[AArch64] Implement TLS relaxations#1213
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Now you have the ability to also build and run tests. It would be great if you work on a setup to test each relaxation building executables, dynamic executables, PIE, shared libraries to make sure that the behavior is consistent. See the discussion here : #885 |
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Hi Shankar Easwaran (@quic-seaswara), I have added a runtime test ( |
Extend IE->LE relaxation in tls_gottprel_page and tls_gottprel_lo to cover global TLS symbols in static executables. Previously only local symbols (without ReserveGOT) were relaxed. Fixes part of qualcomm#1004 Signed-off-by: deepakshirkem <deepakshirke509@gmail.com>
Preserve destination register (Rd) when relaxing TLSDESC_LD64_LO12 to movk in static executables. Previously x0 was hardcoded. Also extend relaxation to cover global symbols in static executables by adding isCodeStatic() check, matching the IE->LE fix. Fixes part of qualcomm#1004 Signed-off-by: deepakshirkem <deepakshirke509@gmail.com>
…cutables Extend TLSDESC->LE relaxation in tls_tlsdesc_page to cover global TLS symbols in static executables by adding isCodeStatic() check. Also fix tls_tlsdesc_lo to always use x0 for the relaxed movk instruction, matching LLD behavior and ensuring the TLS offset is in the correct register after relaxation. Add test for TLSDESC->LE relaxation covering both global and local TLS symbols. Fixes part of qualcomm#1004 Signed-off-by: deepakshirkem <deepakshirke509@gmail.com>
For PIE executables, relax TLSDESC sequences to Initial Exec (IE) instead of keeping the expensive TLSDESC runtime resolver call. Changes: - scanLocalReloc/scanGlobalReloc: detect isPIE() and create IE GOT entry with R_AARCH64_TLS_TPREL64 dynamic relocation instead of TLSDESC GOT with R_AARCH64_TLSDESC - tls_tlsdesc_lo: rewrite ldr to IE GOT load into x0 for PIE - tls_tlsdesc_add: emit nop for PIE (matching static behavior) - tls_call: emit nop for PIE (matching static behavior) - Update DESC.test placeholder with correct CHECK lines - Add TLS_DESC_PIE.test to verify TLSDESC->IE relaxation Fixes part of qualcomm#1004 Signed-off-by: deepakshirkem <deepakshirke509@gmail.com>
Add TLS_Relaxation_Verify test using real compiler-generated TLS relocations to verify end-to-end correctness of relaxations: - TLSDESC->LE for static executables (movz+movk+nop+nop) - TLSDESC->IE for PIE executables (adrp+ldr+nop+nop) - R_AARCH64_TLS_TPREL64 dynamic reloc present in PIE Add IE_PIE test to verify IE relocations remain as GOT-indirect adrp+ldr in PIE executables. Fixes part of qualcomm#1004 Signed-off-by: deepakshirkem <deepakshirke509@gmail.com>
Local TLS symbols in PIE executables were incorrectly getting R_AARCH64_TLS_TPREL64 dynamic relocations. Since local symbols have no name in the dynamic symbol table, the dynamic linker cannot resolve these relocations, causing a segmentation fault at runtime. Fix by checking rsym->isLocal() in the PIE path: - Local symbols: fill GOT at link time (TLSStaticSymbolValue) - Global symbols: emit R_AARCH64_TLS_TPREL64 dynamic reloc This bug was caught by adding runtime tests that actually execute the linked binary under QEMU. Add TLS_RunTest to verify TLS relaxations work correctly at runtime for static, PIE, and dynamic executables. Fixes part of qualcomm#1004 Signed-off-by: deepakshirkem <deepakshirke509@gmail.com>
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Fixes part of #1004
Implements TLS relaxations for AArch64 covering all TLS access models supported by the AArch64 ABI
Implementation follows LLD's AArch64 TLS relaxation in lld/ELF/Arch/AArch64.cpp (relaxTlsGdToLe, relaxTlsGdToIe,
relaxTlsIeToLe).
CC Parth (@parth-07) Shankar Easwaran (@quic-seaswara) quic-areg