Use trie for removeStringLiteralsMatchedByTemplateLiterals by eps1lon · Pull Request #3331 · microsoft/typescript-go

Sebastian "Sebbie" Silbermann (eps1lon) · 2026-04-02T20:08:39Z

Port of microsoft/TypeScript#63343
Fixes microsoft/TypeScript#63342

Actual implementation is vibe-coded with Claude Opus 4.6 (1M context)

Copilot

Pull request overview

This PR ports the TypeScript change to speed up removeStringLiteralsMatchedByTemplateLiterals by indexing template-literal patterns by their leading text, reducing repeated full scans when pruning redundant string-literal constituents during union reduction.

Changes:

Introduces an internal trie node type for indexing template-literal prefixes.
Adds trie construction + lookup helpers to find a matching template literal efficiently.
Refactors removeStringLiteralsMatchedByTemplateLiterals to use the trie (when beneficial) and to separately handle template literals vs string-mapping patterns.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
internal/checker/types.go	Adds `templateLiteralTrieNode` type to support prefix trie indexing.
internal/checker/relater.go	Adds trie build + lookup helpers that leverage `texts[0]` as the prefix key for template-literal matching.
internal/checker/checker.go	Refactors string-literal pruning to use trie-based matching for template literals and preserves string-mapping handling.

Optimize removeStringLiteralsMatchedByTemplateLiterals by building a prefix trie from TemplateLiteralType patterns and using O(L) trie traversal per string literal instead of O(m) linear scan across all templates. StringMappingType templates (which cannot be trie-indexed) are checked separately. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Jake Bailey (jakebailey) · 2026-04-08T03:23:39Z

 }

+func (c *Checker) buildTemplateLiteralTrieFromTypes(templateTypes []*Type) *templateLiteralTrieNode {
+	root := &templateLiteralTrieNode{}


For this, you will probably benefit from using core.Arena to avoid a bunch of small allocs of these nodes, given they're all generated once in this func. Can just write var arena core.Arena[templateLiteralTrieNode] and then do arena.New() instead of &templateLiteralTrieNode{}.

Ugh, so, I never hit send on this :(

Jake Bailey (jakebailey) · 2026-08-14T20:00:43Z

TypeScript Bot (@typescript-bot) perf test this faster

typescript-automation · 2026-08-14T20:00:48Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`perf test this faster`	✅ Started	👀 Results

typescript-automation · 2026-08-14T20:30:42Z

Jake Bailey (@jakebailey)
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - native}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_115,480	_115,480	_~	_~	_~	_{p=1.000 n=12}
_Types	_96,945	_96,945	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{149,702k (± 0.47%)}	_{149,080k (± 0.63%)}	_~	_147,286k	_151,414k	_{p=0.266 n=12}
_{Memory Allocs}	_{2,247,386 (± 0.01%)}	_{2,247,351 (± 0.00%)}	_~	_2,247,198	_2,247,572	_{p=0.943 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.040s (± 3.03%)}	_{0.040s (± 4.27%)}	_~	_0.036s	_0.044s	_{p=0.676 n=12}
_{Bind Time}	_{0.013s (±13.37%)}	_{0.012s (±11.58%)}	_~	_0.010s	_0.018s	_{p=0.697 n=12}
_{Check Time}	_{0.506s (± 0.73%)}	_{0.504s (± 0.58%)}	_~	_0.497s	_0.511s	_{p=0.466 n=12}
_{Emit Time}	_{0.270s (± 2.15%)}	_{0.271s (± 2.39%)}	_~	_0.259s	_0.292s	_{p=0.744 n=12}
_{Total Time}	_{0.836s (± 0.73%)}	_{0.834s (± 0.77%)}	_~	_0.822s	_0.858s	_{p=0.619 n=12}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_{846,772 (± 0.11%)}	_{846,936 (± 0.09%)}	_~	_844,433	_848,311	_{p=0.932 n=12}
_Types	_{249,915 (± 0.00%)}	_{249,912 (± 0.00%)}	_~	_249,910	_249,914	_{p=0.717 n=12}
_{Memory Used}	_{793,279k (± 0.09%)}	_{793,597k (± 0.07%)}	_~	_792,454k	_795,260k	_{p=0.478 n=12}
_{Memory Allocs}	_{13,038,229 (± 0.05%)}	_{13,038,941 (± 0.06%)}	_~	_13,030,261	_13,076,325	_{p=0.977 n=12}
_{Config Time}	_{0.016s (± 1.13%)}	_0.016s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.283s (± 2.55%)}	_{0.281s (± 1.77%)}	_~	_0.263s	_0.291s	_{p=0.401 n=12}
_{Bind Time}	_{0.063s (±15.23%)}	_{0.064s (±17.12%)}	_~	_0.057s	_0.119s	_{p=0.741 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_{1.644s (± 1.07%)}	_{1.649s (± 1.16%)}	_~	_1.616s	_1.719s	_{p=0.853 n=12}
_{Total Time}	_{2.021s (± 1.17%)}	_{2.027s (± 1.32%)}	_~	_1.983s	_2.135s	_{p=0.799 n=12}
_{mui-docs - native}
_Errors	_{11,278 (± 0.02%)}	_{11,279 (± 0.02%)}	_~	_11,273	_11,282	_{p=0.853 n=12}
_Symbols	_4,230,792	_4,230,792	_~	_~	_~	_{p=1.000 n=12}
_Types	_1,591,020	_1,591,020	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{4,853,578k (± 0.03%)}	_{4,853,389k (± 0.03%)}	_~	_4,850,141k	_4,857,558k	_{p=0.977 n=12}
_{Memory Allocs}	_{48,413,484 (± 0.04%)}	_{48,414,099 (± 0.04%)}	_~	_48,369,012	_48,462,483	_{p=0.887 n=12}
_{Config Time}	_0.019s	_0.019s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.678s (± 1.90%)}	_{0.673s (± 1.82%)}	_~	_0.637s	_0.695s	_{p=0.639 n=12}
_{Bind Time}	_{0.003s (±13.14%)}	_{0.003s (±29.74%)}	_~	_0.002s	_0.007s	_{p=0.729 n=12}
_{Check Time}	_{18.768s (± 0.73%)}	_{18.673s (± 0.77%)}	_~	_18.262s	_18.979s	_{p=0.291 n=12}
_{Emit Time}	_{0.526s (± 0.34%)}	_{0.528s (± 0.24%)}	_~	_0.524s	_0.531s	_{p=0.097 n=12}
_{Total Time}	_{20.932s (± 0.74%)}	_{20.832s (± 0.80%)}	_~	_20.326s	_21.183s	_{p=0.298 n=12}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,394,411	_1,394,411	_~	_~	_~	_{p=1.000 n=12}
_Types	_443,627	_443,627	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{1,643,434k (± 0.27%)}	_{1,644,158k (± 0.18%)}	_~	_1,634,080k	_1,651,711k	_{p=0.713 n=12}
_{Memory Allocs}	_{96,911,809 (± 0.04%)}	_{96,920,143 (± 0.02%)}	_~	_96,875,224	_96,998,710	_{p=0.410 n=12}
_{Config Time}	_{0.003s (±12.29%)}	_{0.003s (±18.37%)}	_~	_0.002s	_0.004s	_{p=0.601 n=12}
_{Parse Time}	_{0.198s (± 3.14%)}	_{0.194s (± 3.47%)}	_~	_0.177s	_0.207s	_{p=0.354 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.824s (± 0.37%)}	_{1.814s (± 0.63%)}	_~	_1.788s	_1.848s	_{p=0.110 n=12}
_{Emit Time}	_{0.304s (± 3.62%)}	_{0.290s (± 5.41%)}	_~	_0.242s	_0.319s	_{p=0.242 n=12}
_{Total Time}	_{25.262s (± 0.71%)}	_{25.070s (± 0.52%)}	_~	_24.801s	_25.438s	_{p=0.089 n=12}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_337,618	_337,618	_~	_~	_~	_{p=1.000 n=12}
_Types	_198,941	_198,941	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{319,619k (± 0.03%)}	_{319,602k (± 0.03%)}	_~	_319,237k	_319,852k	_{p=0.876 n=12}
_{Memory Allocs}	_{4,660,721 (± 0.01%)}	_{4,660,791 (± 0.01%)}	_~	_4,659,573	_4,663,002	_{p=0.887 n=12}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.116s (± 4.61%)}	_{0.118s (± 4.34%)}	_~	_0.102s	_0.131s	_{p=0.744 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.056s (± 0.45%)}	_{1.045s (± 0.49%)}	_{-0.012s (- 1.10%)}	_1.035s	_1.058s	_{p=0.002 n=12}
_{Emit Time}	_{0.156s (± 6.71%)}	_{0.159s (± 8.81%)}	_~	_0.116s	_0.185s	_{p=0.640 n=12}
_{Total Time}	_{1.382s (± 0.92%)}	_{1.378s (± 0.98%)}	_~	_1.341s	_1.405s	_{p=0.810 n=12}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_305,341	_305,341	_~	_~	_~	_{p=1.000 n=12}
_Types	_182,038	_182,038	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{277,284k (± 0.03%)}	_{277,320k (± 0.03%)}	_~	_277,058k	_277,536k	_{p=0.478 n=12}
_{Memory Allocs}	_{1,628,064 (± 0.01%)}	_{1,628,199 (± 0.01%)}	_~	_1,627,594	_1,628,613	_{p=0.347 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.082s (± 4.59%)}	_{0.081s (± 5.15%)}	_~	_0.070s	_0.092s	_{p=0.599 n=12}
_{Bind Time}	_{0.027s (±11.04%)}	_{0.030s (±10.97%)}	_~	_0.024s	_0.039s	_{p=0.336 n=12}
_{Check Time}	_{0.701s (± 0.59%)}	_{0.700s (± 0.66%)}	_~	_0.691s	_0.713s	_{p=0.521 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.824s (± 0.53%)}	_{0.822s (± 0.61%)}	_~	_0.813s	_0.843s	_{p=0.417 n=12}
_{vscode - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_7,731,630	_7,731,630	_~	_~	_~	_{p=1.000 n=12}
_Types	_2,662,693	_2,662,693	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{5,225,839k (± 0.01%)}	_{5,226,491k (± 0.01%)}	_~	_5,224,530k	_5,228,209k	_{p=0.128 n=12}
_{Memory Allocs}	_{40,495,184 (± 0.03%)}	_{40,504,966 (± 0.04%)}	_{+9,783 (+ 0.02%)}	_40,489,351	_40,568,823	_{p=0.024 n=12}
_{Config Time}	_{0.061s (± 0.53%)}	_{0.061s (± 0.53%)}	_~	_0.060s	_0.062s	_{p=0.246 n=12}
_{Parse Time}	_{1.612s (± 1.34%)}	_{1.572s (± 2.16%)}	_~	_1.467s	_1.663s	_{p=0.058 n=12}
_{Bind Time}	_{0.331s (± 0.77%)}	_{0.368s (±15.81%)}	_~	_0.326s	_0.613s	_{p=0.578 n=12}
_{Check Time}	_{9.836s (± 0.18%)}	_{9.734s (± 1.27%)}	_~	_9.293s	_9.855s	_{p=0.117 n=12}
_{Emit Time}	_{2.919s (± 0.55%)}	_{3.163s (±10.38%)}	_~	_2.851s	_4.302s	_{p=0.855 n=12}
_{Total Time}	_{14.838s (± 0.24%)}	_{14.981s (± 1.60%)}	_~	_14.713s	_15.839s	_{p=0.810 n=12}
_{webpack - native}
_Errors	₂	₂	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,380	_1,380	_~	_~	_~	_{p=1.000 n=12}
_Types	₃₄₀	₃₄₀	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{194,373k (± 0.06%)}	_{194,409k (± 0.08%)}	_~	_193,987k	_194,871k	_{p=0.682 n=12}
_{Memory Allocs}	_{824,276 (± 0.39%)}	_{823,060 (± 0.16%)}	_~	_819,985	_827,603	_{p=0.671 n=12}
_{Config Time}	_0.008s	_0.008s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.205s (± 2.14%)}	_{0.204s (± 2.22%)}	_~	_0.193s	_0.215s	_{p=0.989 n=12}
_{Bind Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.213s (± 2.08%)}	_{0.212s (± 2.13%)}	_~	_0.201s	_0.223s	_{p=0.876 n=12}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,020,005	_1,020,005	_~	_~	_~	_{p=1.000 n=12}
_Types	_376,891	_376,891	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{603,425k (± 0.01%)}	_{603,422k (± 0.02%)}	_~	_603,007k	_603,579k	_{p=0.713 n=12}
_{Memory Allocs}	_{4,749,823 (± 0.03%)}	_{4,748,527 (± 0.04%)}	_~	_4,745,006	_4,752,302	_{p=0.198 n=12}
_{Config Time}	_0.003s	_0.003s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.146s (± 3.23%)}	_{0.143s (± 2.65%)}	_~	_0.136s	_0.156s	_{p=0.339 n=12}
_{Bind Time}	_{0.040s (±18.20%)}	_{0.042s (±15.26%)}	_~	_0.032s	_0.065s	_{p=0.425 n=12}
_{Check Time}	_{1.080s (± 0.85%)}	_{1.085s (± 0.85%)}	_~	_1.059s	_1.103s	_{p=0.259 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.277s (± 0.85%)}	_{1.286s (± 1.10%)}	_~	_1.257s	_1.313s	_{p=0.311 n=12}

System info unknown

Hosts

native

Scenarios

Compiler-Unions - native
angular-1 - native
mui-docs - native
strada-build-src - native
strada-compiler - native
ts-pre-modules - native
vscode - native
webpack - native
xstate-main - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

Developer Information:

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Sebastian "Sebbie" Silbermann (eps1lon) marked this pull request as ready for review April 2, 2026 20:19

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Sebastian "Sebbie" Silbermann (eps1lon) force-pushed the sebbie/ftl/batched-removal branch from 430ac1c to d7118cd Compare April 7, 2026 09:30

Sebastian "Sebbie" Silbermann (eps1lon) mentioned this pull request Apr 7, 2026

type checking complexity with multiple template literals in unions microsoft/TypeScript#63342

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Sebastian "Sebbie" Silbermann (eps1lon) force-pushed the sebbie/ftl/batched-removal branch 2 times, most recently from c216139 to b318e23 Compare April 7, 2026 11:32

Ryan Cavanaugh (RyanCavanaugh) added this to the Possible Improvement milestone Apr 17, 2026

Jake Bailey (jakebailey) reviewed Aug 14, 2026

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Use trie for removeStringLiteralsMatchedByTemplateLiterals - #3331

Use trie for removeStringLiteralsMatchedByTemplateLiterals#3331
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