[PATCH] D116277: [RISCV] Use vmv.x.s to build one element splat vector.

Mon Dec 27 23:15:19 PST 2021

craig.topper added a comment.

In D116277#3211132 <https://reviews.llvm.org/D116277#3211132>, @jacquesguan wrote:

> In D116277#3210767 <https://reviews.llvm.org/D116277#3210767>, @craig.topper wrote:
>
>> Do you have a particular microarchitecture where this is a faster sequence?
>>
>> Why only integer and not FP?
>
> I think that vmv.s.x has less demand on VL and VTYPE, so using vmv.s.x instead vmv.v.x might reduce the amount of VSETVLI instructions that we will insert.
>
> I missed the floating point scalar move instruction, if you think it make sense, I will add it.

Can this prevent .vx instructions from being recognized from an arithmetic operation plus a splat?

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  https://reviews.llvm.org/D116277/new/

https://reviews.llvm.org/D116277