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: 2026-02-12T17:34:38Z

Lists: pgsql-hackers

Attachments

v14-0001-Remove-uses-of-popcount-builtins.patch (text/plain)

On Thu, Feb 12, 2026 at 11:58:37AM +0700, John Naylor wrote:
> I have a better idea, but it depends on re-thinking feature detection
> and compile-time vs run-time checks, and that's not quite ready to
> share, so let's shelve this for now.

Sounds good.

> Anyway, I think 0001 and 0002 are ready for commit.

Committed.  I've attached rebased versions of the remaining patches under
consideration.

-- 
nathan

Commits

Make use of pg_popcount() in more places.
- f33b8793fd73 19 (unreleased) landed
Remove uses of popcount builtins.
- eb9ab7e0930a 19 (unreleased) landed
Remove some unnecessary optimizations in popcount code.
- cb7b2e5e8efb 19 (unreleased) landed
Remove specialized word-length popcount implementations.
- a4688988835f 19 (unreleased) landed
Move x86-64-specific popcount code to pg_popcount_x86.c.
- 79e232ca013c 19 (unreleased) landed
Refactor some SIMD and popcount macros.
- 25dc4850747b 19 (unreleased) landed
Rename "fast" and "slow" popcount functions.
- 8c6653516c5a 19 (unreleased) landed
Rename pg_popcount_avx512.c to pg_popcount_x86.c.
- fbe327e5b465 19 (unreleased) landed
Remove trailing zero words from Bitmapsets
- a8c09daa8bb1 17.0 cited
Don't use _BitScanForward64/_BitScanReverse64 on 32-bit MSVC builds
- 53ea2b7ad050 16.0 cited