Finding optimal module orientations in macrocell placement

An ILP (integer linear programming) formulation for finding the optimal module orientations in macrocell placement is reported. Compared to earlier approaches which work only for two-terminal nets based on the Euclidean metric for wire length estimation, the proposed method handles multi-terminal nets based on the Manhattan metric of the minimum bounding box of the pin positions which is more accurate. Experimental results of Benchmark examples have shown 7 to 11% reductions of half-perimeter cost wiring length.