CROP: Fast and effective congestion refinement of placement

Modern circuits become harder to route with the ever decreasing design features. Previous routability-driven placement techniques are usually tightly coupled with the underlying placers. So usually they cannot be easily integrated into various placement tools. In this paper, we propose a tool called CROP (Congestion Refinement of Placement) for mixedsize placement solutions. CROP is independent of any placer. It takes a legalized placement solution and then relocates the modules to improve routability without significantly disturbing the original placement solution. CROP interleaves a congestion-driven module shifting technique and a congestion-driven detailed placement technique. Basically the shifting technique targets at better allocating the routing resources. Shifting in each direction can be formulated as a linear program (LP) for resizing each G-Cell. Instead of solving the computationally expensive LP, we discover that the LP formulation could be relaxed and solved by a very e...

• Type: Journal
• Year: 2009
• Where: ICCAD
• Authors: Yanheng Zhang, Chris Chu
• Keywords: Detailed Placement, Hardware, ICCAD 2009, Placement Solutions, Placement Technique