> De: "John Rose" <john.r.r...@oracle.com> > À: "Brian Goetz" <brian.go...@oracle.com> > Cc: "valhalla-spec-experts" <valhalla-spec-experts@openjdk.java.net> > Envoyé: Mercredi 30 Janvier 2019 01:20:50 > Objet: Re: Valhalla EG notes Jan 16, 2019
> On Jan 29, 2019, at 12:27 PM, Brian Goetz < [ mailto:brian.go...@oracle.com | > brian.go...@oracle.com ] > wrote: >> But, now we a problem: we have existing code that erases arrays to >> `Object[]`, >> but after the flag day, such code will erase to Array instead. > Maybe, another way to address this, besides bridging distinct > descriptors, is to declare that the old descriptors describe > the new types. > After all, the old descriptors will be dead (to Java) after the > translation strategy stops using them. Make all descriptors > of the form `[T` erase to `Array` or some subtype. > This isa lossy translation, which means the interpreter will have > to do extra runtime type checks on xaload/xastore instructions. > The JIT probably won't care. The scheme might shipwreck > on reflection, since we need to distinguish all the array classes > reflectively, but maybe that's where Crasses (runtime class > mirrors) come in handy, to make that distinction. Put another > way, int[] and String[] and Object[] are mirrored by Crasses, > not proper classes. yes, String[].class == Array.class.getSpecialization(String.class) Note that even if String is a reference type, here we still want the specialization, unlike for generics, so an Array is a special kind of generics that requires full reification. > Maybe there's a solution along this path. Or maybe the floor > gives way at some point and you are plunged into the basement > where the monsters are. the risk is more a Franckenstein's monster than Cthulhu IMO > — John Rémi
