function my_shutdown() {
    xdebug_notify(xdebug_get_monitored_functions());
    xdebug_stop_function_monitor();
}

xdebug_start_function_monitor(['exit']);
register_shutdown_function('my_shutdown');

function bar() {
    echo 'hello';
    exit(1);
}
bar();

It will report an empty array, but I'd expect it to be non-empty since "exit(1)" was called.