I'm working on cost-modeling, and am integrating some smaller changes from this proof-of-concept PR:
https://github.com/openjdk/jdk/pull/20964

This is a pure refactoring - no change in behaviour. I'm presenting it like this because it will make reviews easier.

The goal here is that VTransformNode::apply only needs a single argument. This is important, as we will soon add more components that need to be updated during apply. That way, we can simply add more parts to VTransformApplyState, and do not need to add more arguments to VTransformNode::apply.

And yes: I have considering passing the apply_state as const. While this may be possible with the current code state, the upcoming changes from https://github.com/openjdk/jdk/pull/20964 will require non-const access to the apply_state (e.g. for set_memory_state).