Re: [PATCH] Disable guality tests for powerpc*-linux*

[Bill Schmidt <wschmidt at linux dot vnet dot ibm dot com>]

Hi Jakub,

Thanks for the information; I really do appreciate it!

On Tue, 2016-03-29 at 17:33 +0200, Jakub Jelinek wrote:
> On Tue, Mar 29, 2016 at 08:19:39AM -0500, Bill Schmidt wrote:
> > When you say that "the debug info quality is already pretty bad on
> > powerpc*," do you mean that it is known to be bad, or simply that we
> > have a lot of guality failures that may or may not indicate that the
> > debug info is bad?  I don't have experiential evidence of bad debug info
> > that shows up during debugging sessions.  Perhaps these are corner cases
> 
> A lot of effort has been spent on x86_64/i?86 to improve the debug info
> for optimized code, while far less effort has been spent on it for say
> powerpc* or s390*.  Many of the guality testcases are derived from
> real-world programs, such as the Linux kernel or python or other packages
> where the lack of QoI of debug info (or sometimes even wrong debug info)
> caused some tool failures or has been a major obstackle to users so that
> they couldn't debug something important.
> And for evidence, we have e.g. in redhat.com bugzilla, significantly more
> complains about debug info on powerpc*/s390* than on i?86/x86_64.

This is good information.  Unfortunately, this is the first time I've
been made aware of it.  If these bugs aren't posted to the FSF bugzilla,
or mirrored to us, we are ignorant that there is even a problem.  At the
moment I'm not aware of any bug reports about debug info on powerpc*.
Please pass these along to me as they arise.  We can't prioritize what
we can't see.

> > before I joined this project, and from what others tell me, for at least
> > a decade.  As you suggest here, others have always told me just to
> > ignore the existing guality failures.  However, this can easily lead to
> 
> Then you've been told wrong suggestions.  You should just keep comparing
> the results against older ones.

That is what I meant.  I apologize for the unclear language.

> 
> > The other point, "it would be really very much desirable if
> > anyone had time to analyze some of them and improve stuff," has to be
> > answered by "apparently nobody does."  I am currently tracking well over
> 
> That would be a wrong answer, several man-years have been spent on analyzing
> and improving those, by Alex, myself, Richi, various others.

Again, this is good information to know about.  But the "stuff" we were
talking about was the failures on powerpc*, and I took what you said to
mean that nobody was working on those.  It sounds like you're saying
that the community has spent time on debug improvements for optimized
code on x86_64/i?86, but only for that target.  Is that a fair
statement?  If so, it seems unsurprising that you would get more bug
reports for the debug information on powerpc* and s/390.

I'm not trying to be critical here.  I'm trying to understand the value
offered by these tests (which I do much better now, thanks), since we
have to prioritize our work carefully for the resources that we have.

Thanks,
Bill