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core/vm: optimize copy-less data retrievals

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This commit is contained in:
Péter Szilágyi 2017-08-14 17:08:49 +03:00
parent d8aaa3a215
commit f8d8b56b28
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GPG Key ID: E9AE538CEDF8293D
4 changed files with 75 additions and 54 deletions
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16
core/vm/common.go
View File

@ -34,7 +34,21 @@ func calcMemSize(off, l *big.Int) *big.Int {
// getData returns a slice from the data based on the start and size and pads
// up to size with zero's. This function is overflow safe.
func getData(data []byte, start, size *big.Int) []byte {
func getData(data []byte, start uint64, size uint64) []byte {
length := uint64(len(data))
if start > length {
start = length
}
end := start + size
if end > length {
end = length
}
return common.RightPadBytes(data[start:end], int(size))
}
// getDataBig returns a slice from the data based on the start and size and pads
// up to size with zero's. This function is overflow safe.
func getDataBig(data []byte, start *big.Int, size *big.Int) []byte {
dlen := big.NewInt(int64(len(data)))
s := math.BigMin(start, dlen)

99
core/vm/contracts.go
View File

@ -149,30 +149,41 @@ func (c *dataCopy) Run(in []byte) ([]byte, error) {
// bigModExp implements a native big integer exponential modular operation.
type bigModExp struct{}
var (
big1 = big.NewInt(1)
big4 = big.NewInt(4)
big8 = big.NewInt(8)
big16 = big.NewInt(16)
big32 = big.NewInt(32)
big64 = big.NewInt(64)
big96 = big.NewInt(96)
big480 = big.NewInt(480)
big1024 = big.NewInt(1024)
big3072 = big.NewInt(3072)
big199680 = big.NewInt(199680)
)
// RequiredGas returns the gas required to execute the pre-compiled contract.
func (c *bigModExp) RequiredGas(input []byte) uint64 {
// Pad the input with zeroes to the minimum size to read the field lengths
input = common.RightPadBytes(input, 96)
var (
baseLen = new(big.Int).SetBytes(input[:32])
expLen = new(big.Int).SetBytes(input[32:64])
modLen = new(big.Int).SetBytes(input[64:96])
baseLen = new(big.Int).SetBytes(getData(input, 0, 32))
expLen = new(big.Int).SetBytes(getData(input, 32, 32))
modLen = new(big.Int).SetBytes(getData(input, 64, 32))
)
if len(input) > 96 {
input = input[96:]
} else {
input = input[:0]
}
// Retrieve the head 32 bytes of exp for the adjusted exponent length
var expHead *big.Int
if big.NewInt(int64(len(input))).Cmp(baseLen) <= 0 {
expHead = new(big.Int)
} else {
offset := int(baseLen.Uint64())
input = common.RightPadBytes(input, offset+32)
if expLen.Cmp(big.NewInt(32)) > 0 {
expHead = new(big.Int).SetBytes(input[offset : offset+32])
if expLen.Cmp(big32) > 0 {
expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), 32))
} else {
expHead = new(big.Int).SetBytes(input[offset : offset+int(expLen.Uint64())])
expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), expLen.Uint64()))
}
}
// Calculate the adjusted exponent length
@ -181,29 +192,29 @@ func (c *bigModExp) RequiredGas(input []byte) uint64 {
msb = bitlen - 1
}
adjExpLen := new(big.Int)
if expLen.Cmp(big.NewInt(32)) > 0 {
adjExpLen.Sub(expLen, big.NewInt(32))
adjExpLen.Mul(big.NewInt(8), adjExpLen)
if expLen.Cmp(big32) > 0 {
adjExpLen.Sub(expLen, big32)
adjExpLen.Mul(big8, adjExpLen)
}
adjExpLen.Add(adjExpLen, big.NewInt(int64(msb)))
// Calculate the gas cost of the operation
gas := new(big.Int).Set(math.BigMax(modLen, baseLen))
switch {
case gas.Cmp(big.NewInt(64)) <= 0:
case gas.Cmp(big64) <= 0:
gas.Mul(gas, gas)
case gas.Cmp(big.NewInt(1024)) <= 0:
case gas.Cmp(big1024) <= 0:
gas = new(big.Int).Add(
new(big.Int).Div(new(big.Int).Mul(gas, gas), big.NewInt(4)),
new(big.Int).Sub(new(big.Int).Mul(big.NewInt(96), gas), big.NewInt(3072)),
new(big.Int).Div(new(big.Int).Mul(gas, gas), big4),
new(big.Int).Sub(new(big.Int).Mul(big96, gas), big3072),
)
default:
gas = new(big.Int).Add(
new(big.Int).Div(new(big.Int).Mul(gas, gas), big.NewInt(16)),
new(big.Int).Sub(new(big.Int).Mul(big.NewInt(480), gas), big.NewInt(199680)),
new(big.Int).Div(new(big.Int).Mul(gas, gas), big16),
new(big.Int).Sub(new(big.Int).Mul(big480, gas), big199680),
)
}
gas.Mul(gas, math.BigMax(adjExpLen, big.NewInt(1)))
gas.Mul(gas, math.BigMax(adjExpLen, big1))
gas.Div(gas, new(big.Int).SetUint64(params.ModExpQuadCoeffDiv))
if gas.BitLen() > 64 {
@ -213,23 +224,25 @@ func (c *bigModExp) RequiredGas(input []byte) uint64 {
}
func (c *bigModExp) Run(input []byte) ([]byte, error) {
// Pad the input with zeroes to the minimum size to read the field lengths
input = common.RightPadBytes(input, 96)
var (
baseLen = new(big.Int).SetBytes(input[:32]).Uint64()
expLen = new(big.Int).SetBytes(input[32:64]).Uint64()
modLen = new(big.Int).SetBytes(input[64:96]).Uint64()
baseLen = new(big.Int).SetBytes(getData(input, 0, 32)).Uint64()
expLen = new(big.Int).SetBytes(getData(input, 32, 32)).Uint64()
modLen = new(big.Int).SetBytes(getData(input, 64, 32)).Uint64()
)
if len(input) > 96 {
input = input[96:]
// Pad the input with zeroes to the minimum size to read the field contents
input = common.RightPadBytes(input, int(baseLen+expLen+modLen))
} else {
input = input[:0]
}
// Handle a special case when both the base and mod length is zero
if baseLen == 0 && modLen == 0 {
return []byte{}, nil
}
// Retrieve the operands and execute the exponentiation
var (
base = new(big.Int).SetBytes(input[:baseLen])
exp = new(big.Int).SetBytes(input[baseLen : baseLen+expLen])
mod = new(big.Int).SetBytes(input[baseLen+expLen : baseLen+expLen+modLen])
base = new(big.Int).SetBytes(getData(input, 0, baseLen))
exp = new(big.Int).SetBytes(getData(input, baseLen, expLen))
mod = new(big.Int).SetBytes(getData(input, baseLen+expLen, modLen))
)
if mod.BitLen() == 0 {
// Modulo 0 is undefined, return zero
@ -286,14 +299,11 @@ func (c *bn256Add) RequiredGas(input []byte) uint64 {
}
func (c *bn256Add) Run(input []byte) ([]byte, error) {
// Ensure we have enough data to operate on
input = common.RightPadBytes(input, 128)
x, err := newCurvePoint(input[:64])
x, err := newCurvePoint(getData(input, 0, 64))
if err != nil {
return nil, err
}
y, err := newCurvePoint(input[64:128])
y, err := newCurvePoint(getData(input, 64, 64))
if err != nil {
return nil, err
}
@ -310,14 +320,11 @@ func (c *bn256ScalarMul) RequiredGas(input []byte) uint64 {
}
func (c *bn256ScalarMul) Run(input []byte) ([]byte, error) {
// Ensure we have enough data to operate on
input = common.RightPadBytes(input, 96)
p, err := newCurvePoint(input[:64])
p, err := newCurvePoint(getData(input, 0, 64))
if err != nil {
return nil, err
}
p.ScalarMult(p, new(big.Int).SetBytes(input[64:96]))
p.ScalarMult(p, new(big.Int).SetBytes(getData(input, 64, 32)))
return p.Marshal(), nil
}

2
core/vm/contracts_test.go
View File

@ -325,7 +325,7 @@ func TestPrecompiledBn256Pairing(t *testing.T) {
}
// Behcnmarks the sample inputs from the elliptic curve pairing check EIP 197.
func BenchmarkPrecompiledPairing(bench *testing.B) {
func BenchmarkPrecompiledBn256Pairing(bench *testing.B) {
for _, test := range bn256PairingTests {
benchmarkPrecompiled("08", test, bench)
}

8
core/vm/instructions.go
View File

@ -337,7 +337,7 @@ func opCallValue(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack
}
func opCalldataLoad(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
stack.push(new(big.Int).SetBytes(getData(contract.Input, stack.pop(), common.Big32)))
stack.push(new(big.Int).SetBytes(getDataBig(contract.Input, stack.pop(), big32)))
return nil, nil
}
@ -352,7 +352,7 @@ func opCalldataCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, st
cOff = stack.pop()
l = stack.pop()
)
memory.Set(mOff.Uint64(), l.Uint64(), getData(contract.Input, cOff, l))
memory.Set(mOff.Uint64(), l.Uint64(), getDataBig(contract.Input, cOff, l))
evm.interpreter.intPool.put(mOff, cOff, l)
return nil, nil
@ -380,7 +380,7 @@ func opCodeCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack
cOff = stack.pop()
l = stack.pop()
)
codeCopy := getData(contract.Code, cOff, l)
codeCopy := getDataBig(contract.Code, cOff, l)
memory.Set(mOff.Uint64(), l.Uint64(), codeCopy)
@ -395,7 +395,7 @@ func opExtCodeCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, sta
cOff = stack.pop()
l = stack.pop()
)
codeCopy := getData(evm.StateDB.GetCode(addr), cOff, l)
codeCopy := getDataBig(evm.StateDB.GetCode(addr), cOff, l)
memory.Set(mOff.Uint64(), l.Uint64(), codeCopy)