5 research outputs found
Precondition Inference via Partitioning of Initial States
Precondition inference is a non-trivial task with several applications in
program analysis and verification. We present a novel iterative method for
automatically deriving sufficient preconditions for safety and unsafety of
programs which introduces a new dimension of modularity. Each iteration
maintains over-approximations of the set of \emph{safe} and \emph{unsafe}
\emph{initial} states. Then we repeatedly use the current abstractions to
partition the program's \emph{initial} states into those known to be safe,
known to be unsafe and unknown, and construct a revised program focusing on
those initial states that are not yet known to be safe or unsafe. An
experimental evaluation of the method on a set of software verification
benchmarks shows that it can solve problems which are not solvable using
previous methods.Comment: 19 pages, 8 figure
Affine Disjunctive Invariant Generation with Farkas' Lemma
Invariant generation is the classical problem that aims at automated
generation of assertions that over-approximates the set of reachable program
states in a program. We consider the problem of generating affine invariants
over affine while loops (i.e., loops with affine loop guards, conditional
branches and assignment statements), and explore the automated generation of
disjunctive affine invariants. Disjunctive invariants are an important class of
invariants that capture disjunctive features in programs such as multiple
phases, transitions between different modes, etc., and are typically more
precise than conjunctive invariants over programs with these features. To
generate tight affine invariants, existing constraint-solving approaches have
investigated the application of Farkas' Lemma to conjunctive affine invariant
generation, but none of them considers disjunctive affine invariants
Dual analysis for proving safety and finding bugs
10.1016/j.scico.2012.07.004Science of Computer Programming784390-411SCPG
Dual analysis for proving safety and finding bugs
10.1145/1774088.1774538Proceedings of the ACM Symposium on Applied Computing2137-214