darwin, ppc - improve debug for mdebug-stack

Darwin uses an out of line save when complete context
needs to be saved, including the vector regs.

This patch prints the status of that when -mdebug=stack
is given.

gcc/

2019-05-12  Iain Sandoe  <iain@sandoe.co.uk>

	* config/rs6000/rs6000.c (debug_stack_info): When -mdebug=stack
	is given, print the state of the EH "save world" computation for
	Darwin.

From-SVN: r271101

gcc/ChangeLog

+2019-05-12  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* config/rs6000/rs6000.c (debug_stack_info): When -mdebug=stack
+	is given, print the state of the EH "save world" computation for
+	Darwin.
+
 2019-05-11  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/59813

gcc/config/rs6000/rs6000.c

@@ -24721,6 +24721,9 @@ debug_stack_info (rs6000_stack_t *info)
 
     fprintf (stderr, "\tsave-strategy       =  %04x\n", info->savres_strategy);
 
+  if (info->abi == ABI_DARWIN)
+    fprintf (stderr, "\tWORLD_SAVE_P        = %5d\n", WORLD_SAVE_P(info));
+
   fprintf (stderr, "\n");
 }