Abstract: Examples herein describe techniques for optimizing a hardware design for an integrated circuit. Instead of trying multiple optimization strategies each time design code is synthesized, the embodiments herein describe identifying the optimal or best optimization strategy for a particular combinational module in the design code only one time. Then, each time the design code is synthesized in the future, a synthesis tool recognizes the combinational module and selects the best optimization strategy. To do so, the synthesis tool generates a signature using the circuit structure represented by a netlist. The synthesis tool traverses the netlist and assigns unique integers to the primary inputs, the combination instances, and the primary outputs. These integers can then be fed into a signature generator which outputs a signature for the combinational module.