[all-commits] [llvm/llvm-project] de34a9: [X86] Add -mskip-rax-setup support to align with GCC

[Phoebe Wang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: de34a940ae72dfa6425a025538484f9505ca1d42
      https://github.com/llvm/llvm-project/commit/de34a940ae72dfa6425a025538484f9505ca1d42
  Author: Phoebe Wang <pengfei.wang at intel.com>
  Date:   2021-11-18 (Thu, 18 Nov 2021)

  Changed paths:
    M clang/include/clang/Basic/CodeGenOptions.def
    M clang/include/clang/Driver/Options.td
    M clang/lib/CodeGen/CodeGenModule.cpp
    M clang/lib/Driver/ToolChains/Clang.cpp
    A clang/test/CodeGen/pr23258.c
    M clang/test/Driver/x86_features.c
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    A llvm/test/CodeGen/X86/pr23258.ll

  Log Message:
  -----------
  [X86] Add -mskip-rax-setup support to align with GCC

AMD64 ABI mandates caller to specify the number of used SSE registers
when passing variable arguments.
GCC also provides option -mskip-rax-setup to skip the setup of rax when
SSE is disabled. This helps to reduce the code size, see pr23258.

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D112413