SKB-Tree: A Fixed-Outline Driven Representation for Modern Floorplanning Problems

In this paper, we propose an SKB-tree representation for two modern floorplaning problems: fixed-outline and voltage-island driven floorplanning. Since SKB-tree can dynamically allocate regions for blocks so that all blocks can be placed into a specific outline for each solution, it is a suitable representation for dealing with the fixed-outline constraint. Due to this good property, we also use it to deal with the voltage-island driven floorplanning. Different from previous works, we constrain blocks of the same voltage to be placed into one region to save power routing resource, simplify power planning, and reduce IR Drop. Experimental results show the feasibility of SKB-tree. For the fixed-outline constraint with zero deadspace, SKB-tree achieved significantly better wirelength than A-FP, Parquet 4.0, ZDS, and SAFFOA. SKB-tree can get better results than other fixed-outline driven floorplanners because it only needs to focus on wirelength optimization during simulated annealing. Besides, for voltage island driven floorplanning, SKB-tree also consumes less power and wirelength.