[PATCH][AArch64] Cleanup memset

[Wilco Dijkstra]

Hi Andrew,

>> Yes, otherwise it's hard to test or prove it helps performance after all. We've
>> had issues with the non-64 ZVA sizes before, so it's best to keep it simple.
>>
>> I'm also trying to reduce the amount of code and avoid unnecessary proliferation
>> of almost identical ifuncs. I think we can remove most of the memset ifuncs,
>> it seems we need one version without ZVA and a ZVA version for size 64.
>
> I am trying to understand what was the decision here.  The main reason
> is OcteonTX2 does ZVA 128 which was faster than doing one without
> (OcteonTX1 is similar but has an errata which causes ZVA to be turned
> off).

So you're saying there may soon be a new microarchitecture which supports
ZVA size 128? Is there a significant speedup? Is querying the ZVA size fast?

Cheers,
Wilco