functions with compound parameters are never const in firm

This should fix fehler200.c

ir/opt/funccall.c

@@ -508,8 +508,23 @@ static mtp_additional_properties check_const_or_pure_function(ir_graph *irg, int
 {
 	ir_node *end, *endbl;
 	int j;
+	ir_entity *entity   = get_irg_entity(irg);
+	ir_type   *type     = get_entity_type(entity);
+	size_t     n_params = get_method_n_params(type);
+	size_t     i;
+	mtp_additional_properties may_be_const = mtp_property_const;
 	mtp_additional_properties prop = get_irg_additional_properties(irg);
 
+	/* libfirm handles aggregate parameters by passing around pointers to
+	 * stuff in memory, so if we have compound parameters we are never const */
+	for (i = 0; i < n_params; ++i) {
+		ir_type *param = get_method_param_type(type, i);
+		if (is_compound_type(param)) {
+			prop        &= ~mtp_property_const;
+			may_be_const = mtp_no_property;
+		}
+	}
+
 	if (prop & mtp_property_const) {
 		/* already marked as a const function */
 		return mtp_property_const;
@@ -533,7 +548,7 @@ static mtp_additional_properties check_const_or_pure_function(ir_graph *irg, int
 
 	end   = get_irg_end(irg);
 	endbl = get_nodes_block(end);
-	prop  = mtp_property_const;
+	prop  = may_be_const;
 
 	ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
 	inc_irg_visited(irg);