rl in rows: + lb = loop_body(blocks, bs) + if any(re.match(r'^shrq\s+%cl', t) for t in lb): + continue + r6 = shortest(blocks, succ, lab, h, bs, need=6) + rp = shortest(blocks, succ, lab, h, bs, need=38) + if r6: + walks.append((r6[0], r6[1], r6[2], n, sp, rl, rp)) + walks.sort() + # the look-ahead step: a loop with the indirect call and WITHOUT the step shift + look = None + for n, h, bs, sp, rl in rows: + lb = loop_body(blocks, bs) + if not any(t.startswith('callq *') for t in lb) or any(re.match(r'^shrq\s+%cl', t) for t in lb): + continue + r = shortest(blocks, succ, lab, h, bs, need=1, nocall=True) + if r and (look is None or r[0] < look[0]): + look = r + out[name] = (len(ins), best, look, walks) + return out + + +def dump(path, target, need): + for name, pat in TARGETS: + if name != target: + continue + b = symbol_bodies(path, [re.compile(pat)]) + body = merged(b) + ins = instrs(body); blocks = blocks_of(ins); loops = natural_loops(blocks); succ, pred = cfg(blocks) + lab = {i: l for i, (l, _) in enumerate(blocks)} + best = None + for h, bs in loops.items(): + r = shortest(blocks, succ, lab, h, bs, need=need, nocall=name.startswith('P')) + if r and (best is None or r[0] < best[0]): + best = r + print(f'### {target} need={need}: {best[0]} instrs, {best[1]} reads, {best[2]} stores') + for sg in best[4]: + print(' --') + for t in sg: + print(' ' + t) + + +if __name__ == '__main__': + if len(sys.argv) > 3 and sys.argv[2] in dict(TARGETS): + dump(sys.argv[1], sys.argv[2], int(sys.argv[3])) + sys.exit() + cols = [one(p) for p in sys.argv[1:]] + print("target " + "".join(f"{os.path.basename(p)[:22]:>60}" for p in sys.argv[1:])) + print("K: total | prologue | walk loop | paths: tag-skip, first-word MISS, first-word pass + pre_eq fail (the 83% path at L9), pass + fused short; F: per-byte loops; P: per-position no-match path without / with the rep probe") + for name, _ in TARGETS: + line = f"{name:<12}" + for c in cols: + v = c.get(name) + if v is None: + line += f"{'-':>42}"; continue + if name.startswith('K'): + n, hdr, ln, sp, rl, r, rx, pro, rp, rf = v + fmt = lambda q: f'{q[0]}/{q[1]}r{q[2]}s' if q else '-' + line += f"{f'{n} | pro {pro} | L{ln} sp{sp} rd{rl} | skip {fmt(r)} miss {fmt(rx)} pre {fmt(rp)} fused {fmt(rf)}':>60}" + elif name.startswith('F'): + n, rows = v + line += f"{f'{n} | ' + ' '.join(f'{r[0] if r else 0}/{r[1] if r else 0}r' for _, _, _, _, r in rows):>42}" + else: + n, best, look, walks = v + if best is None: + line += f"{f'{n} | no loop':>42}" + else: + hdr, r, ln, sp, rl, r3 = best + lk = f' look {look[0]}/{look[1]}r' if look else ' look -' + if walks: + lk += ' walk miss ' + ' '.join(f'{w[0]}/{w[1]}r' for w in walks[:2]) + ' pre ' + ' '.join(f'{w[6][0]}/{w[6][1]}r' if w[6] else '-' for w in walks[:2]) + line += f"{(f'{n} | norep {r[0]}/{r[1]}r{r[2]}s rep {r3[0]}/{r3[1]}r{r3[2]}s' if r3 else f'{n} | norep {r[0]}/{r[1]}r{r[2]}s') + lk:>42}" + print(line) diff --git a/tools/copycat.py b/tools/copycat.py new file mode 100644 index 0000000..e1f7012 --- /dev/null +++ b/tools/copycat.py @@ -0,0 +1,187 @@ +#!/usr/bin/env python3 +"""Catalogue every byte-moving call in the emitted release asm, with LENGTHS. + +WHY THE ASM AND NOT THE SOURCE +------------------------------ +A source grep finds the copies you WROTE. It cannot find the ones the compiler +made, and it cannot tell you which of yours survived inlining. Only the `.s` +shows: + + * a fixed-size stack temporary the optimiser zeroes with a `memset` call, + * a `fill` / `copy_from_slice` whose RUNTIME length made it a real call where + a constant length would have inlined, + * a by-value struct move or return that moves more than it looks like, + * a copy the optimiser INTRODUCED (an argument spill, a materialised temp), + * and, the other way, which of your written copies LLVM already inlined away + -- so you do not "optimise" a call that does not exist. + +`__rust_alloc_zeroed` is counted alongside them: it is a memset the allocator +performs on your behalf, and it is invisible to a grep for `memset`. + +LENGTHS +------- +Where the length register is loaded from an immediate right before the call, +that constant is the exact byte count and is reported. Windows x64 passes +memcpy(dst=rcx, src=rdx, len=r8); SysV passes (rdi, rsi, rdx). A call with no +constant length is a RUNTIME length -- which is itself the finding, because a +constant-length copy would have been inlined instead of called. + +WHAT "REDUCIBLE" MEANS +---------------------- +An encoder MUST move literal bytes into its output; that traffic is the job. +The target is not "zero calls", it is "no call that moves bytes a second time, +or moves bytes nobody reads". Every candidate still has to be A/B'd -- on this +workspace's record most "obvious redundant hop" removals measure ~0. + +usage: python tools/copycat.py [asm.s] [--side enc|dec|all] [--min N] [--const] +""" +import re +import sys +from collections import defaultdict + +LABEL = re.compile(r"^([A-Za-z_$][\w$.@]*):") +BLOCK = re.compile(r"^(\.?L[A-Za-z0-9_$.]+):") +MEMCALL = re.compile( + r"^\s*call[q]?\s+_?(memcpy|memmove|memset|__rust_alloc_zeroed)\b") +JMP_BACK = re.compile(r"^\s*j[a-z]{1,3}\s+(\.?L[A-Za-z0-9_$.]+)\s*$") +# Immediate into a length register, either ABI. Windows x64: r8/r8d. SysV: rdx/edx. +IMM_LEN = re.compile( + r"^\s*mov[lq]?\s+\$(\d+),\s*%(r8d|r8|edx|rdx|esi|rsi)\b") + +SIDE = [ + ("train", ("5train", "train5train", "select_fastcover", "10Dictionary")), + ("dec", ("decode", "decompress", "10compressed", "7huffman12HuffmanTable", + "read_table", "parse_ncount", "BitRev")), + ("enc", ("6encode", "encode", "compress", "HuffCTable", "3fse", "7huffman", + "2mt", "5train")), +] + + +def side_of(sym): + for name, keys in SIDE: + for k in keys: + if k in sym: + return name + return "other" + + +def demangle(sym): + s = re.sub(r"^_R[A-Za-z]*", "", sym) + s = re.sub(r"C[sS][A-Za-z0-9_]{10,}_", "", s) + s = re.sub(r"\d+(?=[a-zA-Z_])", "::", s) + return s.replace("::::", "::")[-66:] + + +def main(): + args = sys.argv[1:] + side_want, min_n, want_const = "all", 1, False + if "--side" in args: + k = args.index("--side") + side_want = args[k + 1] + del args[k:k + 2] + if "--min" in args: + k = args.index("--min") + min_n = int(args[k + 1]) + del args[k:k + 2] + if "--const" in args: + want_const = True + args.remove("--const") + if args: + path = args[0] + else: + import glob + import os + c = glob.glob("target/release/deps/rusty_zstd-*.s") + if not c: + sys.exit("no asm; run: cargo rustc --release -p rusty_zstd -- --emit asm") + path = max(c, key=os.path.getmtime) + + lines = open(path, encoding="utf-8", errors="replace").read().splitlines() + + sym_at, block_start, loop_blocks = [], {}, set() + cur = "" + for i, ln in enumerate(lines): + m = LABEL.match(ln) + if m and not m.group(1).startswith(("anon.", ".L")): + cur = m.group(1) + b = BLOCK.match(ln) + if b: + block_start[b.group(1)] = i + j = JMP_BACK.match(ln) + if j and j.group(1) in block_start and block_start[j.group(1)] < i: + loop_blocks.add(j.group(1)) + sym_at.append(cur) + + counts = defaultdict(lambda: defaultdict(int)) + inloop = defaultdict(int) + consts = defaultdict(list) # sym -> [(kind, len)] + runtime = defaultdict(int) + cur_block = None + for i, ln in enumerate(lines): + b = BLOCK.match(ln) + if b: + cur_block = b.group(1) + m = MEMCALL.match(ln) + if not m: + continue + kind, sym = m.group(1), sym_at[i] + counts[sym][kind] += 1 + if cur_block in loop_blocks: + inloop[sym] += 1 + # Walk back a few instructions for an immediate into the length reg. + n = None + for k in range(i - 1, max(i - 7, 0), -1): + mm = IMM_LEN.match(lines[k]) + if mm: + n = int(mm.group(1)) + break + if re.match(r"^\s*call", lines[k]): + break + if n is None: + runtime[sym] += 1 + else: + consts[sym].append((kind, n)) + + rows = [] + for sym, kinds in counts.items(): + sd = side_of(sym) + if side_want != "all" and sd != side_want: + continue + tot = sum(kinds.values()) + if tot < min_n: + continue + rows.append((tot, sym, sd, kinds, inloop[sym], runtime[sym])) + rows.sort(reverse=True) + + g = defaultdict(int) + for _, _, _, kinds, _, _ in rows: + for k, v in kinds.items(): + g[k] += v + print(f"asm: {path}") + print(f"side={side_want} symbols={len(rows)} memcpy={g['memcpy']} " + f"memset={g['memset']} memmove={g['memmove']} " + f"alloc_zeroed={g['__rust_alloc_zeroed']}") + print(f"\n{'tot':>4} {'cpy':>4} {'set':>4} {'mov':>4} {'0al':>4} " + f"{'loop':>5} {'rtlen':>6} side symbol") + for tot, sym, sd, kinds, nl_, rt in rows: + print(f"{tot:>4} {kinds.get('memcpy',0):>4} {kinds.get('memset',0):>4} " + f"{kinds.get('memmove',0):>4} {kinds.get('__rust_alloc_zeroed',0):>4} " + f"{(nl_ or ''):>5} {(rt or ''):>6} {sd:<5} {demangle(sym)}") + print("\n'loop' = calls in a block something jumps BACK to; they multiply " + "by the trip count.") + print("'rtlen' = calls whose length is NOT a compile-time constant. A " + "constant-length\n copy would have been INLINED, so every " + "one of these is a real call.") + + if want_const: + print("\nCONSTANT-LENGTH calls (exact bytes, from the length register):") + for _, sym, sd, _, _, _ in rows: + if not consts[sym]: + continue + tot = sum(n for _, n in consts[sym]) + det = ", ".join(f"{k}:{n}" for k, n in sorted(consts[sym])[:6]) + print(f" {tot:>8} B {sd:<5} {demangle(sym)}\n {det}") + + +if __name__ == "__main__": + main() diff --git a/tools/icount.sh b/tools/icount.sh new file mode 100644 index 0000000..c3b053c --- /dev/null +++ b/tools/icount.sh @@ -0,0 +1,46 @@ +#!/bin/bash +# Per-symbol instruction count from the emitted release asm. +# +# DETERMINISTIC: same toolchain + same source = same number on any machine +# under any load. That is the whole point -- a 2-instruction change is a +# verdict here, where on a drifting box no paired A/B could resolve it. +# +# CAVEATS THAT TRAVEL WITH THE NUMBER: +# * It cannot price work moved BETWEEN branches. Hoisting a subexpression two +# sibling `if` arms shared measured +33 instructions while executing strictly +# less. Ask whether the change is straight-line before trusting the sign. +# * It systematically favours outlining and branch-merging, so never let it +# decide `#[inline(never)]`. +# * It scores every FAST PATH as a loss: the new arm is new code and the old +# arm has to stay. Price a fast path in CALLS avoided instead. +# +# usage: tools/icount.sh > before.txt ; ... ; tools/icount.sh > after.txt +# diff <(cut -d' ' -f2- before.txt) ... or tools/icount.sh --diff before.txt +set -u +cd "$(dirname "$0")/.." || exit 1 +S=$(ls -t target/release/deps/rusty_zstd-*.s 2>/dev/null | head -1) +[ -z "$S" ] && { echo "no asm; run: cargo rustc --release -p rusty_zstd -- --emit asm" >&2; exit 1; } + +dump() { + awk ' + /^[A-Za-z_$][A-Za-z0-9_$.@]*:/ { sym=substr($0,1,index($0,":")-1); next } + /^\.?L[A-Za-z0-9_$.]*:/ { next } + /^[[:space:]]*\./ { next } + /^[[:space:]]*$/ { next } + /^[[:space:]]*#/ { next } + sym != "" { c[sym]++ } + END { for (s in c) printf "%8d %s\n", c[s], s } + ' "$S" | sort -rn +} + +if [ "${1:-}" = "--diff" ]; then + BEFORE="$2" + dump > /tmp/icount_after.$$ + echo "delta before after symbol" + join -j 2 -o 0,1.1,2.1 <(sort -k2 "$BEFORE") <(sort -k2 /tmp/icount_after.$$) 2>/dev/null \ + | awk '{ d=$3-$2; if (d!=0) printf "%+6d %7d %7d %s\n", d, $2, $3, $1 }' \ + | sort -n + rm -f /tmp/icount_after.$$ +else + dump +fi diff --git a/tools/loopscan.py b/tools/loopscan.py new file mode 100644 index 0000000..514eb4c --- /dev/null +++ b/tools/loopscan.py @@ -0,0 +1,200 @@ +#!/usr/bin/env python3 +"""Find the four mechanically-detectable inefficiencies in innermost loops. + +Reading the emitted assembly of a hot function and asking what each instruction +is FOR is the only instrument that finds this class -- each costs 2-10 +instructions, so nothing profiles as a hotspot and a reviewer walks past all of +them. These four patterns need no judgement at all, which is exactly why they +find things a careful reader misses: + + HALF-STORE a store narrower than the loop's widest register (a `movq %xmm`, + or a 128-bit store out of a `ymm`). The loop is doing half the + work its registers are shaped for; pairing two groups halves the + pack+store overhead. + + NARROW a small outputs-per-trip count next to a much larger one in the + same kernel -- a tail that could step wider, or share loads with + its neighbour. + + INVARIANT a `set1`/`vpbroadcast`/constant load INSIDE the loop body. It does + not depend on the induction variable and belongs above it. + + SELECT three or more `pcmpeq` in one body: a compare/mask/merge chain a + single `pshufb` table lookup replaces. + +CAVEAT THAT MUST TRAVEL WITH THE OUTPUT. These are CANDIDATES, not findings. A +`pshufb` rewrite that removes ALU ops but not per-trip overhead can still lose +on a short body -- one measured 3.125 instructions per output against the +compare-chain it replaced at 2.812, and only won (2.188) once the trips were +paired. Price every candidate at its paired width before believing it. + +usage: python tools/loopscan.py [asm.s] [--sym REGEX] [--min-trip N] +""" +import re +import sys + +LABEL = re.compile(r"^(\.?L[A-Za-z0-9_$.]+|[A-Za-z_$][\w$.@]*):") +JMP_ANY = re.compile(r"^\s*(j[a-z]{1,3})\s+(\.?L[A-Za-z0-9_$.]+)\s*$") +DIRECTIVE = re.compile(r"^\s*\.") +YMM = re.compile(r"%ymm\d+") +XMM = re.compile(r"%xmm\d+") +# stores: mnemonic then a memory destination as the LAST operand +STORE = re.compile(r"^\s*(v?mov[a-z]*|v?movnt[a-z]*)\s+(%[a-z0-9]+),\s*[-\d(]") +# INVARIANT must be UNAMBIGUOUS or it manufactures findings. The first version +# also matched `pshufd $0, %xmm, %xmm`, which broadcasts a value just LOADED in +# the body -- loop-VARIANT -- and it flagged three loops whose real constants +# LLVM had already hoisted above the backedge. Only a load from a rip-relative +# constant INSIDE the body is genuinely invariant, so that is all this matches +# now. A detector that fires on correct code is worse than no detector. +BROADCAST = re.compile( + r"(?:vpbroadcast|vbroadcast)[a-z0-9]*\s+[^,]*\(%rip\)|movdq[au]\s+[^,]*\(%rip\)" +) +PCMPEQ = re.compile(r"\bv?pcmpeq[bwdq]\b") +CALLISH = re.compile(r"^\s*(call|callq)\b") + + +def blocks(lines): + """label -> (start_index, end_index) of its instruction range.""" + idx = {} + order = [] + for i, ln in enumerate(lines): + m = LABEL.match(ln) + if m: + idx[m.group(1)] = i + order.append((m.group(1), i)) + ends = {} + for k, (name, i) in enumerate(order): + ends[name] = order[k + 1][1] if k + 1 < len(order) else len(lines) + return idx, ends + + +def current_symbol(order_syms, i): + lo, hi = 0, len(order_syms) - 1 + best = "" + for name, pos in order_syms: + if pos <= i: + best = name + else: + break + return best + + +def store_width(ln): + """Width in bytes of a store instruction, from its register operand.""" + m = STORE.match(ln) + if not m: + return 0 + reg = m.group(1) + if "ymm" in reg: + return 32 + if "xmm" in reg: + # movq %xmm -> 8 bytes; movd -> 4; otherwise a full 16 + mn = ln.strip().split()[0] + if mn.endswith("q"): + return 8 + if mn.endswith("d"): + return 4 + return 16 + if reg.startswith("%r"): + return 8 + if reg.startswith("%e"): + return 4 + return 1 + + +def main(): + args = sys.argv[1:] + sym_filter = None + if "--sym" in args: + k = args.index("--sym") + sym_filter = re.compile(args[k + 1]) + del args[k : k + 2] + min_trip = 0 + if "--min-trip" in args: + k = args.index("--min-trip") + min_trip = int(args[k + 1]) + del args[k : k + 2] + if args: + path = args[0] + else: + import glob, os + + c = glob.glob("target/release/deps/rusty_zstd-*.s") + if not c: + sys.exit("no asm; run: cargo rustc --release -p rusty_zstd -- --emit asm") + path = max(c, key=os.path.getmtime) + + lines = open(path, encoding="utf-8", errors="replace").read().splitlines() + idx, ends = blocks(lines) + order_syms = [ + (m.group(1), i) + for i, ln in enumerate(lines) + if (m := LABEL.match(ln)) and not m.group(1).startswith((".L", "anon.")) + ] + + # An innermost loop: a block whose last instruction jumps BACK to its own + # label (or to a label at/above its start with no intervening label target). + findings = [] + for name, start in idx.items(): + if not name.startswith(".L"): + continue + end = ends.get(name, start) + body = lines[start + 1 : end] + if not body: + continue + # does the block jump back to itself? + backedge = False + for ln in body: + m = JMP_ANY.match(ln) + if m and m.group(2) == name: + backedge = True + if not backedge: + continue + instrs = [ + ln + for ln in body + if ln.strip() and not DIRECTIVE.match(ln) and not LABEL.match(ln) + ] + if any(CALLISH.match(ln) for ln in instrs): + continue # not a tight kernel loop + n = len(instrs) + if n < 3: + continue + sym = current_symbol(order_syms, start) + if sym_filter and not sym_filter.search(sym): + continue + has_ymm = any(YMM.search(ln) for ln in instrs) + has_xmm = any(XMM.search(ln) for ln in instrs) + widest = 32 if has_ymm else (16 if has_xmm else 8) + stores = [(ln, store_width(ln)) for ln in instrs if store_width(ln)] + bytes_out = sum(w for _, w in stores) + if bytes_out < min_trip: + continue + flags = [] + if stores: + mx = max(w for _, w in stores) + if mx < widest: + flags.append(f"HALF-STORE(store {mx}B < reg {widest}B)") + inv = [ln.strip() for ln in instrs if BROADCAST.search(ln)] + if inv: + flags.append(f"INVARIANT({len(inv)} broadcast in body)") + ncmp = sum(1 for ln in instrs if PCMPEQ.search(ln)) + if ncmp >= 3: + flags.append(f"SELECT({ncmp} pcmpeq)") + if not flags: + continue + findings.append((sym, name, n, bytes_out, flags)) + + findings.sort(key=lambda f: (-len(f[4]), -f[2])) + print(f"asm: {path}") + print(f"innermost loops flagged: {len(findings)}\n") + print(f"{'instrs':>6} {'outB':>6} symbol / block") + for sym, blk, n, out, flags in findings: + short = sym[-60:] if len(sym) > 60 else sym + print(f"{n:>6} {out:>6} {short} [{blk}]") + for f in flags: + print(f"{'':>13} -> {f}") + + +if __name__ == "__main__": + main() diff --git a/tools/panic_census.py b/tools/panic_census.py new file mode 100644 index 0000000..86680a6 --- /dev/null +++ b/tools/panic_census.py @@ -0,0 +1,272 @@ +#!/usr/bin/env python3 +"""Rank the GUARD BRANCHES in a release build: conditional jumps that exist +only to reach a panic. + +WHY THIS AND NOT AN INSTRUCTION COUNT +------------------------------------- +A static instruction count is the right primary counter for a straight-line +change, but it is a blunt instrument for proving an index in range: it moves +when inlining moves, and it mixes the guard you removed in with every other +change LLVM made. The guard-branch count isolates exactly that class, and it +does not drift when an inlining boundary shifts. + +THE DETECTOR HAS NO FREE PARAMETER, DELIBERATELY +------------------------------------------------ +The obvious rule -- "does a panic symbol appear within N lines of the branch +target" -- is a knob, and a knob has to be swept before it can be quoted. Swept +on a real codec it produced 95/115/119/120/125/128/132/143 for budgets 4..64: +monotonic, no plateau, i.e. it was measuring the knob and not the program. Panic +blocks share tails and sit next to one another, so a window either stops short +of the shared `call` or falls through into an unrelated neighbour. + +So the rule here is structural: walk the branch target to its FIRST control +transfer (following unconditional jumps), and ask whether that transfer is a +panic call. Nothing to tune, and it cannot drift with block layout. + +NAMING THE LINE +--------------- +Debug line tables attribute an inlined bounds check to `core/src/slice/index.rs` +-- the check, not the caller -- so every guard in the codec reads as the same +useless line. But every panic call passes a `&core::panic::Location`, which +rustc emits as an `anon.*` rodata object holding {&str file, u32 line, u32 col}. +Reading that names the line of OUR code that failed to prove its index. It needs +no debug info and no source edit, so it cannot perturb what it measures. + +usage: python tools/panic_census.py [asm.s] [--all] [--sym REGEX] +""" +import re +import sys +from collections import defaultdict + +PANIC_RE = re.compile( + r"panic_bounds_check|panic_const_(?:div|rem)_by_zero|panic_fmt|" + r"panic_misaligned|slice_(?:start|end)_index|panic_out_of_range|" + r"unwrap_failed|panic_no_value|panic_cannot_unwind" +) +COND_JMP = re.compile(r"^\s*(j(?!mp\b)[a-z]{1,3})\s+(\.?L[A-Za-z0-9_$.]+)\s*$") +UNCOND_JMP = re.compile(r"^\s*jmp\s+(\.?L[A-Za-z0-9_$.]+)\s*$") +CALL = re.compile(r"^\s*(?:call|callq|jmp)\s+\*?([A-Za-z_$.][\w$.@]*)") +LABEL = re.compile(r"^(\.?L[A-Za-z0-9_$.]+|[A-Za-z_$][\w$.@]*):") +LEA_ANON = re.compile(r"lea[ql]?\s+(anon\.[0-9a-f]+(?:\.\d+)?)\(%rip\)") +DIRECTIVE = re.compile(r"^\s*\.") + + +def parse(path): + lines = open(path, encoding="utf-8", errors="replace").read().splitlines() + # label -> index of its first instruction line + label_at = {} + for i, ln in enumerate(lines): + m = LABEL.match(ln) + if m: + label_at[m.group(1)] = i + return lines, label_at + + +def _unescape(sv): + """Decode a gas .asciz/.ascii operand body into bytes.""" + out = bytearray() + i = 0 + while i < len(sv): + c = sv[i] + if c != "\\": + out.append(ord(c) & 0xFF) + i += 1 + continue + i += 1 + if i >= len(sv): + break + d = sv[i] + if d.isdigit(): + j = i + while j < len(sv) and j < i + 3 and sv[j].isdigit(): + j += 1 + out.append(int(sv[i:j], 8) & 0xFF) + i = j + else: + out.append({"n": 10, "t": 9, "r": 13, "0": 0}.get(d, ord(d))) + i += 1 + return bytes(out) + + +def read_anon_locations(lines): + """anon.N -> (file_symbol, line). + + rustc emits a `core::panic::Location` as `.quad ` followed + by a packed payload: u64 string length, u32 line, u32 col. On this target + the payload is a single `.asciz` with octal escapes rather than `.long` + directives, so it has to be decoded rather than pattern-matched. + """ + out = {} + n = len(lines) + for i in range(n): + m = re.match(r"^(anon\.[0-9a-f]+(?:\.\d+)?):", lines[i]) + if not m: + continue + name = m.group(1) + quad = None + payload = None + for j in range(i + 1, min(i + 8, n)): + s = lines[j].strip() + if re.match(r"^anon\.", s) or re.match(r"^\.section", s): + break + q = re.match(r"\.quad\s+([A-Za-z_$.][\w$.@]*)", s) + if q and quad is None: + quad = q.group(1) + continue + a = re.match(r'\.(?:asciz|ascii)\s+"(.*)"\s*$', s) + if a and quad is not None: + payload = _unescape(a.group(1)) + break + if quad is not None and payload is not None and len(payload) >= 12: + line_no = int.from_bytes(payload[8:12], "little") + out[name] = (quad, line_no) + return out + + +def read_str_symbols(lines): + """file-str symbol -> the path it holds.""" + out = {} + for i, ln in enumerate(lines): + m = LABEL.match(ln) + if not m: + continue + name = m.group(1) + for j in range(i + 1, min(i + 4, len(lines))): + s = lines[j].strip() + a = re.match(r'\.ascii\s+"(.*)"$', s) or re.match(r'\.asciz\s+"(.*)"$', s) + if a: + v = a.group(1) + if "/" in v or "\\" in v or v.endswith(".rs"): + out[name] = v.replace("\\\\", "/") + break + if not DIRECTIVE.match(lines[j]): + break + return out + + +def first_transfer(lines, label_at, label, seen=None): + """Walk from `label` to the first control transfer, following unconditional + jumps. Returns (kind, operand) where kind is 'call' | 'cond' | 'end'.""" + if seen is None: + seen = set() + if label in seen or label not in label_at: + return ("end", None) + seen.add(label) + i = label_at[label] + 1 + while i < len(lines): + ln = lines[i] + if LABEL.match(ln): + # fell through into the next block + nxt = LABEL.match(ln).group(1) + return first_transfer(lines, label_at, nxt, seen) + s = ln.strip() + if not s or DIRECTIVE.match(ln): + i += 1 + continue + u = UNCOND_JMP.match(ln) + if u: + return first_transfer(lines, label_at, u.group(1), seen) + c = CALL.match(ln) + if c: + return ("call", c.group(1)) + if COND_JMP.match(ln): + return ("cond", COND_JMP.match(ln).group(2)) + if re.match(r"^\s*(ret|ud2|int3)", ln): + return ("end", s.split()[0]) + i += 1 + return ("end", None) + + +def anon_in_block(lines, label_at, label, seen=None): + """Find the Location operand reachable from `label`.""" + if seen is None: + seen = set() + if label in seen or label not in label_at: + return None + seen.add(label) + i = label_at[label] + 1 + while i < len(lines): + ln = lines[i] + if LABEL.match(ln): + return anon_in_block(lines, label_at, LABEL.match(ln).group(1), seen) + m = LEA_ANON.search(ln) + if m: + return m.group(1) + u = UNCOND_JMP.match(ln) + if u: + return anon_in_block(lines, label_at, u.group(1), seen) + if CALL.match(ln) or re.match(r"^\s*(ret|ud2)", ln): + return None + i += 1 + return None + + +def current_symbol(lines, upto): + """Nearest preceding non-.L label -- the function this block belongs to.""" + for i in range(upto, -1, -1): + m = LABEL.match(lines[i]) + if m and not m.group(1).startswith(".L") and not m.group(1).startswith("anon."): + return m.group(1) + return "" + + +def main(): + args = [a for a in sys.argv[1:]] + show_all = "--all" in args + args = [a for a in args if a != "--all"] + sym_filter = None + if "--sym" in args: + k = args.index("--sym") + sym_filter = re.compile(args[k + 1]) + del args[k : k + 2] + if args: + path = args[0] + else: + import glob, os + + cands = glob.glob("target/release/deps/rusty_zstd-*.s") + if not cands: + sys.exit("no asm found; run: cargo rustc --release -p rusty_zstd -- --emit asm") + path = max(cands, key=os.path.getmtime) + + lines, label_at = parse(path) + anon = read_anon_locations(lines) + strs = read_str_symbols(lines) + + per_sym = defaultdict(int) + per_site = defaultdict(int) + total = 0 + for i, ln in enumerate(lines): + m = COND_JMP.match(ln) + if not m: + continue + kind, op = first_transfer(lines, label_at, m.group(2)) + if kind != "call" or not op or not PANIC_RE.search(op): + continue + total += 1 + sym = current_symbol(lines, i) + if sym_filter and not sym_filter.search(sym): + continue + per_sym[sym] += 1 + a = anon_in_block(lines, label_at, m.group(2)) + if a and a in anon: + fsym, line_no = anon[a] + f = strs.get(fsym, fsym) + per_site[(f, line_no)] += 1 + else: + per_site[("", 0)] += 1 + + print(f"asm: {path}") + print(f"guard branches (conditional jumps whose target's first transfer is a panic call): {total}\n") + print(f"{'guards':>7} symbol") + n = len(per_sym) if show_all else 25 + for sym, c in sorted(per_sym.items(), key=lambda kv: -kv[1])[:n]: + print(f"{c:>7} {sym}") + print(f"\n{'guards':>7} source site (the line that failed to prove its index)") + for (f, l), c in sorted(per_site.items(), key=lambda kv: -kv[1])[: (None if show_all else 30)]: + short = f.split("/")[-1] if f != "" else f + print(f"{c:>7} {short}:{l}") + + +if __name__ == "__main__": + main()