Re: Popcount optimization using AVX512

On Thu, Apr 18, 2024 at 10:11:08PM +0000, Devulapalli, Raghuveer wrote:
>> On that note, is it necessary to also check for avx512f?  At the moment,
>> we are assuming that's supported if the other AVX-512 instructions are
>> available.
> 
> No, it's not needed. There are no CPU's with avx512bw/avx512popcnt
> without avx512f.  Unfortunately though, avx512popcnt does not mean
> avx512bw (I think the deprecated Xeon Phi processors falls in this
> category) which is why we need both.

Makes sense, thanks.  I'm planning to commit this fix sometime early next
week.

-- 
Nathan Bossart
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