Generating pattern-based estimated RC data with analysis of route information

A method and apparatus for improving physical synthesis of a circuit design is described. In one exemplary embodiment, post-route information of nets in the circuit design is analyzed. The post-route information includes, for each of the nets, a predicted route property, a post-route property, and a set of physical and/or timing attributes for that net. For each of the attributes, a set of attribute ranges is derived for the corresponding attribute to bin the nets into a Gaussian distribution for that attribute. Net routing constraints are generated for the circuit design based on the attribute ranges derived. The net routing constraints are applied to one or more of the nets during subsequent placement-based optimizations of the circuit design.