{PrefixFrom(v6, 0), true},
		{PrefixFrom(v6, 32), true},
		{PrefixFrom(v6, 128), true},
		{PrefixFrom(v6, 129), false},

		{PrefixFrom(Addr{}, -2), false},
		{PrefixFrom(Addr{}, -1), false},
		{PrefixFrom(Addr{}, 0), false},
		{PrefixFrom(Addr{}, 32), false},
		{PrefixFrom(Addr{}, 128), false},
	}
	for _, tt := range tests {
		got := tt.ipp.IsValid()
		if got != tt.want {

			ipv4: func() []netip.Addr {
				ip, _ := netip.ParseAddr("1.0.0.0")
				ip2, _ := netip.ParseAddr("255.255.255.255")
				return []netip.Addr{ip, ip2}
			},
			ipv6: func() []netip.Addr {
				return []netip.Addr{}
			},
		},
		{
			name: "one ipv6",
			ips:  []string{"::1"},
			ipv4: func() []netip.Addr {
				return []netip.Addr{}
			},
			ipv6: func() []netip.Addr {
				ip, _ := netip.ParseAddr("::1")

	*addr = new

	unlock()
	return
}

//go:nosplit
func Xchg64(addr *uint64, new uint64) (old uint64) {
	lockAndCheck(addr)

	old = *addr
	*addr = new

	unlock()
	return
}

//go:nosplit
func Cas64(addr *uint64, old, new uint64) (swapped bool) {
	lockAndCheck(addr)

	if (*addr) == old {
		*addr = new
		unlock()
		return true
	}

	unlock()
	return false
}

	MOVD	addr+0(FP), RARG0
	MOVD	sz+8(FP), RARG1
	MOVD	sp+16(FP), RARG2
	MOVD	pc+24(FP), RARG3
	// void __asan_write_go(void *addr, uintptr_t sz, void *sp, void *pc);
	MOVD	$__asan_write_go(SB), FARG
	JMP	asancall<>(SB)

// func runtime·asanunpoison(addr unsafe.Pointer, sz uintptr)
TEXT	runtime·asanunpoison(SB), NOSPLIT, $0-16
	MOVD	addr+0(FP), RARG0
	MOVD	sz+8(FP), RARG1
	// void __asan_unpoison_go(void *addr, uintptr_t sz);

		if err == nil {
			ip := from.Addr // copy from.Addr; ip escapes, so this line allocates 16 bytes
			*addr = UDPAddr{IP: ip[:], Port: from.Port, Zone: zoneCache.name(int(from.ZoneId))}
		}
	}
	if err != nil {
		// No sockaddr, so don't return UDPAddr.
		addr = nil
	}
	return n, addr, err
}

func (c *UDPConn) readFromAddrPort(b []byte) (n int, addr netip.AddrPort, err error) {
	var ip netip.Addr

//go:linkname asanread
//go:nosplit
func asanread(addr unsafe.Pointer, sz uintptr) {
	sp := getcallersp()
	pc := getcallerpc()
	doasanread(addr, sz, sp, pc)
}

//go:linkname asanwrite
//go:nosplit
func asanwrite(addr unsafe.Pointer, sz uintptr) {
	sp := getcallersp()
	pc := getcallerpc()
	doasanwrite(addr, sz, sp, pc)
}

//go:noescape
func doasanread(addr unsafe.Pointer, sz, sp, pc uintptr)

//go:noescape

	MOVQ	addr+0(FP), RARG0
	MOVQ	sz+8(FP), RARG1
	MOVQ	sp+16(FP), RARG2
	MOVQ	pc+24(FP), RARG3
	// void __asan_write_go(void *addr, uintptr_t sz, void *sp, void *pc);
	MOVQ	$__asan_write_go(SB), AX
	JMP	asancall<>(SB)

// func runtime·asanunpoison(addr unsafe.Pointer, sz uintptr)
TEXT	runtime·asanunpoison(SB), NOSPLIT, $0-16
	MOVQ	addr+0(FP), RARG0
	MOVQ	sz+8(FP), RARG1
	// void __asan_unpoison_go(void *addr, uintptr_t sz);

		}
		// See struct sockaddr_in
		daddr = net.IPv4(
			addr.Addr.Addr[0], addr.Addr.Addr[1], addr.Addr.Addr[2], addr.Addr.Addr[3])
	} else {
		addr, err = unix.GetsockoptIPv6MTUInfo(
			int(fd), unix.IPPROTO_IPV6,
			constants.SoOriginalDst)
		if err != nil {
			log.Errorf("Error to ipv6 getsockopt: %v", err)
			return
		}
		// See struct sockaddr_in6
		daddr = addr.Addr.Addr[:]
	}
	// See sockaddr_in6 and sockaddr_in

)

const Enabled = true

func Acquire(addr unsafe.Pointer) {
	runtime.RaceAcquire(addr)
}

func Release(addr unsafe.Pointer) {
	runtime.RaceRelease(addr)
}

func ReleaseMerge(addr unsafe.Pointer) {
	runtime.RaceReleaseMerge(addr)
}

func Disable() {
	runtime.RaceDisable()
}

func Enable() {
	runtime.RaceEnable()
}

func Read(addr unsafe.Pointer) {
	runtime.RaceRead(addr)
}

func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (int, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.writeTo(b, addr)
	if err != nil {
		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
	}
	return n, err
}

// WriteTo implements the [PacketConn] WriteTo method.
func (c *IPConn) WriteTo(b []byte, addr Addr) (int, error) {
	if !c.ok() {