[all-commits] [llvm/llvm-project] b43dd2: [InstCombine] improve fold for icmp_eq_and to icmp...

[ZCBing via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b43dd2f6c4a370f11a386dde73ad9bb51a0b6b5c
      https://github.com/llvm/llvm-project/commit/b43dd2f6c4a370f11a386dde73ad9bb51a0b6b5c
  Author: Chenbing Zheng <Chenbing.Zheng at streamcomputing.com>
  Date:   2022-07-05 (Tue, 05 Jul 2022)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/test/Transforms/InstCombine/lshr-and-negC-icmpeq-zero.ll

  Log Message:
  -----------
  [InstCombine] improve fold for icmp_eq_and to icmp_ult

In D95959, the improve analysis for "C >> X" broken the fold
((%x & C) == 0) --> %x u< (-C) iff (-C) is power of two.

It simplifies C, but fails to satisfy the fold condition.
This patch try to restore C before the fold.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D128790