device: remove code using unsafe

There is no performance impact.

name                             old time/op  new time/op  delta
TrieIPv4Peers100Addresses1000-8  78.6ns ± 1%  79.4ns ± 3%    ~     (p=0.604 n=10+9)
TrieIPv4Peers10Addresses10-8     29.1ns ± 2%  28.8ns ± 1%  -1.12%  (p=0.014 n=10+9)
TrieIPv6Peers100Addresses1000-8  78.9ns ± 1%  78.6ns ± 1%    ~     (p=0.492 n=10+10)
TrieIPv6Peers10Addresses10-8     29.3ns ± 2%  28.6ns ± 2%  -2.16%  (p=0.000 n=10+10)

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Josh Bleecher Snyder 2021-11-08 11:15:06 -08:00 committed by Jason A. Donenfeld
parent ef8d6804d7
commit 4d87c9e824

View file

@ -7,6 +7,7 @@ package device
import ( import (
"container/list" "container/list"
"encoding/binary"
"errors" "errors"
"math/bits" "math/bits"
"net" "net"
@ -32,45 +33,24 @@ type trieEntry struct {
perPeerElem *list.Element perPeerElem *list.Element
} }
func isLittleEndian() bool {
one := uint32(1)
return *(*byte)(unsafe.Pointer(&one)) != 0
}
func swapU32(i uint32) uint32 {
if !isLittleEndian() {
return i
}
return bits.ReverseBytes32(i)
}
func swapU64(i uint64) uint64 {
if !isLittleEndian() {
return i
}
return bits.ReverseBytes64(i)
}
func commonBits(ip1, ip2 []byte) uint8 { func commonBits(ip1, ip2 []byte) uint8 {
size := len(ip1) size := len(ip1)
if size == net.IPv4len { if size == net.IPv4len {
a := (*uint32)(unsafe.Pointer(&ip1[0])) a := binary.BigEndian.Uint32(ip1)
b := (*uint32)(unsafe.Pointer(&ip2[0])) b := binary.BigEndian.Uint32(ip2)
x := *a ^ *b x := a ^ b
return uint8(bits.LeadingZeros32(swapU32(x))) return uint8(bits.LeadingZeros32(x))
} else if size == net.IPv6len { } else if size == net.IPv6len {
a := (*uint64)(unsafe.Pointer(&ip1[0])) a := binary.BigEndian.Uint64(ip1)
b := (*uint64)(unsafe.Pointer(&ip2[0])) b := binary.BigEndian.Uint64(ip2)
x := *a ^ *b x := a ^ b
if x != 0 { if x != 0 {
return uint8(bits.LeadingZeros64(swapU64(x))) return uint8(bits.LeadingZeros64(x))
} }
a = (*uint64)(unsafe.Pointer(&ip1[8])) a = binary.BigEndian.Uint64(ip1[8:])
b = (*uint64)(unsafe.Pointer(&ip2[8])) b = binary.BigEndian.Uint64(ip2[8:])
x = *a ^ *b x = a ^ b
return 64 + uint8(bits.LeadingZeros64(swapU64(x))) return 64 + uint8(bits.LeadingZeros64(x))
} else { } else {
panic("Wrong size bit string") panic("Wrong size bit string")
} }