* ipa-polymorphic-call.c

	(ipa_polymorphic_call_context::get_dynamic_type): Short circuit the
	case when call target is already known.

From-SVN: r223733

gcc/ChangeLog

+2015-05-26  Jan Hubicka  <hubicka@ucw.cz>
+
+	* ipa-polymorphic-call.c
+	(ipa_polymorphic_call_context::get_dynamic_type): Short circuit the
+	case when call target is already known.
+
 2015-05-26  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	PR target/65979

gcc/ipa-polymorphic-call.c

@@ -1561,6 +1561,11 @@ ipa_polymorphic_call_context::get_dynamic_type (tree instance,
 	  ref = OBJ_TYPE_REF_EXPR (ref);
 	  ref = walk_ssa_copies (ref);
 
+	  /* If call target is already known, no need to do the expensive
+ 	     memory walk.  */
+	  if (is_gimple_min_invariant (ref))
+	    return false;
+
 	  /* Check if definition looks like vtable lookup.  */
 	  if (TREE_CODE (ref) == SSA_NAME
 	      && !SSA_NAME_IS_DEFAULT_DEF (ref)