| From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
|---|---|
| To: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
| Cc: | John Naylor <johncnaylorls(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: refactor architecture-specific popcount code |
| Date: | 2026-01-15 18:02:31 |
| Message-ID: | 652cab58-8dfb-4514-a6b0-218a3edb0699@iki.fi |
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| Lists: | pgsql-hackers |
On 15/01/2026 18:08, Nathan Bossart wrote:
> On Thu, Jan 15, 2026 at 11:42:14AM +0200, Heikki Linnakangas wrote:
>> Yeah, I noticed that on x86_64, pg_popcount_optimized is always a function
>> pointer with runtime check, even if you use compiler flags to target a CPU
>> where the special instructions are available unconditionally.
>
> I wonder how close we are to being able to just require SSE4.2/POPCNT for
> x86-64 builds. I suppose there's always a chance that someone will try to
> run Postgres 19 on a CPU from the aughts... In any case, avoiding the
> function pointer when possible seems like a good follow-up.
It's not really our decision. Packagers choose which architecture to
target and which compiler options to build with. We ought to just
respect those choices.
- Heikki
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