Automatic Verification of Loop Invariants

Loop invariants play a major role in program verification and drastically speed up processes like automatic test case generation. Though various techniques have been applied to automatic loop invariants generation, most interesting ones often generate only candidate invariants. Thus, a key issue, to take advantage of these invariants in a verification process, is to check that these candidate loop invariants are actual invariants. This paper introduces an original technique based on constraint programming for automatic verification of inductive loop invariants. This new approach is efficient to detect spurious invariants and nicely performs verification of valid invariants under boundedness restrictions. First experiments on classical benchmarks are very promising.