Re: BUG #15121: Multiple UBSAN errors

On 2018-03-19 14:41:23 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On 2018-03-19 14:20:33 -0400, Tom Lane wrote:
> >> I tried -O3 with gcc 7.3.1 (Fedora 26), and that passes check-world
> >> just fine.  Then I tried -O3 with gcc 8.0.1 (prerelease Fedora 28),
> >> and indeed that's got some problems.
> 
> >> Note that 1-D and 2-D arrays print fine, it's only 3-D or deeper
> >> that print wrong.  Very odd.  Maybe it's bad code on our part,
> >> but I think the odds are at least as good that it's a new gcc bug.
> 
> > Might be worth trying with a new clang, I think it's been a bit ahead on
> > the quality of the ubsan (et al) integration quality.
> 
> I'm not talking about ubsan, I'm just talking about whether our regression
> tests pass with the higher -O level.

Oh. I think I'll setup two BF animals that continually run using
debian's gcc-snapshot package, once with O0 and once with O3.

Greetings,

Andres Freund