[PATCH] D94444: [RFC][Scalable] Add scalable shuffle intrinsic to extract evens from a pair of vectors

[Cameron McInally via Phabricator via llvm-commits]

cameron.mcinally added a comment.

> In D94444#2497697 <https://reviews.llvm.org/D94444#2497697>, @paulwalker-arm wrote:
> <A x Elt> llvm.experimental.vector.extract.elements(<B x Elt> %invec, i32 index, i32 stride)

Working through this now. @paulwalker-arm, have you given any thought to what happens to A below?

<vscale x A x double> llvm.experimental.vector.extract.elements(<vscale x 2 x double> %invec, i32 0, i32 4)

What should A be here? It should really be 0.5, but my understanding is we're not doing fractional VLs. I suppose that we could restrict stride to be >= the known VL.

I also wonder what A should be with odd strides, like 3. Any thoughts on that?


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