Horton

Re: refactor architecture-specific popcount code

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: John Naylor <johncnaylorls@gmail.com>
Cc: Greg Burd <greg@burd.me>, Heikki Linnakangas <hlinnaka@iki.fi>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2026-02-10T18:45:35Z
Lists: pgsql-hackers

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On Sat, Feb 07, 2026 at 03:54:31PM +0700, John Naylor wrote:
> Okay, this is looking good. I have just one more suggestion: For 0002,
> just copy the word-wise functions verbatim. That way, it's a pure
> refactoring commit and the exception doesn't need explaining. With
> that, I'd say go ahead and commit 0001/2.

Seems reasonable.  Here is an updated patch set.  I've also swapped 0003
and 0004.

> Then after a bit more research, the final form of the inline functions
> can be visible in a single commit. I've tested S390X already and hope
> to test one other platform.

Thanks.  Looking forward to the results.

-- 
nathan

Commits

  1. Make use of pg_popcount() in more places.

  2. Remove uses of popcount builtins.

  3. Remove some unnecessary optimizations in popcount code.

  4. Remove specialized word-length popcount implementations.

  5. Move x86-64-specific popcount code to pg_popcount_x86.c.

  6. Refactor some SIMD and popcount macros.

  7. Rename "fast" and "slow" popcount functions.

  8. Rename pg_popcount_avx512.c to pg_popcount_x86.c.

  9. Remove trailing zero words from Bitmapsets

  10. Don't use _BitScanForward64/_BitScanReverse64 on 32-bit MSVC builds