您可以这样简单地编写自己的函数：

function get_old_link($url) {
        global $wpdb;

        // get only url path 
        $parse = parse_url($url);
        $path = trim($parse[\'path\'], "/");

        // get last part as slug
        $arr = explode("/", $path);
        $slug = end($arr);

        // find post id by meta_key and meta_value
        $row = $wpdb->get_row("SELECT post_id FROM $wpdb->postmeta WHERE meta_key = \'_wp_old_slug\' AND meta_value = \'{$slug}\'");

        if(!empty($row->post_id))
            return get_permalink($row->post_id);
}