An Efficient Placement Speedup Technique Based on Graph Signal Processing

Abstract

Placement is a critical task with high computation complexity in VLSI physical design. Modern analytical placers formulate the placement objective as a nonlinear optimization task, which suffers a long iteration time. To accelerate and enhance the placement process, recent studies have turned to deep learning-based approaches, particularly leveraging graph convolution networks (GCNs). However, learning-based placers require time- and data-consuming model training due to the complexity of circuit placement that involves large-scale cells and design-specific graph statistics. This article proposes GiFt, a parameter-free initialization technique for accelerating placement, rooted in graph signal processing. GiFt excels at capturing multiresolution smooth signals of circuit graphs to generate optimized initial placement solutions without the need for time-consuming model training, and meanwhile significantly reduces the number of iterations required by analytical placers. Moreover, we present GiFtPlus, an enhanced version of GiFt, which is more efficient in handling large-scale circuit placement and can accommodate location constraints. Experimental results on public benchmarks show that GiFt and GiFtPlus significantly improve placement efficiency, while achieving competitive or superior performance compared to state-of-the-art placers. In particular, the recently proposed GPU-accelerated analytical placer DREAMPlace uses up to 50% more total runtime than GiFtPlus-DREAMPlace.