Re: Upstreaming OpenRISC with GCC mainline

[Stafford Horne <shorne@gmail.com>]

On Thu, Oct 28, 2021, 7:13 AM Joseph Myers <joseph@codesourcery.com> wrote:

> On Thu, 28 Oct 2021, Stafford Horne via Libc-alpha wrote:
>
> > The question now being, how should I go about upstreaming?  Should I
> > just backport my gcc patches to gcc-11 and move forward?  Or should I
> > work to fixup all of the GCC mainline issues the correct way?  I think
> > the second option may take quite some time though.
>
> What are you doing differently in your GCC or glibc ports that results in
> getting these warnings for OpenRISC but not for other architectures?
> That's a key thing to understand, separately for each issue (for example,
> S/390 sometimes has problems with warnings not seen on other architectures
> because it sets various tuning parameters differently).  In some cases, it
> might be that GCC *should* warn for other architectures, in which case an
> upstream GCC bug needs reporting about the missing warning.  For example,
> I can see no good reason for the "'strcmp' argument 2 declared attribute
> 'nonstring'" warnings you quote to depend on the architecture; they should
> appear on all architectures or none.
>
> Then, if a warning is a false positive (and really is still present with
> current GCC mainline), adding an initialization is not normally the
> appropriate fix; rather, for uninitialized warnings we use DIAG_* to
> suppress them, with a comment explaining the analysis of *why* the warning
> is a false positive.  For example, in sysdeps/ieee754/flt-32/s_log1pf.c we
> already have a use of those macros for what looks like the specific
> warning case you quote; if, despite that, you see the warning for a
> different place in the same file for the same variable, it might be
> reasonable to repeat the same macro calls and comment there, if the same
> analysis applies.


Hi Joseph,

Thanks for the comments.  I have been watching the testsresults mails:

  https://sourceware.org/pipermail/libc-testresults/2021q4/008772.html
  https://sourceware.org/pipermail/libc-testresults/2021q4/008773.html

I was seeing failures there and thought the warnings I was seeing were
affecting all architectures.  But now I see the builds are mostly clean.
So it's something I'll have to track down.

Now with your input I have some ideas. If I do need patches I'll use the
proper DIAG_* macros as you mentioned. I am familiar with those.

-Stafford