[all-commits] [llvm/llvm-project] 2025e0: [LV] Make sure VF doesn't exceed compile time know...

[ebrevnov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2025e0985c2a1aa481620eef5312d48415b7f8b4
      https://github.com/llvm/llvm-project/commit/2025e0985c2a1aa481620eef5312d48415b7f8b4
  Author: Evgeniy Brevnov <ybrevnov at azul.com>
  Date:   2021-12-13 (Mon, 13 Dec 2021)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/test/Transforms/LoopVectorize/X86/limit-vf-by-tripcount.ll

  Log Message:
  -----------
  [LV] Make sure VF doesn't exceed compile time known TC

For the simple copy loop (see test case) vectorizer selects VF equal to 32 while the loop is known to have 17 iterations only. Such behavior makes no sense to me since such vector loop will never be executed. The only case we may want to select VF large than TC is masked vectoriztion. So I haven't touched that case.

Reviewed By: dmgreen

Differential Revision: https://reviews.llvm.org/D114528