A trajectory-based strict semantics for program slicing

We define a program semantics that is preserved by dependence-based slicing algorithms. It is a natural extension, to non-terminating programs, of the semantics introduced by Weiser (which only considered terminating ones) and, as such, is an accurate characterisation of the semantic relationship between a program and the slice produced by these algorithms. Unlike other approaches, apart from Weiser’s original one, it is based on strict standard semantics which models the ‘normal’ execution of programs on a von Neumann machine and, thus, has the advantage of being intuitive. This is essential since one of the main applications of slicing is program comprehension. Although our semantics handles non-termination, it is defined wholly in terms of finite trajectories, without having to resort to complex, counter-intuitive, non-standard models of computation. As well as being simpler, unlike other approaches to this problem, our semantics is substitutive. Substitutivity is an important property becauseit greatly enhances the ability to reason about correctness of meaning-preserving program transformations such as slicing

srcSlice: very efficient and scalable forward static slicing

A highly efficient lightweight forward static slicing approach is presented and evaluated. The approach does not compute the program/system dependence graph but instead dependence and control information is com-puted as needed while computing the slice on a variable. The result is a list of line numbers, dependent vari-ables, aliases, and function calls that are part of the slice for all variables (both local and global) for the entire system. The method is implemented as a tool, called srcSlice, on top of srcML, an XML representation of source code. The approach is highly scalable and can generate the slices for all variables of the Linux kernel in approximately 20min on a typical desktop. Benchmark results are compared with the CodeSurfer slicing tool from GrammaTech Inc., and the approach compares well with regard to accuracy of slices. Copyright

Formalizing executable dynamic and forward slicing.

This paper uses a projection theory of slicing to formalize the definition of executable dynamic and forward program slicing. Previous definitions, when given, have been operational, and previous descriptions have been algorithmic. The projection framework is used to provide a declarative formulation in terms of the different equivalences preserved by the different forms of slicing.The analysis of dynamic slicing reveals that the slicing criterion introduced by Korel and Laski contains three inter-woven criteria. It is shown how these three conceptually distinct criteria can be disentangled to reveal two new criteria. The analysis of dynamic slicing also reveals that the subsumes relationship between static and dynamic slicing is more intricate that previous authors have claimed.Finally, the paper uses the projection theory to investigate theoretical properties of forward slicing. This is achieved by first re-formulating forward slicing to provide an executable forward slice. This definition allows for formal investigation of the relationship between forward and backward slicing

Formalizing executable dynamic and forward slicing

This paper uses a projection theory of slicing to formalize the definition of executable dynamic and forward program slicing. Previous definitions, when given, have been operational, and previous descriptions have been algorithmic. The projection framework is used to provide a declarative formulation in terms of the different equivalences preserved by the different forms of slicing. The analysis of dynamic slicing reveals that the slicing criterion introduced by Korel and Laski contains three inter-woven criteria. It is shown how these three conceptually distinct criteria can be disentangled to reveal two new criteria. The analysis of dynamic slicing also reveals that the subsumes relationship between static and dynamic slicing is more intricate that previous authors have claimed. Finally, the paper uses the projection theory to investigate theoretical properties of forward slicing. This is achieved by first re-formulating forward slicing to provide an executable forward slice. This definition allows for formal investigation of the relationship between forward and backward slicing. 1