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core, params: polish net gas metering PR a bit

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This commit is contained in:
Péter Szilágyi
2018-09-18 16:24:35 +03:00
parent caa2c23a38
commit 5d921fa3a0
11 changed files with 167 additions and 228 deletions
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121
core/vm/gas_table.go
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@ -116,79 +116,70 @@ func gasReturnDataCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *
}
func gasSStore(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var (
y, x = stack.Back(1), stack.Back(0)
val = evm.StateDB.GetState(contract.Address(), common.BigToHash(x))
)
// This checks for 3 scenario's and calculates gas accordingly
// 1. From a zero-value address to a non-zero value (NEW VALUE)
// 2. From a non-zero value address to a zero-value address (DELETE)
// 3. From a non-zero to a non-zero (CHANGE)
if val == (common.Hash{}) && y.Sign() != 0 {
// 0 => non 0
return params.SstoreSetGas, nil
} else if val != (common.Hash{}) && y.Sign() == 0 {
// non 0 => 0
evm.StateDB.AddRefund(params.SstoreRefundGas)
return params.SstoreClearGas, nil
} else {
// non 0 => non 0 (or 0 => 0)
return params.SstoreResetGas, nil
}
}
// gasSStoreEip1283 calculates SSTORE gas cost according to EIP-1283
func gasSStoreEip1283(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var (
y, x = stack.Back(1), stack.Back(0)
current = evm.StateDB.GetState(contract.Address(), common.BigToHash(x))
)
//1. If current value equals new value (this is a no-op), 200 gas is deducted.
//2. If current value does not equal new value
// 2.1 If original value equals current value (this storage slot has not been changed by the current execution context)
// 2.1.1 If original value is 0, 20000 gas is deducted.
// 2.1.2 Otherwise, 5000 gas is deducted. If new value is 0, add 15000 gas to refund counter.
// 2.2 If original value does not equal current value (this storage slot is dirty), 200 gas is deducted. Apply both of the following clauses.
// 2.2.1 If original value is not 0
// 2.2.1.1 If current value is 0 (also means that new value is not 0), remove 15000 gas from refund counter. We can prove that refund counter will never go below 0.
// 2.2.1.2 If new value is 0 (also means that current value is not 0), add 15000 gas to refund counter.
// 2.2.2 If original value equals new value (this storage slot is reset)
// 2.2.2.1 If original value is 0, add 19800 gas to refund counter.
// 2.2.2.2 Otherwise, add 4800 gas to refund counter.
new := common.BigToHash(y)
if current == new {
// 1. current == new
return 200, nil
}
original := evm.StateDB.GetStateOriginal(contract.Address(), common.BigToHash(x))
// 2
if original == current { // 2.1
if original == (common.Hash{}) { // 2.1.1
return 20000, nil
}
// 2.1.2
if new == (common.Hash{}) {
evm.StateDB.AddRefund(15000)
}
return 5000, nil
}
// 2.2
if original != (common.Hash{}) { // 2.2.1
if current == (common.Hash{}) { // 2.2.1.1
evm.StateDB.SubRefund(15000)
} else {
// 2.2.1.2
evm.StateDB.AddRefund(15000)
// The legacy gas metering only takes into consideration the current state
if !evm.chainRules.IsConstantinople {
// This checks for 3 scenario's and calculates gas accordingly:
//
// 1. From a zero-value address to a non-zero value (NEW VALUE)
// 2. From a non-zero value address to a zero-value address (DELETE)
// 3. From a non-zero to a non-zero (CHANGE)
switch {
case current == (common.Hash{}) && y.Sign() != 0: // 0 => non 0
return params.SstoreSetGas, nil
case current != (common.Hash{}) && y.Sign() == 0: // non 0 => 0
evm.StateDB.AddRefund(params.SstoreRefundGas)
return params.SstoreClearGas, nil
default: // non 0 => non 0 (or 0 => 0)
return params.SstoreResetGas, nil
}
}
if original == new { // 2.2.2
if original == (common.Hash{}) {
evm.StateDB.AddRefund(19800)
} else {
evm.StateDB.AddRefund(4800)
// The new gas metering is based on net gas costs (EIP-1283):
//
// 1. If current value equals new value (this is a no-op), 200 gas is deducted.
// 2. If current value does not equal new value
// 2.1. If original value equals current value (this storage slot has not been changed by the current execution context)
// 2.1.1. If original value is 0, 20000 gas is deducted.
// 2.1.2. Otherwise, 5000 gas is deducted. If new value is 0, add 15000 gas to refund counter.
// 2.2. If original value does not equal current value (this storage slot is dirty), 200 gas is deducted. Apply both of the following clauses.
// 2.2.1. If original value is not 0
// 2.2.1.1. If current value is 0 (also means that new value is not 0), remove 15000 gas from refund counter. We can prove that refund counter will never go below 0.
// 2.2.1.2. If new value is 0 (also means that current value is not 0), add 15000 gas to refund counter.
// 2.2.2. If original value equals new value (this storage slot is reset)
// 2.2.2.1. If original value is 0, add 19800 gas to refund counter.
// 2.2.2.2. Otherwise, add 4800 gas to refund counter.
value := common.BigToHash(y)
if current == value { // noop (1)
return params.NetSstoreNoopGas, nil
}
original := evm.StateDB.GetCommittedState(contract.Address(), common.BigToHash(x))
if original == current {
if original == (common.Hash{}) { // create slot (2.1.1)
return params.NetSstoreInitGas, nil
}
if value == (common.Hash{}) { // delete slot (2.1.2b)
evm.StateDB.AddRefund(params.NetSstoreClearRefund)
}
return params.NetSstoreCleanGas, nil // write existing slot (2.1.2)
}
if original != (common.Hash{}) {
if current == (common.Hash{}) { // recreate slot (2.2.1.1)
evm.StateDB.SubRefund(params.NetSstoreClearRefund)
} else if value == (common.Hash{}) { // delete slot (2.2.1.2)
evm.StateDB.AddRefund(params.NetSstoreClearRefund)
}
}
return 200, nil
if original == value {
if original == (common.Hash{}) { // reset to original inexistent slot (2.2.2.1)
evm.StateDB.AddRefund(params.NetSstoreResetClearRefund)
} else { // reset to original existing slot (2.2.2.2)
evm.StateDB.AddRefund(params.NetSstoreResetRefund)
}
}
return params.NetSstoreDirtyGas, nil
}
func makeGasLog(n uint64) gasFunc {