[PATCH] D124921: [SCEV] Fold umin_seq to umin using implied poison reasoning

[Nikita Popov via Phabricator via llvm-commits]

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Similar to how we convert logical and/or to bitwise and/or, we should also convert umin_seq to umin based on implied poison reasoning. In `%x umin_seq %y`, if `%y` being poison implies `%x` being poison, then we don't need the sequential evaluation: Having `%y` contribute towards the result will never make the result more poisonous. An important corollary of this is that if `%y` is never poison, we also don't need the sequential evaluation.

This avoids some of the regressions in D124910 <https://reviews.llvm.org/D124910>.


https://reviews.llvm.org/D124921

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll

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