[all-commits] [llvm/llvm-project] 79934b: AMDGPU: Preserve dead carry-out when shrinking add...

[Matt Arsenault via All-commits]

  Branch: refs/heads/users/arsenm/amdgpu/foldoperands-shrink-dead-carry
  Home:   https://github.com/llvm/llvm-project
  Commit: 79934b781a25b4f6074e6ea6d9dad37b64ae08ad
      https://github.com/llvm/llvm-project/commit/79934b781a25b4f6074e6ea6d9dad37b64ae08ad
  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

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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