Functional Engineering Change Order (ECO) is necessary for logic rectification at late design stages. Existing works mainly focus on identifying a minimal logic difference between the original netlist and the revised netlist, which is called a patch. The patch is then implemented by technology mapping using spare cells. However, there may be insufficient spare cells around the physical location of the patch, or the wires connecting spare cells are too long, thus causing timing violations and routing congestion. In this paper, we propose a resource-aware functional patch generation approach by gate count and wiring cost estimations. In particular, we estimate the number of spare cells required by a patch and define a cost of wire length on it, which considers the physical location of the patch and a set of nearby spare cells. As a result, the patch with minimal wiring cost instead of minimal size is produced. The experiments are conducted on nine industrial testcases. These testcases reflect real problems faced by designers, and the results show our method is promising.

Resource-aware functional ECO patch generation

For a combinational circuit, area-complexity is a measure that estimates the logic area of the circuit without mapping to logic gates. Several measures like literal count, number of primary input/outputs, etc. have been used in the past as area-complexity metrics. In this paper, we propose a novel area-complexity measure using the theory of Boolean difference and Taylor expansion for Boolean functions. We demonstrate how to capture the area-complexity of a Boolean function using the complexity of its Boolean derivatives. We evaluate the metric on circuits from MCNC benchmark suite and a sizeable collection of randomly generated circuits. We compare our metric with existing techniques based on literal-count and BDD properties. We show that the new area-complexity measure is accurate within 10% of the actual number of gates synthesized using ABC as opposed to at least 100% and 15% for the metrics based on literal-count and BDD properties respectively. We also show the robustness of our metric across three different gate-libraries.

A. Kagliwal

Papers

Measuring Area-Complexity Using Boolean Difference