[Bug libgomp/78468] [7 regression] libgomp.c/reduction-10.c and many more FAIL

["vogt at linux dot vnet.ibm.com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78468

--- Comment #16 from Dominik Vogt <vogt at linux dot vnet.ibm.com> ---
In emit-rtl.c:init_emit(), the alignment of the virtual_stack_dynamic pointer
is hard coded to STACK_BOUNDARY:

  REGNO_POINTER_ALIGN (VIRTUAL_STACK_DYNAMIC_REGNUM) = STACK_BOUNDARY; 

The backend must make sure that this promise is kept.  If that's what's
happening the Sparc backend then needs a fix similar to this Aix patch:

https://gcc.gnu.org/ml/gcc-patches/2016-11/msg01036.html
(r242589)

The idea (on AIX) is to round up the allocation size of the parameters area if
the function does dynamic allocation (calls_alloca is true).  This logic had to
be replicated in some macros in aix.h.  A solution for sparc probably looks
similar.