Uncovering dependence clusters and linchpin functions

Abstract

Abstract-Dependence clusters are (maximal) collections of mutually dependent source code entities according to some dependence relation. Their presence in software complicates many maintenance activities including testing, refactoring, and feature extraction. Despite several studies finding them common in production code, their formation, identification, and overall structure are not well understood, partly because of challenges in approximating true dependences between program entities. Previous research has considered two approximate dependence relations: a fine-grained statement-level relation using control and data dependences from a program's System Dependence Graph and a coarser relation based on function-level controlflow reachability. In principal, the first is more expensive and more precise than the second.Using a collection of twenty programs, we present an empirical investigation of the clusters identified by these two approaches.In support of the analysis, we consider hybrid cluster types that works at the coarser function-level but is based on the higher-precision statement-level dependences. The three types of clusters are compared based on their slice sets using two clustering metrics. We also perform extensive analysis of the programs to identify linchpin functions -functions primarily responsible for holding a cluster together. Results include evidence that the less expensive, coarser approaches can often be used as effective proxies for the more expensive, finer-grained approaches.Finally, the linchpin analysis shows that linchpin functions can be effectively and automatically identified.

An empirical study on dependence clusters for effort-aware fault-proneness prediction

“…Binkley et al [7] compared the following two types of dependence clusters: slice-based dependence clusters at the statement-level and SEA-based dependence clusters at the function-level. They found that the less expensive SEAbased dependence clusters could be used as an effective proxy for the more expensive slice-based dependence clusters.…”

“…The concept of a dependence cluster was originally introduced by Binkley and Harman [8]. They treat program statements as basic units, however, they note that dependence clusters can be also defined at coarser granularities, such as at the function-level [7]. For a given program, the identification of function-level dependence clusters consists of two steps.…”

“…In functionlevel dependence clusters, functions are regarded as the basic units and each cluster consists of at least two functions. According to Binkley et al [7], the function-level dependence clusters can offer an effective proxy for the more expensive statement-level dependence clusters.…”