[all-commits] [llvm/llvm-project] fd3cc2: [SelectionDAG] Fold undemanded operand to UNDEF fo...

[Björn Pettersson via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: fd3cc204de96728991837259ba3959dd69a235b6
      https://github.com/llvm/llvm-project/commit/fd3cc204de96728991837259ba3959dd69a235b6
  Author: Björn Pettersson <bjorn.a.pettersson at ericsson.com>
  Date:   2025-06-25 (Wed, 25 Jun 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/test/CodeGen/AMDGPU/shufflevector.v3bf16.v2bf16.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v3bf16.v3bf16.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v3f16.v2f16.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v3f16.v3f16.ll
    M llvm/test/CodeGen/X86/vec_int_to_fp.ll

  Log Message:
  -----------
  [SelectionDAG] Fold undemanded operand to UNDEF for VECTOR_SHUFFLE (#145524)

Always let SimplifyDemandedVectorElts fold either side of a
VECTOR_SHUFFLE to UNDEF if no elements are demanded from that side.

For a single use this could be done by SimplifyDemandedVectorElts
already, but in case the operand had multiple uses we did not eliminate
the use.



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