digraph cfg2 {
    graph [dpi=300];
    rankdir=LR;

    "p != nil is true" [shape=box];
    "p != nil is false" [shape=box];

    "x := 0" -> "p != nil";
    "p != nil" -> "p != nil is true";
    "p != nil is true" -> "x = p.f";
    "p != nil" -> "p != nil is false";
    "p != nil is false" -> "return x";
    "x = p.f" -> "return x";
}