SafeChoice: a novel clustering algorithm for wirelength-driven placement.

ABSTRACTThis paper presents SafeChoice (SC), a novel clustering algorithm for wirelength-driven placement. Unlike all previous approaches, SC is proposed based on a fundamental theorem, safe condition which guarantees that clustering would not degrade the placement wirelength. To derive such a theorem, we first introduce the concept of safe clustering, i.e., do clustering without degrading the placement quality. To check the safe condition for pair-wise clustering, we propose selective enumeration technique. SC maintains a global priority queue (PQ) based on the safeness and area of potential clusters. Iteratively the cluster at the top of the PQ is formed. SC automatically stops clustering when generating more clusters would degrade the placement wirelength. To achieve other clustering objectives, e.g., any target clustering ratio, SC is able to perform under three different modes. Comprehensive experimental results show that the clusters produced by SC consistently help the placer to achieve the best wirelength among all other clustering algorithms.