ISSN:1040-550X    

DOI:10.1002/smr.4360070302

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractProgram slicing can be used to aid in a variety of software maintenance activities including code understanding, code testing, debugging, and program re‐engineering. Program slicing (as well as other program analysis functions including ripple analysis) can be efficiently performed on an internal program representation called asystem dependence graph(SDG). This paper will describe a new method for calculating transitive dependencies in the presence of recursion. This method requires neither the (explicit) calculation of the GMOD and GREF sets nor the construction of a linkage grammar and the corresponding subordinate characteristic graphs of the linkage grammar's nonterminals. Additionally, a beneficial side effect of this method is that it provides us with a new method for performinginterprocedural, flow‐sensitive data flow analysis.Finally, this paper will illustrate the versatility of the SDG as an internal program representation by briefly describing a tool that we have developed that permits slicing, dicing, ripple analysis, and other static analysis functions to be performed on programs written in a subset of ANSI C (e.g., C withoutgotosandpointe

ISSN:1040-550X    

DOI:10.1002/smr.4360070303

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractInterprocedural dataflow analysis is useful in compiler optimization, automatic vectorization and parallelization, dataflow anomaly detection, and software maintenance applications such as program revalidation, and software tools that make a program more understandable by showing data dependencies. These applications require the solution of dataflow problems such as reaching definitions, live variables, available expressions, and definition‐use chains. When solving these problems interprocedurally, the context of each call must be taken into account. In this paper, a method to solve this kind of dataflow problem is presented. This method consists of special dataflow equations that are solved for a program flowgraph. In deference to calling context, separate sets, calledentryandbodysets, are maintained at each node in the flowgraph. The entry set contains calling‐context effects that enter a procedure. The body set contains effects that result from statements in the procedure. By isolating calling‐context effects in the entry set, a call's nonkilled calling context is preserved by means of a simple intersection operation done at the return node for that call. The main advantages of this method are its precision and low complexity, and the fact that the presence of recursion does not affect the accuracy of the r

ISSN:1040-550X    

DOI:10.1002/smr.4360070304

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA method is described for obtaining useful information from legacy code. The approach uses formal proven program transformations, which preserve or refine the semantics of a construct while changing its form. The applicability of a transformation in a particular syntactic context is checked before application. By using an appropriate sequence of transformations, the extracted representation is guaranteed to be equivalent to the code. In this paper, we focus on the results of using this approach in the reverse‐engineering of medium‐scale, industrial software, written mostly in languages such as assembler and JOVIAL. Results from both benchmark algorithms and heavily modified, geriatric software are summarized. It is concluded that the approach is viable, for self‐contained code, and that useful design information may be extracted from legacy systems at economic cost. We conclude that formal methods have an important practical role in the reverse‐engineering

ISSN:1040-550X    

DOI:10.1002/smr.4360070305

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:1040-550X    

DOI:10.1002/smr.4360070306

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:1040-550X    

DOI:10.1002/smr.4360070301

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY