Towards scalable compositional analysis by refactoring design models

Abstract

Automated finite-state verification techniques have matured considerably in the past several years, but state-space explosion remains an obstacle to their use. Theoretical lower bounds on complexity imply that all of the techniques that have been developed to avoid or mitigate state-space explosion depend on models that are "well-formed" in some way, and will usually fail for other models. This further implies that, when analysis is applied to models derived from designs or implementations of actual software systems, a model of the system "as built" is unlikely to be suitable for automated analysis. In particular, compositional, hierarchical analysis (where state-space explosion is avoided by simplifying models of subsystems at several levels of abstraction) depend on the modular structure of the model to be analyzed. We describe how as-built finite-state models can be refactored for compositional state-space analysis, applying a series of transformations to produce an equivalent model whose structure exhibits suitable modularity. The process is supported by a parser which can parse a subset of Promela syntax and transform Promela code into refactored state graphs.

An enhanced flow analysis technique for detecting unreachability faults in concurrent systems

“…7(b) that the action stop is, in fact, unreachable. 5 There is no way to efficiently enumerate all execution paths because the enumeration problem is exponential in complexity. In the proposed technique, we only aim at a balance between practicality and completeness.…”

Crafting a Promela Front-End with Abstract Data Types to Mitigate the Sensitivity of (Compositional) Analysis to Implementation Choices

“…That is, no feasible subsystems and composing hierarchies exist in this structure, particularly when client number is large. In [4,5], we proposed an approach called model refactoring to enable compositional analysis for systems which are originally prohibited by their as-built architecture. The refactoring consists a set of transformations.…”

“…In [5], we described the basic tool support 3 for refactoring and showed that a refactored elevator system can be analyzed up to hundreds of elevators but global analysis and compositional analysis (without refactoring) can only analyze up to 4 elevators.…”

“…This behavior can be effectively transformed by refactoring (It uses value processes to model value change for each array element e1_lst [i]. Readers who are interested in these technical details, please refer to [5]). …”