[all-commits] [llvm/llvm-project] 2e3fa4: [AMDGPU] Insert before and after instructions that...

[Stephen Thomas via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2e3fa4ba9e0b65cf59f7b67a8bdf2377611cd067
      https://github.com/llvm/llvm-project/commit/2e3fa4ba9e0b65cf59f7b67a8bdf2377611cd067
  Author: Stephen Thomas <104134586+stepthomas at users.noreply.github.com>
  Date:   2025-03-21 (Fri, 21 Mar 2025)

  Changed paths:
    M llvm/lib/Target/AMDGPU/MCA/AMDGPUCustomBehaviour.cpp
    M llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
    M llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
    A llvm/test/CodeGen/AMDGPU/force-wait-after-always-gds.mir
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.add.gs.reg.rtn.ll
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.ordered.swap.ll
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.sub.gs.reg.rtn.ll

  Log Message:
  -----------
  [AMDGPU] Insert before and after instructions that always use GDS (#131338)

It is an architectural requirement that there must be no outstanding GDS
instructions when an "always GDS" instruction is issued, and also that
an always GDS instruction must be allowed to complete.

Insert waits on DScnt/LGKMcnt prior to (if necessary) and subsequent to
(unconditionally) any always GDS instruction, and an additional S_NOP if
the subsequent wait was followed by S_ENDPGM.

Always GDS instructions are GWS instructions, DS_ORDERED_COUNT,
DS_ADD_GS_REG_RTN, and DS_SUB_GS_REG_RTN (the latter two as considered
always GDS as of this patch).



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