> De: "Brian Goetz" <brian.go...@oracle.com> > À: "Remi Forax" <fo...@univ-mlv.fr> > Cc: "Frederic Parain" <frederic.par...@oracle.com>, "valhalla-spec-experts" > <valhalla-spec-experts@openjdk.java.net> > Envoyé: Mardi 14 Avril 2020 15:56:06 > Objet: Re: null checks vs. class resolution, and translation strategy for > casts
>> How it is better than a new opcode "unbox" with exactly the same semantics ? > For one, an “unbox” opcode assumes that the VM understands the fictitious > relationship between the val and ref projections. But these are language > fictions; the VM sees only classes related by extension and sealing. No, your assuming that the semantics of unbox implies that the verifier will check for 'sealness', this is not the case, unbox <==> checkcast restricted to inline type (so with eager loading). You're free to unbox an Object to a Point, by example. Rémi
