[all-commits] [llvm/llvm-project] c3e9d0: [lld-macho][LTO] Emit `__llvm_addrsig` for `--icf=...

[alx32 via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c3e9d05ce8044612ecae2eb27dd5ca52b612a8ac
      https://github.com/llvm/llvm-project/commit/c3e9d05ce8044612ecae2eb27dd5ca52b612a8ac
  Author: alx32 <103613512+alx32 at users.noreply.github.com>
  Date:   2026-06-05 (Fri, 05 Jun 2026)

  Changed paths:
    M lld/MachO/LTO.cpp
    M lld/test/MachO/icf-safe-thunks.ll

  Log Message:
  -----------
  [lld-macho][LTO] Emit `__llvm_addrsig` for `--icf=safe_thunks` (#188486)

LTO was emitting `__llvm_addrsig` metadata when `--icf=safe` was
specified, but not for `--icf=safe_thunks`. After the recent PR
https://github.com/llvm/llvm-project/pull/188400 that makes safe ICF
conservative without `__llvm_addrsig` (marking all symbols as
address-significant when the section is absent), this omission caused
safe_thunks to silently degrade for all LTO-compiled objects: every
symbol became `keepUnique`, preventing body folding entirely.

Fix this by also enabling `EmitAddrsig` when `icfLevel` is
`safe_thunks`. This allows the LTO backend to emit precise
address-significance metadata, so that only truly address-significant
functions get thunk treatment while non-address-significant identical
functions can still be body-folded.

Add a regression test that verifies LTO + `--icf=safe_thunks` correctly
body-folds non-address-significant identical functions, which would fail
without this fix due to missing addrsig metadata.



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