[PATCH] D63505: [InstCombine] Fold icmp eq/ne (and %x, C), 0 iff (-C) is power of two -> %x u</u>= (-C) earlier.

[Huihui Zhang via Phabricator via llvm-commits]

huihuiz updated this revision to Diff 206042.
huihuiz retitled this revision from "[InstCombine] Fold icmp eq/ne (and %x, ~C), 0 -> %x u</u>= 0 earlier, C+1 is power of 2." to "[InstCombine] Fold  icmp eq/ne (and %x, C), 0 iff (-C) is power of two -> %x u</u>= (-C)  earlier.".
huihuiz added a comment.

Yes , this reorder expose yet another missing fold. As regression in test/Transforms/InstCombine/pr17827.ll

Simplify 'shl' inequality test into 'and' equality test should fix this issue. I am posting this into another differential, link shortly.

icmp ult/uge (shl %x, C2), C1 iff C1 is power of two -> icmp eq/ne (and %x, (lshr -C1, C2)), 0


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D63505/new/

https://reviews.llvm.org/D63505

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/test/Transforms/InstCombine/lshr-and-negC-icmpeq-zero.ll
  llvm/test/Transforms/InstCombine/pr17827.ll
  llvm/test/Transforms/InstCombine/shl-and-negC-icmpeq-zero.ll

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