Re: Improve CRC32C performance on SSE4.2

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: Nathan Bossart <nathandbossart@gmail.com>

Cc: John Naylor <johncnaylorls@gmail.com>, 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: 2025-06-23T15:10:45Z

Lists: pgsql-hackers

Commits

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Include _mm512_zextsi128_si512() in AVX-512 configure probes.
- ccd5bc93fdfe 18.0 landed
Properly fix AVX-512 CRC calculation bug
- 43da394304fb 18.0 landed
Workaround code generation bug in clang
- f83f14881c7a 18.0 landed
Compute CRC32C using AVX-512 instructions where available
- 3c6e8c123896 18.0 landed
Inline CRC computation for small fixed-length input on x86
- e2809e3a1015 18.0 landed
Be more paranoid in configure's checks for CRC and POPCNT intrinsics.
- fdb5dd6331e3 18.0 cited

Nathan Bossart <nathandbossart@gmail.com> writes:
> 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:

> Unfortunately, this will probably require more than replacing
> _mm512_castsi512_si128 with _mm512_zextsi512_si128 because the latter
> doesn't exist.

I was imagining just including _mm512_zextsi128_si512() in the
code being tested during configure, so that we fall back to
the non-AVX-512 code if the compiler is too old to have it.
I don't really feel a need to work harder than that.

			regards, tom lane