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[Frama-c-discuss] Proving properties with land?

  • Subject: [Frama-c-discuss] Proving properties with land?
  • From: loic.correnson at cea.fr (Loïc Correnson)
  • Date: Mon, 4 Sep 2017 11:06:56 +0200
  • In-reply-to: <CAChk8mBOcjs6xkpQS65L8y1HAkqF_eAmNUaphmi=W3R9PpubMw@mail.gmail.com>
  • References: <CAChk8mBOcjs6xkpQS65L8y1HAkqF_eAmNUaphmi=W3R9PpubMw@mail.gmail.com>
Properties on bitwise operations are difficult to prove by simply using SMT solvers.
However, the Interactive Prover of WP in Frama-C/Gui, might help you. There are several tactics available to transform and/or prove bitwise expressions.
	L.



> Le 15 août 2017 à 23:22, Yifan Lu <me at yifanlu.com> a écrit :
> 
> I have the following simple function
> 
> int test(unsigned char x) {
>    int y;
>    y = (int)x & 0x5;
>    //@ assert 0 <= (x & 0x1);
>    //@ assert 0 <= (x & 0x4);
>    return y;
> }
> 
> The first assertion goes through but the second one cannot be proved.
> 
> My options: -wp -wp-rte -wp-init-const -wp-model ref -wp-split
> 
> Eventually, I want to prove something more complicated such as
> 
> /*@ lemma alignment: \forall integer x, y; x <= y && y % 4 == 0 ==>
> ((x + 3) & 4) <= y;
>  @*/
> 
> But I can't even get a simple toy property proven.
> 
> Thanks,
> Yifan
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