[all-commits] [llvm/llvm-project] dc1fad: [MCP] Enhance MCP copy Instruction removal for spe...

[Vettel via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: dc1fadef232948712ea5cb327b79213475941f11
      https://github.com/llvm/llvm-project/commit/dc1fadef232948712ea5cb327b79213475941f11
  Author: Vettel <924105575 at qq.com>
  Date:   2023-12-26 (Tue, 26 Dec 2023)

  Changed paths:
    M llvm/lib/CodeGen/MachineCopyPropagation.cpp
    A llvm/test/CodeGen/AMDGPU/mcp-implicit-clobber.mir
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-nearbyint-vp.ll
    M llvm/test/CodeGen/X86/shift-i128.ll
    M llvm/test/CodeGen/X86/shift-i256.ll
    M llvm/test/CodeGen/X86/smulo-128-legalisation-lowering.ll
    M llvm/test/CodeGen/X86/vector-interleaved-load-i16-stride-7.ll
    M llvm/test/CodeGen/X86/vector-interleaved-load-i64-stride-7.ll
    M llvm/test/CodeGen/X86/vector-interleaved-load-i8-stride-5.ll
    M llvm/test/CodeGen/X86/vector-interleaved-load-i8-stride-6.ll
    M llvm/test/CodeGen/X86/vector-interleaved-load-i8-stride-7.ll
    M llvm/test/CodeGen/X86/vector-interleaved-load-i8-stride-8.ll
    M llvm/test/CodeGen/X86/vector-interleaved-store-i16-stride-7.ll
    M llvm/test/CodeGen/X86/wide-scalar-shift-legalization.ll

  Log Message:
  -----------
  [MCP] Enhance MCP copy Instruction removal for special case(reapply) (#74239)

Machine Copy Propagation Pass may lose some opportunities to further
remove the redundant copy instructions during the ForwardCopyPropagateBlock
procedure. When we Clobber a "Def" register, we also need to remove the record 
from the copy maps that indicates "Src" defined "Def" to ensure the correct semantics
of the ClobberRegister function.  This patch reapplies #70778 and addresses the corner 
case bug  #73512 specific to the AMDGPU backend. Additionally, it refines the criteria 
for removing empty records from the copy maps, thereby enhancing overall safety.

For more information, please see the C++ test case generated code in 
"vector.body" after the MCP Pass: https://gcc.godbolt.org/z/nK4oMaWv5.