Resource-Aware Functional ECO Patch Generation

Abstract

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.