[all-commits] [llvm/llvm-project] 433696: [InstCombine] relax constraints on mask-of-add

[RotateRight via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 433696911a0b8e1b94abd8d8f192380ba7867b61
      https://github.com/llvm/llvm-project/commit/433696911a0b8e1b94abd8d8f192380ba7867b61
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2020-11-17 (Tue, 17 Nov 2020)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    M llvm/test/Transforms/InstCombine/and.ll

  Log Message:
  -----------
  [InstCombine] relax constraints on mask-of-add

There are 2 changes:
1. Remove the unnecessary one-use check.
2. Remove the unnecessary power-of-2 check.

https://rise4fun.com/Alive/V6fP

  Name: add with low mask
  Pre: (C1 & (-1 u>> countLeadingZeros(C2))) == 0
  %a = add i8 %x, C1
  %r = and i8 %a, C2
  =>
  %r = and i8 %x, C2