SugarC: Scalable Desugaring of Real-World Preprocessor Usage into Pure C

Variability-aware analysis is critical for ensuring the quality of configurable C software. An important step toward the development of variability-aware analysis at scale is to transform real-world C software that uses both C and preprocessor into pure C code, by replacing the preprocessor's compile-time variability with C's runtime-variability. In this work, we design and implement a desugaring tool, SugarC, that transforms away real-world preprocessor usage. SugarC augments C's formal grammar specification with translation rules, performs simultaneous type checking during desugaring, and introduces numerous optimizations to address challenges that appear in real-world preprocessor usage. The experiments on DesugarBench, a benchmark consisting of 108 manually-created programs, show that SugarC supports many more language features than two existing desugaring tools. When applied on three real-world configurable C software, SugarC desugared 774 out of 813 files in the three programs, taking at most ten minutes in the worst case and less than two minutes for 95% of the C files.