Horton

RE: Improve CRC32C performance on SSE4.2

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

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From: "Devulapalli, Raghuveer" <raghuveer.devulapalli@intel.com>
To: John Naylor <johncnaylorls@gmail.com>, Andy Fan <zhihuifan1213@163.com>
Cc: Jesper Pedersen <jesperpedersen.db@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, Tomas Vondra <tomas@vondra.me>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, "Shankaran, Akash" <akash.shankaran@intel.com>
Date: 2025-06-16T18:31:11Z
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.

Attachments

Attached is a simple reproducer. It passes with clang v16 -O0, but fails with 17 and 18 only when built with -O0. 

Build command: clang main.c -O0

Hope this helps. 
Raghuveer

> -----Original Message-----
> From: John Naylor <johncnaylorls@gmail.com>
> Sent: Sunday, June 15, 2025 7:39 PM
> To: Andy Fan <zhihuifan1213@163.com>
> Cc: Jesper Pedersen <jesperpedersen.db@gmail.com>; Nathan Bossart
> <nathandbossart@gmail.com>; Tomas Vondra <tomas@vondra.me>; Devulapalli,
> Raghuveer <raghuveer.devulapalli@intel.com>; pgsql-
> hackers@lists.postgresql.org; Shankaran, Akash <akash.shankaran@intel.com>
> Subject: Re: Improve CRC32C performance on SSE4.2
> 
> On Sun, Jun 15, 2025 at 8:32 AM Andy Fan <zhihuifan1213@163.com> wrote:
> >
> > Jesper Pedersen <jesperpedersen.db@gmail.com> writes:
> >
> > Hi,
> >
> > Thank you Nathan, Tomas and Jesper for the answers. The patch at [0]
> > works for me and I could work with master smoothly now.
> 
> Pushed, thanks for testing! I'll do some more testing to see what versions/levels
> are affected and file a bug report, but it'll be a few days before I get to it.
> 
> --
> John Naylor
> Amazon Web Services
>