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remove a lot of allocations

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This commit is contained in:
Kevaundray Wedderburn 2025-07-10 22:18:05 +01:00
parent 23b254c892
commit 4bc38e05e7
1 changed files with 44 additions and 27 deletions
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71
core/vm/contracts.go
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@ -396,24 +396,34 @@ var (
// else: return x ** 2 // 16 + 480 * x - 199680
//
// where is x is max(length_of_MODULUS, length_of_BASE)
func byzantiumMultComplexity(x *big.Int) *big.Int {
func byzantiumMultComplexity(x uint64) *big.Int {
switch {
case x.Cmp(big64) <= 0:
x.Mul(x, x) // x ** 2
case x.Cmp(big1024) <= 0:
// (x ** 2 // 4 ) + ( 96 * x - 3072)
x = new(big.Int).Add(
new(big.Int).Rsh(new(big.Int).Mul(x, x), 2),
new(big.Int).Sub(new(big.Int).Mul(big96, x), big3072),
)
case x <= 64:
return new(big.Int).SetUint64(x * x)
case x <= 1024:
// x^2 / 4 + 96*x - 3072
result := x*x/4 + 96*x - 3072
return new(big.Int).SetUint64(result)
default:
// (x ** 2 // 16) + (480 * x - 199680)
x = new(big.Int).Add(
new(big.Int).Rsh(new(big.Int).Mul(x, x), 4),
new(big.Int).Sub(new(big.Int).Mul(big480, x), big199680),
)
// For large x, use big.Int arithmetic to avoid overflow
// x^2 / 16 + 480*x - 199680
xBig := new(big.Int).SetUint64(x)
// Calculate x^2
xSquared := new(big.Int).Mul(xBig, xBig)
// Calculate x^2 / 16 (right shift by 4 bits)
xSquaredDiv16 := new(big.Int).Rsh(xSquared, 4)
// Calculate 480 * x
x480 := new(big.Int).Mul(big480, xBig)
// Calculate 480 * x - 199680
x480Minus199680 := new(big.Int).Sub(x480, big199680)
// Add the two parts together
return new(big.Int).Add(xSquaredDiv16, x480Minus199680)
}
return x
}
// berlinMultComplexity implements the multiplication complexity formula for Berlin.
@ -423,18 +433,28 @@ func byzantiumMultComplexity(x *big.Int) *big.Int {
// ceiling(x/8)^2
//
// where is x is max(length_of_MODULUS, length_of_BASE)
func berlinMultComplexity(x *big.Int) *big.Int {
x = new(big.Int).Add(x, big7) // x + 7
x = new(big.Int).Rsh(x, 3) // (x + 7) / 8
return new(big.Int).Mul(x, x) // ((x + 7) / 8) ^ 2
func berlinMultComplexity(x uint64) *big.Int {
// TODO: The preceding line is too smart.
// TODO: The issue is that (x+7) / 8 can overflow
// TODO: if x > 2^64 - 7
ceilDiv8 := (x >> 3) + ((x&7 + 7) >> 3) // safe ceil(x / 8)
z := new(big.Int).SetUint64(ceilDiv8)
return new(big.Int).Mul(z, z) // square without overflow
}
// Slow Bigint way (benchmark this)
// func berlinMultComplexity(xInt uint64) *big.Int {
// x := new(big.Int).SetUint64(xInt)
// x = new(big.Int).Add(x, big7) // x + 7
// x = new(big.Int).Rsh(x, 3) // (x + 7) / 8
// return new(big.Int).Mul(x, x) // ((x + 7) / 8) ^ 2
// }
// osakaMultComplexity implements the multiplication complexity formula for Osaka.
//
// For x <= 32: returns 16
// For x > 32: returns 2 * ceiling(x/8)^2
func osakaMultComplexity(x *big.Int) *big.Int {
if x.Cmp(big32) <= 0 {
func osakaMultComplexity(x uint64) *big.Int {
if x <= 32 {
return big.NewInt(16)
}
// For x > 32, return 2 * berlinMultComplexity(x)
@ -478,8 +498,7 @@ func byzantiumGasCalc(baseLen, expLen, modLen uint64, expHead *big.Int) uint64 {
}
// Calculate multiplication complexity
// Use SetUint64 to avoid int64 overflow
multComplexity := byzantiumMultComplexity(new(big.Int).SetUint64(maxLen))
multComplexity := byzantiumMultComplexity(maxLen)
// Calculate iteration count
iterationCount := calculateIterationCount(expLen, expHead, byzantiumMultiplier)
@ -503,8 +522,7 @@ func berlinGasCalc(baseLen, expLen, modLen uint64, expHead *big.Int) uint64 {
}
// Calculate multiplication complexity
// Use SetUint64 to avoid int64 overflow
multComplexity := berlinMultComplexity(new(big.Int).SetUint64(maxLen))
multComplexity := berlinMultComplexity(maxLen)
// Calculate iteration count
iterationCount := calculateIterationCount(expLen, expHead, berlinMultiplier)
@ -534,8 +552,7 @@ func osakaGasCalc(baseLen, expLen, modLen uint64, expHead *big.Int) uint64 {
}
// Calculate multiplication complexity
// Use SetUint64 to avoid int64 overflow
multComplexity := osakaMultComplexity(new(big.Int).SetUint64(maxLen))
multComplexity := osakaMultComplexity(maxLen)
// Calculate iteration count
iterationCount := calculateIterationCount(expLen, expHead, osakaMultiplier)