Take:
```
int f(short a, short b)
{
  if (a > b)
  {
        int aa = a;
        int bb = b;
        bb++;
        int t = aa > bb ? aa : bb;
        return t;
  }
  return 0;
}
```

This should be optimized to just:
```
int f0(short a, short b)
{
  if (a > b)
  {
        return a;
  }
  return 0;
}
```

As if a is equal b+1 (that is the only case where a>b matters), then `extend<a>` and `extend<b>+1` are still equal.