[PATCH] D134648: [LangRef] Update text for vscale to be more flexible but maintain original intent.

[Amara Emerson via Phabricator via llvm-commits]

aemerson added a comment.

In D134648#3819413 <https://reviews.llvm.org/D134648#3819413>, @tschuett wrote:

> In D134648#3819317 <https://reviews.llvm.org/D134648#3819317>, @aemerson wrote:
>
>> In D134648#3819122 <https://reviews.llvm.org/D134648#3819122>, @tschuett wrote:
>>
>>> I am still in favour of `llvm.aarch64.sme.vscale()`.
>>
>> I'm not sure this solves the problem, as after a transition to streaming mode, the value returned by vanilla `vscale()` will also be different.
>
> `llvm.vscale()` would still return the  sve-scale.

Sorry if I'm misunderstanding you. After a transition to streaming mode, all SVE vectors become SVL length. If you were to use `llvm.vscale()` to compute a vector's size in this mode, it *must* return the same value as `llvm.aarch64.sme.vscale()`. In the case of streaming compatible functions which may be executing in any mode, I don't think you can know which intrinsic to call at compile time in order to get the correct vector length.


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