1. A computer program product for determining a deadlock condition in a circuit, the computer program product comprising a non-transitory computer-readable storage medium containing computer program code for: receiving a circuit design corresponding to the circuit, the circuit design comprising multiple subsystems that includes a plurality of ports; receiving a transaction definition associated with at least one of the plurality of ports; generating a deadlock property based on the transaction definition; analyzing data flow through the circuit design based on the deadlock property; generating a helper assertion capturing how the data flows through the circuit design, based on analysis from the analyzing step; and checking for an absence of the deadlock condition within the circuit based on the helper assertion.