Re: LLVM 16 (opaque pointers)

Hi,

On 2023-10-21 10:48:47 +1300, Thomas Munro wrote:
> On Thu, Oct 19, 2023 at 6:20 AM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> > Interestingly, a new problem just showed up on the the RHEL9 s390x
> > machine "lora", where a previously reported problem [1] apparently
> > re-appeared. It complains about incompatible layout, previously
> > blamed on mismatch between clang and LLVM versions. I can see that
> > its clang is v15 from clues in the conflig log, but I don't know which
> > version of LLVM is being used. However, I see now that --with-llvm
> > was literally just turned on, so there is no reason to think that this
> > would have worked before or this work is relevant. Strange though --
> > we must be able to JIT further than that on s390x because we have
> > crash reports in other threads (ie we made it past this and into other
> > more advanced brokenness).
>
> I see that Mark has also just enabled --with-llvm on some POWER Linux
> animals, and they have failed in various ways. The failures are
> strangely lacking in detail. It seems we didn't have coverage before,
> and I recall that there were definitely versions of LLVM that *didn't*
> work for our usage in the past, which I'll need to dredge out of the
> archives. I will try to get onto a cfarm POWER machine and see if I
> can reproduce that, before and after these commits, and whose bug is
> it etc.

I'm quite sure that jiting did pass on ppc64 at some point.

> I doubt I can get anywhere near an s390x though, and we definitely had
> pre-existing problems on that arch.

IMO an LLVM bug, rather than a postgres bug, but I guess it's all a matter of
perspective.
https://github.com/llvm/llvm-project/issues/53009#issuecomment-1042748553

I had made another bug report about this issue at some point, but I can't
refind it right now.

Greetings,

Andres Freund