PROGRAM SLICING TECHNIQUES AND ITS APPLICATIONS

Program understanding is an important aspect in Software Maintenance and Reengineering. Understanding the program is related to execution behaviour and relationship of variable involved in the program. The task of finding all statements in a program that directly or indirectly influence the value for an occurrence of a variable gives the set of statements that can affect the value of a variable at some point in a program is called a program slice. Program slicing is a technique for extracting parts of computer programs by tracing the programs’ control and data flow related to some data item. This technique is applicable in various areas such as debugging, program comprehension and understanding, program integration, cohesion measurement, re-engineering, maintenance, testing where it is useful to be able to focus on relevant parts of large programs. This paper focuses on the various slicing techniques (not limited to) like static slicing, quasi static slicing, dynamic slicing and conditional slicing. This paper also includes various methods in performing the slicing like forward slicing, backward slicing, syntactic slicing and semantic slicing. The slicing of a program is carried out using Java which is a object oriented programming language

Slicing of Object-Oriented Software

Software maintenance activities generally account for more than one third of time during the software development cycle. It has been found out that certain regions of a program can cause more damage than other regions, if they contain bugs. In order to find these high-risk areas, we use slicing to obtain a static backward slice of a program. Our project deals with the implementation of different intermediate graphical representations for an input source program such as the Control Dependence Graph, the Program Dependence Graph, the Class Dependence Graph and the System Dependence Graph. Once a graphical representation of an input program is obtained, slicing is performed on the program using its System Dependence Graph and a two pass graph reachability algorithm proposed by Horwitz, to obtain a static backward slice

Analysis of Slice-Based Metrics for Aspect-Oriented Programs

To improve separation of concerns in software design and implementation, the technique of Aspect-Oriented Programming (AOP) was introduced. But AOP has a lot of features like aspects, advices, point-cuts, join-points etc., and because of these the usage of the existing intermediate graph representations is rendered useless. In our work we have defined a new intermediate graph representation for AOP. The construction of SDG is automated by analysing the bytecode of aspect-oriented programs that incorporates the representation of aspect-oriented features. After constructing the SDG, we propose a slicing algorithm that uses the intermediate graph and computes slices for a given AOP. Program slicing has numerous applications in software engineering activities like debugging, testing, maintenance, model checking etc. To implement our proposed slicing technique, we have developed a prototype tool that takes an AOP as input and compute its slices using our proposed slicing algorithm. To evaluate our proposed technique, we have considered some case studies by taking open source projects. The comparative study of our proposed slicing algorithm with some existing algorithms show that our approach is an efficient and scalable approach of slicing for different applications with respect to aspect-oriented programs. Software metrics are used to measure certain aspects of software. Using the slicing approach we have computed eight software metrics which quantitatively and qualitatively analyse the whole aspect project. We have compiled a metrics suite for AOP and an automated prototype tool is developed for helping the process of SDLC

Dynamic Slicing of Object-Oriented Programs

Software maintenance activity is one of the most important part of software development cycle. Certain regions of a program cause more damage than other regions resulting in errors, if they contain bugs. So, it is important to debug and find those areas. We use slicing criteria to obtain a static backward slice of a program to find these areas. An intermediate graphical representation is obtained for an input source program such as the Program Dependence Graph, the Class Dependence Graph and the System Dependence Graph. Slicing is performed on the System Dependence Graph using a two pass graph reachability algorithm proposed by Horwitz[3], and a static backward slice is obtained. After obtaining static slice, dynamic slice is calculated for the given input variable using an algorithm where in a statement, a set of variables and the input values for these variables are taken as input and a dynamic slice is obtained

Forward dynamic slicing

Program slicing is a very important part of program development and maintenance . It is used for a number of applications such as program debugging, reverse engineering, software testing, software maintenance, etc. It is a programmer’s most important tool for debugging. We have come a long way since Weiser first introduced the concept of slicing. Initially, static slices were used but now mainly dynamic slices are being used. Programmers worldwide are busy trying to develop better and more efficient slicing techniques. In this paper we have proposed a new precise forward dynamic slicing algorithm.Our algorithm is based on marking and unmarking the stable and unstable edges in the PDG according to their execution. We have calculated slices by using intermediate representation in the form of program dependency graph(PDG). We have intoduced modified notions of stable and unstable edges and used them to draw MPDG(Modified Program Dependency Graph). We have tested our algorithm by taking two sample programs. Our research has been confined to simple C and C++ programs

Identifying reusable functions in code using specification driven techniques

The work described in this thesis addresses the field of software reuse. Software reuse is widely considered as a way to increase the productivity and improve the quality and reliability of new software systems. Identifying, extracting and reengineering software. components which implement abstractions within existing systems is a promising cost-effective way to create reusable assets. Such a process is referred to as reuse reengineering. A reference paradigm has been defined within the RE(^2) project which decomposes a reuse reengineering process in five sequential phases. In particular, the first phase of the reference paradigm, called Candidature phase, is concerned with the analysis of source code for the identification of software components implementing abstractions and which are therefore candidate to be reused. Different candidature criteria exist for the identification of reuse-candidate software components. They can be classified in structural methods (based on structural properties of the software) and specification driven methods (that search for software components implementing a given specification).In this thesis a new specification driven candidature criterion for the identification and the extraction of code fragments implementing functional abstractions is presented. The method is driven by a formal specification of the function to be isolated (given in terms of a precondition and a post condition) and is based on the theoretical frameworks of program slicing and symbolic execution. Symbolic execution and theorem proving techniques are used to map the specification of the functional abstractions onto a slicing criterion. Once the slicing criterion has been identified the slice is isolated using algorithms based on dependence graphs. The method has been specialised for programs written in the C language. Both symbolic execution and program slicing are performed by exploiting the Combined C Graph (CCG), a fine-grained dependence based program representation that can be used for several software maintenance tasks

Regression test selection model: a comparison between ReTSE and pythia

As software systems change and evolve over time regression tests have to be run to validate these changes. Regression testing is an expensive but essential activity in software maintenance. The purpose of this paper is to compare a new regression test selection model called ReTSE with Pythia. The ReTSE model uses decomposition slicing in order to identify the relevant regression tests. Decomposition slicing provides a technique that is capable of identifying the unchanged parts of a system. Pythia is a regression test selection technique based on textual differencing. Both techniques are compare using a Power program taken from Vokolos and Frankl’s paper. The analysis of this comparison has shown promising results in reducing the number of tests to be run after changes are introduced

System dependence graphs in sequential Erlang

The system dependence graph (SDG) is a data structure used in the imperative paradigm for different static analysis, and particularly, for program slicing. Program slicing allows us to determine the part of a program (called slice) that influences a given variable of interest. Thanks to the SDG, we can produce precise slices for interprocedural programs. Unfortunately, the SDG cannot be used in the functional paradigm due to important features that are not considered in this formalism (e.g., pattern matching, higher-order, composite expressions, etc.). In this work we propose the first adaptation of the SDG to a functional language facing these problems. We take Erlang as the host language and we adapt the algorithms used to slice the SDG to produce precise slices of Erlang interprocedural programs. As a proof-of-concept, we have implemented a program slicer for Erlang based on our SDGs.This work has been partially supported by the Spanish Ministerio de Ciencia e Innovaci´on under grant TIN2008-06622-C03-02 and by the Generalitat Valenciana under grant PROMETEO/2011/052. Salvador Tamarit was partially supported by the Spanish MICINN under FPI grant BES-2009-015019Silva Galiana, JF.; Tamarit Muñoz, S.; Tomás Franco, C. (2012). System dependence graphs in sequential Erlang. En Fundamental Approaches to Software Engineering. Springer Verlag (Germany). 486-500. https://doi.org/10.1007/978-3-642-28872-2_33S486500Agrawal, H., Horgan, J.R.: Dynamic program slicing. In: Programming Language Design and Implementation (PLDI), pp. 246–256 (1990)Brown, C.: Tool Support for Refactoring Haskell Programs. PhD thesis, School of Computing, University of Kent, Canterbury, Kent, UK (2008)Cheda, D., Silva, J., Vidal, G.: Static slicing of rewrite systems. Electron. Notes Theor. Comput. Sci. 177, 123–136 (2007)Ferrante, J., Ottenstein, K.J., Warren, J.D.: The Program Dependence Graph and Its Use in Optimization. ACM Transactions on Programming Languages and Systems 9(3), 319–349 (1987)Field, J., Ramalingam, G., Tip, F.: Parametric program slicing. In: Proceedings of the 22nd ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, POPL 1995, pp. 379–392. ACM, New York (1995)Horwitz, S., Reps, T., Binkley, D.: Interprocedural slicing using dependence graphs. ACM Transactions Programming Languages and Systems 12(1), 26–60 (1990)Korel, B., Laski, J.: Dynamic Program Slicing. Information Processing Letters 29(3), 155–163 (1988)Larsen, L., Harrold, M.J.: Slicing object-oriented software. In: Proceedings of the 18th International Conference on Software Engineering, ICSE 1996, pp. 495–505. IEEE Computer Society, Washington, DC (1996)Liang, D., Harrold, M.J.: Slicing objects using system dependence graphs. In: Proceedings of the International Conference on Software Maintenance, ICSM 1998, pp. 358–367. IEEE Computer Society, Washington, DC (1998)Lindahl, T., Sagonas, K.F.: Typer: a type annotator of erlang code. In: Sagonas, K.F., Armstrong, J. (eds.) Erlang Workshop, pp. 17–25. ACM (2005)Lindahl, T., Sagonas, K.F.: Practical type inference based on success typings. In: Bossi, A., Maher, M.J. (eds.) PPDP, pp. 167–178. ACM (2006)Ochoa, C., Silva, J., Vidal, G.: Dynamic slicing based on redex trails. In: Proceedings of the 2004 ACM SIGPLAN Symposium on Partial Evaluation and Semantics-Based Program Manipulation, PEPM 2004, pp. 123–134. ACM, New York (2004)Reps, T., Turnidge, T.: Program Specialization via Program Slicing. In: Danvy, O., Thiemann, P., Glück, R. (eds.) Dagstuhl Seminar 1996. LNCS, vol. 1110, pp. 409–429. Springer, Heidelberg (1996)Rodrigues, N.F., Barbosa, L.S.: Component identification through program slicing. In: Proc. of Formal Aspects of Component Software (FACS 2005). Elsevier ENTCS, pp. 291–304. Elsevier (2005)Tip, F.: A survey of program slicing techniques. Journal of Programming Languages 3(3), 121–189 (1995)Tóth, M., Bozó, I., Horváth, Z., Lövei, L., Tejfel, M., Kozsik, T.: Impact Analysis of Erlang Programs Using Behaviour Dependency Graphs. In: Horváth, Z., Plasmeijer, R., Zsók, V. (eds.) CEFP 2009. LNCS, vol. 6299, pp. 372–390. Springer, Heidelberg (2010)Walkinshaw, N., Roper, M., Wood, M., Roper, N.W.M.: The java system dependence graph. In: Third IEEE International Workshop on Source Code Analysis and Manipulation, p. 5 (2003)Weiser, M.: Program Slicing. In: Proceedings of the 5th International Conference on Software Engineering, pp. 439–449. IEEE Press (1981)Widera, M.: Flow graphs for testing sequential erlang programs. In: Proceedings of the 2004 ACM SIGPLAN Workshop on Erlang, ERLANG 2004, pp. 48–53. ACM, New York (2004)Widera, M., Informatik, F.: Concurrent erlang flow graphs. In: Proceedings of the Erlang/OTP User Conference (2005)Zhao, J.: Slicing aspect-oriented software. In: Proceedings of the 10th International Workshop on Program Comprehension, IWPC 2002, pp. 251–260. IEEE Computer Society, Washington, DC (2002

Utilizing the notion of removable blocks to enhance program slicing algorithms

Program slicing is a program decomposition technique that transforms a large program into a smaller one that contains only statements relevant to the computation of a selected function. Applications of program slicing can be found in software testing, debugging and maintenance where program slicing essentially reduces the amount of data that has to be analyzed in order to comprehend a program or parts of its functionality. In this thesis, two program slicing algorithms based on the notion of removable blocks are presented and they are (1) a general static program slicing algorithm and (2) criterion based hybrid program slicing algorithm. The thesis introduced new syntax tree representation using removable blocks and theorized a new navigation technique for the same. The new static slicing algorithm combined with the enhanced dynamic slicing algorithm is used to derive the criterion based hybrid slicing algorithm. The hybrid program slicing algorithm allows the user to define the range of accuracy between static and dynamic program slicing. These algorithms compute slices that are executable for structured and object-oriented programs. It uses the executable property of new static slicing to reduce the input source code to dynamic slicing to save the time and space. The introduced program slicing approaches are part of M[barbelow]ontreal O[barbelow]bject-O[barbelow]riented S[barbelow]licing E[barbelow]nvironment (MOOSE). MOOSE utilizes the information derived from the program slicing algorithms to enhance the functionality and usability of the framework. The preliminary tests with the basic hybrid program slicing algorithm indicate that hybrid program slicing can reduce the algorithmic time and space for the slice computation as compared to the dynamic program slicing