static A test_helper(Object o) {
        // this includes a check for null with both branches taken
        return (A)o;
    }


    // Loop is unswitched because of the test null for null from the
    // checkcast above, unsafe access is copied in each branch, the
    // compiler sees a memory access to a null object
    static int test1(Object o, long offset) {
        int f = 0;
        for (int i = 0; i < 100; i++) {
            A a = test_helper(o);
            f = UNSAFE.getInt(a, offset);
        }
        return f;
    }

Results in:

#  Internal Error (/home/roland/hs/hotspot/src/share/vm/opto/compile.cpp:1720), pid=24319, tid=24364
#  assert(flat != TypePtr::BOTTOM) failed: cannot alias-analyze an untyped ptr: adr_type = NULL+12