[PATCH] D47775: [AArch64][SVE] Add SPLAT_VECTOR ISD Node

Mon Sep 30 04:42:10 PDT 2019

jmolloy requested changes to this revision.
jmolloy added a comment.
This revision now requires changes to proceed.

Hi Graham,

I really like the addition of a new ISD opcode for this. I do have one inline comment.

James

================
Comment at: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp:3544

+  if (MaskV->isNullValue() && VT.isScalableVector()) {
+    // Canonical splat form of first element of first input vector.
----------------
It feels to me like this is a canonicalization that should be a DAGCombine rather than in the builder. Is this here specifically because the ISD::vector_shuffle is not representable with scalable vectors?

If not, I'd prefer this be moved to a canonical dag combine. In general, I feel logic here should be at a minimum because it runs before targets can override or pattern match themselves.

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D47775/new/

https://reviews.llvm.org/D47775