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We introduce Ultimate TestGen, a novel tool for automatic test-case generation. Like many other test-case generators, Ultimate TestGen builds on verification technology, i.e., it checks the (un)reachability of test goals and generates test cases ...

The verification of Ultimate Automizer works on an SMT-LIB-based model of a C program. If we choose an SMT-LIB theory of (mathematical) integers, the translation is not precise, because we overapproximate bitwise operations. In this paper we ...

We address the verification problem for concurrent program that dynamically create (fork) new threads or destroy (join) existing threads. We present a reduction to the verification problem for concurrent programs with a fixed number of threads. ...

Ultimate Taipan integrates trace abstraction with algebraic program analysis on path programs. Taipan supports data race checking in concurrent programs through a reduction to reachability checking. Though the subsequent verification is not tuned ...

The verification approach of Ultimate Automizer utilizes SMT formulas. This paper presents techniques to keep the size of the formulas small. We focus especially on a normal form, called CommuHash normal form that was easy to implement and had a ...

Over the last years, witness-based validation of verification results has become an established practice in software verification: An independent validator re-establishes verification results of a software verifier using verification witnesses, which are ...

Ultimate GemCutter verifies concurrent programs using the CEGAR paradigm, by generalizing from spurious counterexample traces to larger sets of correct traces. We integrate classical CEGAR generalization with orthogonal generalization across ...

In SMT solver based verification, the program to be verified is often given in an intermediate verification language such as Boogie. We present a program transformation that aims at splitting mathematical arrays (i.e., maps, which are typically ...

Given a verification problem for a concurrent program (with a fixed number of threads) over infinite data domains, we can construct a model checking problem for an abstraction of the concurrent program through a Petri net (a problem which can be ...

The design of the modern, enterprise-class IBM z15 branch predictor is described. Implemented as a multi-level look-ahead structure, the branch predictor is capable of predicting branch direction and target addresses, augmented with multiple auxiliary ...

Ultimate Taipan is a software model checker that combines trace abstraction with abstract interpretation on path programs. In this year’s version, we replaced our abstract interpretation engine and now use a combination of multiple abstraction ...

Static program analyzers are increasingly effective in checking correctness properties of programs and reporting any errors found, often in the form of error traces. However, developers still spend a significant amount of time on debugging. This ...

We present a method that allows us to infer expressive invariants for programs that manipulate arrays and, more generally, data that are modeled using maps (including the program memory which is modeled as a map over integer locations). The ...

In 2014, Heizmann et al. proposed a novel framework for program termination analysis. The analysis starts with a termination proof of a sample path. The path is generalized to a Büchi automaton (BA) whose language (by construction) represents a set of ...

Ever since the seminal work on SLAM and BLAST, software model checking with counterexample-guided abstraction refinement (CEGAR) has been an active topic of research. The crucial procedure here is to analyze a sequence of program statements (the ...

Ultimate Taipan is a software model checker for C programs. It is based on a CEGAR variant, trace abstractionï ź[7], where program abstractions, counterexample selection and abstraction refinement are based on automata. Ultimate Taipan constructs path ...

Ultimate Automizer is a software verifier that implements an automata-based approach for the verification of safety and liveness properties. A central new feature that speeded up the abstraction refinement of the tool is an on-demand construction of ...

We consider the problem of state-space reduction for nondeterministic weakly-hierarchical visibly pushdown automata Vpa. Vpa recognize a robust and algorithmically tractable fragment of context-free languages that is natural for modeling programs.

We ...

Standard verification tools provide a counterexample to witness a specification violation, and, since a few years, such a witness can be validated by an independent validator using an exchangeable witness format. This way, information about the ...

Ultimate Automizer is a software verification tool that implements an automata-based approach for the analysis of safety and liveness problems. The version that participates in this year's competition is able to analyze non-reachability, memory safety, ...