[PATCH] D52148: [InstCombine] foldICmpWithLowBitMaskedVal(): handle uncanonical ((-1 << y) >> y) mask

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri created this revision.
lebedev.ri added reviewers: spatel, craig.topper, RKSimon.

The last low-bit-mask-pattern-producing-pattern i can think of.

https://rise4fun.com/Alive/UGzE <- non-canonical
But we can not canonicalize it because of extra uses.

https://bugs.llvm.org/show_bug.cgi?id=38123


Repository:
  rL LLVM

https://reviews.llvm.org/D52148

Files:
  lib/Transforms/InstCombine/InstCombineCompares.cpp
  test/Transforms/InstCombine/canonicalize-low-bit-mask-v4-and-icmp-eq-to-icmp-ule.ll
  test/Transforms/InstCombine/canonicalize-low-bit-mask-v4-and-icmp-ne-to-icmp-ugt.ll

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