Proving Conditional Termination

Abstract. The precondition for safe execution of a procedure is useful for understanding, verifying and debugging programs. We have previously presented a cegar-based approach for inferring necessary and sufficient preconditions based on the iterative abstraction-refinement of the set of safe and unsafe states until they become disjoint. A drawback of that approach is that safe and unsafe traces are explored separately and each time they are built entirely before being checked for consistency. In this paper, we present an eager approach that explores shared prefixes between safe and unsafe traces conjointly. As a result, individual state sets, by construction, fulfil the property of separation between safe and unsafe states without requiring any refinement. Experiments using our implementation of this technique in the precondition generator P-Gen show a significant improvement compared to our previous cegar-based method. In some cases the running time drops from several minutes to several seconds.

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“…Extending it to the liveness context such as termination [6,11] is an area we are interested in for future work.…”

Section: Resultsmentioning

confidence: 99%

Necessary and Sufficient Preconditions via Eager Abstraction

Seghir

Schrammel

2014

Programming Languages and Systems

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“…In the context of termination, Bozga et al [5], proposed a method to generate exact preconditions for a restricted class of programs. Other techniques for inferring preconditions for termination are applicable to a larger set of programs [10], however they only generate sufficient preconditions.…”

Section: Resultsmentioning

confidence: 99%

Counterexample-Guided Precondition Inference

Seghir

Kroening

2013

Programming Languages and Systems

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Abstract. The precondition for an assertion inside a procedure is useful for understanding, verifying and debugging programs. As the procedure might be used in multiple calling-contexts within a program, the precondition should be sufficiently general to enable re-use. We present an extension of counterexample-guided abstraction refinement (CEGAR) for automated precondition inference. Starting with an over-approximation of both the set of safe and unsafe states, we iteratively refine them until they become disjoint. The resulting precondition is then necessary and sufficient for the validity of the assertion, which prevents false alarms. We have implemented our approach in a tool called P-Gen. We present experimental results on string and array-manipulating programs.

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“…However, there are only few methods for under-approximating analysis. In this work, we use a method similar to Cook et al [2008] to obtain under-approximating preconditions w.r.t. property p: we infer an over-approximating precondition w.r.t.…”

Section: Overview Of the Approachmentioning

confidence: 99%

Bit-Precise Procedure-Modular Termination Analysis

Chen

David

Kroening

et al. 2017

ACM Trans. Program. Lang. Syst.

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Non-termination is the root cause of a variety of program bugs, such as hanging programs and denial-ofservice vulnerabilities. This makes an automated analysis that can prove the absence of such bugs highly desirable. To scale termination checks to large systems, an interprocedural termination analysis seems essential. This is a largely unexplored area of research in termination analysis, where most effort has focussed on small but difficult single-procedure problems.We present a modular termination analysis for C programs using template-based interprocedural summarisation. Our analysis combines a context-sensitive, over-approximating forward analysis with the inference of under-approximating preconditions for termination. Bit-precise termination arguments are synthesised over lexicographic linear ranking function templates. Our experimental results show the advantage of interprocedural reasoning over monolithic analysis in terms of efficiency, while retaining comparable precision.

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Proving Conditional Termination

Abstract: Abstract. We describe a method for synthesizing reasonable underapproximations to weakest preconditions for termination-a long-standing open problem. The paper provides experimental evidence to demonstrate the usefulness of the new procedure.

Cited by 64 publications

References 26 publications

Necessary and Sufficient Preconditions via Eager Abstraction

Necessary and Sufficient Preconditions via Eager Abstraction

Counterexample-Guided Precondition Inference

Bit-Precise Procedure-Modular Termination Analysis

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