[all-commits] [llvm/llvm-project] 897d92: [InstCombine] generalize 2 LSB of demanded bits fo...

[Sanjay Patel via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 897d92faeff65e5fcccaeaf28cd992bec8f05a50
      https://github.com/llvm/llvm-project/commit/897d92faeff65e5fcccaeaf28cd992bec8f05a50
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2022-02-07 (Mon, 07 Feb 2022)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
    M llvm/test/Transforms/InstCombine/mul-masked-bits.ll

  Log Message:
  -----------
  [InstCombine] generalize 2 LSB of demanded bits for X*X

This is a follow-up suggested in D119060.
Instead of checking each of the bottom 2 bits individually,
we can check them together and handle the possibility that
we demand both together.

https://alive2.llvm.org/ce/z/C2ihC2

Differential Revision: https://reviews.llvm.org/D119139