[all-commits] [llvm/llvm-project] b69919: [GVN LoadPRE] Add an option to disable splitting b...

[serguei-katkov via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: b69919b537fffcc5b6aaa6d78e2c039725a81f5b
      https://github.com/llvm/llvm-project/commit/b69919b537fffcc5b6aaa6d78e2c039725a81f5b
  Author: Serguei Katkov <serguei.katkov at azul.com>
  Date:   2020-10-27 (Tue, 27 Oct 2020)

  Changed paths:
    M llvm/include/llvm/Transforms/Scalar/GVN.h
    M llvm/lib/Passes/PassBuilder.cpp
    M llvm/lib/Transforms/Scalar/GVN.cpp
    A llvm/test/Transforms/GVN/PRE/load-pre-split-backedge.ll

  Log Message:
  -----------
  [GVN LoadPRE] Add an option to disable splitting backedge

GVN Load PRE can split the backedge causing breaking the loop structure where the latch
contains the conditional branch with for example induction variable.

Different optimizations expect this form of the loop, so it is better to preserve it for some time.
This CL adds an option to control an ability to split backedge.

Default value is true so technically it is NFC and current behavior is not changed.

Reviewers: fedor.sergeev, mkazantsev, nikic, reames, fhahn
Reviewed By: mkazasntsev
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D89854