DAPA: A Dataflow-Aware Analytical Placement Algorithm for Modern Mixed-Size Circuit Designs

Abstract

This article presents an analytical-based placement algorithm to handle dataflow constraint for mixed-size circuits. To quickly obtain a better placement at an early stage, engineers often reference dataflow of a design to determine the relative locations of cells and macros. To achieve this target, this paper presents two methods to make a placement follow this constraint. First, we give larger weights to those nets which connect to datapath-oriented objects in the beginning, and then gradually shrink the values by the modified Gompertz curve according to the status of placement utilization in order to shorten their distances without interfering with object distribution. Second, we define desirable placement regions for each datapath-oriented object and propose a novel sigmoid function to give additional penalties to these objects in the analytical placement formulation if they are not in the regions. The experiment demonstrates that our methodology can obtain better results than the other approach which does not consider dataflow constraint. Not only wirelength but also routability will be improved in the resulting placement. Furthermore, our placer outperforms the RTL-aware dataflow-driven macro placer.