Great performance improvements have been achieved in the 5th generation.
GOF ECO has employed a range of automatic ECO techniques, including:
The Structure Method leverages the resemblance between the implementation and reference netlists, replacing only the differing sub-circuits while retaining the existing logic as much as possible. Therefore, the method's effectiveness can be enhanced by using the same constraint in the synthesis process after RTL changes.
The Reorder Method modifies the endpoints within the logic cone's internal expression to produce an optimal fix, resulting in a minimum size ECO patch.
Meanwhile, the Cut Point Method endeavors to correct any potential signals in the implementation netlist by identifying the best location to fix non-equivalences with the least patch possible.
For example, if an RTL change introduces an AND gate into a combinational signal, the signal's name may be altered, or the signal may have been optimized away after synthesis. In such cases, GOF can identify the best location in the netlist to add the AND gate and achieve an optimal fix to match the RTL change.
To determine the most suitable result, GOF applies all three methods, assesses their performance, and selects the one with the minimum patch size.
Figure 1: Automatic ECO Methodologies
| Gates On the Fly | Cadence Conformal ECO | Synopsys Formality Ultra | |
| Performance |  | | |
| Flexibility | | | |
| Price | | | |
