[PATCH] D87196: [InstCombine] Fold abs of known negative operand

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
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If we know that the abs operand is known negative, we can replace it with a neg.

To avoid computing known bits twice, I've removed the fold for the non-negative case from InstSimplify. Both the non-negative and the negative case are handled by InstCombine now, with one known bits call.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D87196

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  llvm/test/Transforms/InstCombine/abs-intrinsic.ll
  llvm/test/Transforms/InstSimplify/abs_intrinsic.ll

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