B3 ref model

[Dan Smith]

> On Apr 25, 2022, at 3:08 PM, Remi Forax <forax at univ-mlv.fr> wrote:
> 
> Ok, maybe i've not understood correctly how B3 model works,
> for me being a B3 is a runtime property, not a type property.
> 
> By example, if there is an Object but the VM knows the only possible type is a B3 and the value is not null then the VM is free to emit several stores, because it's a B3, so tearing can occur.
> 
> Said differently, B3 allows tearing, so B3.val and B3.ref allow tearing.
> 
> If i do not want tearing, then B3 has to be stored in a field volatile or i have to declare the class as a B2.
> 
> Did i get it right ?

The model we've designed is that B3 instances can be represented as *objects* or *primitive values*. Objects enforce atomicity as part of their encapsulation behavior; primitive values do not. Whether something is an object or not is a property of types—ref and val at the language level, L and Q at the JVM level.