Horton

Re: Improving and extending int128.h to more of numeric.c

Dean Rasheed <dean.a.rasheed@gmail.com>

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From: Dean Rasheed <dean.a.rasheed@gmail.com>
To: John Naylor <johncnaylorls@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2025-08-04T14:58:15Z
Lists: pgsql-hackers 
On Fri, 18 Jul 2025 at 07:42, John Naylor <johncnaylorls@gmail.com> wrote:
>
> While testing something else on s390x, I noticed that __int128 support
> is broken on that platform at least for some versions of clang [1],
> and I see improvement there with this patch:
>
> Query 1:
> HEAD:  3015ms
> Patch: 2206ms
>
> Query 2:
> HEAD:  3394ms
> Patch: 2514ms

Thanks for testing.

On Fri, 18 Jul 2025 at 07:47, John Naylor <johncnaylorls@gmail.com> wrote:
>
> On Thu, Jul 17, 2025 at 2:30 PM Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
> >
> > BTW, my other motivation for doing this was to simplify the numeric
> > code. Even if this had zero performance benefit, as long as it didn't
> > make things any slower, I would argue that it's worth doing.
>
> I gathered that was the main motivation, and I agree. I looked over
> 0005 and don't see any issues.

Thanks for reviewing. If there are no objections, I'll push this
shortly (though I'll change INT64_HEX_FORMAT to PRIx64, since it looks
like the former is about to go away).

Regards,
Dean

Commits

  1. Guard against division by zero in test_int128 module.

  2. Extend int128.h to support more numeric code.

  3. Simplify non-native 64x64-bit multiplication in int128.h.

  4. Optimise non-native 128-bit addition in int128.h.

  5. Refactor int128.h, bringing the native and non-native code together.

  6. Convert src/tools/testint128.c into a test module.