Re: [Check-devel] Failures in check_check and check_check_export

[<chr...@ma...>]

On 2020-05-27 17:59, Ken Moffat via Check-devel wrote:
> That new build has now been booted.  I then built check and ran the
> tests - they all passed, so I did need to get away from the host
> glibc which was sitting under chroot.
> 
> I think a -O1 build might be a bit slower than I like, and detuning
> from glibc's default of -O2 feels odd, but I guess I'm on the way
> forward and with a variety of things to try over the next week or
> so.
> 
> Thanks again to you both!

Good news!  You're welcome!

I think if you want to pursue this it's either a bug in glibc because 
they're relying on undefined behaviour, or a bug in GCC because an 
optimization is unsound.

If you do want to narrow it down, and get back most of your performance, 
you can make a list of optimization flags enabled by -O2 that aren't 
enabled by -O1, and then do a binary search for the offender.  This 
would also be more useful information for a bug report.  Of course, this 
might require some patience...

Chris