static <V> Node<V> tabAt(Node<V>[] tab, int i) {
    try {
      Object o = Unsafe.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);
      return (Node<V>)o;
    }
    catch (Throwable throwable) {
      throw new RuntimeException(throwable);
    }
  }
static <V> Node<V> tabAt(Node<V>[] tab, int i)