[PATCH] D85782: [X86][ELF] Prefer lowering MC_GlobalAddress operands to .Lfoo$local only for STV_DEFAULT globals

[ben via Phabricator via llvm-commits]

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This patch restricts the behaviour of referencing via .Lfoo$local local aliases, introduced in https://reviews.llvm.org/D73230, to STV_DEFAULT globals only.

GNU now  recommends -fvisiblity=hidden (https://gcc.gnu.org/wiki/Visibility) so my understanding is that there will be very few STV_DEFAULT symbols.

Benefits:

- Improves the size of object files by using fewer STT_SECTION symbols.
- Improves the assembly (as there are fewer  .Lfoo$local  labels).
- The code reads a bit better (it was not obvious to me without going back to the code reviews why the canBenefitFromLocalAlias function currently doesn't consider visibility).
- Restores the effectiveness of the --wrap linker option and makes the behavior of --wrap consistent between LTO and normal builds references within a translation-unit. See comments on https://reviews.llvm.org/D73230 for more.


https://reviews.llvm.org/D85782

Files:
  llvm/lib/IR/Globals.cpp
  llvm/test/CodeGen/AArch64/emutls.ll
  llvm/test/CodeGen/ARM/emutls.ll
  llvm/test/CodeGen/X86/2008-03-12-ThreadLocalAlias.ll
  llvm/test/CodeGen/X86/code-model-elf-pic-nosip.ll
  llvm/test/CodeGen/X86/code-model-elf-pic-sip.ll
  llvm/test/CodeGen/X86/code-model-elf-pie.ll
  llvm/test/CodeGen/X86/code-model-elf.ll
  llvm/test/CodeGen/X86/semantic-interposition-comdat.ll
  llvm/test/CodeGen/X86/tailcallpic1.ll
  llvm/test/CodeGen/X86/tailcallpic3.ll
  llvm/test/CodeGen/X86/tailccpic1.ll

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