One embodiment of the present invention provides a system that facilitates placing
flip-flops in an integrated circuit based on timing requirements. The system operates
by first receiving a netlist for flip-flop connectivity. Next, the system determines
a metal layer class definition for each signal in the netlist based upon timing
requirements of a corresponding flip-flop. The system then classifies a flip-flop
instance using the metal layer class definition by defining a flip-flop type for
each flip-flop instance and associating the flip-flop with a group of other flip-flops
that have a same metal layer class definition. Finally, determining a position
for the group by replacing an existing repeater in the integrated circuit with
the group of flip-flops.
