Why getAndAddInt method with no safepoint checks inside?

Environment: jdk1.8

public static AtomicInteger num = new AtomicInteger(0);

public static void main(String[] args) throws Throwable {
    Runnable runnable = () -> {
        for (int i = 0; i < 1000000000; i++) {
            num.getAndAdd(1);
        }
    };

    Thread t1 = new Thread(runnable);
    Thread t2 = new Thread(runnable);
    t1.start();
    t2.start();

    System.out.println("before sleep");
    Thread.sleep(1000);
    System.out.println("after sleep");

    System.out.println(num);
}

I saw this question :The main thread exceeds the set sleep time (I want to add comments to this question, but I don' have enough reputation, so I create this new question. If this is a discouraged operation， I'm sorry for this.)

But I don't know why getAndAddInt method with no safepoint checks inside? Doesn't the getAndAddInt method also contain native methods?