[all-commits] [llvm/llvm-project] 9e22c7: [DAG] canCreateUndefOrPoison - only compute shift ...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9e22c7a0ea87228dffcdfd7ab62724f72e0b3e30
      https://github.com/llvm/llvm-project/commit/9e22c7a0ea87228dffcdfd7ab62724f72e0b3e30
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2024-06-01 (Sat, 01 Jun 2024)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

  Log Message:
  -----------
  [DAG] canCreateUndefOrPoison - only compute shift amount knownbits when not poison

Since #93182 we can now call computeKnownBits inside getValidMaximumShiftAmount to determine the bounds of the shift amount ensuring that it wasn't poison, meaning if we did freeze the ahift amount, isGuaranteedNotToBeUndefOrPoison would then fail as we can't call computeKnownBits through FREEZE for potentially poison values.

I'm still reducing a decent test case but wanted to get the buildbot fix ASAP.



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