Re: [POWER10] __morestack calls from pcrel code

[Tulio Magno Quites Machado Filho <tuliom@ascii.art.br>]

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