Abstract: A method for resolving overlaps in the cell placement (placement legalization) during the physical design phase of an integrated chip design is described. This problem arises in several contexts within the physical design automation area including global and detailed placement, physical synthesis, and ECO (Engineering Change Order) mode for timing/design closure The method involves capturing a view of a given placement, solving a global two-dimensional area migration model and locally perturbing the cells to resolve the overlaps with minimal changes to the given placement. The method first captures a two-dimensional view of the placement including blockage-space, free-space and the given location of cells by defining physical regions. The desired global area migration across the physical regions of the placement image is determined such that it satisfies area capacity-demand constraints.

Abstract: A generalized method for optimizing the global placement of a VLSI chip across multiple cost metrics, such as total wire length, timing, congestion, and signal integrity is described. The method relies upon a “look ahead” technique, combined with any generic cost function that can be used to set placement directives. These placement directives include net weights and cell spreading. The method of performing the placement involves the iterative reuse of the process of successive partitioning. This iterative reuse establishes the capability of looking ahead to determine what is to happen. Based on the look ahead, it is possible to evaluate the qualities of the placement about to be generated. The method proceeds through the placement from while maintaining the current state of the placement along with the look-ahead state of the placement.