consolidated VM notes for primitive classes

[John Rose]

Brian and I hammered out a document this week that
captures what we think is emerging as our shared
understanding of how adapt the JVM to support
primitive classes.

It is still white-hot, not even off the press, but I think
it is worth looking it even in its unfinished state.

https://github.com/openjdk/valhalla-docs/blob/main/site/design-notes/state-of-valhalla/03-vm-model.md

That is the JVM side, only.  Most of it is already
prototyped in HotSpot, some is not.

I’ll let Brian speak for the valhalla-doc repository
as a whole, but I wanted to get this out there for
tomorrow’s meeting.

— John