[PATCH] D63670: [InstCombine][NFC] Add test to show missing fold for icmp ult/uge (shl %x, C2), C1.

Huihui Zhang via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Jun 21 14:00:55 PDT 2019


huihuiz created this revision.
huihuiz added reviewers: lebedev.ri, efriedma.
Herald added a project: LLVM.

'shl' inequality test

  icmp ult/uge (shl %x, C2), C1 iff C1 is power of two

can be simplified as 'and' equality test

  icmp eq/ne (and %x, (lshr -C1, C2)), 0.


Repository:
  rL LLVM

https://reviews.llvm.org/D63670

Files:
  llvm/test/Transforms/InstCombine/shl-and-unsigned-cmp-const.ll
  llvm/test/Transforms/InstCombine/shl-unsigned-cmp-const.ll

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