[all-commits] [llvm/llvm-project] 8a3d7c: [PowerPC] Turn on CR-Logical reducer pass

Nemanja Ivanovic via All-commits all-commits at lists.llvm.org
Thu Oct 17 11:23:22 PDT 2019

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 8a3d7c9cbd305764d1f6c2d42cdd82cf2876b99f
  Author: Nemanja Ivanovic <nemanja.i.ibm at gmail.com>
  Date:   2019-10-17 (Thu, 17 Oct 2019)

  Changed paths:
    M llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
    M llvm/test/CodeGen/PowerPC/2008-10-28-f128-i32.ll
    M llvm/test/CodeGen/PowerPC/brcond.ll
    M llvm/test/CodeGen/PowerPC/pr42492.ll
    M llvm/test/CodeGen/PowerPC/tocSaveInPrologue.ll
    M llvm/test/CodeGen/PowerPC/vec-min-max.ll

  Log Message:
  [PowerPC] Turn on CR-Logical reducer pass

Quite a while ago, we implemented a pass that will reduce the number of
CR-logical operations we emit. It does so by converting a CR-logical operation
into a branch. We have kept this off by default because it seemed to cause a
significant regression with one benchmark.
However, that regression turned out to be due to a completely unrelated
reason - AADB introducing a self-copy that is a priority-setting nop and it was
just exacerbated by this pass.

Now that we understand the reason for the only degradation, we can turn this
pass on by default. We have long since fixed the cause for the degradation.

Differential revision: https://reviews.llvm.org/D52431

llvm-svn: 375152

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