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https://github.com/ethereum/go-ethereum.git
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commit
This commit is contained in:
Kevaundray Wedderburn
parent
355228b011
commit
23b254c892
1 changed files with 188 additions and 78 deletions
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@ -360,6 +360,20 @@ type bigModExp struct {
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eip7883 bool
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}
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// Constants for modexp gas calculation
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const (
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byzantiumMultiplier = 8
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berlinMultiplier = 8
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osakaMultiplier = 16
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byzantiumDivisor = 20
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berlinDivisor = 3
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osakaDivisor = 3
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berlinMinGas = 200
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osakaMinGas = 500
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)
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var (
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big1 = big.NewInt(1)
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big3 = big.NewInt(3)
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@ -374,7 +388,7 @@ var (
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big199680 = big.NewInt(199680)
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)
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// modexpMultComplexity implements bigModexp multComplexity formula, as defined in EIP-198
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// byzantiumMultComplexity implements bigModexp multComplexity formula, as defined in EIP-198
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//
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// def mult_complexity(x):
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// if x <= 64: return x ** 2
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@ -382,7 +396,7 @@ var (
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// else: return x ** 2 // 16 + 480 * x - 199680
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//
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// where is x is max(length_of_MODULUS, length_of_BASE)
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func modexpMultComplexity(x *big.Int) *big.Int {
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func byzantiumMultComplexity(x *big.Int) *big.Int {
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switch {
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case x.Cmp(big64) <= 0:
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x.Mul(x, x) // x ** 2
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@ -402,98 +416,194 @@ func modexpMultComplexity(x *big.Int) *big.Int {
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return x
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}
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// berlinMultComplexity implements the multiplication complexity formula for Berlin.
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//
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// def mult_complexity(x):
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//
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// ceiling(x/8)^2
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//
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// where is x is max(length_of_MODULUS, length_of_BASE)
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func berlinMultComplexity(x *big.Int) *big.Int {
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x = new(big.Int).Add(x, big7) // x + 7
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x = new(big.Int).Rsh(x, 3) // (x + 7) / 8
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return new(big.Int).Mul(x, x) // ((x + 7) / 8) ^ 2
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}
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// osakaMultComplexity implements the multiplication complexity formula for Osaka.
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//
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// For x <= 32: returns 16
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// For x > 32: returns 2 * ceiling(x/8)^2
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func osakaMultComplexity(x *big.Int) *big.Int {
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if x.Cmp(big32) <= 0 {
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return big.NewInt(16)
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}
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// For x > 32, return 2 * berlinMultComplexity(x)
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berlinComplexity := berlinMultComplexity(x)
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return new(big.Int).Lsh(berlinComplexity, 1) // 2 * berlinComplexity
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}
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// calculateIterationCount calculates the number of iterations for the modexp precompile.
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// This is the adjusted exponent length used in gas calculation.
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func calculateIterationCount(expLen uint64, expHead *big.Int, multiplier uint64) uint64 {
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var iterationCount uint64
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if expLen <= 32 && expHead.Sign() == 0 {
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iterationCount = 0
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} else if expLen <= 32 {
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// For small exponents, use MSB position - 1
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if bitLen := expHead.BitLen(); bitLen > 0 {
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iterationCount = uint64(bitLen - 1)
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}
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} else {
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// For large exponents: (expLen - 32) * multiplier + MSB position - 1
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iterationCount = (expLen - 32) * multiplier
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if bitLen := expHead.BitLen(); bitLen > 0 {
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iterationCount += uint64(bitLen - 1)
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}
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}
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// Return at least 1
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if iterationCount == 0 {
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return 1
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}
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return iterationCount
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}
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// byzantiumGasCalc calculates the gas cost for the modexp precompile using Byzantium rules.
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func byzantiumGasCalc(baseLen, expLen, modLen uint64, expHead *big.Int) uint64 {
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// Calculate max(baseLen, modLen)
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maxLen := baseLen
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if modLen > maxLen {
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maxLen = modLen
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}
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// Calculate multiplication complexity
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// Use SetUint64 to avoid int64 overflow
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multComplexity := byzantiumMultComplexity(new(big.Int).SetUint64(maxLen))
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// Calculate iteration count
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iterationCount := calculateIterationCount(expLen, expHead, byzantiumMultiplier)
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// Calculate gas: (multComplexity * iterationCount) / byzantiumDivisor
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gas := new(big.Int).Mul(multComplexity, new(big.Int).SetUint64(iterationCount))
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gas.Div(gas, big.NewInt(byzantiumDivisor))
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if gas.BitLen() > 64 {
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return math.MaxUint64
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}
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return gas.Uint64()
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}
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// berlinGasCalc calculates the gas cost for the modexp precompile using Berlin rules.
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func berlinGasCalc(baseLen, expLen, modLen uint64, expHead *big.Int) uint64 {
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// Calculate max(baseLen, modLen)
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maxLen := baseLen
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if modLen > maxLen {
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maxLen = modLen
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}
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// Calculate multiplication complexity
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// Use SetUint64 to avoid int64 overflow
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multComplexity := berlinMultComplexity(new(big.Int).SetUint64(maxLen))
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// Calculate iteration count
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iterationCount := calculateIterationCount(expLen, expHead, berlinMultiplier)
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// Calculate gas: (multComplexity * iterationCount) / berlinDivisor
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gas := new(big.Int).Mul(multComplexity, new(big.Int).SetUint64(iterationCount))
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gas.Div(gas, big.NewInt(berlinDivisor))
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if gas.BitLen() > 64 {
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return math.MaxUint64
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}
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// Return at least berlinMinGas
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gasUint64 := gas.Uint64()
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if gasUint64 < berlinMinGas {
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return berlinMinGas
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}
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return gasUint64
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}
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// osakaGasCalc calculates the gas cost for the modexp precompile using Osaka rules.
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func osakaGasCalc(baseLen, expLen, modLen uint64, expHead *big.Int) uint64 {
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// Calculate max(baseLen, modLen)
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maxLen := baseLen
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if modLen > maxLen {
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maxLen = modLen
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}
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// Calculate multiplication complexity
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// Use SetUint64 to avoid int64 overflow
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multComplexity := osakaMultComplexity(new(big.Int).SetUint64(maxLen))
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// Calculate iteration count
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iterationCount := calculateIterationCount(expLen, expHead, osakaMultiplier)
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// Calculate gas: (multComplexity * iterationCount) / osakaDivisor
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gas := new(big.Int).Mul(multComplexity, new(big.Int).SetUint64(iterationCount))
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gas.Div(gas, big.NewInt(osakaDivisor))
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if gas.BitLen() > 64 {
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return math.MaxUint64
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}
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// Return at least osakaMinGas
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gasUint64 := gas.Uint64()
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if gasUint64 < osakaMinGas {
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return osakaMinGas
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}
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return gasUint64
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}
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// RequiredGas returns the gas required to execute the pre-compiled contract.
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func (c *bigModExp) RequiredGas(input []byte) uint64 {
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var (
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baseLen = new(big.Int).SetBytes(getData(input, 0, 32))
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expLen = new(big.Int).SetBytes(getData(input, 32, 32))
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modLen = new(big.Int).SetBytes(getData(input, 64, 32))
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)
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// Parse input lengths
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baseLenBig := new(big.Int).SetBytes(getData(input, 0, 32))
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expLenBig := new(big.Int).SetBytes(getData(input, 32, 32))
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modLenBig := new(big.Int).SetBytes(getData(input, 64, 32))
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// Convert to uint64, capping at max value
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baseLen := baseLenBig.Uint64()
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if baseLenBig.BitLen() > 64 {
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baseLen = math.MaxUint64
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}
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expLen := expLenBig.Uint64()
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if expLenBig.BitLen() > 64 {
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expLen = math.MaxUint64
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}
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modLen := modLenBig.Uint64()
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if modLenBig.BitLen() > 64 {
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modLen = math.MaxUint64
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}
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// Skip the header
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if len(input) > 96 {
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input = input[96:]
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} else {
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input = input[:0]
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}
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// Retrieve the head 32 bytes of exp for the adjusted exponent length
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var expHead *big.Int
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if big.NewInt(int64(len(input))).Cmp(baseLen) <= 0 {
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if uint64(len(input)) <= baseLen {
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expHead = new(big.Int)
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} else {
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if expLen.Cmp(big32) > 0 {
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expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), 32))
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if expLen > 32 {
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expHead = new(big.Int).SetBytes(getData(input, baseLen, 32))
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} else {
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expHead = new(big.Int).SetBytes(getData(input, baseLen.Uint64(), expLen.Uint64()))
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expHead = new(big.Int).SetBytes(getData(input, baseLen, expLen))
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}
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}
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// Calculate the adjusted exponent length
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var msb int
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if bitlen := expHead.BitLen(); bitlen > 0 {
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msb = bitlen - 1
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}
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adjExpLen := new(big.Int)
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if expLen.Cmp(big32) > 0 {
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adjExpLen.Sub(expLen, big32)
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if c.eip7883 {
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adjExpLen.Lsh(adjExpLen, 4)
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} else {
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adjExpLen.Lsh(adjExpLen, 3)
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}
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}
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adjExpLen.Add(adjExpLen, big.NewInt(int64(msb)))
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// Calculate the gas cost of the operation
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gas := new(big.Int)
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if modLen.Cmp(baseLen) < 0 {
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gas.Set(baseLen)
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// Choose the appropriate gas calculation based on the EIP flags
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if c.eip7883 {
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return osakaGasCalc(baseLen, expLen, modLen, expHead)
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} else if c.eip2565 {
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return berlinGasCalc(baseLen, expLen, modLen, expHead)
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} else {
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gas.Set(modLen)
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return byzantiumGasCalc(baseLen, expLen, modLen, expHead)
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}
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maxLenOver32 := gas.Cmp(big32) > 0
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if c.eip2565 {
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// EIP-2565 (Berlin fork) has three changes:
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//
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// 1. Different multComplexity (inlined here)
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// in EIP-2565 (https://eips.ethereum.org/EIPS/eip-2565):
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//
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// def mult_complexity(x):
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// ceiling(x/8)^2
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//
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// where is x is max(length_of_MODULUS, length_of_BASE)
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gas.Add(gas, big7)
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gas.Rsh(gas, 3)
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gas.Mul(gas, gas)
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var minPrice uint64 = 200
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if c.eip7883 {
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minPrice = 500
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if maxLenOver32 {
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gas.Add(gas, gas)
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} else {
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gas = big.NewInt(16)
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}
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}
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if adjExpLen.Cmp(big1) > 0 {
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gas.Mul(gas, adjExpLen)
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}
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// 2. Different divisor (`GQUADDIVISOR`) (3)
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gas.Div(gas, big3)
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if gas.BitLen() > 64 {
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return math.MaxUint64
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}
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return max(minPrice, gas.Uint64())
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}
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// Pre-Berlin logic.
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gas = modexpMultComplexity(gas)
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if adjExpLen.Cmp(big1) > 0 {
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gas.Mul(gas, adjExpLen)
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}
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gas.Div(gas, big20)
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if gas.BitLen() > 64 {
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return math.MaxUint64
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}
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return gas.Uint64()
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}
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func (c *bigModExp) Run(input []byte) ([]byte, error) {
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