[all-commits] [llvm/llvm-project] 0f946a: [InstrProf] Add option to disable loop opt after PGO

[Ellis Hoag via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0f946a50a485fe51f6a57335b660291ac05dab0b
      https://github.com/llvm/llvm-project/commit/0f946a50a485fe51f6a57335b660291ac05dab0b
  Author: Ellis Hoag <ellis.sparky.hoag at gmail.com>
  Date:   2022-08-17 (Wed, 17 Aug 2022)

  Changed paths:
    M llvm/lib/Passes/PassBuilderPipelines.cpp

  Log Message:
  -----------
  [InstrProf] Add option to disable loop opt after PGO

Add the `-enable-post-pgo-loop-rotation` option to enable or disable the loop rotation transformation [1]. With some instrumentations, e.g., function entry coverage [2], loop rotation is not necessary and can lead to some surprise differences in codegen, even for functions where instrumentation is blocked with `noprofile` or `skipprofile`. The default value is `true` so the default behavior does not change.

[1] https://www.llvm.org/docs/LoopTerminology.html#loop-terminology-loop-rotate
[2] https://reviews.llvm.org/D116180

Reviewed By: phosek

Differential Revision: https://reviews.llvm.org/D131817