Architecture-aware routability-driven placer for large-scale mixed-size designs

In this study, the authors have presented a simple but robust routability-driven placement for the mixed-size designs. The proposed technique is implemented through (i) look-ahead legalisation-based global placement, (ii) congestion removal and (iii) detailed placement stages. A balanced clustering technique has been proposed to group the circuit blocks into clusters based on the types of circuit blocks and their connectivity. A 0-1 integer programming-based global placement method is framed, which performs look-ahead legalisation. A new site information table concept is introduced to keep the information about each placement cell. Based on the divide conquer strategy, placement area is divided into a region to reduce problem size. A force-directed method has been conceived to select an appropriate region for global placement for the blocks of a cluster. A new congestion removal approach substitutes the legalisation stage to remove circuit block congestion and pin density in different regions. Finally, a gain-based strategy has been introduced for routability-driven detailed placement. The proposed technique is implemented and tested on ICCAD 2012 benchmark circuits. It achieves 1.92 and 0.13% improvements in terms of half perimeter wirelength and routing congestion w.r.t. recent placers.