RE: Popcount optimization using AVX512

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

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

To: Nathan Bossart <nathandbossart@gmail.com>

Cc: Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <dgrowleyml@gmail.com>, "Andres Freund" <andres@anarazel.de>, Alvaro Herrera <alvherre@alvh.no-ip.org>, "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: 2024-03-29T17:25:14Z

Lists: pgsql-hackers

Commits

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Fix __attribute__((target(...))) usage.
- 41b98ddb77bf 18.0 landed
Use __attribute__((target(...))) for AVX-512 support.
- f78667bd910e 18.0 landed
Fix code for probing availability of AVX-512.
- 598e0114a3b1 17.0 landed
Optimize visibilitymap_count() with AVX-512 instructions.
- 41c51f0c68b2 17.0 landed
Optimize pg_popcount() with AVX-512 instructions.
- 792752af4eb5 17.0 landed
Inline pg_popcount() for small buffers.
- deb1486c7d36 17.0 landed
Avoid function call overhead of pg_popcount() in syslogger.c.
- 4133c1f45c54 17.0 landed
Refactor code for setting pg_popcount* function pointers.
- 6687430c98f3 17.0 landed
Inline pg_popcount{32,64} into pg_popcount().
- cc4826dd5e52 17.0 landed
Remove MSVC scripts
- 1301c80b2167 17.0 cited
Use ARMv8 CRC instructions where available.
- f044d71e331d 11.0 cited
Use Intel SSE 4.2 CRC instructions where available.
- 3dc2d62d0486 9.5.0 cited

> A counterexample is the CRC32C code.  AFAICT we assume the presence of
> CPUID in that code (and #error otherwise).  I imagine its probably safe to
> assume the compiler understands CPUID if it understands AVX512 intrinsics,
> but that is still mostly a guess.

If AVX-512 intrinsics are available, then yes you will have CPUID. CPUID is much older in the hardware/software timeline than AVX-512.

Thanks,
Paul