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

TL;DR

This study explores how specializing software configurations at compile-time by removing unused options can significantly improve non-functional properties like size, security, and performance, demonstrated through experiments on the x264 encoder.

Contribution

It introduces a controlled experiment framework for compile-time specialization of run-time options and quantifies its benefits on a real-world video encoder.

Findings

Specialization reduces binary size and attack surface.

Performance improvements are observed with fewer options.

Benefits depend on the number of options removed.

Abstract

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.