[PATCH] D116362: [TTI] Support ScalableVectorType in getShuffleCost with SK_Broadcast kind

[JunMa via Phabricator via llvm-commits]

junparser added a comment.

In D116362#3213897 <https://reviews.llvm.org/D116362#3213897>, @dmgreen wrote:

> This looks like it would treat the default cost of a broadcast as scalarising the first n elements from a <vscale x n x iM> vector, which doesn't sound right. Unless we are assuming that the default vscale is 1.

Yes， This patch keeps same behavior as before (release mode).

> I would suspect that the cost should either be invalid or to be "cheap" under assumption that the operation is always present. AArch64 has some cost overrides in its backend for certain types of scalable broadcasts.

without target override，we cannot compute scalable vector broadcasts here. So I think set invalid for scalabe vector here make sense.


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https://reviews.llvm.org/D116362