Take:
```
typedef int si;
typedef unsigned ui;

si f(si a)
{
    ui t = a;
    t = ~t;
    si a1 = t;
    return a1;
}

si f1(si a)
{
    return ~a;
}

int g(si a)
{
    return f(a) + f1(a) == (si)(2*(~a));
}
```
g should optimize to 1 which it does on the RTL level