On Wed, Jul 14, 2021 at 8:01 PM Alan Modra <amo...@gmail.com> wrote:
>
> On Wed, Jun 30, 2021 at 05:06:30PM -0300, Tulio Magno Quites Machado Filho 
> wrote:
> > Alan Modra via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> >
> > > Compiling gcc/testsuite/gcc.dg/split-*.c and others with -mcpu=power10
> > > and linking with a non-pcrel libgcc results in crashes due to the
> > > power10 pcrel code not having r2 set for the generic-morestack.c
> > > functions called from __morestack.  There is also a problem when
> > > non-pcrel code calls a pcrel libgcc.  See the patch comments.
> > >
> > > A similar situation theoretically occurs with ELFv1 multi-toc
> > > executables, when __morestack might be located in a different toc
> > > group to its caller.  This patch makes no attempt to fix that, since
> > > the gold linker does not support multi-toc (gold is needed for proper
> > > support of -fsplit-stack code) nor does gcc emit __morestack calls
> > > that support multi-toc.
> > >
> > > Bootstrapped and regression tested power64le-linux with both
> > > -mcpu=power10 and -mcpu=power9.  OK for mainline and backporting to
> > > gcc-11 and gcc-10?
> > >
> > >     * config/rs6000/morestack.S (R2_SAVE): Define.
> > >     (__morestack): Save and restore r2.  Set up r2 for called
> > >     functions.
> >
> > Thanks! This patch solved the issue I was seeing.
> >
> > If it gets merged, can this patch be backported to GCC 10 and 11, please?
> >
> > --
> > Tulio Magno
>
> https://gcc.gnu.org/pipermail/gcc-patches/2021-June/573978.html
>
> This patch has now been unreviewed for over two weeks.  I expected a
> rubber stamp style approval;  This assembly file is all mine, I know
> the ABI and how .eh_frame driven exception handling works on powerpc.
> So I'm going to claim the patch is obvious enough to someone with a
> good understanding of what is going on in morestack.S and commit under
> the "obvious" rule after allowing a few more days for comment.

This patch is okay.

Thanks, David

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