re PR target/50289 ([avr]: call-prologues saving/restoring global register variables)

	PR target/50289
	* config/avr/avr.c (sequent_regs_live): Don't recognize sequences
	that contain global register variable.

From-SVN: r178528

gcc/ChangeLog

+2011-09-05  Georg-Johann Lay  <avr@gjlay.de>
+
+	PR target/50289
+	* config/avr/avr.c (sequent_regs_live): Don't recognize sequences
+	that contain global register variable.
+
 2011-09-05  Richard Guenther  <rguenther@suse.de>
 
 	* tree-cfg.c (replace_uses_by): Use fold_stmt, not fold_stmt_inplace.

gcc/config/avr/avr.c

@@ -522,6 +522,17 @@ sequent_regs_live (void)
 
   for (reg = 0; reg < 18; ++reg)
     {
+      if (fixed_regs[reg])
+        {
+          /* Don't recognize sequences that contain global register
+             variables.  */
+      
+          if (live_seq != 0)
+            return 0;
+          else
+            continue;
+        }
+      
       if (!call_used_regs[reg])
 	{
 	  if (df_regs_ever_live_p (reg))