-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Am 08.11.2012 03:36, schrieb BGB: > On 11/7/2012 7:02 PM, Remi Forax wrote: >> On 11/07/2012 11:30 PM, BGB wrote: >>> On 11/7/2012 4:15 PM, Vitaly Davidovich wrote: >>>> Hi John, >>>> >>>> Nice to see this effort moving forward. While reading >>>> the JEP, I can't help but think how complicated this >>>> sounds for JVM implementors. Is introducing bytecodes >>>> and new value type representation definitely a >>>> nonstarter? I'm thinking a setup akin to the CLR. >>>> >>>> I certainly understand the attraction of keeping bytecode >>>> the same, but wouldn't it make the JVM impl more >>>> straightforward (and thus more robust, stable, >>>> performant, etc) if value types/structs were first class >>>> citizens? >>>> >>>> I'm sure you've thought about this plenty so I'm mostly >>>> curious to hear your take on the tradeoffs and generally >>>> on how you think this approach will shake out. >>>> >>> agreed, though it need not be "that" bad (probably it would >>> be mostly handled by a dynamic check on the reference or on >>> the object?). >>> >>> >>> I think it would be nice if, say, a particular class could >>> be marked as "lockPermanently", so any new instances of the >>> given class would have this property by default. >>> >>> like, say, if we could do something like: @LockPermanently >>> public class Foo ... >>> >>> or: @ValueClass public class Foo ... >>> >>> this could be partly so that the JVM could look at the >>> class and be like "hey, this class is always locked" and >>> possibly optimize it a little more aggressively. >>> >>> otherwise, things would mostly be as-is (the ability to do >>> this on a per-instance basis is an interesting idea...). >> that the basic idea but then you want array of value type >> ... then you want ArrayList of value type ... then you want >> to retrofit wrapper type like j.l.Integer, j.l.Double etc, to >> be value type when it's possible ... and after having >> duplicated the whole world to have one version for reference >> object and one for value object, you may think that tagging >> object at runtime as proposed is perhaps a better idea. yes, >> you will have to add some dynamic check (leading to a deopt) >> but that the price to pay to avoid the duplication mess. > > could be, however, the above is assuming that the only > available option were the static case. > > very possibly, the actual implementation would be as the > dynamic case, and the dynamic case would probably still be > usable as well, but the static case would exist mostly as an > additional optimization hint, as well as potentially to reduce > the typing required to create an object (because it could be > handled more automatically, say, it auto-locks when "<init>" > finishes or similar, like the JIT reacts specially to the > presence of the annotation or similar). > > either way works I guess though... >
I would suggest both options. For new classes where I know that it will be a value type it would be nice to permanently mark it as this. > >> Rémi >> >>> >>>> Thanks >>>> >>>> Sent from my phone >>>> >>>> On Nov 7, 2012 4:36 PM, "John Rose" >>>> <john.r.r...@oracle.com <mailto:john.r.r...@oracle.com>> >>>> wrote: >>>> >>>> Thanks! This will move the conversation forward. >>>> >>>> -- John (on my iPhone) >>>> >>>> On Nov 7, 2012, at 1:25 PM, mark.reinh...@oracle.com >>>> <mailto:mark.reinh...@oracle.com> wrote: >>>> >>>>> Posted: http://openjdk.java.net/jeps/169 >>>>> >>>>> - Mark >>>> _______________________________________________ mlvm-dev >>>> mailing list mlvm-dev@openjdk.java.net >>>> <mailto:mlvm-dev@openjdk.java.net> >>>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev >>>> >>>> >>>> >>>> _______________________________________________ mlvm-dev >>>> mailing list mlvm-dev@openjdk.java.net >>>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev >>> >>> >>> _______________________________________________ mlvm-dev >>> mailing list mlvm-dev@openjdk.java.net >>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev >> _______________________________________________ mlvm-dev >> mailing list mlvm-dev@openjdk.java.net >> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev > > _______________________________________________ mlvm-dev > mailing list mlvm-dev@openjdk.java.net > http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev > - -- ############################## # A Digital's Life # ############################## Nickname: Noctarius Location: Germany Meet me at: Ohloh: http://www.ohloh.net/accounts/noctarius Web: http://www.noctarius.com XMPP/Jabber: noctar...@jabber.ccc.de -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.12 (MingW32) Comment: Using GnuPG with Mozilla - http://www.enigmail.net/ iQIcBAEBAgAGBQJQm35UAAoJEH/g+YBfahrqRTYP/0hH7if0xzWU6P9c+oT278yA nWiIa5/AHUFIrbZtS/HWg9InD5WjrvumHSxIPnDnVC5TqhiY7+2HHY8bUnJHe0lL sWRGTMpV2bPBSiyRG9Yr0hEjpp5erke/y7rVAoq71AqoJwritHGi1O63Alb8FuJz ZR2qlR5ykw0sHOX8b0+xb8MAcfmVgmcX1dJYH7uwkyZHN4RoJbxq9ED6cK+4Wa+4 EQylFxK5E0gKnUHpE19spK4pvVFy8UV1R02CqAdSnzB0MEY5BeHtu5osASZBPfsl ul0ib0CVy3CY3AtkiLqoKJtoZBxLgf3WBesJMhrozl/f3qDJ6MZNI+zjNJp9x+DH hIjl10UE7oOMBx3L7TlcNu+mu/5W0nQSSzP+UD5zSOI1qmORhnaT1rgWEzOr2X1a Vi5CTkJbCaZZVAHZ3FppfaZUtg+morlhv+pal8nHhMfw28Ui48APTygtbg0nEWgv tcpgqs9jH14etRfMZdVcRIvuuXcjjw5v0kcuzi1PrK8XnXODNJVS6SkCAbXPe1jz QiXz6PwEhkZ9QAf1lQa1i+ur3KqoLTYXyhmIQT0PvFIlZ1cpsjgJ/6Inic9g37Cy Llk1bdA2+3xfWI6u+avTZg9cy9qi6M/sMALRLZzmAMgMFJDGMeELB/CT2xdM4xGp honp+8QcOUf+hO+ADAs+ =IA0d -----END PGP SIGNATURE----- _______________________________________________ mlvm-dev mailing list mlvm-dev@openjdk.java.net http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
