(function() {
    var o = {a:1};
    var p = {a:2, l:13};
    var result = 0;
    for (var i = 0; i < 1000000; ++i) {
        result ^= o.a;
        var tmp = o;
        o = p;
        p = tmp;
    }
    if (result != 0)
        throw "Error: bad result: " + result;
})();