--- layout: fc_discuss_archives title: Message 70 from Frama-C-discuss on January 2014 ---
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[Frama-c-discuss] Frama-C: Detecting unreachable code?



Hi,
Actually, the verification condition generated for Alt-Ergo is of the form:

*...
(* Context: first-order axioms for memory model, .... *)
...

goal g: false*

Obviously, the VC is invalid if you condiser that the context is 
consistent. But in general, SMT solvers answer "unknown" instead of 
"invalid" when working on fragments of logic on which they are not 
complete.

I tried other provers: cvc3 says "unknown", and cvc4 and z3 timeout 
after 10 seconds.

Mohamed Iguernelala.
Senior R&D Engineer, OCamlPro
Research Associate, VALS team, LRI.
http://www.iguer.info


Le 24/01/2014 03:36, Dharmalingam Ganesan a ?crit :
> Hi,
>
> Thanks for all responses. I'm not sure why the following code cannot considered invalid; I always get "unknown".
>
> Any comments?
>
> frama-c -wp -wp-rte non_sense.c -lib-entry
>
>
>
> int i = 0;
>
> /*@
>    @ behavior BUG:
>    @  assumes i == 5;
>    @  ensures \result == -2;
> */
>
> int main()
> {
>    if (0 <= i  && i <= 10)
>    {
>       return -1;
>    }
>
>    if (i == 5)
>    {
>       return -2;
>    }
>
>    return 0;
> }
>
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