[PATCH] D26091: [ValueTracking] recognize more variants of smin/smax

[Sanjay Patel via llvm-commits]

spatel created this revision.
spatel added reviewers: sanjoy, efriedma, majnemer.
spatel added a subscriber: llvm-commits.
Herald added a subscriber: mcrosier.

Try harder to detect obfuscated min/max patterns: the initial pattern was added with https://reviews.llvm.org/D9352 / https://reviews.llvm.org/rL236202. There was a bug fix for PR27137 at https://reviews.llvm.org/rL264996, but I think we can do better by folding the corresponding smax pattern and commuted variants.

For the PR27137 test case, we could further transform that to a mask with the smeared sign bit (ashr/and/not), but I'm not sure if we want to do that in IR?


https://reviews.llvm.org/D26091

Files:
  lib/Analysis/ValueTracking.cpp
  test/Transforms/InstCombine/max-of-nots.ll
  test/Transforms/InstCombine/select.ll

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