Earlier quoted context omitted.
Ah right yes conflict of terminology. In the JVM devirtualising means making a virtual object a full object again, so the opposite of what you want to be happening. I don't think the JVM really names the optimisation you're talking about, but it does do it, through either a global assumption based on the class hierarchy, or an inline cache with a local guard.
What do you mean by “virtual object”, an object which has been broken up on the stack instead of a “real” object living as a single entity on the heap?
Remember back in cs101 where you had class animal, with subclasses dog and cat. You can call speak() on animal and get either ruff or meow depending on what animal is. Animal is a virtual object. The system needs to do some work to figure out which speak to call every time, the work isn't too bad, but it turns out that cpus basically never have the right thing in the cache, so it ends up being very slow compared to most of what you are doing.
When we say devirtualize we mean that we know animal is always a cat so we don't have to look up which speak to use.