[all-commits] [llvm/llvm-project] e5972f: [AMDGPU] Simplify VCCZ bug handling

[jayfoad via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: e5972f2a04ee48a9190cd25f0d5b24cbca4d47f2
      https://github.com/llvm/llvm-project/commit/e5972f2a04ee48a9190cd25f0d5b24cbca4d47f2
  Author: Jay Foad <jay.foad at amd.com>
  Date:   2019-10-30 (Wed, 30 Oct 2019)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
    M llvm/test/CodeGen/AMDGPU/smrd-vccz-bug.ll

  Log Message:
  -----------
  [AMDGPU] Simplify VCCZ bug handling

Summary:
VCCZBugHandledSet was used to make sure we don't apply the same
workaround more than once to a single cbranch instruction, but it's not
necessary because the workaround involves inserting an s_waitcnt
instruction, which is enough for subsequent iterations to detect that no
further workaround is necessary.

Also beef up the test case to check that the workaround was only applied
once. I have also manually verified that the test still passes even if I
hack the big do-while loop in runOnMachineFunction to run a minimum of
five iterations.

Subscribers: arsenm, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69621