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[Frama-c-discuss] [Value analysis] Validating a function with behavior spec.

  • Subject: [Frama-c-discuss] [Value analysis] Validating a function with behavior spec.
  • From: moy at adacore.com (Yannick Moy)
  • Date: Fri, 13 Apr 2012 11:12:19 +0200
  • In-reply-to: <CAOH62JgyUC8+2cHf-bsPmVnWcL+JxyV88mnVo9gHc0j5Ym=JqQ@mail.gmail.com>
  • References: <CAFaEDLCHYJtescjnsqs6gE5q_Nx5+CWSg_3AD=f9pN_AHhq4=w@mail.gmail.com> <CAOH62JgyUC8+2cHf-bsPmVnWcL+JxyV88mnVo9gHc0j5Ym=JqQ@mail.gmail.com>
On 04/13/2012 11:03 AM, Pascal Cuoq wrote:
> To answer your question, you cannot prove the kind of functional
> property you desire with the value analysis. On the other hand,
> for your example, either Jessie or Wp look like they have a good
> chance.

Pascal, just to satisfy my curiosity, what is causing imprecisions in 
the value analysis in the code:

                 retval = (uint8)val;
		/*@ assert retval == val; */


Is it the cast which is treated as an unknown function?
Then its transition function could be modeled more precisely I guess, 
which would allow value analysis to prove both assertions, right?

What about the postconditions, would value analysis be able to prove 
them? I guess it could if you analyze each behavior separately 
(otherwise you'd need a disjunctive domain), maybe that's what you do 
already?

-- 
Yannick Moy, Senior Software Engineer, AdaCore