[all-commits] [llvm/llvm-project] 28963d: [GlobalISel] Don't DCE LIFETIME_START/LIFETIME_END...

[Amara Emerson via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 28963d895b529e90b8b99716516ae4e422592797
      https://github.com/llvm/llvm-project/commit/28963d895b529e90b8b99716516ae4e422592797
  Author: Amara Emerson <amara at apple.com>
  Date:   2021-03-17 (Wed, 17 Mar 2021)

  Changed paths:
    M llvm/lib/CodeGen/GlobalISel/Utils.cpp
    A llvm/test/CodeGen/AArch64/GlobalISel/lifetime-marker-no-dce.mir

  Log Message:
  -----------
  [GlobalISel] Don't DCE LIFETIME_START/LIFETIME_END markers.

These are pseudos without any users, so DCE was killing them in the combiner.

Marking them as having side effects doesn't seem quite right since they don't.

Gives a nice 0.3% geomean size win on CTMark -Os.

Differential Revision: https://reviews.llvm.org/D98811