diff options
Diffstat (limited to 'core/vm/gas_table.go')
| -rw-r--r-- | core/vm/gas_table.go | 117 |
1 files changed, 54 insertions, 63 deletions
diff --git a/core/vm/gas_table.go b/core/vm/gas_table.go index 77250978d..10b4f719a 100644 --- a/core/vm/gas_table.go +++ b/core/vm/gas_table.go @@ -117,78 +117,69 @@ 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 + // 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 + } + } + // 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 } - // 2.1.2 - if new == (common.Hash{}) { - evm.StateDB.AddRefund(15000) + if value == (common.Hash{}) { // delete slot (2.1.2b) + evm.StateDB.AddRefund(params.NetSstoreClearRefund) } - 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) + 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) } } - if original == new { // 2.2.2 - if original == (common.Hash{}) { - evm.StateDB.AddRefund(19800) - } else { - evm.StateDB.AddRefund(4800) + 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 200, nil + return params.NetSstoreDirtyGas, nil } func makeGasLog(n uint64) gasFunc { |