223 lines
		
	
	
		
			9.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			223 lines
		
	
	
		
			9.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// Copyright 2020 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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	"errors"
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	"github.com/ethereum/go-ethereum/common"
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	"github.com/ethereum/go-ethereum/common/math"
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	"github.com/ethereum/go-ethereum/params"
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)
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const (
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	ColdAccountAccessCostEIP2929 = uint64(2600) // COLD_ACCOUNT_ACCESS_COST
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	ColdSloadCostEIP2929         = uint64(2100) // COLD_SLOAD_COST
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	WarmStorageReadCostEIP2929   = uint64(100)  // WARM_STORAGE_READ_COST
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)
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// gasSStoreEIP2929 implements gas cost for SSTORE according to EIP-2929"
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//
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// When calling SSTORE, check if the (address, storage_key) pair is in accessed_storage_keys.
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// If it is not, charge an additional COLD_SLOAD_COST gas, and add the pair to accessed_storage_keys.
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// Additionally, modify the parameters defined in EIP 2200 as follows:
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//
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// Parameter 	Old value 	New value
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// SLOAD_GAS 	800 	= WARM_STORAGE_READ_COST
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// SSTORE_RESET_GAS 	5000 	5000 - COLD_SLOAD_COST
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//
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//The other parameters defined in EIP 2200 are unchanged.
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// see gasSStoreEIP2200(...) in core/vm/gas_table.go for more info about how EIP 2200 is specified
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func gasSStoreEIP2929(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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	// If we fail the minimum gas availability invariant, fail (0)
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	if contract.Gas <= params.SstoreSentryGasEIP2200 {
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		return 0, errors.New("not enough gas for reentrancy sentry")
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	}
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	// Gas sentry honoured, do the actual gas calculation based on the stored value
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	var (
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		y, x    = stack.Back(1), stack.peek()
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		slot    = common.Hash(x.Bytes32())
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		current = evm.StateDB.GetState(contract.Address(), slot)
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		cost    = uint64(0)
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	)
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	// Check slot presence in the access list
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	if addrPresent, slotPresent := evm.StateDB.SlotInAccessList(contract.Address(), slot); !slotPresent {
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		cost = ColdSloadCostEIP2929
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		// If the caller cannot afford the cost, this change will be rolled back
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		evm.StateDB.AddSlotToAccessList(contract.Address(), slot)
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		if !addrPresent {
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			// Once we're done with YOLOv2 and schedule this for mainnet, might
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			// be good to remove this panic here, which is just really a
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			// canary to have during testing
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			panic("impossible case: address was not present in access list during sstore op")
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		}
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	}
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	value := common.Hash(y.Bytes32())
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	if current == value { // noop (1)
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		// EIP 2200 original clause:
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		//		return params.SloadGasEIP2200, nil
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		return cost + WarmStorageReadCostEIP2929, nil // SLOAD_GAS
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	}
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	original := evm.StateDB.GetCommittedState(contract.Address(), x.Bytes32())
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	if original == current {
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		if original == (common.Hash{}) { // create slot (2.1.1)
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			return cost + params.SstoreSetGasEIP2200, nil
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		}
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		if value == (common.Hash{}) { // delete slot (2.1.2b)
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			evm.StateDB.AddRefund(params.SstoreClearsScheduleRefundEIP2200)
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		}
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		// EIP-2200 original clause:
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		//		return params.SstoreResetGasEIP2200, nil // write existing slot (2.1.2)
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		return cost + (params.SstoreResetGasEIP2200 - ColdSloadCostEIP2929), nil // write existing slot (2.1.2)
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	}
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	if original != (common.Hash{}) {
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		if current == (common.Hash{}) { // recreate slot (2.2.1.1)
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			evm.StateDB.SubRefund(params.SstoreClearsScheduleRefundEIP2200)
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		} else if value == (common.Hash{}) { // delete slot (2.2.1.2)
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			evm.StateDB.AddRefund(params.SstoreClearsScheduleRefundEIP2200)
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		}
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	}
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	if original == value {
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		if original == (common.Hash{}) { // reset to original inexistent slot (2.2.2.1)
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			// EIP 2200 Original clause:
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			//evm.StateDB.AddRefund(params.SstoreSetGasEIP2200 - params.SloadGasEIP2200)
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			evm.StateDB.AddRefund(params.SstoreSetGasEIP2200 - WarmStorageReadCostEIP2929)
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		} else { // reset to original existing slot (2.2.2.2)
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			// EIP 2200 Original clause:
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			//	evm.StateDB.AddRefund(params.SstoreResetGasEIP2200 - params.SloadGasEIP2200)
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			// - SSTORE_RESET_GAS redefined as (5000 - COLD_SLOAD_COST)
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			// - SLOAD_GAS redefined as WARM_STORAGE_READ_COST
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			// Final: (5000 - COLD_SLOAD_COST) - WARM_STORAGE_READ_COST
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			evm.StateDB.AddRefund((params.SstoreResetGasEIP2200 - ColdSloadCostEIP2929) - WarmStorageReadCostEIP2929)
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		}
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	}
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	// EIP-2200 original clause:
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	//return params.SloadGasEIP2200, nil // dirty update (2.2)
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	return cost + WarmStorageReadCostEIP2929, nil // dirty update (2.2)
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}
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// gasSLoadEIP2929 calculates dynamic gas for SLOAD according to EIP-2929
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// For SLOAD, if the (address, storage_key) pair (where address is the address of the contract
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// whose storage is being read) is not yet in accessed_storage_keys,
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// charge 2100 gas and add the pair to accessed_storage_keys.
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// If the pair is already in accessed_storage_keys, charge 100 gas.
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func gasSLoadEIP2929(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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	loc := stack.peek()
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	slot := common.Hash(loc.Bytes32())
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	// Check slot presence in the access list
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	if _, slotPresent := evm.StateDB.SlotInAccessList(contract.Address(), slot); !slotPresent {
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		// If the caller cannot afford the cost, this change will be rolled back
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		// If he does afford it, we can skip checking the same thing later on, during execution
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		evm.StateDB.AddSlotToAccessList(contract.Address(), slot)
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		return ColdSloadCostEIP2929, nil
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	}
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	return WarmStorageReadCostEIP2929, nil
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}
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// gasExtCodeCopyEIP2929 implements extcodecopy according to EIP-2929
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// EIP spec:
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// > If the target is not in accessed_addresses,
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// > charge COLD_ACCOUNT_ACCESS_COST gas, and add the address to accessed_addresses.
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// > Otherwise, charge WARM_STORAGE_READ_COST gas.
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func gasExtCodeCopyEIP2929(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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	// memory expansion first (dynamic part of pre-2929 implementation)
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	gas, err := gasExtCodeCopy(evm, contract, stack, mem, memorySize)
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	if err != nil {
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		return 0, err
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	}
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	addr := common.Address(stack.peek().Bytes20())
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	// Check slot presence in the access list
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	if !evm.StateDB.AddressInAccessList(addr) {
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		evm.StateDB.AddAddressToAccessList(addr)
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		var overflow bool
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		// We charge (cold-warm), since 'warm' is already charged as constantGas
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		if gas, overflow = math.SafeAdd(gas, ColdAccountAccessCostEIP2929-WarmStorageReadCostEIP2929); overflow {
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			return 0, ErrGasUintOverflow
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		}
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		return gas, nil
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	}
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	return gas, nil
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}
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// gasEip2929AccountCheck checks whether the first stack item (as address) is present in the access list.
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// If it is, this method returns '0', otherwise 'cold-warm' gas, presuming that the opcode using it
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// is also using 'warm' as constant factor.
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// This method is used by:
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// - extcodehash,
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// - extcodesize,
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// - (ext) balance
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func gasEip2929AccountCheck(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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	addr := common.Address(stack.peek().Bytes20())
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	// Check slot presence in the access list
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	if !evm.StateDB.AddressInAccessList(addr) {
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		// If the caller cannot afford the cost, this change will be rolled back
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		evm.StateDB.AddAddressToAccessList(addr)
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		// The warm storage read cost is already charged as constantGas
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		return ColdAccountAccessCostEIP2929 - WarmStorageReadCostEIP2929, nil
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	}
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	return 0, nil
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}
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func makeCallVariantGasCallEIP2929(oldCalculator gasFunc) gasFunc {
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	return func(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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		addr := common.Address(stack.Back(1).Bytes20())
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		// Check slot presence in the access list
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		if !evm.StateDB.AddressInAccessList(addr) {
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			evm.StateDB.AddAddressToAccessList(addr)
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			// The WarmStorageReadCostEIP2929 (100) is already deducted in the form of a constant cost
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			if !contract.UseGas(ColdAccountAccessCostEIP2929 - WarmStorageReadCostEIP2929) {
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				return 0, ErrOutOfGas
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			}
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		}
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		// Now call the old calculator, which takes into account
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		// - create new account
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		// - transfer value
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		// - memory expansion
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		// - 63/64ths rule
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		return oldCalculator(evm, contract, stack, mem, memorySize)
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	}
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}
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var (
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	gasCallEIP2929         = makeCallVariantGasCallEIP2929(gasCall)
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	gasDelegateCallEIP2929 = makeCallVariantGasCallEIP2929(gasDelegateCall)
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	gasStaticCallEIP2929   = makeCallVariantGasCallEIP2929(gasStaticCall)
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	gasCallCodeEIP2929     = makeCallVariantGasCallEIP2929(gasCallCode)
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)
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func gasSelfdestructEIP2929(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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	var (
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		gas     uint64
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		address = common.Address(stack.peek().Bytes20())
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	)
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	if !evm.StateDB.AddressInAccessList(address) {
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		// If the caller cannot afford the cost, this change will be rolled back
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		evm.StateDB.AddAddressToAccessList(address)
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		gas = ColdAccountAccessCostEIP2929
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	}
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	// if empty and transfers value
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	if evm.StateDB.Empty(address) && evm.StateDB.GetBalance(contract.Address()).Sign() != 0 {
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		gas += params.CreateBySelfdestructGas
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	}
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	if !evm.StateDB.HasSuicided(contract.Address()) {
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		evm.StateDB.AddRefund(params.SelfdestructRefundGas)
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	}
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	return gas, nil
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}
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