We have two functions ck, that are supposed to compare the two inputs and make the test fail if they are not equal.

    void ck(long x, long y) {
        if (x != y) {
            throw new RuntimeException(" x = " + Long.toHexString(x) + ", y = " + Long.toHexString(y));
        }
    }

    void ck(double x, double y) {
        if (x == x && y == y && x != y) {
            ck(x, y);
        }
    }

The long throws a RuntimeException.
The one for double goes into an infinite recursion, and eventually throws a StackOverflowError. This does not make much sense.
I spoke with the original author [~psandoz], he agrees to replace it with an analogue RuntimeException.

    void ck(double x, double y) {
        if (x == x && y == y && x != y) {
            throw new RuntimeException(...);
        }
    }

Code introduced in JDK-8151163.
Bug in JDK-8282555 encountered both this endless recursion as the RuntimeException, of the respective ck functions.