[RS6000] PR81996, __builtin_return_address(0) fails
rs6000_return_addr assumes that the stack link is at frame+0, which is
true for count>0. For count==0, rs6000_return_addr is called with
frame==frame_pointer_rtx and the stack link is *not* at frame+0 if
-fstack-protector-all or -fsanitize=address because rs6000.h sets
FRAME_GROWS_DOWNWARD for those options.
PR target/81996
* gcc/config/rs6000/rs6000.c (rs6000_return_addr): Use
stack_pointer_rtx for count 0. Update comments. Break up
large rtl expression.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@252901
138bc75d-0d04-0410-961f-
82ee72b054a4