Optimizing Nonmonotonic Interconnect Using Functional Simulation and Logic Restructuring

The relatively poor scaling of interconnect in modern digital circuits necessitates a number of design optimizations, which must typically be iterated several times to meet the specified performance objectives. Such iterations are often due to the difficulty of early delay estimation, particularly before placement. Therefore, effective logic restructuring to reduce interconnect delay has been a major challenge in physical synthesis, a phase during which more accurate delay estimates can be finally gathered. In this paper, we develop a new approach that enhances modern high-performance logic synthesis techniques with flexibility and accuracy in the physical domain. This approach is based on the following: 1) a novel criterion based on path monotonicity, which identifies those interconnects that are amenable to optimization through logic restructuring, and 2) a synthesis algorithm relying on logic simulation and placement information to identify placed subcircuits that hold promise for interconnect reduction. Experiments indicate that our techniques find optimization opportunities and improve interconnect delay by 11.7% on average at less than 2% wirelength and area overhead.