[all-commits] [llvm/llvm-project] c593bf: [GlobalISel] Don't combine instructions which are ...

[Jessica Paquette via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: c593bf534222f2206f89b6a61993125b2475b954
      https://github.com/llvm/llvm-project/commit/c593bf534222f2206f89b6a61993125b2475b954
  Author: Jessica Paquette <jpaquette at apple.com>
  Date:   2020-05-27 (Wed, 27 May 2020)

  Changed paths:
    M llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
    A llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-not-really-equiv-insts.mir

  Log Message:
  -----------
  [GlobalISel] Don't combine instructions which are fed by memory instructions.

If we have a memory instruction (e.g. a load), we shouldn't combine it away in
some trivial combine.

It's possible that, say, a call lives between the instructions. This could
modify the value loaded, making the load instructions not safe to fold.

Differential Revision: https://reviews.llvm.org/D80053