How to identify reorderable code Code reordering problems (.NET)

internal static volatile int s_x = 0;
internal static volatile int s_y = 0;
internal static volatile int s_ya = 0;

void ThreadA() {
    s_x = 1;
    s_ya = s_y;
}

Processing.Add(ItemNumber, null);
AsyncTask.Begin(InternalRequestCallback, Remove, ItemNumber);