[all-commits] [llvm/llvm-project] 1e9afa: Re-apply "[JumpThreading] Ignore free instructions"

[Hans via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1e9afab875696ebf1a8abb5637f04735411ee0b7
      https://github.com/llvm/llvm-project/commit/1e9afab875696ebf1a8abb5637f04735411ee0b7
  Author: Hans Wennborg <hans at chromium.org>
  Date:   2021-09-24 (Fri, 24 Sep 2021)

  Changed paths:
    M llvm/include/llvm/Transforms/Scalar/JumpThreading.h
    M llvm/lib/Transforms/Scalar/JumpThreading.cpp
    M llvm/test/Transforms/JumpThreading/free_instructions.ll
    M llvm/test/Transforms/PhaseOrdering/inlining-alignment-assumptions.ll

  Log Message:
  -----------
  Re-apply "[JumpThreading] Ignore free instructions"

It seems the crashes we saw wasn't caused by this (see comments on the review).

> This is basically D108837 but for jump threading. Free instructions
> should be ignored for the threading decision. JumpThreading already
> skips some free instructions (like pointer bitcasts), but does not
> skip various free intrinsics -- in fact, it currently gives them a
> fairly large cost of 2.
>
> Differential Revision: https://reviews.llvm.org/D110290

This reverts commit 4604695d7c20e72b551a1a5224f3de877cb41bd3.