Browsing by Author "Tabakov, Deian"

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    Dynamic Assertion-Based Verification for SystemC
    (2011) Tabakov, Deian; Vardi, Moshe Y.
    SystemC has emerged as a de facto standard modeling language for hardware and embedded systems. However, the current standard does not provide support for temporal specifications. Specifically, SystemC lacks a mechanism for sampling the state of the model at different types of temporal resolutions, for observing the internal state of modules, and for integrating monitors efficiently into the model's execution. This work presents a novel framework for specifying and efficiently monitoring temporal assertions of SystemC models that removes these restrictions. This work introduces new specification language primitives that (1) expose the inner state of the SystemC kernel in a principled way, (2) allow for very fine control over the temporal resolution, and (3) allow sampling at arbitrary locations in the user code. An efficient modular monitoring framework presented here allows the integration of monitors into the execution of the model, while at the same time incurring low overhead and allowing for easy adoption. Instrumentation of the user code is automated using Aspect-Oriented Programming techniques, thereby allowing the integration of user-code-level sample points into the monitoring framework. While most related approaches optimize the size of the monitors, this work focuses on minimizing the runtime overhead of the monitors. Different encoding configurations are identified and evaluated empirically using monitors synthesized from a large benchmark of random and pattern temporal specifications. The framework and approaches described in this dissertation allow the adoption of assertion-based verification for SystemC models written using various levels of abstraction, from system level to register-transfer level. An advantage of this work is that many existing specification languages call be adopted to use the specification primitives described here, and the framework can easily be integrated into existing implementations of SystemC.
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    Experimental evaluation of explicit and symbolic automata-theoretic algorithms
    (2006) Tabakov, Deian; Vardi, Moshe Y.
    The automata-theoretic approach to the problem of program verification requires efficient minimization and complementation of nondeterministic finite automata. This work presents a direct empirical comparison of well-known automata minimization algorithms, and also of a symbolic and an explicit approach to complementing automata. I propose a probabilistic framework for testing the performance of automata-theoretic algorithms, and use it to compare empirically Brzozowski's and Hopcroft's minimization algorithms. While Hopcroft's algorithm has better overall performance, the experimental results show that Brzozowski's algorithm performs better for "high-density" automata. In this work I also analyze complementation by considering automaton universality as a model-checking problem. A novel encoding presented here allows this problem to be solved symbolically via a model-checker. I compare the performance of this approach to that of the standard explicit algorithm which is based on the subset construction, and show that the explicit approach unexpectedly performs an order of magnitude better.