Re: test failure with gcc-12 -O3 -march=native

Hi,

On 2022-08-11 20:06:02 -0500, Justin Pryzby wrote:
> On Thu, Aug 11, 2022 at 01:03:43PM -0700, Andres Freund wrote:
> > Hi,
> >
> > For my optimized builds I've long used -O3 -march=native. After one of the
>
> On what kind of arch ?

x86-64 cascadelake. I've since debugged this further. It's not even -march
that's the problem, it's the difference between -mtune=broadwell and
-mtune=skylake, even with -march=x86-64.

> > Given that I did not encounter this problem with gcc-12 before, and that
> > gcc-12 has been released, it seems less likely to be a bug in our code
> > highlighted by a new optimization and more likely to be a bug in a gcc bugfix,
> > but it's definitely not clear.
>
> debian testing is now defaulting to gcc-12.
> https://tracker.debian.org/news/1348007/accepted-gcc-defaults-1198-source-into-unstable/
>
> Are you sure you were building with gcc-12 and not gcc(default) which, until 3
> weeks ago, was gcc-11 ?

Yes.

I'm now bisecting...

Greetings,

Andres Freund