[all-commits] [llvm/llvm-project] 6b03ce: [LICM] Simplify (X < A && X < B) into (X < MIN(A, ...

[Max Kazantsev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6b03ce374e0dc64868b4b6665056dfc3fda0e98f
      https://github.com/llvm/llvm-project/commit/6b03ce374e0dc64868b4b6665056dfc3fda0e98f
  Author: Max Kazantsev <mkazantsev at azul.com>
  Date:   2023-03-10 (Fri, 10 Mar 2023)

  Changed paths:
    M llvm/lib/Transforms/Scalar/LICM.cpp
    M llvm/test/CodeGen/AMDGPU/wave32.ll
    M llvm/test/CodeGen/PowerPC/sms-cpy-1.ll
    M llvm/test/Transforms/LICM/min_max.ll

  Log Message:
  -----------
  [LICM] Simplify (X < A && X < B) into (X < MIN(A, B)) if MIN(A, B) is loop-invariant

We don't do this transform in InstCombine in general case for arbitrary values, because cost of
AND and 2 ICMP's isn't higher than of MIN and ICMP. However, LICM also has a notion
about the loop structure. This transform becomes profitable if `A` and `B` are loop-invariant and
`X` is not: by doing this, we can compute min outside the loop.

Differential Revision: https://reviews.llvm.org/D143726
Reviewed By: nikic