B. Korel and J. Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13(3):187-- 195, 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....is not dramatically smaller than the program itself the program dependencies are too coarse [11] Also, data and control flow analysis of real life programs is non trivial. For programs with pointers, the necessary points to analysis makes dependencies even more coarse [9] Dynamic slicing [3, 7, 13] is a variant of slicing that takes a concrete program run into account. The basic idea is that within a concrete run, one can determine more accurate data dependencies between variables, rather than summarizing them as in static slicing. In the dynamic slice of x # , as above, x # is dependent on ....

B. Korel and J. Laski. Dynamic slicing of computer programs. The Journal of Systems and Software, 13(3):187--195, Nov. 1990.

....Specific invariant checkers have been designed to detect illegal memory usage or array bound violations. By combining slicing with observation, one obtains dynamic slicing: a slice that is valid for a specific execution only, and hence more precise than a slice that applies for all executions [1, 6, 11]. In principle, a dynamic slicing tool does not require source code as long as it can intercept all read write accesses to program state and thus trace actual dependencies. As an example of dynamic slicing, assume that after the execution of the code above, we find that buf contains a = 0 and ....

B. Korel and J. Laski. Dynamic slicing of computer programs. The Journal of Systems and Software, 13(3):187-- 195, Nov. 1990.

....of statements. A slice is an executable subset of program statements that preserves the original behavior of the program with respect to a subset of variables of interest and at a given program point. Several variants of this notion have been proposed in the literature, such as dynamic slicing [58], quasi static slicing [83] simultaneous dynamic slicing [37] and conditioned slicing [14] Forms of slicing that are based on amore general framework of transformations, including the simple statement deletion, have also been proposed [39] This paper discusses statement deletion based slicing ....

....produced an unexpected result on some input to the program. However, a static slice may very often contain statements which have no influence on the values of the variables of interest for the particular execution in which the anomalous behavior of the program was discovered. Korel and Lasky [57, 58] proposed an alternative slicing definition, namely dynamic slicing, which uses dynamic analysis to identify all and only the statements that affect the variables of interest on the particular anomalous execution trace. In this way, the size of the slice can be considerably reduced, thus allowing ....

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B. Korel and J. Laski, "Dynamic slicing of computer programs", The Journal of Systems and Software, vol. 13, no. 3, 1990, pp. 187-195.

....architecture slices. The feasibility and the expected benefits of the approach is demonstrated through a study of part of an electronic commerce system and a run time execution of its architecture using a tool. The notion of DSAS draws on earlier work on dynamic program slicing techniques [17, 1, 10, 9] and static software architecture slicing techniques [20, 16] While a static slice is determined independently of the input at compile time, a dynamic slice is determined according to a particular input at run time, hence smaller in size than its static counterpart. In contrast to a program slice ....

.... [Korel86] Agrawal90] Type [Stafford98] Zhao97] Horwitz90] Dynamic Forward Architecture [Song99] Korel94] Table 2 Categories of related work The concept of program slicing was first proposed by Weiser [19] and later extended by Agrawal, Hogan [1] Korel and Laski [9] to dynamic program slicing so as to identify unique dynamic behavior of a program under a given input with respect to some variable of interest. Korel and Yalamanchili [10] proposed a way of computing program slices namely, forward dynamic program slicing that doesn t require the construction of ....

B. Korel and J. Laski, "Dynamic Slicing of Computer Programs", Journal of Systems Software, 1990, pp. 187--195.

....by observing execution behavior for dynamic slicing. The dynamic slicing approach can be used to approximate static slices by constructing a union of program slices for each variable in the program over a large number of test runs [14] Different dynamic slicing methods are introduced in e.g. [10], 1] In [1] Agrawal and Horgan presented a precise dynamic slicing method, which is based on the graph representation of the dynamic dependences. This graph, called Dynamic Dependence Graph (DDG) includes a distinct vertex for each occurrence of a statement. A dynamic slice created from the DDG ....

....we compute and store the set of statements that affect the currently executed instruction. This way we avoid any superfluous information (which may be unbounded) Prior to the desciption of the algorithm some basic concepts and notations are overviewed and introduced. For clarity we rely on [10] but in some cases the necessary modifications have been made. We demonstrate our concepts for dynamic slicing by applying them on the example program in Figure 1. We apply a program representation which considers only the definition and the use of variables and, in addition, it considers direct ....

B. Korel and J. Laski. Dynamic slicing in computer programs. The Journal of Systems and Software, 13(3):187-- 195, 1990.

....(V) at the program point (s) A static slice is computed by static dependence analysis without making assumptions regarding a program s input and therefore is valid for all possible executions of the program. Dynamic slicing of Programs was originally introduced by Korel and Laski in 1988 [14, 15]. In the case of dynamic slicing of programs, unlike the case of static slicing of programs where all dependences that occur in all possible executions of the program are considered, only the dependences that occur in a specific execution of the program are taken into account. There are some ....

....where all dependences that occur in all possible executions of the program are considered, only the dependences that occur in a specific execution of the program are taken into account. There are some different definitions for the notion of dynamic slice proposed based on different motivations [1 5, 8, 12 15, 19]. Originally, Korel and Laski defined a dynamic slice (of a sequential program) as an executable part of the program whose behavior is identical to that of the original program with respect to a subset of variables of interest and at execution position q. 14] Agrawal and Horgan defined a ....

B. Korel and J. Laski, "Dynamic Slicing of Computer Programs," The Journal of Systems Software, Vol. 13, pp. 187-195, 1990.

....but only to the intermediate, generated, C program. Using the approach of origin tracking, the generated C constructs will have the original preprocessor directives as origins. Program slicing. A recently introduced notion in the area of debugging and testing is that of a dynamic program slice [KL90, AH90, KSF92] A dynamic program slice is that part of the program that actually determines the value of a given variable at a given occurrence in a program. Clearly, origins describe to some extent a similar notion. We will investigate how these notions are related and whether it is possible ....

B. Korel and J. Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13:187--195, 1990.

....is regarded as the most common activity during the life time of the program. Hypotheses , at the code, algorithmic and application domain levels, are major drivers to program understanding in the corrective maintenance activities [24, 4, 14] Program slicing, both static [25, 8] and dynamic [13, 10, 1], is also a technique often used in maintenance activities such as comprehension, design recovery and risk migration. The technique was further used to identify functionalities [9] Determining slicing criteria [7] was achieved using symbolic execution [11] Another important issue in managing ....

B. Korel and J. Laski. Dynamic Slicing of Computer Program. The Journal of Systems and Software, 1990.

.... Animator sifts through all the communication between modules to find the subset that is going to or coming from the active module(s) it is a Program Slicing tool as originally defined by Weiser [Weiser81] and extensively explored by others for debugging, testing, and reengineering programs[Agrawal93, Beck93, Gallagher91, Horwitz89, Korel90, and Musa93]. However, because it operates at the architecture rather than the program level, it differs markedly from this work. First, the intellectual core of those efforts are the identification and isolation of a minimal (according to some definition) subset of the program that influenced (or might have ....

Korel, B., and Laski, J. Dynamic Slicing of Computer Programs. Journal of Systems Software 13:187-195 1990

....scenario is the result of the state changes C = # 1 , # n induced by the executed statements. Applying delta debugging to minimize C means to isolate exactly those state changes that were relevant in producing the final state very much like well known dynamic slicing techniques [1, 4, 7], but relying on partial execution rather than analysis of control and data flow and thus showing real causality instead of potential causality. As an example, consider the following PERL program. It reads in two numbers a and b and computes the sum sum = # b i =a i as well as the product ....

B. Korel and J. Laski. Dynamic slicing of computer programs. The Journal of Systems and Software, 13(3):187--195, Nov. 1990.

....is the initial assignment to the variable a. The program slice will thus consist of these two statements. The part of the program that is included in the slice is set in bold typeface in the figure. Extensive descriptions of slicing algorithms can be found in papers by Weiser [Wei84] Korel [KL88, KL90], Horwitz, Reps and Binkley [HRB88, HRB90] Agrawal [AH90, Agr91] and Kamkar [KSF92, Kam93] Main proc(7) proc(8) Figure 5. An example of an execution tree. PROGRAM AnotherExample(input,output) BEGIN a: 3; b: 7; write(b) b: a 3; END. Figure 6. A program slice for C= b: a 3, b . 6 ....

Bogdan Korel and Janusz Laski. Dynamic Slicing of Computer Programs. The Journal of Systems and Software, 13:187--195, 1990.

.... L 2 :pos 1 = 3 k B 3 :pos = L 3 :pos = 3 k B 3 :val = 2 B 3 :pos = 2 3 k L 3 :val = B 3 :val R k L 2 :val = L 3 :val B 3 :val s 1 s 2 Figure 4: Slice partitioning a statement s in a program is a set of all the statements upon which s depends, directly or indirectly [5]. In attribute grammars, attribute evaluation of a given parse tree can be considered to be a sequence of evaluation of node attributes, and we can de ne dynamic program slices for a given attribute grammar description and its input program. For example, the sequence on the right side in Fig. 4 is ....

B. Korel and J. Laski. Dynamic slicing of computer programs. J. System Software, 13:187-195, 1990.

....the results of these computations may be different yet not point to an error. For example, if the order of summation is different on these machines, then rounding errors may produce different results. For this reason, we do not consider different target machines in this context. Program slicing [4, 7, 5, 8] attempts to solve the inverse problem: given a breakpoint (and possibly a variable) find all parts of the program that were executed on the path(s) leading to this breakpoint. If the programmer has selected a specific variable, the slicing debugger may also highlight those parts of the program ....

B. Korel and J. Laski. Dynamic slicing of computer programs. J. Systems and Software, 13(3):187--195, Nov 1990.

....that revealed the error, not under any generic test case. Therefore, dynamic slicing methods are more appropriate than static ones. By using a dynamic slice many statements can be ignored in the process of localizing a bug. Different dynamic slicing methods for debugging are introduced in e.g. [12], 11] 3] In [3] Agrawal and Horgan presented a precise dynamic slicing method which is based on the graph representation of the dynamic dependences. This graph, called a Dynamic Dependence Graph (DDG) includes a distinct vertex for each occurrence of a statement. A dynamic slice created from ....

....that is a pair (i; j) which is written down as i j , where i is the serial number of the instruction at the execution position j. For example 8 7 is the action for the output statement of our example for the same input above. The first precise definition of dynamic slices can be found in [12]. In that paper Korel and Laski defined dynamic slice as an executable program which can be created from the original program by deleting some statements. It is required that for a given input the dynamic slice compute the same values as the original program for a variable v at some selected ....

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Korel, B., and Laski, J. Dynamic slicing in computer programs. The Journal of Systems and Software vol. 13, No. 3, 1990, pp. 187-195.

....at a given statement. Weiser s slicing algorithm calculates static slices, based solely on information contained in source code, by iteratively solving dataflow equations. Other techniques [15, 24, 27, 31] calculate static slices by constructing and walking dependence graphs. Korel and Laski [16] introduced dynamic slicing, in which information gathered during program execution is also used to compute slices. Whereas static slices find statements that may affect (or may be affected by) a given variable at a given point, dynamic slices find statements that may affect (or may be affected ....

....may be affected by) a given variable at a given point, dynamic slices find statements that may affect (or may be affected by) a given variable at a given point under a given execution. Dynamic slicing usually produces smaller slices than static slicing. Dynamic slices are calculated iteratively in [16]; an approach that uses program dependence graphs has also been suggested [1] A great deal of additional work has been done on program slicing. An extensive survey of slicing is given in [32] A more recent survey of dynamic slicing is given in [17] Program dicing was introduced by Lyle and ....

B. Korel and J. Laski. Dynamic slicing of computer programs. The Journal of Systems and Software, 13(3):187-- 195, November 1990.

....and program slicing[31, 19, 15, 24] Introduced by[31] a program slice represents a means of taking a snapshot of a program execution at some point to examine information about the program (variables, data flow, etc. There have been two notions of a slice commonly used: static and dynamic[1, 17, 20]. A static slice represents the set of statements that may affect the value of a variable in a given instance. In contrast, dynamic slices represent the set of statements that actually affect the value of a variable in a given instance. In addition, slices have been used to represent both ....

B. Korel and J.J. Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13(3):187--195, Nov 1990.

....18 detect program faults other than infinite loops, however, strong control dependence gives much finer slices compared to weak control dependence. The definition of datadependence remains the same in both cases. Korel and Laski extended Weiser s static slicing algorithms for the dynamic case [KL90] Their definition of a dynamic slice is different from ours (see Chapter 3) They require that if any one occurrence of a statement in the execution history is included in the slice then all other occurrences of that statement are automatically included in the slice, even when the value of the ....

Bogdan Korel and Janusz Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13(3):187--195, November 1990. 177

....decomposition slice with respect to a variable v consists of all the statement and predicates of the program that might affect the values of the variable v, regardless of any program point. Program slicing has been exploited in data flow testing, thanks to the definition of the dynamic slicing [87, 88]. A dynamic slice on a slicing criterion hX, s q out , V out i is an executable part of a program whose behaviour is identical, for the same set of input data X, to that of the original program with respect to the subset of variables of interest V out , at some execution position q 5 . ....

....quasi static slicing. Quasi static slices fall between 5 The statement s out holds the position q on the program execution path obtained with input X. static slices [133] which preserve a subset of the behaviour of the original program for all possible inputs to the slice) and dynamic slices [88] (which are constructed for a particular execution of the program and are required to preserve the subset of the behaviour of the original program for just one specific input state) Indeed, in quasi static slices some of the input values are fixed, while the behaviour of the program must be ....

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B. Korel and J. Laski, "Dynamic slicing of computer programs", The Journal of Systems and Software, vol. 13, no. 3, Nov. 1990, pp. 187-195.

....it is an overestimate of the Def Use Associations it can lead to generating unnecessary test cases, resulting in more lengthy testing. If we obtain a safe approximation to Def Use Associations solution, then only the latter situation can occur. Debuggers based on static and dynamic slicing methods [1, 19, 21, 34, 41, 43] offer the promise of efficient on line analyses of programs. The aim of slicing is to concentrate the programmer s attention on those parts of the program significant to the computation under current investigation; the more imprecise the static information, the less effectively the slicing method ....

Bogdan Korel and Janusz Laski. Dynamic slicing of computer programs. Journal of Systems Software, 13:187-- 195, 1990.

.... the slice that captures some subset of the program behavior. The slice isolated is easier to be analyzed than the original program as it represents a sub component of the whole program. Two main slicing definitions have been introduced in literature, static slicing [25] and dynamic slicing [16]. These techniques have been successfully employed for program comprehension during different maintenance tasks, like program analysis, testing, debugging. While static slicing is useful for isolating and supporting the comprehension of code implementinga functionality, dynamic slicing has been ....

.... slices of the program composed of statements which affect the computation of interest [24] A survey about program slicing techniques and their applications can be found in [21] In this section we describe two basic approaches to program slicing, called static slicing [25] and dynamic slicing [16]. The difference between them is that a static slice is defined with respect to all the execution paths of the program (both feasible and infeasible) while a dynamic slice only takes into account a particular execution path obtained from one input to the program. 2.1 Background A ....

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B. Korel and J. Laski, "Dynamic slicing of computer programs", The Jour. of Syst. and Soft., vol. 13, no. 3, Nov. 1990, pp. 187-195.

....of slices in terms of denotational semantics. He distinguishes three independent dimensions according to which slices can be categorized: static vs. dynamic, backward vs. forward, and closure vs. executable. Some of the slicing methods in the literature are classified according to these criteria [5, 41, 44, 57, 69, 85]. Moreover, Venkatesh introduces the concept of a quasi static slice. This corresponds to situations where some of the inputs of a program are fixed, and some are unknown. No constructive algorithms for computing slices are presented in [79] In [59] Lakhotia restates a number of static slicing ....

....syntactic properties of slices which can be obtained solely through graph theoretic reasoning, and semantic properties which involve interpretation of the graph representation of a slice. Although the paper only addresses static slicing methods, it is stated that the dynamic slicing methods of [5, 57] may be modeled in a similar way. 2 In fact, one might argue that the while construct may be replaced by the if statement in its body. This type of slice will be discussed in Section 5. Gupta and Soffa present a generic algorithm for static slicing and the solution of related dataflow problems ....

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Korel, B., and Laski, J. Dynamic slicing of computer programs. Journal of Systems and Software 13 (1990), 187--195.

....statically analyzing the data flow and control flow of the program. An alternative approach is to compute the slice based on graph reachability in the program dependence graph, as presented by Ottenstein and Ottenstein [51] and Horowitz, Reps, and Binkley [25] ffl Dynamic slice Korel and Laski [34] define a dynamic (executable) slice as an executable subprogram that computes the values of variables of interest for the specific test case. Their algorithm is an extension of Weiser s algorithm. In order to preserve the behavior of the original program, the dynamic executable slice includes ....

Bogdan Korel and Janusz Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13(3):187 -- 195, November 1990.

....tool based on program dicing to find the likely location of a fault. Because static program slices contain many irrelevant statements that make fault localization inefficient, studying program slicing based on dynamic cases to get the exact execution path is warranted. Dynamic Program Slicing [1, 3, 6, 25] is a powerful facility for debugging and dependency analysis. Nevertheless, it has not been systematically applied to fault localization. In Agrawal s dissertation [6] he briefly alluded to the idea of combining dynamic program slices and data slices for fault localization. Our heuristics are ....

Bogdan Korel and Janusz Laski. Dynamic slicing of computer programs. The Journal of Systems and Software, 13(3):187--195, November 1990.

....systems such as Lukey s PUDSY [Luk80] Adam s LAURA [AL80] and Jackson s ASPECT [Jac93] to identify faults by identifying discrepancies between the program and its specification. Fault localization techniques help a programmer formulate hypotheses about fault location. Program slicing techniques [Wei82, LW87, Agr91, OO84, HRB90, KL90, Ven91, YL88, Pan93] extract statements or procedures on which the specified variable or statement depends, according to predefined criteria. The programmer can select a location containing statements in a slice as his hypothesized location. Fault localization heuristics, such as Collofello and Cousins s ....

....analyzing the data flow and controlflow of the program. An alternative approach is to compute the slice based on graph reachability in the program dependence graph, as presented by Ottenstein and Ottenstein [OO84] and Horwitz, Reps, and Binkeley [HRB90] ffl Dynamic slice Korel and Laski [KL90] define a dynamic (executable) slice as an executable subprogram that computes the values of variables of interest for the specific test case. Their algorithm is an extension of Weiser s algorithm. In order to preserve the behavior of the original program, the dynamic executable slice 20 ....

Bogdan Korel and Janusz Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13(3):187--195, November 1990.

....of the feature of static program slicing. The static program slicing approach cannot resolve runtime ambiguities, thus highlights many spurious statements with no influence on the incorrect results. In this case, the faulty statements cannot be effectively identified. Korel and Laski [KL88a, KL90] extended Weiser s static program slicing to dynamic program slicing (K L slicing) K L slicing defines an executable subset of an original program that computes the same function for given variables and inputs. In this case, their approach does not show the exact influence on a particular value ....

Bogdan Korel and Janusz Laski. Dynamic slicing of computer programs. The Journal of Systems and Software, 13(3):187--195, November 1990.

....[14] can be used to derive powerful language specific debugging tools from algebraic specifications of interpreters. In particular, we show that in addition to standard debugger features such as single stepping, state inspection, and breakpoints a variation of dynamic program slicing [1, 19, 16] can be defined with surprisingly little effort. Our guiding principle is that all these tools are derived from information that is already implicitly contained in the algebraic specification, rather than requiring the specification writer to add extensive descriptions for them. Supported in ....

....calls in each record. One can easily imagine a tool that allows interactive traversal of the stack of activation records, and enables one to inspect the values of arbitrary source level expressions in each scope. 5 Dynamic Program Slicing Myriad variations on the notion of a dynamic program slice [1, 19, 16, 13] can be found in the literature [22] For the purposes of this paper, we define a dynamic slice with respect to the current value of a variable v to be the parts of the program that are necessary for obtaining the current value of v. To see why dynamic slicing is useful for debugging, consider a ....

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Korel, B., and Laski, J. Dynamic slicing of computer programs. Journal of Systems and Software 13 (1990), 187--195.

....we are interested in a slice that preserves the program behavior for a specific program input, rather than that for the set of all inputs. This type of slicing is referred to as dynamic slicing [11] Several different techniques for computation of dynamic slices have been proposed, e.g. [1, 6, 9, 13, 16]. By taking a particular program execution into account, dynamic slicing may significantly reduce the size of the slice as compared to static slicing. The notion of dynamic slicing has been also extended for distributed programs [3, 4, 14] Dynamic program slicing is not only used in software ....

.... backward analysis, i.e. after the execution trace of the program is recorded, the dynamic slicing algorithm traces backwards in the execution trace to compute the dynamic slice. For long program executions a forward approach of dynamic slice computation was proposed in [15] It has been shown [13, 18] that taking into account a particular program execution dynamic slicing may significantly reduce the size of the slice as compared to static slicing. Since dynamic program slicing is based on the actual program execution, different types of run time information about the program can be ....

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B. Korel, J. Laski, "Dynamic slicing in computer programs," The Journal of Systems and Software, vol. 13, No. 3, 1990, pp. 187-195.

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B. Korel and J. Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13(3):187-- 195, 1990.

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B. Korel and J. Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13(3):187--195, November 1990.

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B. Korel and J. Laski. Dynamic slicing in computer programs. The Journal of Systems and Software, 13(3):187-- 195, 1990.

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B. Korel and J. Laski. Dynamic slicing in computer programs. The Journal of Systems and Software, 13(3):187-- 195, 1990.

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B. Korel and J. Laski. Dynamic slicing in computer programs. Journal of Systems Software, 13(3):187--95, 1990.

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B. Korel and J. Laski. Dynamic slicing of computer programs. Journal of Systems and Software, 13(3):187-- 195, 1990.

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B. Korel and J. Laski. Dynamic slicing in computer programs. Journal of Systems Software, 13(3):187--95, 1990.

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B. Korel and J. Laski. Dynamic slicing in computer programs. Journal of Systems Software, 13(3):187--95, 1990.

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Bogdan Korel and Janusz Laski, `Dynamic slicing of computer programs', J. Systems and Software, 13(3), 187--195 (1990).

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Bogdan Korel, Janusz Laski, "Dynamic Slicing of Computer Programs", J. Systems Software 1990.

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Bogdan Korel and Janusz Laski. Dynamic slicing of computer programs. Journal of Systems Software, 13:187--195, 1990.

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