+/**
+ * Computes the costs of a copy according to loop depth
+ * @param root, arg: clear.
+ * @param pos: -1 for perm-copies.
+ * Else the argument position of arg in the phi node root.
+ * @return Must be >= 0 in all cases.
+ */
+int get_costs_loop_depth(ir_node *root, ir_node* arg, int pos);