[PATCH] D108165: [InstCombine] fold signed min/max intrinsics with negated operands

[Sanjay Patel via Phabricator via llvm-commits]

spatel created this revision.
spatel added reviewers: lebedev.ri, nikic, RKSimon.
Herald added subscribers: hiraditya, mcrosier.
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If both operands are negated, we can invert the min/max and do the negation after:
smax (neg nsw X), (neg nsw Y) --> neg nsw (smin X, Y)
smin (neg nsw X), (neg nsw Y) --> neg nsw (smax X, Y)

This is visible as a remaining regression in D98152 <https://reviews.llvm.org/D98152>. I don't see a way to generalize this for 'unsigned' or adapt Negator to handle it. This only appears to be safe with 'nsw':
https://alive2.llvm.org/ce/z/GUy1zJ


https://reviews.llvm.org/D108165

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  llvm/test/Transforms/InstCombine/minmax-intrinsics.ll

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