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Merge pull request #14581 from holiman/byte_opt 

core/vm: improve opByte
This commit is contained in:
Péter Szilágyi 2017-06-13 14:44:19 +03:00 committed by GitHub
parent 732273094c ac9865791a
commit 335abdceb1
4 changed files with 174 additions and 8 deletions
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28
common/math/big.go
View File

@ -130,6 +130,34 @@ func PaddedBigBytes(bigint *big.Int, n int) []byte {
return ret
}
// bigEndianByteAt returns the byte at position n,
// in Big-Endian encoding
// So n==0 returns the least significant byte
func bigEndianByteAt(bigint *big.Int, n int) byte {
words := bigint.Bits()
// Check word-bucket the byte will reside in
i := n / wordBytes
if i >= len(words) {
return byte(0)
}
word := words[i]
// Offset of the byte
shift := 8 * uint(n%wordBytes)
return byte(word >> shift)
}
// Byte returns the byte at position n,
// with the supplied padlength in Little-Endian encoding.
// n==0 returns the MSB
// Example: bigint '5', padlength 32, n=31 => 5
func Byte(bigint *big.Int, padlength, n int) byte {
if n >= padlength {
return byte(0)
}
return bigEndianByteAt(bigint, padlength-1-n)
}
// ReadBits encodes the absolute value of bigint as big-endian bytes. Callers must ensure
// that buf has enough space. If buf is too short the result will be incomplete.
func ReadBits(bigint *big.Int, buf []byte) {

99
common/math/big_test.go
View File

@ -21,6 +21,8 @@ import (
"encoding/hex"
"math/big"
"testing"
"github.com/ethereum/go-ethereum/common"
)
func TestHexOrDecimal256(t *testing.T) {
@ -133,8 +135,44 @@ func TestPaddedBigBytes(t *testing.T) {
}
}
func BenchmarkPaddedBigBytes(b *testing.B) {
func BenchmarkPaddedBigBytesLargePadding(b *testing.B) {
bigint := MustParseBig256("123456789123456789123456789123456789")
for i := 0; i < b.N; i++ {
PaddedBigBytes(bigint, 200)
}
}
func BenchmarkPaddedBigBytesSmallPadding(b *testing.B) {
bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC")
for i := 0; i < b.N; i++ {
PaddedBigBytes(bigint, 5)
}
}
func BenchmarkPaddedBigBytesSmallOnePadding(b *testing.B) {
bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC")
for i := 0; i < b.N; i++ {
PaddedBigBytes(bigint, 32)
}
}
func BenchmarkByteAtBrandNew(b *testing.B) {
bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC")
for i := 0; i < b.N; i++ {
bigEndianByteAt(bigint, 15)
}
}
func BenchmarkByteAt(b *testing.B) {
bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC")
for i := 0; i < b.N; i++ {
bigEndianByteAt(bigint, 15)
}
}
func BenchmarkByteAtOld(b *testing.B) {
bigint := MustParseBig256("0x18F8F8F1000111000110011100222004330052300000000000000000FEFCF3CC")
for i := 0; i < b.N; i++ {
PaddedBigBytes(bigint, 32)
}
@ -174,6 +212,65 @@ func TestU256(t *testing.T) {
}
}
func TestBigEndianByteAt(t *testing.T) {
tests := []struct {
x string
y int
exp byte
}{
{"00", 0, 0x00},
{"01", 1, 0x00},
{"00", 1, 0x00},
{"01", 0, 0x01},
{"0000000000000000000000000000000000000000000000000000000000102030", 0, 0x30},
{"0000000000000000000000000000000000000000000000000000000000102030", 1, 0x20},
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 31, 0xAB},
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 32, 0x00},
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 500, 0x00},
}
for _, test := range tests {
v := new(big.Int).SetBytes(common.Hex2Bytes(test.x))
actual := bigEndianByteAt(v, test.y)
if actual != test.exp {
t.Fatalf("Expected [%v] %v:th byte to be %v, was %v.", test.x, test.y, test.exp, actual)
}
}
}
func TestLittleEndianByteAt(t *testing.T) {
tests := []struct {
x string
y int
exp byte
}{
{"00", 0, 0x00},
{"01", 1, 0x00},
{"00", 1, 0x00},
{"01", 0, 0x00},
{"0000000000000000000000000000000000000000000000000000000000102030", 0, 0x00},
{"0000000000000000000000000000000000000000000000000000000000102030", 1, 0x00},
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 31, 0x00},
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 32, 0x00},
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 0, 0xAB},
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 1, 0xCD},
{"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 0, 0x00},
{"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 1, 0xCD},
{"0000000000000000000000000000000000000000000000000000000000102030", 31, 0x30},
{"0000000000000000000000000000000000000000000000000000000000102030", 30, 0x20},
{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 32, 0x0},
{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 31, 0xFF},
{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 0xFFFF, 0x0},
}
for _, test := range tests {
v := new(big.Int).SetBytes(common.Hex2Bytes(test.x))
actual := Byte(v, 32, test.y)
if actual != test.exp {
t.Fatalf("Expected [%v] %v:th byte to be %v, was %v.", test.x, test.y, test.exp, actual)
}
}
}
func TestS256(t *testing.T) {
tests := []struct{ x, y *big.Int }{
{x: big.NewInt(0), y: big.NewInt(0)},

13
core/vm/instructions.go
View File

@ -256,15 +256,14 @@ func opXor(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stac
}
func opByte(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
th, val := stack.pop(), stack.pop()
if th.Cmp(big.NewInt(32)) < 0 {
byte := evm.interpreter.intPool.get().SetInt64(int64(math.PaddedBigBytes(val, 32)[th.Int64()]))
stack.push(byte)
th, val := stack.pop(), stack.peek()
if th.Cmp(common.Big32) < 0 {
b := math.Byte(val, 32, int(th.Int64()))
val.SetUint64(uint64(b))
} else {
stack.push(new(big.Int))
val.SetUint64(0)
}
evm.interpreter.intPool.put(th, val)
evm.interpreter.intPool.put(th)
return nil, nil
}
func opAddmod(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {

42
core/vm/instructions_test.go Normal file
View File

@ -0,0 +1,42 @@
package vm
import (
"math/big"
"testing"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/params"
)
func TestByteOp(t *testing.T) {
var (
env = NewEVM(Context{}, nil, params.TestChainConfig, Config{EnableJit: false, ForceJit: false})
stack = newstack()
)
tests := []struct {
v string
th uint64
expected *big.Int
}{
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 0, big.NewInt(0xAB)},
{"ABCDEF0908070605040302010000000000000000000000000000000000000000", 1, big.NewInt(0xCD)},
{"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 0, big.NewInt(0x00)},
{"00CDEF090807060504030201ffffffffffffffffffffffffffffffffffffffff", 1, big.NewInt(0xCD)},
{"0000000000000000000000000000000000000000000000000000000000102030", 31, big.NewInt(0x30)},
{"0000000000000000000000000000000000000000000000000000000000102030", 30, big.NewInt(0x20)},
{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 32, big.NewInt(0x0)},
{"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 0xFFFFFFFFFFFFFFFF, big.NewInt(0x0)},
}
pc := uint64(0)
for _, test := range tests {
val := new(big.Int).SetBytes(common.Hex2Bytes(test.v))
th := new(big.Int).SetUint64(test.th)
stack.push(val)
stack.push(th)
opByte(&pc, env, nil, nil, stack)
actual := stack.pop()
if actual.Cmp(test.expected) != 0 {
t.Fatalf("Expected [%v] %v:th byte to be %v, was %v.", test.v, test.th, test.expected, actual)
}
}
}