| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, wenhui qiu <qiuwenhuifx(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Linux likely() unlikely() for PostgreSQL |
| Date: | 2024-07-01 02:07:40 |
| Message-ID: | CAH2-WzmzVM6boze-J20-uaaPgx1geNz5nKESwvzPt8KHr58_Dw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sun, Jun 30, 2024 at 11:23 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> The real win would be if constructs like
>
> if (trouble)
> ereport(ERROR, ...);
>
> could be interpreted as
>
> if (unlikely(trouble))
> ereport(ERROR, ...);
>
> But I surely don't want to make thousands of such changes manually.
> And it's possible that smart compilers already realize this, using
> a heuristic that any path that ends in pg_unreachable() must be
> unlikely. Is there a way to encourage compilers to believe that?
Isn't that what commit 913ec71d68 did, by adding a call to
pg_attribute_cold to ereport?
--
Peter Geoghegan
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