[PATCH] D99027: [InstCombine] Whitelist non-refining folds in SimplifyWithOpReplaced

[Nikita Popov via Phabricator via llvm-commits]

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This is an alternative to D98391 <https://reviews.llvm.org/D98391>/D98585 <https://reviews.llvm.org/D98585>, playing things more conservatively. If `AllowRefinement == false`, then we don't use InstSimplify methods at all, and instead explicitly implement some non-refining folds. Most cases are handled by constant folding, and I only had to add two folds to cover our test cases. While this may lose some optimization power, I think it is safer to approach from this direction, given how many issues this has already caused.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D99027

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/test/Transforms/InstCombine/select.ll
  llvm/test/Transforms/InstSimplify/pr49495.ll

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