cdizy might not terminate

[ClearlyClaire]

Good evening,
I stumbled over a case where cdizy seems to enter an infinite loop.
It is most probably due to widening being incorrectly applied (or fixed-point incorrectly detected), but I haven't been able to track it down yet.

In any case, here is an example exhibiting such behavior:

typedef short Guard;

int res;
int T_res;

void test(int a, int b)
{
    Guard Ret = 0;
    Guard T_Ret = 0;

    int T_a = a;
    int T_b = b;

    int x;
    int T_x;

    if (!Ret) x = a + 2 * b;
    if (!T_Ret) T_x = T_a + 2 * T_b;

L1:;
    Guard G0 = 1;
    Guard T_G0 = 1;
    if (!T_Ret) T_G0 = (1 <= T_b);
    if (!Ret) G0 = (1 <= a);

    if (!T_Ret) if (T_G0) T_x = T_x + 1;
    if (!T_Ret) if (T_G0) T_b = T_b - 1;
    if (!Ret) if (G0) x = x + 1;
    if (!Ret) if (G0) a = a - 1;

    if (!Ret) if (G0) goto L1;
    if (!T_Ret) if (T_G0) goto L1;

    res = x;
    T_res = T_x;

    {char *CP7;}
}

[nimrodpar]

This is a widening issue. I will further investigate but for now: dizy does finish with -w_s=all (precision is poor of course...)