Symbol support for opt_eq_func.

* vm_insnhelper.c (opt_eq_func): optimize for symbol comparison.
  [Bug #13330] [fix GH-1540]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58895 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

vm_insnhelper.c

@@ -1325,6 +1325,11 @@ opt_eq_func(VALUE recv, VALUE obj, CALL_INFO ci, CALL_CACHE cc)
 	    return rb_str_equal(recv, obj);
 	}
     }
+    else if (SYMBOL_P(recv) && SYMBOL_P(obj)) {
+	if (EQ_UNREDEFINED_P(SYMBOL)) {
+	    return (recv == obj) ? Qtrue : Qfalse;
+	}
+    }
 
     {
 	vm_search_method(ci, cc, recv);