Build code analysis with symbolic evaluation

Build process is crucial in software development. However, the analysis support for build code is still limited. In this paper, we present SYMake, an infrastructure and tool for the analysis of build code in make. Due to the dynamic nature of make language, it is challenging to understand and maintain complex Makefiles. SYMake provides a symbolic evaluation algorithm that processes Makefiles and produces a symbolic dependency graph (SDG), which represents the build dependencies (i.e. rules) among files via commands. During the symbolic evaluation, for each resulting string value in an SDG that represents a part of a file name or a command in a rule, SYMake provides also an acyclic graph (called T-model) to represent its symbolic evaluation trace. We have used SYMake to develop algorithms and a tool 1) to detect several types of code smells and errors in Makefiles, and 2) to support build code refactoring, e.g. renaming a variable/target even if its name is fragmented and built from multiple substrings. Our empirical evaluation for SYMake's renaming on several real-world systems showed its high accuracy in entity renaming. Our controlled experiment showed that with SYMake, developers were able to understand Makefiles better and to detect more code smells as well as to perform refactoring more accurately.