Re: Popcount optimization using AVX512

On Fri, Mar 29, 2024 at 03:08:28PM -0500, Nathan Bossart wrote:
>> +#if defined(HAVE__GET_CPUID)
>> +    __get_cpuid_count(7, 0, &exx[0], &exx[1], &exx[2], &exx[3]);
>> +#elif defined(HAVE__CPUID)
>> +    __cpuidex(exx, 7, 0);
> 
> Is there any reason we can't use __get_cpuid() and __cpuid() here, given
> the sub-leaf is 0?

The answer to this seems to be "no."  After additional research,
__get_cpuid_count/__cpuidex seem new enough that we probably want configure
checks for them, so I'll add those back in the next version of the patch.

Apologies for the stream of consciousness today...

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com