[PATCH] D159329: [InstCombine] Recognize `(icmp eq/ne (and X, ~Mask), 0)` pattern in `foldICmpWithLowBitMaskedVal`

[Noah Goldstein via Phabricator via llvm-commits]

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`(icmp eq/ne (and X, ~Mask), 0)` is equivilent to `(icmp eq/ne (and X,
Mask), X` and we sometimes generate the former pattern intentionally
to reduce number of uses of `X`.
Proof: https://alive2.llvm.org/ce/z/3u-usC


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D159329

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/test/Transforms/InstCombine/icmp-and-lowbit-mask.ll
  llvm/test/Transforms/InstCombine/lshr-and-negC-icmpeq-zero.ll
  llvm/test/Transforms/InstCombine/lshr-and-signbit-icmpeq-zero.ll
  llvm/test/Transforms/InstCombine/shl-and-negC-icmpeq-zero.ll
  llvm/test/Transforms/InstCombine/shl-and-signbit-icmpeq-zero.ll

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