Specialization of Run-time Configuration Space at Compile-time: An Exploratory Study

Numerous software systems are highly configurable through run-time options, such as command-line parameters. Users can tune some of the options to meet various functional and non-functional requirements such as footprint, security, or execution time. However, some options are never set for a given system instance, and their values remain the same whatever the use cases of the system. Herein, we design a controlled experiment in which the system's run-time configuration space can be specialized at compile-time and combinations of options can be removed on demand. We perform an in-depth study of the well-known x264 video encoder and quantify the effects of its specialization to its non-functional properties, namely on binary size, attack surface, and performance while ensuring its validity. Our exploratory study suggests that the configurable specialization of a system has statistically significant benefits on most of its analysed non-functional properties, which benefits depend on the number of the debloated options. While our empirical results and insights show the importance of removing code related to unused run-time options to improve software systems, an open challenge is to further automate the specialization process.