FOARS: FLUTE Based Obstacle-Avoiding Rectilinear Steiner Tree Construction

Abstract

Obstacle-avoiding rectilinear Steiner minimal tree (OARSMT) construction is becoming one of the most sought after problems in modern design flow. In this paper we present FOARS, an algorithm to route a multi-terminal net in the presence of obstacles. FOARS is a top down approach which includes partitioning the initial solution into subproblems and using obstacle aware version of Fast Lookup Table based Wirelength Estimation (OA-FLUTE) at a lower level to generate an OAST followed by recombining them with some backend refinement. To construct an initial connectivity graph FOARS uses a novel obstacle-avoiding spanning graph (OASG) algorithm which is a generalization of Zhou's spanning graph algorithm without obstacle [1]. FOARS has a run time complexity of O(n log n). Our experimental results indicate that it outperforms Lin et al. [2] by 2.3% in wirelength. FOARS also has 20% faster run time as compared with Long et al. [3], which is the fastest solution till date.

An exact algorithm for the construction of rectilinear Steiner minimum trees among complex obstacles

“…The computational overhead cause by the pruning procedure is small compared to the savings in the concatenation phase. Table 1 compares the performance of some recently published heuristics [5,6,7] based on the optimal solutions provided by the proposed exact algorithm. The results are quoted from the corresponding papers.…”

“…Liu et al [6] proposed a new framework to generate OARSMT based on the critical paths, which guarantees the existence of desirable solutions. Recently, Ajwani et al [7] proposed a fast lookup table based algorithm to route a multi-terminal net in the presence of rectilinear obstacles. Their algorithm uses the obstacle-avoiding spanning graph to guide the partitioning of the initial solution and constructs the final OARSMT based on an obstacle-aware version of fast lookup table.…”

WiT: Optimal Wiring Topology for Electromigration Avoidance

“…As revealed by Ho et al, if each connection is rectilinear, wire merging with the maximum overlapping can be found by dynamic programming for a single-layer without obstacles [25]. Considering obstacles, the V-shape refinement can help [26].…”

Orthogonal Hyperedge Routing

“…Computing the MRST is NP-Complete [2] and several heuristics and exact methods are given in [5]. A number of heuristic methods have also been developed for finding obstacle-avoiding rectilinear Steiner minimal trees (OARSMTs) [1,6] for automatic connector routing in VLSI design. Our problem differs from the standard problem studied in the VLSI setting because we are interested in supporting circuit construction in an interactive diagramming tool.…”