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Refactor gas calculation constants in contracts.go

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Felix Lange 2025-09-04 15:52:12 +02:00 committed by GitHub
parent 632428cd40
commit 8abe391fa7
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1 changed files with 29 additions and 27 deletions
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56
core/vm/contracts.go
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@ -380,21 +380,7 @@ type bigModExp struct {
eip7883 bool eip7883 bool
} }
// Constants for modexp gas calculation // byzantiumMultComplexity implements the bigModexp multComplexity formula, as defined in EIP-198.
const (
byzantiumMultiplier = 8
berlinMultiplier = 8
osakaMultiplier = 16
byzantiumDivisor = 20
berlinDivisor = 3
osakaDivisor = 3
berlinMinGas = 200
osakaMinGas = 500
)
// byzantiumMultComplexity implements bigModexp multComplexity formula, as defined in EIP-198
// //
// def mult_complexity(x): // def mult_complexity(x):
// if x <= 64: return x ** 2 // if x <= 64: return x ** 2
@ -402,7 +388,7 @@ const (
// else: return x ** 2 // 16 + 480 * x - 199680 // else: return x ** 2 // 16 + 480 * x - 199680
// //
// where is x is max(length_of_MODULUS, length_of_BASE) // where is x is max(length_of_MODULUS, length_of_BASE)
// returns true if an overflow occurred. // returns MaxUint64 if an overflow occurred.
func byzantiumMultComplexity(x uint64) uint64 { func byzantiumMultComplexity(x uint64) uint64 {
switch { switch {
case x <= 64: case x <= 64:
@ -419,7 +405,7 @@ func byzantiumMultComplexity(x uint64) uint64 {
return math.MaxUint64 return math.MaxUint64
} }
// Calculate x^2 / 16 (right shift by 4 bits) // Calculate x^2 / 16
xSqr = xSqr >> 4 xSqr = xSqr >> 4
// Calculate 480 * x (can't overflow if x^2 didn't overflow) // Calculate 480 * x (can't overflow if x^2 didn't overflow)
@ -450,7 +436,8 @@ func berlinMultComplexity(x uint64) uint64 {
return math.MaxUint64 return math.MaxUint64
} }
x /= 8 x /= 8
// x * x
// x^2
carry, x = bits.Mul64(x, x) carry, x = bits.Mul64(x, x)
if carry != 0 { if carry != 0 {
return math.MaxUint64 return math.MaxUint64
@ -495,6 +482,11 @@ func calculateIterationCount(expLen uint64, expHead uint256.Int, multiplier uint
// byzantiumGasCalc calculates the gas cost for the modexp precompile using Byzantium rules. // byzantiumGasCalc calculates the gas cost for the modexp precompile using Byzantium rules.
func byzantiumGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint64 { func byzantiumGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint64 {
const (
multiplier = 8
divisor = 20
)
maxLen := max(baseLen, modLen) maxLen := max(baseLen, modLen)
multComplexity := byzantiumMultComplexity(maxLen) multComplexity := byzantiumMultComplexity(maxLen)
if multComplexity == math.MaxUint64 { if multComplexity == math.MaxUint64 {
@ -502,9 +494,9 @@ func byzantiumGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint6
} }
iterationCount := calculateIterationCount(expLen, expHead, byzantiumMultiplier) iterationCount := calculateIterationCount(expLen, expHead, byzantiumMultiplier)
// Calculate gas: (multComplexity * iterationCount) / byzantiumDivisor // Calculate gas: (multComplexity * iterationCount) / divisor
carry, gas := bits.Mul64(iterationCount, multComplexity) carry, gas := bits.Mul64(iterationCount, multComplexity)
gas /= byzantiumDivisor gas /= divisor
if carry != 0 { if carry != 0 {
return math.MaxUint64 return math.MaxUint64
} }
@ -513,25 +505,36 @@ func byzantiumGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint6
// berlinGasCalc calculates the gas cost for the modexp precompile using Berlin rules. // berlinGasCalc calculates the gas cost for the modexp precompile using Berlin rules.
func berlinGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint64 { func berlinGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint64 {
const (
multiplier = 8
divisor = 3
minGas = 200
)
maxLen := max(baseLen, modLen) maxLen := max(baseLen, modLen)
multComplexity := berlinMultComplexity(maxLen) multComplexity := berlinMultComplexity(maxLen)
if multComplexity == math.MaxUint64 { if multComplexity == math.MaxUint64 {
return math.MaxUint64 return math.MaxUint64
} }
iterationCount := calculateIterationCount(expLen, expHead, berlinMultiplier) iterationCount := calculateIterationCount(expLen, expHead, multiplier)
// Calculate gas: (multComplexity * iterationCount) / berlinDivisor // Calculate gas: (multComplexity * iterationCount) / divisor
carry, gas := bits.Mul64(iterationCount, multComplexity) carry, gas := bits.Mul64(iterationCount, multComplexity)
gas /= berlinDivisor gas /= divisor
if carry != 0 { if carry != 0 {
return math.MaxUint64 return math.MaxUint64
} }
return max(gas, minGas)
return max(gas, berlinMinGas)
} }
// osakaGasCalc calculates the gas cost for the modexp precompile using Osaka rules. // osakaGasCalc calculates the gas cost for the modexp precompile using Osaka rules.
func osakaGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint64 { func osakaGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint64 {
const (
multiplier = 16
divisor = 3
minGas = 500
)
maxLen := max(baseLen, modLen) maxLen := max(baseLen, modLen)
multComplexity := osakaMultComplexity(maxLen) multComplexity := osakaMultComplexity(maxLen)
if multComplexity == math.MaxUint64 { if multComplexity == math.MaxUint64 {
@ -544,8 +547,7 @@ func osakaGasCalc(baseLen, expLen, modLen uint64, expHead uint256.Int) uint64 {
if carry != 0 { if carry != 0 {
return math.MaxUint64 return math.MaxUint64
} }
return max(gas, minGas)
return max(gas, osakaMinGas)
} }
// RequiredGas returns the gas required to execute the pre-compiled contract. // RequiredGas returns the gas required to execute the pre-compiled contract.