Ethereum Virtual Machine (EVM) System Instructions

Introduction

Implementations of the EVM system related instructions.

Module Contents

Functions

create	Creates a new account with associated code.
return_	Halts execution returning output data.
generic_call	Perform the core logic of the CALL* family of opcodes.
call	Message-call into an account.
callcode	Message-call into this account with alternative account’s code.
selfdestruct	Halt execution and register account for later deletion.
delegatecall	Message-call into an account.

Module Details

create

create(evm)

Creates a new account with associated code.

Parameters

evm – The current EVM frame.

def create(evm: Evm) -> None:
    # This import causes a circular import error
    # if it's not moved inside this method
    from ...vm.interpreter import STACK_DEPTH_LIMIT, process_create_message

    # STACK
    endowment = pop(evm.stack)
    memory_start_position = pop(evm.stack)
    memory_size = pop(evm.stack)

    # GAS
    extend_memory = calculate_gas_extend_memory(
        evm.memory, [(memory_start_position, memory_size)]
    )

    charge_gas(evm, GAS_CREATE + extend_memory.cost)

    create_message_gas = max_message_call_gas(Uint(evm.gas_left)) evm.gas_left
    -= create_message_gas

    # OPERATION
    evm.memory += b"\x00" * extend_memory.expand_by
    sender_address = evm.message.current_target
    sender = get_account(evm.env.state, sender_address)

    contract_address = compute_contract_address(
        evm.message.current_target,
        get_account(evm.env.state, evm.message.current_target).nonce,
    )

    if (
        sender.balance < endowment
        or sender.nonce == Uint(2**64 - 1)
        or evm.message.depth + 1 > STACK_DEPTH_LIMIT
    ):
        push(evm.stack, U256(0))
        evm.gas_left = Uint(0)

    # OPERATION
    evm.memory += b"\x00" * extend_memory.expand_by
    sender_addresscreate_message_gas
    elif account_has_code_or_nonce(evm.env.state, contract_address):
        increment_nonce(evm.env.state, evm.message.current_target)
        push(evm.stack, U256(0))
    else:
        call_data = evm.message.current_target
    sendermemory_read_bytes(
            evm.memory, memory_start_position, memory_size
        )

        increment_nonce(evm.env.state, evm.message.current_target)

        child_message = get_account(evm.env.state, sender_address)

    contract_addressMessage(
            caller=evm.message.current_target,
            target=Bytes0(),
            gas=create_message_gas,
            value=endowment,
            data=b"",
            code=call_data,
            current_target=contract_address,
            depth=evm.message.depth + 1,
            code_address=None,
            should_transfer_value=True,
            parent_evm=evm,
        )
        child_evm = compute_contract_address(
        evm.message.current_target,
        get_account(evm.env.state, evm.message.current_target).nonce,
    )process_create_message(child_message, evm.env)

    if (
        sender.balance < endowment
        or sender.nonce == Uint(2**64 - 1)
        or evm.message.depth +child_evm.error:
            incorporate_child_on_error(evm, child_evm)
            push(evm.stack, U256(0))
        else:
            incorporate_child_on_success(evm, child_evm)
            push(
                evm.stack, U256.from_be_bytes(child_evm.message.current_target)
            )

    # PROGRAM COUNTER
    evm.pc += 1 > STACK_DEPTH_LIMIT
    ):
        push(evm.stack, U256(0))
        evm.gas_left += create_message_gas
    elif account_has_code_or_nonce(evm.env.state, contract_address):
        increment_nonce(evm.env.state, evm.message.current_target)
        push(evm.stack, U256(0))
    else:
        call_data = memory_read_bytes(
            evm.memory, memory_start_position, memory_size
        )

        increment_nonce(evm.env.state, evm.message.current_target)

        child_message = Message(
            caller=evm.message.current_target,
            target=Bytes0(),
            gas=create_message_gas,
            value=endowment,
            data=b"",
            code=call_data,
            current_target=contract_address,
            depth=evm.message.depth + 1,
            code_address=None,
            should_transfer_value=True,
            parent_evm=evm,
        )
        child_evm = process_create_message(child_message, evm.env)

        if child_evm.error:
            incorporate_child_on_error(evm, child_evm)
            push(evm.stack, U256(0))
        else:
            incorporate_child_on_success(evm, child_evm)
            push(
                evm.stack, U256.from_be_bytes(child_evm.message.current_target)
            )

    # PROGRAM COUNTER
    evm.pc += 1

return

return_(evm)

Halts execution returning output data.

Parameters

evm – The current EVM frame.

def return_(evm: Evm) -> None:
    # STACK
    memory_start_position = pop(evm.stack)
    memory_size = pop(evm.stack)

    # GAS
    extend_memory = calculate_gas_extend_memory(
        evm.memory, [(memory_start_position, memory_size)]
    )

    charge_gas(evm, GAS_ZERO + extend_memory.cost)

    # OPERATION
    evm.memory += b"\x00" * extend_memory.expand_by
    evm.output = memory_read_bytes(
        evm.memory, memory_start_position, memory_size
    )

    evm.running = False

    # PROGRAM COUNTER
    pass

generic_call

generic_call(evm, gas, value, caller, to, code_address, should_transfer_value, memory_input_start_position, memory_input_size, memory_output_start_position, memory_output_size)

Perform the core logic of the CALL* family of opcodes.

def generic_call(
    evm: Evm,
    gas: Uint,
    value: U256,
    caller: Address,
    to: Address,
    code_address: Address,
    should_transfer_value: bool,
    memory_input_start_position: U256,
    memory_input_size: U256,
    memory_output_start_position: U256,
    memory_output_size: U256,
) -> None:
    from ...vm.interpreter import STACK_DEPTH_LIMIT, process_message

    if evm.message.depth + 1 > STACK_DEPTH_LIMIT:
        evm.gas_left += gas
        push(evm.stack, U256(0))
        return

    call_data = memory_read_bytes(
        evm.memory, memory_input_start_position, memory_input_size
    )
    code = get_account(evm.env.state, code_address).code
    child_message = Message(
        caller=caller,
        target=to,
        gas=gas,
        value=value,
        data=call_data,
        code=code,
        current_target=to,
        depth=evm.message.depth + 1,
        code_address=code_address,
        should_transfer_value=should_transfer_value,
        parent_evm=evm,
    )
    child_evm = process_message(child_message, evm.env)

    if child_evm.error:
        incorporate_child_on_error(evm, child_evm)
        push(evm.stack, U256(0))
    else:
        incorporate_child_on_success(evm, child_evm)
        push(evm.stack, U256(1))

    actual_output_size = min(memory_output_size, U256(len(child_evm.output)))
    memory_write(
        evm.memory,
        memory_output_start_position,
        child_evm.output[:actual_output_size],
    )

call

call(evm)

Message-call into an account.

Parameters

evm – The current EVM frame.

def call(evm: Evm) -> None:
    # STACK
    gas = Uint(pop(evm.stack))
    to = to_address(pop(evm.stack))
    value = pop(evm.stack)
    memory_input_start_position = pop(evm.stack)
    memory_input_size = pop(evm.stack)
    memory_output_start_position = pop(evm.stack)
    memory_output_size = pop(evm.stack)

    # GAS
    extend_memory = calculate_gas_extend_memory(
        evm.memory,
        [
            (memory_input_start_position, memory_input_size),
            (memory_output_start_position, memory_output_size),
        ],
    )
    _account_exists = account_exists(evm.env.state, to)
    create_gas_cost = Uint(0) if _account_exists else GAS_NEW_ACCOUNT
    transfer_gas_cost = Uint(0) if value == 0 else GAS_CALL_VALUE
    message_call_gas = calculate_message_call_gas(
        value,
        gas,
        Uint(evm.gas_left),
        extend_memory.cost,
        GAS_CALL + create_gas_cost + transfer_gas_cost,
    )
    charge_gas(evm, message_call_gas.cost + extend_memory.cost)

    # OPERATION
    evm.memory += b"\x00" * extend_memory.expand_by
    sender_balance = get_account(
        evm.env.state, gas,evm.message.current_target
    ).balance
    if sender_balance < value:
        push(evm.stack, U256(0))
        evm.gas_left += message_call_gas.stipend
    else:
        generic_call(
            evm,
            message_call_gas.stipend,
            value,
            evm.message.current_target, to, valueto,
            True,
            memory_input_start_position,
            memory_input_size,
            memory_output_start_position,
            memory_output_size,
    )
    charge_gas(evm, message_call_gas.cost + extend_memory.cost)

    # OPERATION
    evm.memoryPROGRAM COUNTER
    evm.pc += b"\x00" * extend_memory.expand_by
    sender_balance = get_account(
        evm.env.state, evm.message.current_target
    ).balance
    if sender_balance < value:
        push(evm.stack, U256(0))
        evm.gas_left += message_call_gas.stipend
    else:
        generic_call(
            evm,
            message_call_gas.stipend,
            value,
            evm.message.current_target,
            to,
            to,
            True,
            memory_input_start_position,
            memory_input_size,
            memory_output_start_position,
            memory_output_size,
        )

    # PROGRAM COUNTER
    evm.pc += 1

callcode

callcode(evm)

Message-call into this account with alternative account’s code.

Parameters

evm – The current EVM frame.

def callcode(evm: Evm) -> None:
    # STACK
    gas = Uint(pop(evm.stack))
    code_address = to_address(pop(evm.stack))
    value = pop(evm.stack)
    memory_input_start_position = pop(evm.stack)
    memory_input_size = pop(evm.stack)
    memory_output_start_position = pop(evm.stack)
    memory_output_size = pop(evm.stack)

    # GAS
    to = evm.message.current_target

    extend_memory = calculate_gas_extend_memory(
        evm.memory,
        [
            (memory_input_start_position, memory_input_size),
            (memory_output_start_position, memory_output_size),
        ],
    )
    transfer_gas_cost = Uint(0) if value == 0 else GAS_CALL_VALUE
    message_call_gas = calculate_message_call_gas(
        value,
        gas,
        Uint(evm.gas_left),
        extend_memory.cost,
        GAS_CALL + transfer_gas_cost,
    )
    charge_gas(evm, message_call_gas.cost + extend_memory.cost)

    # OPERATION
    evm.memory += b"\x00" * extend_memory.expand_by
    sender_balance = get_account(
        evm.env.state, gas,evm.message.current_target
    ).balance
    if sender_balance < value:
        push(evm.stack, U256(0))
        evm.gas_left += message_call_gas.stipend
    else:
        generic_call(
            evm,
            message_call_gas.stipend,
            value,
            evm.message.current_target, to, valuecode_address,
            True,
            memory_input_start_position,
            memory_input_size,
            memory_output_start_position,
            memory_output_size,
    )
    charge_gas(evm, message_call_gas.cost + extend_memory.cost)

    # OPERATION
    evm.memoryPROGRAM COUNTER
    evm.pc += b"\x00" * extend_memory.expand_by
    sender_balance = get_account(
        evm.env.state, evm.message.current_target
    ).balance
    if sender_balance < value:
        push(evm.stack, U256(0))
        evm.gas_left += message_call_gas.stipend
    else:
        generic_call(
            evm,
            message_call_gas.stipend,
            value,
            evm.message.current_target,
            to,
            code_address,
            True,
            memory_input_start_position,
            memory_input_size,
            memory_output_start_position,
            memory_output_size,
        )

    # PROGRAM COUNTER
    evm.pc += 1

selfdestruct

selfdestruct(evm)

Halt execution and register account for later deletion.

Parameters

evm – The current EVM frame.

def selfdestruct(evm: Evm) -> None:
    # STACK
    beneficiary = to_address(pop(evm.stack))

    # GAS
    gas_cost = GAS_ZEROGAS_SELF_DESTRUCT
    if not account_exists(evm.env.state, beneficiary):
        gas_cost += GAS_SELF_DESTRUCT_NEW_ACCOUNT

    originator = evm.message.current_target

    refunded_accounts = evm.accounts_to_delete
    parent_evm = evm.message.parent_evm
    while parent_evm is not None:
        refunded_accounts.update(parent_evm.accounts_to_delete)
        parent_evm = parent_evm.message.parent_evm

    if originator not in refunded_accounts:
        evm.refund_counter += REFUND_SELF_DESTRUCT

    charge_gas(evm, gas_cost)

    # OPERATION
    beneficiary_balance = get_account(evm.env.state, beneficiary).balance
    originator_balance = get_account(evm.env.state, originator).balance

    # First Transfer to beneficiary
    set_account_balance(
        evm.env.state, beneficiary, beneficiary_balance + originator_balance
    )
    # Next, Zero the balance of the address being deleted (must come after
    # sending to beneficiary in case the contract named itself as the
    # beneficiary).
    set_account_balance(evm.env.state, originator, U256(0))

    # register account for deletion
    evm.accounts_to_delete.add(originator)

    # HALT the execution
    evm.running = False

    # PROGRAM COUNTER
    pass

delegatecall

delegatecall(evm)

Message-call into an account.

Parameters

evm – The current EVM frame.

def delegatecall(evm: Evm) -> None:
    # STACK
    gas = Uint(pop(evm.stack))
    code_address = to_address(pop(evm.stack))
    memory_input_start_position = pop(evm.stack)
    memory_input_size = pop(evm.stack)
    memory_output_start_position = pop(evm.stack)
    memory_output_size = pop(evm.stack)

    # GAS
    extend_memory = calculate_gas_extend_memory(
        evm.memory,
        [
            (memory_input_start_position, memory_input_size),
            (memory_output_start_position, memory_output_size),
        ],
    )
    message_call_gas = calculate_message_call_gas(
        U256(0), gas, Uint(evm.gas_left), extend_memory.cost, GAS_CALL
    )
    charge_gas(evm, GAS_CALLmessage_call_gas.cost + gas + extend_memory.cost)

    # OPERATION
    evm.memory += b"\x00" * extend_memory.expand_by
    generic_call(
        evm,
        gas,message_call_gas.stipend,
        evm.message.value,
        evm.message.caller,
        evm.message.current_target,
        code_address,
        False,
        memory_input_start_position,
        memory_input_size,
        memory_output_start_position,
        memory_output_size,
    )

    # PROGRAM COUNTER
    evm.pc += 1