[all-commits] [llvm/llvm-project] 2c82a1: [AMDGPU] Omit unnecessary waitcnt before barriers

Austin Kerbow via All-commits all-commits at lists.llvm.org
Fri Jul 29 11:22:02 PDT 2022

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2c82a126d762c14c2f3df2d03a6ae5fb37c3351a
  Author: Austin Kerbow <Austin.Kerbow at amd.com>
  Date:   2022-07-29 (Fri, 29 Jul 2022)

  Changed paths:
    M llvm/lib/Target/AMDGPU/AMDGPU.td
    M llvm/lib/Target/AMDGPU/GCNSubtarget.h
    M llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
    A llvm/test/CodeGen/AMDGPU/back-off-barrier-subtarget-feature.ll
    M llvm/test/CodeGen/AMDGPU/waitcnt-preexisting-vscnt.mir
    M llvm/test/CodeGen/AMDGPU/waitcnt-vscnt.ll

  Log Message:
  [AMDGPU] Omit unnecessary waitcnt before barriers

It is not necessary to wait for all outstanding memory operations before
barriers on hardware that can back off of the barrier in the event of an
exception when traps are enabled. Add a new subtarget feature which
tracks which HW has this ability.

Reviewed By: #amdgpu, rampitec

Differential Revision: https://reviews.llvm.org/D130722

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