Horton

Re: Improve CRC32C performance on SSE4.2

John Naylor <johncnaylorls@gmail.com>

View thread
From: John Naylor <johncnaylorls@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Andy Fan <zhihuifan1213@163.com>, "Devulapalli, Raghuveer" <raghuveer.devulapalli@intel.com>, Jesper Pedersen <jesperpedersen.db@gmail.com>, Tomas Vondra <tomas@vondra.me>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, "Shankaran, Akash" <akash.shankaran@intel.com>
Date: 2025-06-24T03:34:12Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Include _mm512_zextsi128_si512() in AVX-512 configure probes.

  2. Properly fix AVX-512 CRC calculation bug

  3. Workaround code generation bug in clang

  4. Compute CRC32C using AVX-512 instructions where available

  5. Inline CRC computation for small fixed-length input on x86

  6. Be more paranoid in configure's checks for CRC and POPCNT intrinsics.

On Mon, Jun 23, 2025 at 10:05 PM Nathan Bossart
<nathandbossart@gmail.com> wrote:
>
> On Mon, Jun 23, 2025 at 10:51:21AM -0400, Tom Lane wrote:
> > This has broken the build completely on my RHEL8 x86_64 box,
> > with gcc 8.5.0:
> >
> > $ ./configure ...
> > $ make -s
> > pg_crc32c_sse42.c: In function 'pg_comp_crc32c_avx512':
> > pg_crc32c_sse42.c:126:25: warning: implicit declaration of function '_mm512_zextsi128_si512'; did you mean '_mm512_castsi128_si512'? [-Wimplicit-function-declaration]
> >    x0 = _mm512_xor_si512(_mm512_zextsi128_si512(_mm_cvtsi32_si128(crc0)), x0);
> >                          ^~~~~~~~~~~~~~~~~~~~~~
> >                          _mm512_castsi128_si512
>
> It looks like thse weren't added until GCC 10 [0].

Huh, that's surprising because the Intel manual put it in AVX-512F,
the basic core around which everything else is tacked on.

-- 
John Naylor
Amazon Web Services