Development of Semantic Debuggers Based on Refinement Calculus

Abstract

Translation validation based on refinement mappings has been effectively used for validating compiled programs [1,2]. Debugging programs is a very important stage in the software development cycle. An important issue for the debugger-user communication aspect is that of transparency which is the illusion wherein the user gets an impression that he is debugging his source. A debugger is said to exhibit transparent behaviour if it returns exactly the same response for all requests as it would if the target program were not optimized. A debugger that behaves differently for an optimized program exhibits non-transparent behaviour. Various approaches have been envisaged in [3] for debugging optimized programs. In this paper, we show how we can use the methodology of translation validation of optimized programs to design and develop semantic transparent debuggers that permits modifications of variables only if consistent. Our approach uses the proof rule for validating optimized programs described in [4]. Further, we have been able to automate the process of validation and build prototype debuggers in Prolog.