A method to transform the function of a circuit is provided. The method provides a first register-transfer level (RTL) document and a second RTL document, provides a first gate level (GTL) netlist and a second GTL netlist, compares the two RTL documents to identify the instances to be modified, locates the instances to be modified in the first GTL netlist, and transforms the function of the circuit by patching the circuit such that the patched first GTL netlist is equivalent to the second GTL netlist. The method improves performance and efficiency of the transformation by reducing the number of instances to be input into the engineering change order (ECO) engine, and also minimizes change in circuit design.