Using Assertions In Declarative And Operational Models For Automated Debugging

Download or read book Using Assertions in Declarative and Operational Models for Automated Debugging written by Linkoeping University. Dept. of Computer and Information Science and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "The paper presents an improved method for semi- automatic bug localization, by extending the Generalized Algorithmic Debugging Technique, GADT [Fritzson, et.al-91], which uses declarative assertions about program units such as procedures, with operational assertions about program behavior. For example, functional properties are best expressed through declarative assertions about procedure units, whereas order-dependent properties such as race conditions in parallel processing, or sequencing constraints in general, are more easily expressed using operational semantics. A powerful assertion language, called FORMAN, has been developed to this end. Such assertions can be collected into assertion-libraries, which can greatly increase the degree of automation in bug localization. The long-range goal of this work is a semi-automatic debugging and testing system which can be used during large- scale program development of non-trivial programs. The need for such automated debugging support will increase as applications on parallel architectures become more prevalent, since such programs are both harder to write and to debug, partly because of non-sequential execution semantics. Our previously developed GADT method was the first declarative algorithmic debugging technique for procedural imperative languages with side-effects. GADT is generally applicable to procedural languages, and is not dependent on any ad hoc assumptions regarding the subject program. The original form of algorithmic debugging, introduced by Shapiro [Shapiro-82], is however limited to small Prolog programs without side-effects. Another drawback of the original method is the large number of interactions with the user during bug localization. To our knowledge, the extended GADT presented here is the first method which uses powerful operational assertions in algorithmic debugging. In addition to providing support for local-level bug localization within procedures (which is not handled well by basic algorithmic debugging), the operational assertions reduce the number of irrelevant questions to the programmer during bug localization, thus further improving bug localization. Previously, we have enhanced the bug localization properties of GADT, using lookup in a category partition testing database. In addition, we use program slicing, a data flow analysis technique, to dynamically compute which parts of the program are relevant for the search. A prototype of the GADT has been implemented in Pascal, supporting debugging in a subset of Pascal. An interpreter of FORMAN assertions has also been implemented in Pascal. During bug localization, both types of assertions are evaluated on execution traces."