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[Frama-c-discuss] Frama-C: Detecting unreachable code?

To see this with the GUI in a more obvious manner, try this command line:

frama-c-gui -wp foo.c -then ?val

D.

De : Pariente Dillon
Envoy? : jeudi 23 janvier 2014 10:03
? : Frama-C public discussion
Objet : RE: [Frama-c-discuss] Frama-C: Detecting unreachable code?

Hi,

You could also try this:

int main(int i)
{
  if (0 <= i  && i <= 10)
  {
    return -1;
  }

  if (i == 5)
  {
   //@ assert \false;
     return -2;
  }
  return 0;
}

Analyzed by:
frama-c-gui -val -wp foo.c
__retres IN {-1; 0}

For sure, it requires a manual annotation, but in some cases, when it is not affordable to use higher -slevel, it may help.

D.

De : frama-c-discuss-bounces at lists.gforge.inria.fr<mailto:frama-c-discuss-bounces at lists.gforge.inria.fr> [mailto:frama-c-discuss-bounces at lists.gforge.inria.fr] De la part de Nicky Williams
Envoy? : jeudi 23 janvier 2014 09:53
? : Frama-C public discussion
Objet : Re: [Frama-c-discuss] Frama-C: Detecting unreachable code?

Of course, static analysis can only detect unreachable code.
To be sure that THERE IS NO unreachable code you need to do path testing, eg. with the pathcrawler plugin (and to achieve full coverage with no timeouts).
Nicky Williams
On 23/01/2014 09:36, Pascal Cuoq wrote:


On Thu, Jan 23, 2014 at 9:25 AM, Nicholas Mc Guire <der.herr at hofr.at<mailto:der.herr at hofr.at>> wrote:
On Thu, 23 Jan 2014, David MENTRE wrote:

just for completenes here is the code used in the above runs:
int main(int i)
{
  if (0 <= i  && i <= 10)
  {
     return -1;
  }

  if (i == 5)
  {
     /* can never reach here? */
     return -2;
  }

  return 0;
}
Use option -slevel 20 -val in order for Frama-C's value analysis to separate the execution paths where 0 > i, 0 <= i, ...:

$ frama-c -val -slevel 20 t.c
...
[value] ====== VALUES COMPUTED ======
[value] Values at end of function main:
  __retres ? {-1; 0}

There is only one value analysis option to know until you are an advanced user, and it is this one. It is the first and only non-administrative option used in the tutorial of the value analysis.



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