Simultaneous Depth and Area Minimization in LUT-based FPGA Mapping

In this paper, we present an improvement of the FlwoMap algorithm, named CutMap, which combines depth and area minimization during the mapping process by computing min-cost min-height K-feasible cuts for critical nodes for depth minimization and computing min-cost K-feasible cuts for non-critical nodes for area minimization. CutMap guarantees depth-optimal mapping solutions in polynomial time as the FlowMap algorithm but uses considerably fewer K-LUTs. We have implemented CutMap and tested it on the MCNC logic synthesis benchmarks. For depth-optimal mapping solutions, CutMap uses 15% fewer K-LUTs than FlowMap. We also tested CutMap followed by the depth relaxation routines in FlowMap_r algorithm, which achieves area minimization by depth relaxation. CutMap followed FlowMap_r performs better than FlowMap_r.