Improved algorithms for hypergraph bipartitioning

Multilevel Fiduccia-Mattheyses (MLFM) hypergraph partitioning is a fundamental optimization in VLSI CAD physical design. The leading implementation, hMetis, has since 1997 proved itself substantially superior in both runtime and solution quality to even very recent work. In this work, we present two sets of results: (i) new techniques for flat FM-based hypergraph partitioning (which is the core of multilevel implementations), and (ii) a new multilevel implementation that offers leading-edge performance. Our new techniques for flat partitioning confirm the conjecture that specialized partitioning heuristics may be able to actively exploit fixed nodes in partitioning instances arising in the driving top-down placement context. Our FM variant is competitive with traditional FM on instances without terminals and considerably superior on instances with fixed nodes (i.e., arising during top-down placement). Our multilevel FM variant avoids several complex heuristics and non-trivial tunings that often lead to complex implementations; it achieves trade-offs between solution quality and run time that are comparable or better than those achieved by hMetis-1.5.3. We attempt to provide algorithm descriptions that are as detailed and unambiguous as possible, to allow replicability and speed improvements in future research.