rs6000.c (split_stack_arg_pointer_used_p): Scan correct block for use of r12.

	* config/rs6000/rs6000.c (split_stack_arg_pointer_used_p): Scan
	correct block for use of r12.
	(rs6000_expand_split_stack_prologue): Error on r29 asm global reg.

From-SVN: r223878

gcc/ChangeLog

+2015-05-30  Alan Modra  <amodra@gmail.com>
+
+	* config/rs6000/rs6000.c (split_stack_arg_pointer_used_p): Scan
+	correct block for use of r12.
+	(rs6000_expand_split_stack_prologue): Error on r29 asm global reg.
+
 2015-05-29  Dominik Vogt  <vogt@linux.vnet.ibm.com>
 
 	PR target/66215

gcc/config/rs6000/rs6000.c

@@ -23450,7 +23450,7 @@ split_stack_arg_pointer_used_p (void)
   /* Unfortunately we also need to do some code scanning, since
      r12 may have been substituted for the pseudo.  */
   rtx_insn *insn;
-  basic_block bb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
+  basic_block bb = ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb;
   FOR_BB_INSNS (bb, insn)
     if (NONDEBUG_INSN_P (insn))
       {
@@ -25942,6 +25942,13 @@ rs6000_expand_split_stack_prologue (void)
   if (!info->push_p)
     return;
 
+  if (global_regs[29])
+    {
+      error ("-fsplit-stack uses register r29");
+      inform (DECL_SOURCE_LOCATION (global_regs_decl[29]),
+	      "conflicts with %qD", global_regs_decl[29]);
+    }
+
   allocate = info->total_size;
   if (allocate > (unsigned HOST_WIDE_INT) 1 << 31)
     {