[PATCH] D107597: [DAG] Fold concat_vectors(concat_vectors(x,y),concat_vectors(a,b)) -> concat_vectors(x,y,a,b)

[Fraser Cormack via Phabricator via llvm-commits]

frasercrmck added inline comments.


================
Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:19869
+  // TODO: Add scalable vector type support.
+  if (!VT.isFixedLengthVector())
+      return SDValue();
----------------
RKSimon wrote:
> frasercrmck wrote:
> > What would it take to add scalable vector support? I don't think I see anything here that relies on fixed-vector knowledge. If it's lack of testing we may be able to rustle up some test cases with extra wide scalable-vectors which are split during legalization?
> I was getting crashes in the legalizer which looked tricky to deal with - but turns out it was just aarch64 sve concat_vectors lowering not handling numops != 2 - trying a fix now.
Thanks, seems to have improved one of our tests at least!


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  https://reviews.llvm.org/D107597/new/

https://reviews.llvm.org/D107597