Program Tailoring: Slicing by Sequential Criteria

Abstract

Protocol and typestate analyses often report some sequences of
statements ending at a program point P that needs to be
scrutinized, since P may be erroneous or imprecisely
analyzed. Program slicing focuses only on the behavior at P by
computing a slice of the program affecting the values at P. In
this paper, we propose to restrict our attention to the subset of
that behavior at P affected by one or several statement
sequences, called a sequential criterion (SC). By leveraging the
ordering information in a SC, e.g., the temporal order in a few
valid/invalid API method invocation sequences, we introduce a
new technique, program tailoring, to compute a tailored program
that comprises the statements in all possible execution paths
passing through at least one sequence in SC in the given
order. With a prototyping implementation, Tailor, we show why
tailoring is practically useful by conducting two case studies on
seven large real-world Java applications. For program
debugging and understanding, Tailor can complement program
slicing by removing SC-irrelevant statements. For program
analysis, Tailor can enable a pointer analysis, which is
unscalable to a program, to perform a more focused and therefore
potentially scalable analysis to its specific parts containing
hard language features such as reflection.