[PATCH] D157977: [InstCombine] OptimizePointerDifference when a gep has phi ptr

[Biplob Mishra via Phabricator via llvm-commits]

bipmis created this revision.
bipmis added reviewers: dmgreen, momchil.velikov, nikic, RKSimon.
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bipmis requested review of this revision.

For scenarios like  
gep (PHI(X+A, X)), ...) - ( gep X, ...) where X is a ptr and A is a positive index, if the use of this sub results in a cmp with 0, the sub can essentially be folded.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D157977

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
  llvm/lib/Transforms/InstCombine/InstCombineInternal.h
  llvm/test/Transforms/InstCombine/sub-gep.ll

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