php位运算，windows和linux结果为什么不同？

Question

function myHash($str) {

    $hash = 0;
    $s    = md5($str);
    $seed = 5;
    $len  = 32;
    for ($i = 0; $i < $len; $i++) {

        $hash = ($hash << $seed) + $hash + ord($s{$i});
    }
    return $hash & 0x7FFFFFFF;
}

$str = "A8A1B1EF-2B31-6572-B364-1E169C943F8E";


echo myHash($str);  // window 85222734
                    // linux 1473101824