[PATCH] D156657: [InstCombine] Fold icmp(constants[x]) when the range of x is given

[Hongyu Chen via Phabricator via llvm-commits]

XChy updated this revision to Diff 546109.
XChy added a comment.

Already limit it to one variable. But I don't know why it is unlikely to be useful. From my perspective For multi-dimensional arrays, it's possible to have more than one index variable.

Besides, there exists miscompilation, I found just now.  Current state-machine doesn't emit the CmpInst/Poison to guarrantee the index/offset is always not negative. Lack of such range-check would lead to something triggering UB not to doing so. I need to check it later.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D156657/new/

https://reviews.llvm.org/D156657

Files:
  llvm/include/llvm/Transforms/InstCombine/InstCombiner.h
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
  llvm/test/Transforms/InstCombine/load-cmp.ll

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