[PATCH] D22675: AMDGPU: Stay in WQM for non-intrinsic stores

[Nicolai Hähnle via llvm-commits]

nhaehnle created this revision.
nhaehnle added reviewers: arsenm, tstellarAMD, mareko.
nhaehnle added a subscriber: llvm-commits.
Herald added subscribers: kzhuravl, arsenm.

Two types of stores are possible in pixel shaders: stores to memory that are
explicitly requested at the API level, and stores that are an implementation
detail of register spilling or lowering of arrays.

For the first kind of store, we must ensure that helper pixels have no effect
and hence WQM must be disabled. The second kind of store must always be
executed, because the written value may be loaded again in a way that is
relevant for helper pixels as well -- and there are no externally visible
effects anyway.

This is a candidate for the 3.9 release branch.

https://reviews.llvm.org/D22675

Files:
  lib/Target/AMDGPU/SIDefines.h
  lib/Target/AMDGPU/SIInstrFormats.td
  lib/Target/AMDGPU/SIInstrInfo.h
  lib/Target/AMDGPU/SIInstrInfo.td
  lib/Target/AMDGPU/SIInstructions.td
  lib/Target/AMDGPU/SIWholeQuadMode.cpp
  test/CodeGen/AMDGPU/skip-if-dead.ll
  test/CodeGen/AMDGPU/wqm.ll

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