Re: test failure with gcc-12 -O3 -march=native - Mailing list pgsql-hackers

From Andres Freund
Subject Re: test failure with gcc-12 -O3 -march=native
Date
Msg-id 20220812012416.sv4u7d6t2tlj3ui7@awork3.anarazel.de
Whole thread Raw
In response to Re: test failure with gcc-12 -O3 -march=native  (Justin Pryzby <pryzby@telsasoft.com>)
Responses Re: test failure with gcc-12 -O3 -march=native
List pgsql-hackers
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



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