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[InstCombine] Fold x & (-1 >> y) != x to x u> (-1 >> y)

Authored by lebedev.ri on Jul 12 2018, 7:56 AM.

Description

[InstCombine] Fold x & (-1 >> y) != x to x u> (-1 >> y)

Summary:
A complementary fold to D49179.

https://bugs.llvm.org/show_bug.cgi?id=38123
https://rise4fun.com/Alive/Rny

Caveat: one more thing in test/Transforms/InstCombine/icmp-logical.ll breaks.

Reviewers: spatel, craig.topper

Reviewed By: spatel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49205

llvm-svn: 336911