Date: Fri, 29 Mar 2024 10:42:41 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: "Amonson, Paul D" <paul.d.amonson@intel.com>,
	Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <dgrowleyml@gmail.com>,
	Andres Freund <andres@anarazel.de>,
	"Shankaran, Akash" <akash.shankaran@intel.com>,
	Noah Misch <noah@leadboat.com>,
	Matthias van de Meent <boekewurm+postgres@gmail.com>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Subject: Re: Popcount optimization using AVX512
Message-ID: <20240329154241.GB1046039@nathanxps13>
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On Thu, Mar 28, 2024 at 11:10:33PM +0100, Alvaro Herrera wrote:
> We don't do MSVC via autoconf/Make.  We used to have a special build
> framework for MSVC which parsed Makefiles to produce "solution" files,
> but it was removed as soon as Meson was mature enough to build.  See
> commit 1301c80b2167.  If it builds with Meson, you're good.

The latest cfbot build for this seems to indicate that at least newer MSVC
knows AVX512 intrinsics without any special compiler flags [0], so maybe
what I had in v14 is good enough.  A previous version of the patch set [1]
had the following lines:

+  if host_system == 'windows'
+    test_flags = ['/arch:AVX512']
+  endif

I'm not sure if this is needed for older MSVC or something else.  IIRC I
couldn't find any other examples of this sort of thing in the meson
scripts, either.  Paul, do you recall why you added this?

[0] https://cirrus-ci.com/task/5787206636273664?logs=configure#L159
[1] https://postgr.es/m/attachment/158206/v12-0002-Feature-Added-AVX-512-acceleration-to-the-pg_popcoun.patch

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