[PATCH] D42079: AMDGPU: Add a function attribute that shrinks buggy s_buffer opcodes on GFX9

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


================
Comment at: lib/Target/AMDGPU/SIShrinkInstructions.cpp:310-312
+      if (ST.hasBuggySBufferLoadStoreAtomicxN() &&
+          MFI->shrinkBuggySBufferLoadStoreAtomicxN() &&
+          TII->isSMRD(MI.getOpcode())) {
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mareko wrote:
> arsenm wrote:
> > We shouldn't be putting bug workarounds in an optimization pass. This should probably be part of the initial selection
> What initial section are you talking about? Note that the placement of this pass is perfect, because the new code needs to run after SILoadStoreOptimizer.
One option would be to do this in the DAG and split the intrinsics before getting selected in the first place, or we could do this in AdjustInstrPostInstrSelection or in a new bug workaround pass. 

Why does it need to be after SILoadStoreOptimizer? Is it just because it will try to merge and form these? If it's buggy it should just not do that in the first place.


Repository:
  rL LLVM

https://reviews.llvm.org/D42079