Re: vectorized CRC on ARM64

Nathan Bossart <nathandbossart@gmail.com>

From: Nathan Bossart <nathandbossart@gmail.com>

To: John Naylor <johncnaylorls@gmail.com>

Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2026-04-03T13:54:36Z

Lists: pgsql-hackers

On Fri, Apr 03, 2026 at 03:22:59PM +0700, John Naylor wrote:
> I went with the following for v5, and it passes MacOS on my Github CI:
> 
> +  /* set fallbacks */
> +#ifdef USE_ARMV8_CRC32C
> +  /* On e.g. MacOS, our runtime feature detection doesn't work */
> +  pg_comp_crc32c = pg_comp_crc32c_armv8;
> +#else
> +  pg_comp_crc32c = pg_comp_crc32c_sb8;
> +#endif
> + [...crc and pmull checks]
> 
> That should keep scalar hardware support working, but now it'll only
> use direct calls for constant inputs.

v5 LGTM

-- 
nathan

Commits

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

Use C11 alignas instead of pg_attribute_aligned
- 182f6944d3d0 19 (unreleased) landed
- 8061bfd15abe master landed
Add missing guard for __builtin_constant_p
- 936d8974c3bc 18.4 landed
- 676626426285 19 (unreleased) landed
Exit early from pg_comp_crc32c_pmull for small inputs
- 948ef7cdc499 19 (unreleased) landed
Fix unused function warning on Arm platforms
- 2849fe4c9785 19 (unreleased) landed
Compute CRC32C on ARM using the Crypto Extension where available
- fbc57f2bc2ee 19 (unreleased) landed