Effective Legalization with Cell Version Replacement for Hybrid-Row-Height Circuit Designs

In traditional circuit designs, rows within the placement region typically have uniform height. However, a novel hybrid-row-height design paradigm has recently emerged, integrating tall and short rows within the placement region. This innovative approach enhances optimization opportunities for power, performance, and area. Nevertheless, it poses new challenges in placement legalization due to the heterogeneous row and cell structures. Therefore, this paper proposes an effective legalization algorithm with cell version replacement for hybrid-row-height circuit designs. Our approach takes full advantage of multiple versions of the same cell, each with varying dimensions (heights and widths), to incorporate a mechanism for cell version replacement throughout the legalization process. This consideration can help to obtain a legal placement that more closely resembles the global placement, consequently mitigating the increase in half-perimeter wirelength (HPWL). Simul-taneously, it can ensure that the tall-row and short-row resources are not overused, avoiding a non-legal placement. Compared with a baseline and a recent work, experimental results show that our algorithm can achieve the smallest HPWL and runtime.