Lutplace: An Improved Lookup Table-Based Placement for Routability

Congestion estimation is critical in routability-driven placement since it guides subsequent congestion optimization. This paper explores a Rectangular Uniform wire DensitY (RUDY) based algorithm for routability estimation that achieves a better balance between efficiency and accuracy compared to invoking a global router. We build a lookup table based on each net’s pin count and aspect ratio to refine RUDY’s wirelength computation and enhance RUDY’s accuracy in congestion estimation. The experimental results on the DAC 2012 benchmarks show that the lookup table helps improve scaled HPWL by an average of 3.1% and routing congestion by an average of 2.3%.