Hello Paolo, welcome to the Ranch.
You're asking quite a specific question about an advanced topic, and I don't have a direct answer for you. I think the question is hard to answer, because it depends on the implementation details of the JVM. One place you could start looking is at the source code of
OpenJDK (Oracle's
Java 6 and Java 7 are almost equal to OpenJDK). But I think it will not be an easy task to find this out from the source code...