1. A non-transitory computer accessible memory medium comprising program instructions executable by a processor to implement a graphical user interface (GUI) for specifying implementation directives of a graphical program for deployment on a programmable hardware element, wherein the GUI is configured to: receive user input indicating the graphical program; display the graphical program, wherein the graphical program comprises a plurality of interconnected nodes that visually indicate functionality of the graphical program; display one or more nodes of the graphical program, wherein each node of the one or more nodes is configurable in accordance with a directive to generate a respective hardware implementation of the node; display one or more directives, wherein each directive specifies one or more requirements for a hardware implementation of the graphical program, wherein each directive of the one or more directives is selectable for application to a specific type of node in the graphical program; display estimated results generated by a synthesis tool in accordance with a set of selected directives; and store the set of selected directives in association with the graphical program, wherein the graphical program and the selected set of directives are useable by the synthesis tool to generate a hardware configuration program that is deployable to the programmable hardware element.