[all-commits] [llvm/llvm-project] d4c1e0: AMDGPU: Preserve dead carry-out when shrinking add...

[Matt Arsenault via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d4c1e0c7374e5f38eb8ebba8ef356065e86cbc2b
      https://github.com/llvm/llvm-project/commit/d4c1e0c7374e5f38eb8ebba8ef356065e86cbc2b
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2026-09-23 (Wed, 23 Sep 2026)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
    M llvm/test/CodeGen/AMDGPU/GlobalISel/saddsat.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/ssubsat.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.1024bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.128bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.160bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.192bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.224bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.256bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.288bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.320bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.352bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.384bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.448bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.48bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.512bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.576bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.640bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.64bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.704bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.768bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.832bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.896bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.960bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.96bit.ll
    M llvm/test/CodeGen/AMDGPU/bf16.ll
    M llvm/test/CodeGen/AMDGPU/div_v2i128.ll
    M llvm/test/CodeGen/AMDGPU/ds-negative-offset-addressing-mode-loop.ll
    M llvm/test/CodeGen/AMDGPU/fcopysign.bf16.ll
    M llvm/test/CodeGen/AMDGPU/fcopysign.f16.ll
    M llvm/test/CodeGen/AMDGPU/fneg-combines.f16.ll
    M llvm/test/CodeGen/AMDGPU/fold-fi-operand-shrink.mir
    M llvm/test/CodeGen/AMDGPU/fold-immediate-operand-shrink-with-carry.mir
    M llvm/test/CodeGen/AMDGPU/fold-immediate-operand-shrink.mir
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fadd.ll
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fmax.ll
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fmin.ll
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fsub.ll
    M llvm/test/CodeGen/AMDGPU/scratch-simple.ll
    M llvm/test/CodeGen/AMDGPU/trunc-store.ll

  Log Message:
  -----------
  AMDGPU: Preserve dead carry-out when shrinking adds in SIFoldOperands (#225687)

The VOP3 form of add/sub with carry out are sometimes shrunk to the VOPC
form when the carry out is dead. Preserve this information by setting
the dead flag on the new instruction. This alleviates some implicit
dependence on LiveVariables' later recomputation of dead flags.

Co-authored-by: Claude (Opus 4.8) <noreply at anthropic.com>



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