[all-commits] [llvm/llvm-project] 4b62af: [X86][CodeGen] Support flags copy lowering for CCM...

[Shengchen Kan via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4b62afca64a3f18cd57a3b3247330effd4b38098
      https://github.com/llvm/llvm-project/commit/4b62afca64a3f18cd57a3b3247330effd4b38098
  Author: Shengchen Kan <shengchen.kan at intel.com>
  Date:   2024-05-18 (Sat, 18 May 2024)

  Changed paths:
    M llvm/lib/Target/X86/X86FlagsCopyLowering.cpp
    M llvm/lib/Target/X86/X86InstrInfo.cpp
    M llvm/lib/Target/X86/X86InstrInfo.h
    A llvm/test/CodeGen/X86/apx/ccmp-flags-copy-lowering.mir

  Log Message:
  -----------
  [X86][CodeGen] Support flags copy lowering for CCMP/CTEST (#91849)

```
%1:gr64 = COPY $eflags
OP1 may update eflags
$eflags = COPY %1
OP2 may use eflags
```

To use eflags as input at 4th instruction, we need to use SETcc to
preserve the eflags before 2, and update the source condition of OP2
according to value in GPR %1.

In this patch, we support CCMP/CTEST as OP2.



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