1. A method, comprising: recognizing an original hardware description language (HDL) file prescribing an original logic; recognizing an original netlist incorporating said original logic; recognizing a new HDL file prescribing a new logic, wherein said new logic comprises a desired logic change relative to said original logic, wherein said original HDL file and said new HDL file both comprise signals; adding a user hint to both said original HDL file and said new HDL file when one of said signals is different between said new HDL file and said original HDL file; synthesizing a delta netlist using said original HDL file, said original netlist, said new HDL file, and said user hint; and inserting said delta netlist into said original netlist, whereupon said original netlist is incorporating said new logic.