Re: Popcount optimization using AVX512 - Mailing list pgsql-hackers

From Nathan Bossart
Subject Re: Popcount optimization using AVX512
Date
Msg-id ZqmpHjuDlJSjoZVT@nathan
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In response to Re: Popcount optimization using AVX512  (Andres Freund <andres@anarazel.de>)
Responses Re: Popcount optimization using AVX512
List pgsql-hackers
On Tue, Jul 30, 2024 at 07:43:08PM -0700, Andres Freund wrote:
> On 2024-07-30 21:01:31 -0500, Nathan Bossart wrote:
>> The main purpose of the XSAVE compiler check is to determine whether we
>> need to add -mxsave in order to use _xgetbv() [0].  If that wasn't a
>> factor, we could probably skip it.  Earlier versions of the patch used
>> inline assembly in the non-MSVC path to call XGETBV, which I was trying to
>> avoid.
> 
> My point is that _xgetbv() is made available by -mavx512vpopcntdq -mavx512bw
> alone, without needing -mxsave:

Oh, I see.  I'll work on a patch to remove that compiler check, then...

-- 
nathan



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