Horton

RE: Popcount optimization using AVX512

Devulapalli, Raghuveer <raghuveer.devulapalli@intel.com>

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From: "Devulapalli, Raghuveer" <raghuveer.devulapalli@intel.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: "Shankaran, Akash" <akash.shankaran@intel.com>, Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <dgrowleyml@gmail.com>, Ants Aasma <ants.aasma@cybertec.at>, Alvaro Herrera <alvherre@alvh.no-ip.org>, "Amonson, Paul D" <paul.d.amonson@intel.com>, Andres Freund <andres@anarazel.de>, "Noah Misch" <noah@leadboat.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2024-04-18T22:11:08Z
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 that note, is it necessary to also check for avx512f?  At the moment, we are assuming that's supported if the other AVX-512 instructions are available.

No, it's not needed. There are no CPU's with avx512bw/avx512popcnt without avx512f.  Unfortunately though, avx512popcnt does not mean avx512bw (I think the deprecated Xeon Phi processors falls in this category) which is why we need both.