var stack [depth]*node
		tos := -1

		// There are two write barriers per iteration, so i+=2.
		for i := 0; i < b.N; i += 2 {
			if tos == -1 {
				stack[0] = root
				tos = 0
			}

			// Perform one step of reversing the tree.
			n := stack[tos]
			if n.l == nil {
				tos--
			} else {
				n.l, n.r = n.r, n.l
				stack[tos] = n.l
				stack[tos+1] = n.r
				tos++
			}

}

type IfaCacheinfo struct {
	Prefered uint32
	Valid    uint32
	Cstamp   uint32
	Tstamp   uint32
}

type RtMsg struct {
	Family   uint8
	Dst_len  uint8
	Src_len  uint8
	Tos      uint8
	Table    uint8
	Protocol uint8
	Scope    uint8
	Type     uint8
	Flags    uint32
}

type RtNexthop struct {
	Len     uint16
	Flags   uint8
	Hops    uint8
	Ifindex int32
}