[PATCH] D102828: [GlobalISel] Implement splitting of G_SHUFFLE_VECTOR.

Thu May 20 10:05:00 PDT 2021

aemerson added inline comments.

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Comment at: llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp:4231
+  // Further legalization attempts will be needed to do split further.
+  NarrowTy = DstTy.changeNumElements(DstTy.getNumElements() / 2);
+  unsigned NewElts = NarrowTy.getNumElements();
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arsenm wrote:
> I don't like simply discarding NarrowTy. It would be better to compute the type you do handle, and fail if it doesn't match the requested type
But if you do that, fewerElements isn't going to know which narrow type it supports. Legalizing <16 x s64> is going to use a narrow ty of <2 x s64> with the rules as they're written now.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D102828/new/

https://reviews.llvm.org/D102828