Debugging Maude programs via runtime assertion checking and trace slicing

Abstract

In this paper we propose a dynamic analysis methodology for improving the diagnosis of erroneous Maude programs. The key idea is to combine runtime checking and dynamic trace slicing for automatically catching errors at runtime while reducing the size and complexity of the erroneous traces to be analyzed (i.e., those leading to states failing to satisfy some of the assertions). First, we formalize a technique that is aimed at automatically detecting deviations of the program behavior (symptoms) with respect to two types of user-defined assertions: functional assertions and system assertions. The proposed dynamic checking is provably sound in the sense that all errors flagged are definitely violations of the specifications. Then, upon eventual assertion violations we generate accurate trace slices that help identify the cause of the error. Our methodology is based on (i) a logical notation for specifying assertions that are imposed on execution runs; (ii) a runtime checking technique that dynamically tests the assertions; and (iii) a mechanism based on (equational) least general generalization that automatically derives accurate criteria for slicing from falsified assertions. Finally, we report on an implementation of the proposed technique in the assertion-based, dynamic analyzer ABETS and show how the forward and backward tracking of asserted program properties leads to a thorough trace analysis algorithm that can be used for program diagnosis and debugging

Assertion-based analysis via slicing withABETS(system description)

“…Unlike the original trace slicing methodology of where the slicing criterion must be manually determined in advance by the user, ABETS encompasses a runtime assertion-checking mechanism (which is built on top of the slicing engine) that was originally formalized in (Alpuente et al 2016) and preserves the program semantics. This mechanism allows the slicing criteria to be automatically inferred from falsified assertions, thereby offering more automatic support to the analysis of erroneous programs and traces.…”

“…the assertions (Alpuente et al 2016). ABETS is also provided with an automatic program repair facility, which is described in Section 3.2, that suggests fixes to potentially buggy rewrite rules whenever it detects a faulty system state of a trace T that does not satisfy a system assertion S{ϕ}.…”

“…st('S1, 10),st('S2, -2) Several extra features, described in (Alpuente et al 2016), are: (i) an incremental trace slicing capability that allows the computed trace slices to be further simplified by automatically applying backward as well as forward trace slicing w.r.t. user-provided slicing criteria refinements (Alpuente et al 2015); (ii) a program slicing feature for delivering program fragments that include all and only the rules/equations responsible for the detected error.…”

“…The dynamic analyzer ABETS described in this paper facilitates the debugging of Maude programs. It does this by drastically simplifying the size and complexity of the analyzed programs and runs while still showing all relevant information for debugging, which is done by a fruitful combination of runtime assertion checking and slicing that was originally formalized in (Alpuente et al 2016). In assertion-based slicing, the user supplements the Maude program to be analyzed with a set of logical assertions that are checked at runtime.…”

“…The basic algorithms behind ABETS were introduced in (Alpuente et al 2016), where we evaluated them on a prototype implementation of the system. This work describes the latest, fully-fledged ABETS implementation, which improves system efficiency as well as the generality/flexibility of the overall technique.…”