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: 2024-04-18T21:29:55Z
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.

> Thanks for the feedback.  I've attached an updated patch.

(1) Shouldn't it be: return (_xgetbv(0) & 0xe6) == 0xe6; ? Otherwise zmm_regs_available() will return false. 
(2) Nitpick: avx512_popcnt_available and avx512_bw_available() run the same cpuid leaf. You could combine them into one to avoid running cpuid twice. My apologies, I should have mentioned this before.