Extracting variability from C and lifting it to mbeddr

Information about variability is expressed in C through the usage of preprocessor directives which interact in multiple ways with proper C code, leading to systems difficult to understand and analyze. Lifting the variability information into a DSL to explicitly capture the features, relations among them and to the code, would substantially improve today’s state of practice. In this paper we present a study which we performed on 5 large projects (including the Linux kernel) and almost 30M lines of code on extracting variability information from C files. Our main result is that by using simple heuristics, it is possible to interpret a large portion of the variability information present in large systems. Furthermore, we show how we extracted variability information from ChibiOS, a realtime OS available on 14 different core architectures, and how we lifted that information in mbeddr, a DSL-based technology stack for embedded programing with explicit support for variability. Keywords-software product lines; abstraction lifting; embedded software; projectional editors; reverse engineering.