[PATCH] D134354: [AMDGPU][GlobalISel] Support mad/fma_mix selection

[Pierre van Houtryve via Phabricator via llvm-commits]

Pierre-vh marked an inline comment as done.
Pierre-vh added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/AMDGPUGISel.td:156
 
+def gi_vop3_mad_mix_mods :
+    GIComplexOperandMatcher<s64, "selectVOP3PMadMixMods">,
----------------
foad wrote:
> Pierre-vh wrote:
> > foad wrote:
> > > Is this required? I am confused about whether you are now matching VOP3PMadMixMods in TableGen patterns, or only doing it from the C++ code in selectG_FMA.
> > I'm doing it exclusively in C++.
> > This is needed to tell the GlobalISelEmitter that, when it sees "VOP3PMadMixMods" it needs to use the "selectVOP3PMadMixMods" function from AMDGPUInstructionSelector.
> > Without that, it wouldn't import patterns that use it.
> I'm still confused. If we are now importing patterns that use VOP3PMadMixMods, why do you need to do the selection in C++ code?
It's a ComplexPattern
```
def VOP3PMadMixMods  : ComplexPattern<untyped, 2, "SelectVOP3PMadMixMods">;
```
Those functions work with DAG nodes and must be rewritten for GISel so the patterns can be imported
https://llvm.org/docs/GlobalISel/InstructionSelect.html#complexpatterns


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https://reviews.llvm.org/D134354