Horton

Re: refactor architecture-specific popcount code

John Naylor <johncnaylorls@gmail.com>

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From: John Naylor <johncnaylorls@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Greg Burd <greg@burd.me>, Heikki Linnakangas <hlinnaka@iki.fi>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2026-02-23T10:38:01Z
Lists: pgsql-hackers 
On Sun, Feb 22, 2026 at 4:23 AM Nathan Bossart <nathandbossart@gmail.com> wrote:
>
> On Sat, Feb 21, 2026 at 08:49:32AM +0700, John Naylor wrote:
> > In short, I'm in favor of v14, along with the comment about newer
> > compilers from v15.
>
> WFM.  Here's what I have staged for commit.

+1 -- my only nitpick is "Since pg_popcount() uses a function
pointer..." is really "may use".

-- 
John Naylor
Amazon Web Services

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