[all-commits] [llvm/llvm-project] 2a2720: [CSSPGO] Move pseudo probes to the beginning of a ...

[Hongtao Yu via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2a2720a2dec4ad4fdc7ae58939448e51824a12c4
      https://github.com/llvm/llvm-project/commit/2a2720a2dec4ad4fdc7ae58939448e51824a12c4
  Author: Hongtao Yu <hoy at fb.com>
  Date:   2021-04-07 (Wed, 07 Apr 2021)

  Changed paths:
    M llvm/lib/CodeGen/CodeGenPrepare.cpp
    A llvm/test/Transforms/SampleProfile/pseudo-probe-selectionDAG.ll

  Log Message:
  -----------
  [CSSPGO] Move pseudo probes to the beginning of a block to unblock SelectionDAG combine.

Pseudo probes, when scattered in a block, can be chained dependencies of other regular DAG nodes and block DAG combine optimizations. To fix this, scattered probes in a block are grouped and placed at the beginning of the block. This shouldn't affect the profile quality.

Test Plan:

Reviewed By: wenlei, wmi

Differential Revision: https://reviews.llvm.org/D100002