[PATCH] D32530: [SVE][IR] Scalable Vector IR Type

Mon Apr 15 10:02:13 PDT 2019

hfinkel added a comment.

In D32530#1466762 <https://reviews.llvm.org/D32530#1466762>, @rengolin wrote:

> In D32530#1466746 <https://reviews.llvm.org/D32530#1466746>, @huntergr wrote:
>
> > So if we wanted to keep them as intrinsics for now, I think we have one of three options:
> >
> > 1. Leave discussion on more complicated shuffles until later, and only use scalable autovectorization on loops which don't need anything more than splats.
>
>
> Given the current state, this is the easiest path.

I agree, although this is an important part of the model, so we should start having this discussion in parallel (sooner rather than later). I had been under the impression that a set of intrinsics were being proposed for this, but extending shufflevector is also an option worth considering. If these are first-class types, then having first-class instruction support is probably the right path. This deserves it's own RFC.

> 
> 
>> 2. Introduce additional intrinsics for the other shuffle variants as needed
>> 3. Allow shufflevector to accept arbitrary masks so that intrinsics can be used (though possibly only if the output vector is scalable).
> 
> This warrants a larger discussion, which would hinder the current progress.

I agree. We should have a separate RFC on this.

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https://reviews.llvm.org/D32530