re PR rtl-optimization/50496 (ICE in redirect_jump, at jump.c:1497)

2011-11-23  Chung-Lin Tang  <cltang@codesourcery.com>

	PR rtl-optimization/50496
	* jump.c (redirect_jump): Assert fail on nlabel == NULL_RTX
	only after epilogue is created. Add comments.

From-SVN: r181664

gcc/ChangeLog

+2011-11-23  Chung-Lin Tang  <cltang@codesourcery.com>
+
+	PR rtl-optimization/50496
+	* jump.c (redirect_jump): Assert fail on nlabel == NULL_RTX
+	only after epilogue is created. Add comments.
+
 2011-11-22  Richard Henderson  <rth@redhat.com>
 
 	* config/ia64/ia64.c (ia64_expand_atomic_op): Add model parameter.

gcc/jump.c

@@ -1495,7 +1495,18 @@ redirect_jump (rtx jump, rtx nlabel, int delete_unused)
 {
   rtx olabel = JUMP_LABEL (jump);
 
-  gcc_assert (nlabel != NULL_RTX);
+  if (!nlabel)
+    {
+      /* If there is no label, we are asked to redirect to the EXIT block.
+	 When before the epilogue is emitted, return/simple_return cannot be
+	 created so we return 0 immediately.  After the epilogue is emitted,
+	 we always expect a label, either a non-null label, or a
+	 return/simple_return RTX.  */
+
+      if (!epilogue_completed)
+	return 0;
+      gcc_unreachable ();
+    }
 
   if (nlabel == olabel)
     return 1;