Late Breaking Results: Multi-Objective Multi-Bit Flip-Flop Placement Considering Pre-Placed Cells

Clustering single-bit flip-flops (SBFFs) into multi-bit flip-flops (MBFFs) effectively reduces power and area. However, excessive displacement during the clustering and legalization process may incur significant timing degradation. To address this issue, we propose the first comprehensive MBFF placement methodology that addresses excessive displacement caused by pre-placed cells during clustering and legalization while simultaneously optimizing timing, power, area, and bin utilization. Our methodology includes three main features: (1) a force model to relocate flip-flops and reduce timing violations, (2) a clustering and legalization process to reduce timing degradation caused by displacement, and (3) a multi-objective function to identify flip-flop candidates suitable for MBFF clustering. Our methodology outperforms all participating teams in the 2024 CAD Contest at ICCAD on Power and Timing Optimization Using Multi-Bit Flip-Flops, based on exactly the same settings.