[PATCH] D110869: [X86] Implement -fzero-call-used-regs option

[Bill Wendling via Phabricator via llvm-commits]

void created this revision.
void added reviewers: kees, nickdesaulniers, jyknight.
Herald added subscribers: dexonsmith, dang, jdoerfert, pengfei, hiraditya.
Herald added a reviewer: aaron.ballman.
void requested review of this revision.
Herald added projects: clang, LLVM.
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The "-fzero-call-used-regs" option tells the compiler to zero out
certain registers before the function returns. It's also available as a
function attribute: zero_call_used_regs.

The two upper categories are:

- "used": Zero out used registers.
- "all": Zero out all registers, whether used or not.

The individual options are:

- "skip": Don't zero out any registers. This is the default.
- "used": Zero out all used registers.
- "used-arg": Zero out used registers that are used for arguments.
- "used-gpr": Zero out used registers that are GPRs.
- "used-gpr-arg": Zero out used GPRs that are used as arguments.
- "all": Zero out all registers.
- "all-arg": Zero out all registers used for arguments.
- "all-gpr": Zero out all GPRs.
- "all-gpr-arg": Zero out all GPRs used for arguments.

This is used to help mitigate Return-Oriented Programming exploits.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D110869

Files:
  clang/include/clang/Basic/Attr.td
  clang/include/clang/Basic/AttrDocs.td
  clang/include/clang/Basic/CodeGenOptions.def
  clang/include/clang/Driver/Options.td
  clang/lib/CodeGen/CGCall.cpp
  clang/lib/Driver/ToolChains/Clang.cpp
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/test/CodeGen/zero-call-used-regs.c
  clang/test/Misc/pragma-attribute-supported-attributes-list.test
  clang/test/Sema/zero_call_used_regs.c
  llvm/include/llvm/Support/CodeGen.h
  llvm/lib/Target/X86/X86FrameLowering.cpp
  llvm/lib/Target/X86/X86FrameLowering.h
  llvm/lib/Target/X86/X86RegisterInfo.cpp
  llvm/lib/Target/X86/X86RegisterInfo.h
  llvm/test/CodeGen/X86/zero-call-used-regs-all-arg.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-all-gpr-arg.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-all-gpr.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-all.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-fmod.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-skip.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-smoke-tests.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-used-arg.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-used-gpr-arg.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-used-gpr.ll
  llvm/test/CodeGen/X86/zero-call-used-regs-used.ll

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