Re: Linux likely() unlikely() for PostgreSQL

On Sun, Jun 30, 2024 at 11:23 AM Tom Lane <tgl@sss.pgh.pa.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