Abstract: Methods and apparatus of performing floorplanning and routing for function blocks within a die and among multiple die are disclosed. Multiple die together with function blocks within each die may be represented by a flexible hierarchical (FH) tree. An initial floorplan for multiple die may be generated and hot spots between die or among function blocks within a die may be identified. Spacer blocks may be inserted between die, and block inflation may be performed, to remove hot spots. More perturbation of the block positions can be performed on the FH tree to rearrange the blocks and die. After the multiple die floorplanning, a plurality of micro bumps may be mapped to a plurality of pins of blocks of the plurality of die, placement and routing may be performed for the plurality of blocks within each die and connections for the plurality of dies.