function foo(a, b, c, d) {
  let x = 0;
  if (true) {
    if (true) {
      x = a;
    } else {
      x = b;
    }
    x;
  } else {
    if (true) {
      x = c;
    } else {
      x = d;
    }
    x;
  }
  // note: intentionally no phi here so that there are two distinct phis above
}
