The automatic ECO is done by a GofCall script. The flow needs the implementation netlist which is under ECO, and the reference netlist which is re-synthesized from modified RTL. Users provide the non-equivalent points reported by LEC to the tool. GOF uses the built-in Logic Equivalence Check engine to analyze the logic cones of the non-equivalent points and fully utilize any existing logic resource to fix the logic cone in the implementation netlist. The final patch is optimized circuit with minimum gate count that make the logic cone in the implementation netlist equal to the logic cone in the reference netlist. The patch gates can be all spare gates if the '-metalonly' option is enabled. Timing ECO can be done in automatic mode as well. Primetime report file is needed in automatic timing ECO.
When ECO changes are known and ECO size is small or the operations are repetitive like adding inverts on a bus, manual mode ECO is better choice. Since it is more efficient and the final gates touched can be less than automatic mode ECO. Moreover, automatic and manual mode ECO can be interleaved in one GofCall ECO script.
Users can specify the spare gates type in GofCall script and enable '-metalonly' option to tell GOF only use the spare gates for the newly added cells. The flow can be in automatic or manual mode.
GOF reads in Primetime report file and does bottleneck analysis of the violations. The critical path is automatically fixed. User can choose to do timing ECO manually with ECO APIs.
GUI mode ECO has advantage of fast ramping up. It's good for small size ECO. The incremental schematic feature is very helpful for analyzing the netlist before the next step is decided.
The incremental schematic is very useful in pinpointing the logic issues. GOF has exports many useful APIs to fast access the database.