Any type casting done by javac?

To my understanding, if type checking can be done during compilation, the type casting will be done during compilation and will not incur any runtime overhead.

For example

public Child getChild() {
  Parent o = new Child();
  return (Child) o;
}

Is the type casting done during compilation or during runtime?

And is there any general rule to decide if a type casting is done by javac compiler or by the VM?