Verification of Definite Iteration over Arrays with a Loop Exit in C Programs
This work represents the further development of the method for definite iteration verification. It extends the mixed axiomatic semantics method suggested for C-light program verification. This extension includes a verification method for definite iteration over unchangeable arrays with a loop exit in C-light programs. The method includes an inference rule for the iteration without invariants, which uses a special function that expresses loop body. This rule was implemented in verification conditions generator, which is the part of our C-light verification system. To prove generated verification conditions an induction is applied which is a challenge for SMT-solvers. At proof stage the SMT-solver Z3 is used in our verification system. To overcome mentioned difficulty a rewriting strategy for verification conditions is suggested. It allows to verify the definite iteration automatically using Z3. Also the paper describes the application of the theorem prover PVS for automatic proving of such verification conditions. An example, which illustrates the application of these methods, is considered.