[all-commits] [llvm/llvm-project] 9304af: [InstCombine] Fixing wrong select folding in vecto...

[Jorge Botto via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9304af3927caecdb43d3a9b5d16c6a5b7a6b5594
      https://github.com/llvm/llvm-project/commit/9304af3927caecdb43d3a9b5d16c6a5b7a6b5594
  Author: Jorge Botto <23462171+jf-botto at users.noreply.github.com>
  Date:   2024-08-09 (Fri, 09 Aug 2024)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
    A llvm/test/Transforms/InstCombine/pr98435.ll

  Log Message:
  -----------
  [InstCombine] Fixing wrong select folding in vectors with undef elements (#102244)

This PR fixes https://github.com/llvm/llvm-project/issues/98435.
`SimplifyDemandedVectorElts` mishandles the undef by assuming that
!isNullValue() means the condition is true.

By preventing any value that we're not certain equals 1 or 0, it avoids
having to make any particular choice by not demanding bits from a
particular branch with potentially picking a wrong value.

Proof: https://alive2.llvm.org/ce/z/r8CmEu



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications