See http://www.mail-archive.com/[email protected]/msg00891.html

Cristian

On 07/01/14 18:26, Pablo González de Aledo wrote:
I'm sorry, I'm not the original author but I've faced the same problem
before and I also don't understand why Klee does what it does.

May be the next code is simpler, and still explains the issue.

int main() {
int a;
int array[] = {1,2,3,4,5};

klee_make_symbolic(&a, sizeof(a), "a");

if(array[a] == 3)
return 0;
else
return 1;
}

Why does Klee generate 17 solutions when only one is possible (a == 2) ?

Thanks.



2014/1/7 Cristian Cadar <[email protected]
<mailto:[email protected]>>

    I only had a brief look at your code, but it looks like you are
    storing the addresses of the x_i variables into the array, which is
    likely not what you intended.

    Cristian


    On 18/12/13 06:39, Sandeep wrote:

        Hello All,

        Please consider the following program.

        The intension of the program is to let KLEE choose a value of x
          so that
        the path (*temp <= 0) is explored and
        KLEE is able to figure out the value of x  (= 3) for that to
        happen. But
        in addition it is reporting two other paths for x = 1 and x =2,
        despite
        of the fact that there are  only 2 possible paths.

        Also to add, if I call foo with
        foo(x, 10,20,30,40)
        then KLEE report 3 paths (for x = 1 ,2 ,3 ) instead of 1 path
        (as the
        path (*temp > 0) is not feasible for any value of x)


        Can anybody please give me some insight.

                                     int foo(int x, int x1, int x2, int
        x3, int x4) {
                                        int **array = (int **)
                                     malloc(4*sizeof(int *));
                                        array[0] = &x1;
                                        array[1] = &x2;
                                        array[2] = &x3;
                                        array[3] = &x4;

                                        int **ptr = array + x;

                                        int* temp =  *ptr;

                                        if(*temp > 0) {
                                          assert(1);
                                        } else {
                                          assert(0);
                                        }
                                        return *temp;
                                     }


                                     int main() {
                                        int x;

                                        klee_make_symbolic(&x,
        sizeof(x), "x");
                                        klee_assume((x >  0) & (x <
          4)); // To
                                     allow valid memory access on 'array'
                                        return foo(x,10,20,30,-1);
                                     }




        --
        *With Thanks and Regards,*

        Sandeep Dasgupta
        Graduate ( PhD ) in Computer Science
        Room : 1218 Siebel Center for Computer Science


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