test_delegatecall_child_spill_not_double_charged()

Documentation for tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_call.py::test_delegatecall_child_spill_not_double_charged@622620d8.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_call.py::test_delegatecall_child_spill_not_double_charged --fork Amsterdam

Test DELEGATECALL child state gas paid from gas_left is not recharged.

With the gas limit pinned to the Amsterdam tx gas cap and no requested reservoir (state_gas_reservoir=0), the top-level frame starts with no state gas reservoir and the child pays for SSTOREs by spilling from gas_left. The parent frame must not charge the same state growth again at frame end: the header bills the storage sets once, in the state dimension, so a second charge surfaces as inflated gas_used.

mixed funds one set from the reservoir and spills the rest, so the header must stay put however the charge is split.

Source code in tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_call.py

@pytest.mark.parametrize("funding", ["spill", "mixed"])
@pytest.mark.valid_from("EIP8037")
def test_delegatecall_child_spill_not_double_charged(
    state_test: StateTestFiller,
    pre: Alloc,
    fork: Fork,
    funding: str,
) -> None:
    """
    Test DELEGATECALL child state gas paid from `gas_left` is not recharged.

    With the gas limit pinned to the Amsterdam tx gas cap and no requested
    reservoir (`state_gas_reservoir=0`), the top-level frame starts with no
    state gas reservoir and the child pays for SSTOREs by spilling from
    `gas_left`. The parent frame must not charge the same state growth again
    at frame end: the header bills the storage sets once, in the state
    dimension, so a second charge surfaces as inflated `gas_used`.

    `mixed` funds one set from the reservoir and spills the rest, so the
    header must stay put however the charge is split.
    """
    num_sstores = 6
    child_code = (
        sum(
            Op.SSTORE(
                i,
                1,
                # gas accounting
                original_value=0,
                new_value=1,
            )
            for i in range(num_sstores)
        )
        + Op.STOP
    )

    child = pre.deploy_contract(code=child_code)

    caller_code = Op.POP(
        Op.DELEGATECALL(
            gas=Op.GAS,
            address=child,
            args_offset=0,
            args_size=0,
            ret_offset=0,
            ret_size=0,
        )
    )
    caller = pre.deploy_contract(code=caller_code)

    state_gas = child_code.state_cost(fork)
    execution_gas = (
        fork.transaction_intrinsic_cost_calculator()()
        + caller_code.execution_cost(fork)
        + child_code.execution_cost(fork)
    )
    expected_gas_used = max(execution_gas, state_gas)
    assert expected_gas_used == state_gas, (
        "expected state gas to dominate execution gas"
    )

    if funding == "mixed":
        reservoir = Op.SSTORE(new_value=1).state_cost(fork)
    else:
        reservoir = 0

    tx = Transaction(
        to=caller,
        state_gas_reservoir=reservoir,
        sender=pre.fund_eoa(),
    )

    post = {
        caller: Account(storage=dict.fromkeys(range(num_sstores), 1)),
    }
    state_test(
        pre=pre,
        post=post,
        tx=tx,
        blockchain_test_header_verify=Header(gas_used=expected_gas_used),
    )

Parametrized Test Cases

This test generates 2 parametrized test cases across 1 fork.