Re: Query crash with 15.5 on debian bookworm/armv8

On Wed, Dec 27, 2023 at 5:17 AM Clemens Eisserer <linuxhippy(at)gmail(dot)com> wrote:
> > FWIW, since this crash is inside LLVM you could presumably dodge the bug
> > by setting "jit" to off.
>
> Thanks, this indeed solved the crash.
> Just to make sure this crash doesn't have anything to do with my
> setup/config (I'd changed quite a few settings in postgresql.conf),
> I gave it a try on a fresh bookworm install and it also crashed immeditaly.
>
> > As for an actual fix, perhaps a newer version of LLVM is needed?
> > I don't see a problem testing this query on my RPI with Ubuntu 23.10
> > (LLVM 16).
>
> I also gave Ubuntu 23.10 a try (15.4 built with llvm-15) and it worked
> as expected, explain analyze even mentioned the JIT was active.

I can't reproduce this on LLVM 14 on an aarch64 Mac FWIW (after
setting jit_*_cost to 0, as required since the table is empty).

> I've filed a debian bug report with a link to this discussion and a
> plea to build postgresql against llvm >= 15:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1059476

I doubt they'll change that, and in any case we'll need to get to the
bottom of this. Perhaps an assertion build of LLVM will fail in some
illuminating internal assertion? Unfortunately it's a non-trivial
business to get a debug build of LLVM going (it takes oodles of disk
and CPU and a few confusing-to-me steps)...

. o O ( It would be wonderful if assertion-enabled packages were
readily available for a common platform like Debian. I've finally
been spurred on to reach out to the maintainer of apt.llvm.org to ask
about that. It'd also be very handy for automated next-version
monitoring. )