The multilevel placement package mPL6 combines improved implementations of the global placer mPL5 (ISPD05) and the XDP legalizer and detailed placer (ASPDAC06). It consistently produces robust, high-quality solutions to difficult instances of mixed-size placement in fast and scalable run time. Best-choice clustering (ISPD05) is used to construct a hierarchy of problem formulations. Generalized force-directed placement guides global placement at each level of the cluster hierarchy. During the declustering pass from coarsest to finest level, large movable objects are gradually fixed in positions without overlapping with one another. This progressive legalization of large objects during continuous optimization supports determination of a completely overlap-free configuration as close as possible to the continuous solution. Various discrete heuristics are applied to this legalized placement in order to improve the final wirelength.
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