java volatile问题与重排序

public class Main {
    static boolean stop;

    public static void main(String[] args) throws Exception {
        Thread t = new Thread(new Runnable() {

            @Override
            public void run() {
                while (!stop) {
                    try {
                        TimeUnit.SECONDS.sleep(1);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        });

        t.start();

        TimeUnit.SECONDS.sleep(3);
        stop = true;
    }
}

以上代码为什么不会出现死循环呢？