[PATCH] D114542: [CodeGen][SVE] Use whilelo instruction when lowering @llvm.get.active.lane.mask

Thu Nov 25 01:43:44 PST 2021

tschuett added a comment.

In D114542#3153129 <https://reviews.llvm.org/D114542#3153129>, @SjoerdMeijer wrote:

> In D114542#3153102 <https://reviews.llvm.org/D114542#3153102>, @david-arm wrote:
>
>> I think the main difference between SVE and MVE is that for MVE we have to set up some state before entering the loop, and perhaps the actual instruction that generates the predicate uses that state? Whereas for SVE we don't have that problem.
>
> Yep, and I would need to refresh my memory and read the reference manual, but I am almost certain that for MVE we would get wrong results if overflow occurs in the VCTP instructions.

Could you add Metadata to the intrinsic to state the assumptions?

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https://reviews.llvm.org/D114542