[all-commits] [llvm/llvm-project] 2dfb4b: [AMDGPU] Fix incorrect hazard mitigation

Stephen Thomas via All-commits all-commits at lists.llvm.org
Tue Jul 4 06:44:29 PDT 2023

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2dfb4b56fe3c233b4f278a6d17b4ec5780007a8f
  Author: Stephen Thomas <Stephen.Thomas at amd.com>
  Date:   2023-07-04 (Tue, 04 Jul 2023)

  Changed paths:
    M llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
    M llvm/test/CodeGen/AMDGPU/vcmpx-exec-war-hazard.mir

  Log Message:
  [AMDGPU] Fix incorrect hazard mitigation

GCNHazardRecognizer::fixVcmpxExecWARHazard() mitigates a specific hazard
by inserting a wait on sa_sdst==0 if such a wait isn't already present.
Unfortunately, the check for an existing wait incorrectly checks for one
that doesn't actually care about sa_sdst itself, but requires that no
other counters are waited for.

Once the check is performed correctly, a lit test needs to be updated,
since it is currently testing for the incorrect behaviour.

Differential Revision: https://reviews.llvm.org/D154438

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