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: 2025-07-14T21:07:38Z
Lists: pgsql-hackers

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On Mon, 14 Jul 2025 at 11:22, John Naylor <johncnaylorls@gmail.com> wrote:
>
> (Looking at v3) The new test module runs 10 million rather than a
> billion iterations. That still takes 1.2s (after 0005), which seems
> excessive for regular buildfarm testing. It seems like we could get by
> with fewer than that, by using the time of day for the PRNG seed
> (which would also need to be logged on error).

Thanks for looking!

I have reduced the number of iterations and changed it to use the
current time for the PRNG seed. I don't see much value in logging the
seed though, since we already log the inputs that cause any failure.

> > 0005 is the main patch.
> >
> I haven't looked too closely, but wanted to point out:
>
> warning: format ‘%lX’ expects argument of type ‘long unsigned int’,
> but argument 4 has type ‘int32’ {aka ‘int’} [-Wformat=]
>
> ...

Ah yes, thanks for pointing that out.

(The cfbot reports the same warnings, but you have to scroll through a
lot of output to see them. It would be nice if the commitfest app had
an indicator to show if there were any compiler warnings.)

v4 attached.

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.