Re: pgbench test failing on 14beta1 on Debian/i386

On Wed, May 19, 2021 at 9:51 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Christoph Berg <myon(at)debian(dot)org> writes:
> > I can reproducibly get build failures in pgbench on 32-bit i386
> > Debian, both on sid and buster. (The older Debian stretch and Ubuntu
> > bionic are unaffected. Other architectures are also fine.)
>
> The test that's failing came in with
>
> 6b258e3d688db14aadb58dde2a72939362310684
> Author: Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
> Date: Tue Apr 6 11:50:42 2021 +0100
>
> pgbench: Function to generate random permutations.

FWIW this is reproducible on my local Debian/gcc box with -m32, but
not on my FreeBSD/clang box with -m32. permute() produces different
values here:

\set t debug(permute(:size-1, :size, 5432) = 5301702756001087507 and \
permute(:size-2, :size, 5432) = 8968485976055840695 and \
permute(:size-3, :size, 5432) = 6708495591295582115 and \
permute(:size-4, :size, 5432) = 2801794404574855121 and \
permute(:size-5, :size, 5432) = 1489011409218895840 and \
permute(:size-6, :size, 5432) = 2267749475878240183 and \
permute(:size-7, :size, 5432) = 1300324176838786780)

I don't understand any of this stuff at all, but I added a bunch of
printfs and worked out that the first point its local variables
diverge is here:

/* Random offset */
r = (uint64) getrand(&random_state2, 0, size - 1);

... after 4 earlier getrand() produced matching values. Hmm.