GOF Netlist ECO Solutions

What is GOF Netlist ECO Solutions?

Netlist ECO Solutions

GOF Netlist ECO Solutions integrates leading technologies and methodologies to provide complete eco netlist functional solutions. The tool supports automatic ECO, ECO GUI and ECO Script without problems. The auto ECO feature outperforms the ECO in patch size.

The tool makes automatic ECHO in global mode and incremental mode. The global mode can have a complete image of the design and the ECO result can be guaranteed as equivalent.

The advantage of the incremental way is efficiency and performance with GOF Netlist ECO Solutions. Users can focus on problematic logic without being distracted by unrelated things. The tool makes the sketchy view and layout incrementally.

Automatic ECO methodologies

GOF Netlist ECO Solutions has implemented several automatic ECO methods. Methods include:

• Structure method
• Reorder method
• Cut-off method

The Structure Method uses the similarity of the implementation and reference network lists. It maintains the existing logic in the implementation netlist as much as possible and replaces only these different subcircuits. Therefore, it would improve the performance of this method if the synthesis process used the same restriction after changing the RTL.

Reorder method adjusts the endpoints in the inner expression of the logical cone. The correct order of the endpoints would create the optimal fix and therefore result in a minimum-sized ECO patch.

The Cut Point method attempts to correct all potential signals in the implementation list and finds the best place to correct non-equivalences with the minimum patch.

For example, the RTL change can add an AND port to a combinational signal, after the synthesis the combinational signal changed name or the signal may have been optimized. GOF can find the best point on the netlist to add the AND port and get the optimal fix to match the RTL change.

GOF Netlist ECO Solutions evaluates three implementations and chooses the result with minimal patch size.

GOF vs ECO

THE ECO is defective when an ECHO involves a single complicated combinatorial signal. He has difficulty identifying the exact location of the correction. The final results of the ECO have redundant ports after eco execution.

GOF Netlist ECO Solutions can solve the problem well. It can identify the exact location and generate a minimal ECO patch.

The GOF vs ECO page has detailed coverage in the performance comparison.

GUI and script mode

Sometimes it makes no sense to resynthesize the multi-million-port design to have only one inverter added. It is not a good practice to use the text editor to change a Giga-byte-sized netlist. If a project is reasonably verified, ECOs involving more than 20 ports should be less than 10%. For those 90% small or replicated size ECOs, the global mode automatic ECO is exaggerated and inefficient. Gates On the Fly gives users the flexibility to choose GUI and Script mode for these small or replicated ECOs.

With the help of GUI and Script, manual work becomes much simpler and more accurate. Sometimes the eco's manual result always offers better results than automatic ECO. More importantly, the return time is much shorter.

In GUI mode, Gates On the Fly has an incremental system mechanism (GofTrace) and fits well into the isolation of problematic logic. After the logic in ECO is isolated in the schema, ECO mode can be activated and ECO operations can be performed in the same schema.

GOF can analyze physical database files, Design Exchange Format (DEF), and Library Exchange Format (LEF). When loading the physical database, GOF can view the physical layout and connections through the LayoutViewer window. The LayoutViewer window has full interactivity with the incremental schema, GofTrace window. This unified platform serves Metal Only ECO very well. The user can resolve the Metal Only ECO at one stop, instead of going back and off between the backend and the front end.

ECO GUI mode has a steep learning curve for beginners and infrequent users.

Script mode has the same Perl syntax, which can easily integrate existing netlist processing scripts. Script mode is good for replicated jobs, such as inserting AND for all output pins. In addition, script mode exports many netlist processing APIs, such as scan design, endpoint tracking support, and logical cone extraction.

By combining netlist processing APIs and Perl's programming algorithm, powerful built-in tools can be created efficiently.

Mixed mode

ECOs can become very complicated in some scenarios. Using only automatic mode would give unacceptable results. To achieve the optimal ECO patch, automatic ECO and manual ECHO should be used together.

For example, the ECO enclosure on the right side requires a new bus port (IN_B) to control half of the logic (LOGIC B) that is originally controlled by bus port A (IN_A). LOGIC A and LOGIC B may overlap. LOGIC C also needs to be corrected and has changes in the path of the data that must be made by automatic ECO.

When applying only automatic ECO, correction 1 (IN_A/IN_B/LOGIC-A/LOGIC-B) needs ~200 ports. Use the GOF APIs to analyze the logical paths of port IN_A for STATE_A_reg and STATE_B_reg, you can find that LOGIC A and LOGIC B have very few shared ones. By duplicating these shared gates, there would be a clean cut of LOGIC A and LOGIC B to make them be driven IN_A and IN_B separately.

System requirements

Linux (32bit ou 64bit).