Horton

RE: Popcount optimization using AVX512

Amonson, Paul D <paul.d.amonson@intel.com>

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From: "Amonson, Paul D" <paul.d.amonson@intel.com>
To: Nathan Bossart <nathandbossart@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: 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>
Date: 2024-03-29T17:11:18Z
Lists: pgsql-hackers

Commits

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  1. Fix __attribute__((target(...))) usage.

  2. Use __attribute__((target(...))) for AVX-512 support.

  3. Fix code for probing availability of AVX-512.

  4. Optimize visibilitymap_count() with AVX-512 instructions.

  5. Optimize pg_popcount() with AVX-512 instructions.

  6. Inline pg_popcount() for small buffers.

  7. Avoid function call overhead of pg_popcount() in syslogger.c.

  8. Refactor code for setting pg_popcount* function pointers.

  9. Inline pg_popcount{32,64} into pg_popcount().

  10. Remove MSVC scripts

  11. Use ARMv8 CRC instructions where available.

  12. Use Intel SSE 4.2 CRC instructions where available.

> 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?

I asked internal folks here in-the-know and they suggested I add it. I personally am not a Windows guy. If it works without it and you are comfortable not including the lines, I am fine with it.

Thanks,
Paul