[all-commits] [llvm/llvm-project] 3d04a3: [SelectionDAG] Improve isGuaranteedNotToBeUndefOrP...

[Björn Pettersson via All-commits]

  Branch: refs/heads/users/bjope/prepare_2
  Home:   https://github.com/llvm/llvm-project
  Commit: 3d04a3b11539083519973d65db78d2595a767d54
      https://github.com/llvm/llvm-project/commit/3d04a3b11539083519973d65db78d2595a767d54
  Author: Bjorn Pettersson <bjorn.a.pettersson at ericsson.com>
  Date:   2025-07-17 (Thu, 17 Jul 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    M llvm/test/CodeGen/X86/div-rem-pair-recomposition-signed.ll
    M llvm/test/CodeGen/X86/pr62286.ll

  Log Message:
  -----------
  [SelectionDAG] Improve isGuaranteedNotToBeUndefOrPoison

Add special handling of EXTRACT_SUBVECTOR, INSERT_SUBVECTOR,
EXTRACT_VECTOR_ELT, INSERT_VECTOR_ELT and SCALAR_TO_VECTOR in
isGuaranteedNotToBeUndefOrPoison. Make use of DemandedElts to
improve the analysis and only check relevant elements for each
operand.

Also start using DemandedElts in the recursive calls that
check isGuaranteedNotToBeUndefOrPoison for all operands for
operations that do not create undef/poison. We can do that for
a number of elementwise operations for which the DemandedElts
can be applied to every operand (e.g. ADD, OR, BITREVERSE, TRUNCATE).



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