abandon all U-types, welcome to L-world (or, what I learned in Burlington)

[John Rose]

On Nov 19, 2017, at 3:33 PM, forax at univ-mlv.fr wrote:
> 
> but you need a way disambiguate a reference type from a value type at runtime in the interpreter.
> You also nedd to teach JITs to propagate L vs which Q info on local variables for generics specialization (and it works even if the inlining fails because the boxing/wrapping in the thread local storage is done by the adapters so the JITed code doesn't have to be conservative).

Yes, that leads to the sort of tag bot schemes I alluded to. I didn’t want to go into detail because it is a spec. list not a dev. list. On the dev. list we will say more about it. The problems seem solvable especially after the MVT prototyping experience on HotSpot, and I hope the IBM experience corroborates.