Valhalla EG minutes Feb 14, 2018

[Tobi Ajila]

> 4. arrays
> We need a new bytecode to create a flattenable/non-nullable array
> existing bytecodes do not create flattenable arrays with the new model of
container marking flattenable
> rather than by type
On a related note, it might be worth it to also consider the implication of
flattened arrays and atomic operations. The Varhandle API currently
supports a variety of atomic updates on elements of both primitive and
reference arrays. Platform support for atomic updates on memory <= 64bits
is fairly standard, but supporting anything larger becomes more difficult.

This probably falls under the general category of 'tearing and atomicity
concerns with writing flattenable values'. I suspect the answer might be to
disallow atomic operations on flattenable fields/arrays and to allow
tearing for updates, but this is probably worth a discussion.

--Tobi