Summarizing Calling Contexts

Library developers often have to deal with client compatibility issues across versions of a library that are identical in their API specification. The reason for this can often be traced to some unspecified assumptions made by the client about the behaviour of exported library functions. Earlier work in this direction includes [4] . One could partially address this problem by analyzing the data flow across the context at which these library functions are called, i.e., through a summary of the flow of data from the function returns back to the function entry. As a first step in this direction, we present a generic method to implement a class of data flow analyses summarizing information flow across contexts. The paper is organized as follows. Section 3 defines function summaries and Weighted Push Down Systems (WPDSs) and recalls the program transformation used to model program paths by runs of the WPDS and obtain function summaries. Section 4 proposes the notion of Context Summaries and in section 4.1 describes the alternative Control Flow Graph (CFG) to WPDS transformation that is the main result of this paper. Section 5 describes the implementation of our tool and section 6 contains some experimental results. Finally, section 7 concludes with some ideas for future work. 3 Background