[all-commits] [llvm/llvm-project] 40fa7f: [AMDGPU] Fix computed kill mask (#122736)

[Piotr Sobczak via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 40fa7f5e8b315159d45aa280c771af5998bdc75e
      https://github.com/llvm/llvm-project/commit/40fa7f5e8b315159d45aa280c771af5998bdc75e
  Author: Piotr Sobczak <piotr.sobczak at amd.com>
  Date:   2025-01-14 (Tue, 14 Jan 2025)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIWholeQuadMode.cpp
    M llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.wqm.demote.ll
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.kill.ll
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.wqm.demote.ll
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.wqm.vote.ll
    M llvm/test/CodeGen/AMDGPU/si-annotate-cf-kill.ll
    M llvm/test/CodeGen/AMDGPU/skip-if-dead.ll
    M llvm/test/CodeGen/AMDGPU/wave32.ll
    M llvm/test/CodeGen/AMDGPU/wqm.ll

  Log Message:
  -----------
  [AMDGPU] Fix computed kill mask (#122736)

Replace S_XOR with S_ANDN2 when computing the kill mask in demote/kill
lowering. This has the effect of AND'ing demote/kill condition with exec
which is needed for proper live mask update.

The S_XOR is inadequate because it may return true for lane with exec=0.

This patch fixes an image corruption in game.

I think the issue went unnoticed because demote/kill condition is often
naturally dependent on exec, so AND'ing with exec is usually not
required.



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