ethereum.forks.bpo5.vm.interpreterethereum.forks.amsterdam.vm.interpreter

Ethereum Virtual Machine (EVM) Interpreter.

.. contents:: Table of Contents :backlinks: none :local:

Introduction

A straightforward interpreter that executes EVM code.

STACK_DEPTH_LIMIT

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STACK_DEPTH_LIMIT = Uint(1024)

MAX_CODE_SIZE

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MAX_CODE_SIZE = 0x6000

MAX_INIT_CODE_SIZE

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MAX_INIT_CODE_SIZE = 2 * MAX_CODE_SIZE

MessageCallOutput

Output of a particular message call.

Contains the following:

  1. `gas_left`: remaining gas after execution.
  2. `refund_counter`: gas to refund after execution.
  3. `logs`: list of `Log` generated during execution.
  4. `accounts_to_delete`: Contracts which have self-destructed.
  5. `error`: The error from the execution if any.
  6. `return_data`: The output of the execution.
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@dataclass
class MessageCallOutput:

gas_left

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    gas_left: Uint

refund_counter

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    refund_counter: U256

logs

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    logs: Tuple[Log, ...]

accounts_to_delete

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    accounts_to_delete: Set[Address]

error

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    error: Optional[EthereumException]

return_data

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    return_data: Bytes

process_message_call

If message.target is empty then it creates a smart contract else it executes a call from the message.caller to the message.target.

Parameters

message : Transaction specific items.

Returns

output : MessageCallOutput Output of the message call

def process_message_call(message: Message) -> MessageCallOutput:
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    """
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    If `message.target` is empty then it creates a smart contract
105
    else it executes a call from the `message.caller` to the `message.target`.
106
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    Parameters
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    ----------
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    message :
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        Transaction specific items.
111
112
    Returns
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    -------
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    output : `MessageCallOutput`
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        Output of the message call
116
117
    """
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    block_env = message.block_env
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    refund_counter = U256(0)
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    if message.target == Bytes0(b""):
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        is_collision = account_has_code_or_nonce(
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            block_env.state, message.current_target
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        ) or account_has_storage(block_env.state, message.current_target)
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        track_address(message.tx_env.state_changes, message.current_target)
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        if is_collision:
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            return MessageCallOutput(
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                Uint(0),
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                U256(0),
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                tuple(),
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                set(),
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                AddressCollision(),
132
                Bytes(b""),
133
            )
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        else:
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            evm = process_create_message(message)
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    else:
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        if message.tx_env.authorizations != ():
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            refund_counter += set_delegation(message)
139
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        delegated_address = get_delegated_code_address(message.code)
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        if delegated_address is not None:
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            message.disable_precompiles = True
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            message.accessed_addresses.add(delegated_address)
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            message.code = get_account(block_env.state, delegated_address).code
134
            message.code_address = delegated_address
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            message.code_address = delegated_address
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            track_address(message.block_env.state_changes, delegated_address)
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        evm = process_message(message)
149
150
    if evm.error:
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        logs: Tuple[Log, ...] = ()
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        accounts_to_delete = set()
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    else:
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        logs = evm.logs
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        accounts_to_delete = evm.accounts_to_delete
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        refund_counter += U256(evm.refund_counter)
157
158
    tx_end = TransactionEnd(
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        int(message.gas) - int(evm.gas_left), evm.output, evm.error
160
    )
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    evm_trace(evm, tx_end)
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    return MessageCallOutput(
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        gas_left=evm.gas_left,
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        refund_counter=refund_counter,
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        logs=logs,
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        accounts_to_delete=accounts_to_delete,
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        error=evm.error,
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        return_data=evm.output,
170
    )

process_create_message

Executes a call to create a smart contract.

Parameters

message : Transaction specific items.

Returns

evm: :py:class:~ethereum.forks.bpo5.vm.Evm~ethereum.forks.amsterdam.vm.Evm Items containing execution specific objects.

def process_create_message(message: Message) -> Evm:
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    """
175
    Executes a call to create a smart contract.
176
177
    Parameters
178
    ----------
179
    message :
180
        Transaction specific items.
181
182
    Returns
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    -------
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    evm: :py:class:`~ethereum.forks.bpo5.vm.Evm`
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    evm: :py:class:`~ethereum.forks.amsterdam.vm.Evm`
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        Items containing execution specific objects.
186
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    """
188
    state = message.block_env.state
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    transient_storage = message.tx_env.transient_storage
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    # take snapshot of state before processing the message
191
    begin_transaction(state, transient_storage)
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    # If the address where the account is being created has storage, it is
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    # destroyed. This can only happen in the following highly unlikely
195
    # circumstances:
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    # * The address created by a `CREATE` call collides with a subsequent
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    #   `CREATE` or `CREATE2` call.
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    # * The first `CREATE` happened before Spurious Dragon and left empty
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    #   code.
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    destroy_storage(state, message.current_target)
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    # In the previously mentioned edge case the preexisting storage is ignored
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    # for gas refund purposes. In order to do this we must track created
204
    # accounts. This tracking is also needed to respect the constraints
205
    # added to SELFDESTRUCT by EIP-6780.
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    mark_account_created(state, message.current_target)
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    increment_nonce(state, message.current_target)
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    nonce_after = get_account(state, message.current_target).nonce
210
    track_nonce_change(
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        message.state_changes,
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        message.current_target,
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        U64(nonce_after),
214
    )
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    capture_pre_code(message.tx_env.state_changes, message.current_target, b"")
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    evm = process_message(message)
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    if not evm.error:
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        contract_code = evm.output
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        contract_code_gas = Uint(len(contract_code)) * GAS_CODE_DEPOSIT
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        try:
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            if len(contract_code) > 0:
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                if contract_code[0] == 0xEF:
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                    raise InvalidContractPrefix
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            charge_gas(evm, contract_code_gas)
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            if len(contract_code) > MAX_CODE_SIZE:
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                raise OutOfGasError
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        except ExceptionalHalt as error:
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            rollback_transaction(state, transient_storage)
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            merge_on_failure(message.state_changes)
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            evm.gas_left = Uint(0)
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            evm.output = b""
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            evm.error = error
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        else:
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            # Note: No need to capture pre code since it's always b"" here
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            set_code(state, message.current_target, contract_code)
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            commit_transaction(state, transient_storage)
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            if contract_code != b"":
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                track_code_change(
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                    message.state_changes,
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                    message.current_target,
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                    contract_code,
243
                )
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            commit_transaction(state, transient_storage)
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            merge_on_success(message.state_changes)
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    else:
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        rollback_transaction(state, transient_storage)
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        rollback_transaction(state, transient_storage)
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        merge_on_failure(message.state_changes)
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    return evm

process_message

Move ether and execute the relevant code.

Parameters

message : Transaction specific items.

Returns

evm: :py:class:~ethereum.forks.bpo5.vm.Evm~ethereum.forks.amsterdam.vm.Evm Items containing execution specific objects

def process_message(message: Message) -> Evm:
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    """
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    Move ether and execute the relevant code.
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    Parameters
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    ----------
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    message :
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        Transaction specific items.
260
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    Returns
262
    -------
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    evm: :py:class:`~ethereum.forks.bpo5.vm.Evm`
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    evm: :py:class:`~ethereum.forks.amsterdam.vm.Evm`
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        Items containing execution specific objects
265
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    """
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    state = message.block_env.state
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    transient_storage = message.tx_env.transient_storage
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    if message.depth > STACK_DEPTH_LIMIT:
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        raise StackDepthLimitError("Stack depth limit reached")
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    transient_storage = message.tx_env.transient_storage
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    code = message.code
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    valid_jump_destinations = get_valid_jump_destinations(code)
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    evm = Evm(
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        pc=Uint(0),
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        stack=[],
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        memory=bytearray(),
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        code=code,
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        gas_left=message.gas,
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        valid_jump_destinations=valid_jump_destinations,
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        logs=(),
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        refund_counter=0,
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        running=True,
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        message=message,
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        output=b"",
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        accounts_to_delete=set(),
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        return_data=b"",
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        error=None,
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        accessed_addresses=message.accessed_addresses,
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        accessed_storage_keys=message.accessed_storage_keys,
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        state_changes=message.state_changes,
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    )
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    # take snapshot of state before processing the message
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    begin_transaction(state, transient_storage)
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    track_address(message.state_changes, message.current_target)
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    if message.should_transfer_value and message.value != 0:
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        move_ether(
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        # Track value transfer
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        sender_balance = get_account(state, message.caller).balance
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        recipient_balance = get_account(state, message.current_target).balance
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        track_address(message.state_changes, message.caller)
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        capture_pre_balance(
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            message.tx_env.state_changes, message.caller, sender_balance
307
        )
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        capture_pre_balance(
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            message.tx_env.state_changes,
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            message.current_target,
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            recipient_balance,
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        )
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        move_ether(
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            state, message.caller, message.current_target, message.value
316
        )
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        sender_new_balance = get_account(state, message.caller).balance
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        recipient_new_balance = get_account(
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            state, message.current_target
321
        ).balance
322
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        track_balance_change(
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            message.state_changes,
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            message.caller,
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            U256(sender_new_balance),
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        )
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        track_balance_change(
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            message.state_changes,
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            message.current_target,
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            U256(recipient_new_balance),
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        )
333
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    try:
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        if evm.message.code_address in PRE_COMPILED_CONTRACTS:
336
            if not message.disable_precompiles:
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                evm_trace(evm, PrecompileStart(evm.message.code_address))
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                PRE_COMPILED_CONTRACTS[evm.message.code_address](evm)
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                evm_trace(evm, PrecompileEnd())
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        else:
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            while evm.running and evm.pc < ulen(evm.code):
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                try:
343
                    op = Ops(evm.code[evm.pc])
344
                except ValueError as e:
345
                    raise InvalidOpcode(evm.code[evm.pc]) from e
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                evm_trace(evm, OpStart(op))
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                op_implementation[op](evm)
349
                evm_trace(evm, OpEnd())
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351
            evm_trace(evm, EvmStop(Ops.STOP))
352
353
    except ExceptionalHalt as error:
354
        evm_trace(evm, OpException(error))
355
        evm.gas_left = Uint(0)
356
        evm.output = b""
357
        evm.error = error
358
    except Revert as error:
359
        evm_trace(evm, OpException(error))
360
        evm.error = error
361
362
    if evm.error:
299
        # revert state to the last saved checkpoint
300
        # since the message call resulted in an error
301
        rollback_transaction(state, transient_storage)
363
        rollback_transaction(state, transient_storage)
364
        if not message.is_create:
365
            merge_on_failure(evm.state_changes)
366
    else:
303
        commit_transaction(state, transient_storage)
367
        commit_transaction(state, transient_storage)
368
        if not message.is_create:
369
            merge_on_success(evm.state_changes)
370
    return evm