[PATCH] D126273: [DAGCombiner][VP] Add DAGCombine for merging VP_FADD and VP_FMUL to VP_FMA.

[Simon Moll via Phabricator via llvm-commits]

simoll added inline comments.


================
Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:23061
+      return false;
+    return AllowFusionGlobally || N->getFlags().hasAllowContract();
+  };
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RKSimon wrote:
> It'd be very useful if we pulled stuff like this out and shared it between all the various FMA generating combines.
Yes. It is possible to lift the existing DAGCombiner Patterns to work on VP SDNodes as well as on regular SDNodes.
I've implemented this in the LLVM stack for SX-Aurora under the LLVM license, ie it could be upstreamed:

https://github.com/sx-aurora-dev/llvm-project/blob/feature/generalized_pattern_rewriting/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp#L13859

You could rephrase this patch using the generalized pattern-rewriting technique. I'd happy to help with that!

The same applies to https://reviews.llvm.org/D121187


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D126273/new/

https://reviews.llvm.org/D126273