[PATCH] D50417: [InstCombine] fold fneg into constant operand of fmul/fdiv

[Sanjay Patel via Phabricator via llvm-commits]

spatel created this revision.
spatel added reviewers: mcberg2017, arsenm, wristow.
Herald added subscribers: wdng, mcrosier.

I think this is the missing IR fold noted in https://reviews.llvm.org/D50195, but AFAICT, we don't need any fast-math to enable the transform. FP negation can always be folded into an fmul/fdiv constant to eliminate the fneg.

I've limited this to one-use to ensure that we are eliminating an instruction rather than replacing fneg by a potentially expensive fdiv or fmul.


https://reviews.llvm.org/D50417

Files:
  lib/Transforms/InstCombine/InstCombineAddSub.cpp
  test/Transforms/InstCombine/fneg.ll

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