----- Mail original ----- > De: "daniel smith" <daniel.sm...@oracle.com> > À: "Remi Forax" <fo...@univ-mlv.fr> > Cc: "valhalla-spec-experts" <valhalla-spec-experts@openjdk.java.net> > Envoyé: Mercredi 2 Décembre 2020 16:35:06 > Objet: Re: Using a Condy instead of a Constant_Utf8
>> On Dec 2, 2020, at 3:53 AM, Remi Forax <fo...@univ-mlv.fr> wrote: >> >> Using a condy that returns a String instead of a method descriptor in the >> bytecode ? >> I'm currently trying to remove the uses of Unsafe.defineAnonymousClass to use >> Lookup.defineHiddenClass instead. >> There is one case where i dynamically patch a method descriptor so I can >> select >> how many arguments will be sent to a closure, >> i.e. in the bytecode i put all arguments on the stack but because i've >> patched >> the callee descriptor, only some of them will be used. >> >> I see defineAnonymousClass has a way to push data to a template class file >> and >> defineHiddenClass has a way to pull the data from the template class file. >> But i can not currently pull data that will be used by a NameAndType info >> because the descriptor_index has to be a Constant_Utf8 index and can not be a >> condy with a String as descriptor. > > The trouble I see with changing NameAndType is that verification needs a > static > string. At that stage, it's too early to be resolving condys. yes, thanks, I think the other Dan (Hedinga) already said that but i've a hard time to remember it. > >> This is related to Lazy static final field [1] and also to class templating >> in >> general because it equivalent to seeing all the template holes as condy even >> if >> it"s less efficient because you need to duplicate the whole constant pool. > > Lazy static fields, if I understand the proposal correctly, use a condy to > determine the _value_ of the field, but not its _type_. Linkage behavior is > unchanged. > > Similarly, our preferred story for templating right now is to use normal Utf8 > strings for descriptors, and give each species different side-channel type > information, computed via condy. This side information is needed fairly early, > but verification is entirely descriptor-string-based. good to know. Rémi
