Re: invokedynamic and subclasses

2015-06-27 Thread Mike Jarmy
I've gotten this working with a simplified version of the inlining cache in
Remi's cookbook.  Thanks guys.

Performance is about twice as slow as invokevirtual, which I am really
pleased with.

On Wed, Jun 24, 2015 at 9:53 AM, Rémi Forax  wrote:

> Hi Mike,
> i've compiled a small list of patterns,
>   https://code.google.com/p/jsr292-cookbook/
>
> take a look to the first inlining cache example.
>
> cheers,
> Rémi
>
> Le 24 juin 2015 14:19:32 CEST, Mike Jarmy  a écrit :
> >I've been experimenting with invokedynamic in a compiler for a dynamic
> >language
> >that I'm working on, and I've run into a problem that I'm having
> >difficulty
> >solving.
> >
> >Let's say I have a class called A (Java syntax used for clarity):
> >
> >public class A {
> >}
> >
> >And another called B, that is a subclass of A:
> >
> >public class B extends A {
> >public Value foo;
> >public Value bar;
> >}
> >
> >There will be lots of other subclasses of A as well (let's call them C,
> >D,
> >E,
> >etc), some of which will have a field called foo, and some of which
> >won't.
> >The
> >class A will never have any fields -- its sole purpose is to be the
> >base
> >class
> >of everything else.
> >
> >I have been able to successfully use a static bootstrap method in B, so
> >that I
> >can compile a call to invokedynamic on the imaginary method get_foo()
> >of an
> >instance of B, and then reroute the call inside B's bootstrap method
> >via
> >MethodHandles.Lookup.findGetter(), and finally return the current value
> >of
> >foo.
> >So far, so good.
> >
> >However, at the place where I am compiling the invokedynamic
> >instruction, I
> >have no idea if the target is a B, C, D, or what.  All I know is that
> >it
> >must
> >be an A.
> >
> >So what I really want to be able to do (I think) is to use a static
> >bootstrap
> >method in A. I want get_foo() to succeed for every invokedynamic call
> >to an
> >instance of A who's *subclass* really does have a field called foo.
> >
> >Unfortunately there doesn't seem to be a way to make A do what I want.
> >I
> >understand why that is -- foo doesn't exist in A, so there is no way to
> >create
> >a findGetter() call.  But I'm hoping there might be some clever way to
> >do it
> >anyway.  I've tried all kinds of different approaches (making yet
> >another
> >invokedynamic call from inside A, etc, etc) but I can't come up with
> >anything
> >that works.
> >
> >Any ideas?
> >
> >By the way, I've figured out how to do this the "old" way, by
> >generating
> >interfaces for each class that has e.g. a foo field, and casting to
> >that
> >interface every time I compile a get_foo() invocation.  This works, and
> >its
> >reasonably performant, but using invokedynamic seems like it would be a
> >more
> >elegant and flexible solution.
> >
> >
> >
> >
> >___
> >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


Re: invokedynamic and subclasses

2015-06-24 Thread Douglas Campos
JRuby also chains the bootstraps, you might find inspiration here:
https://github.com/jruby/jruby/blob/master/core/src/main/java/org/jruby/runtime/invokedynamic/InvokeDynamicSupport.java

On Wed, Jun 24, 2015 at 11:25 AM, Mike Jarmy  wrote:

> Jochen -- that comes tantalizingly close to making sense to me :-).  I
> don't quite follow all of the terminology yet, but the basic idea that you
> describe of chaining bootstrap calls is sort of like what I had vaguely
> designed in my head.  Once I am doing learning how all this works I should
> be able to make my language work just the way I hoped it would.
>
> On Wed, Jun 24, 2015 at 10:16 AM, Jochen Theodorou 
> wrote:
>
>> Hi Mike,
>>
>> First of all, the bootstrap method does not have to be in the same class.
>> In Groovy we have for example one bootstrap method for all classes only. It
>> is part of the runtime then you could say.
>>
>>
>> We do it like this. We have two bootstrap methods in the Groovy runtime
>> (you don't need to have them in the class). The first one is normally
>> called and will produce a handle to call the second one. I tend to call the
>> first one the static bootstrapper and the second one the dynamic
>> bootstrapper. The dynamic bootstrapper will be called like a method (takes
>> an Object[]), thus I will have all the arguments of the call as well as the
>> receiver. This I can use to identify runtime classes and produce a new
>> handle that fits my needs and replaces the first one. This method also is a
>> fallback. The installed handle usually has to be guarded (like first call
>> with B, second with C), and we use the dynamic bootstrapper as fallback. Of
>> course you can easily check more cases and implement a polymorphic inline
>> cache.
>>
>> Of course that implies, that if the dynamic bootstrapper is called it
>> will also have to do the first execution of the target (like getting the
>> value of the field foo). We use (part of) the produced method handle for
>> this. And of course the callsite will have to be mutable then
>>
>> Does this help you out? It works quite good for Groovy.
>>
>> bye blackdrag
>>
>>
>> Am 24.06.2015 14:19, schrieb Mike Jarmy:
>>
>>> I've been experimenting with invokedynamic in a compiler for a dynamic
>>> language
>>> that I'm working on, and I've run into a problem that I'm having
>>> difficulty
>>> solving.
>>>
>>> Let's say I have a class called A (Java syntax used for clarity):
>>>
>>>  public class A {
>>>  }
>>>
>>> And another called B, that is a subclass of A:
>>>
>>>  public class B extends A {
>>>  public Value foo;
>>>  public Value bar;
>>>  }
>>>
>>> There will be lots of other subclasses of A as well (let's call them C,
>>> D, E,
>>> etc), some of which will have a field called foo, and some of which
>>> won't. The
>>> class A will never have any fields -- its sole purpose is to be the base
>>> class
>>> of everything else.
>>>
>>> I have been able to successfully use a static bootstrap method in B, so
>>> that I
>>> can compile a call to invokedynamic on the imaginary method get_foo() of
>>> an
>>> instance of B, and then reroute the call inside B's bootstrap method via
>>> MethodHandles.Lookup.findGetter(), and finally return the current value
>>> of foo.
>>> So far, so good.
>>>
>>> However, at the place where I am compiling the invokedynamic
>>> instruction, I
>>> have no idea if the target is a B, C, D, or what.  All I know is that it
>>> must
>>> be an A.
>>>
>>> So what I really want to be able to do (I think) is to use a static
>>> bootstrap
>>> method in A. I want get_foo() to succeed for every invokedynamic call to
>>> an
>>> instance of A who's *subclass* really does have a field called foo.
>>>
>>> Unfortunately there doesn't seem to be a way to make A do what I want. I
>>> understand why that is -- foo doesn't exist in A, so there is no way to
>>> create
>>> a findGetter() call.  But I'm hoping there might be some clever way to
>>> do it
>>> anyway.  I've tried all kinds of different approaches (making yet another
>>> invokedynamic call from inside A, etc, etc) but I can't come up with
>>> anything
>>> that works.
>>>
>>> Any ideas?
>>>
>>> By the way, I've figured out how to do this the "old" way, by generating
>>> interfaces for each class that has e.g. a foo field, and casting to that
>>> interface every time I compile a get_foo() invocation.  This works, and
>>> its
>>> reasonably performant, but using invokedynamic seems like it would be a
>>> more
>>> elegant and flexible solution.
>>>
>>>
>>>
>>> ___
>>> mlvm-dev mailing list
>>> mlvm-dev@openjdk.java.net
>>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
>>>
>>>
>>
>> --
>> Jochen "blackdrag" Theodorou
>> blog: http://blackdragsview.blogspot.com/
>>
>>
>> ___
>> mlvm-dev mailing list
>> mlvm-dev@openjdk.java.net
>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
>>
>
>
> _

Re: invokedynamic and subclasses

2015-06-24 Thread Mike Jarmy
Jochen -- that comes tantalizingly close to making sense to me :-).  I
don't quite follow all of the terminology yet, but the basic idea that you
describe of chaining bootstrap calls is sort of like what I had vaguely
designed in my head.  Once I am doing learning how all this works I should
be able to make my language work just the way I hoped it would.

On Wed, Jun 24, 2015 at 10:16 AM, Jochen Theodorou 
wrote:

> Hi Mike,
>
> First of all, the bootstrap method does not have to be in the same class.
> In Groovy we have for example one bootstrap method for all classes only. It
> is part of the runtime then you could say.
>
>
> We do it like this. We have two bootstrap methods in the Groovy runtime
> (you don't need to have them in the class). The first one is normally
> called and will produce a handle to call the second one. I tend to call the
> first one the static bootstrapper and the second one the dynamic
> bootstrapper. The dynamic bootstrapper will be called like a method (takes
> an Object[]), thus I will have all the arguments of the call as well as the
> receiver. This I can use to identify runtime classes and produce a new
> handle that fits my needs and replaces the first one. This method also is a
> fallback. The installed handle usually has to be guarded (like first call
> with B, second with C), and we use the dynamic bootstrapper as fallback. Of
> course you can easily check more cases and implement a polymorphic inline
> cache.
>
> Of course that implies, that if the dynamic bootstrapper is called it will
> also have to do the first execution of the target (like getting the value
> of the field foo). We use (part of) the produced method handle for this.
> And of course the callsite will have to be mutable then
>
> Does this help you out? It works quite good for Groovy.
>
> bye blackdrag
>
>
> Am 24.06.2015 14:19, schrieb Mike Jarmy:
>
>> I've been experimenting with invokedynamic in a compiler for a dynamic
>> language
>> that I'm working on, and I've run into a problem that I'm having
>> difficulty
>> solving.
>>
>> Let's say I have a class called A (Java syntax used for clarity):
>>
>>  public class A {
>>  }
>>
>> And another called B, that is a subclass of A:
>>
>>  public class B extends A {
>>  public Value foo;
>>  public Value bar;
>>  }
>>
>> There will be lots of other subclasses of A as well (let's call them C,
>> D, E,
>> etc), some of which will have a field called foo, and some of which
>> won't. The
>> class A will never have any fields -- its sole purpose is to be the base
>> class
>> of everything else.
>>
>> I have been able to successfully use a static bootstrap method in B, so
>> that I
>> can compile a call to invokedynamic on the imaginary method get_foo() of
>> an
>> instance of B, and then reroute the call inside B's bootstrap method via
>> MethodHandles.Lookup.findGetter(), and finally return the current value
>> of foo.
>> So far, so good.
>>
>> However, at the place where I am compiling the invokedynamic instruction,
>> I
>> have no idea if the target is a B, C, D, or what.  All I know is that it
>> must
>> be an A.
>>
>> So what I really want to be able to do (I think) is to use a static
>> bootstrap
>> method in A. I want get_foo() to succeed for every invokedynamic call to
>> an
>> instance of A who's *subclass* really does have a field called foo.
>>
>> Unfortunately there doesn't seem to be a way to make A do what I want. I
>> understand why that is -- foo doesn't exist in A, so there is no way to
>> create
>> a findGetter() call.  But I'm hoping there might be some clever way to do
>> it
>> anyway.  I've tried all kinds of different approaches (making yet another
>> invokedynamic call from inside A, etc, etc) but I can't come up with
>> anything
>> that works.
>>
>> Any ideas?
>>
>> By the way, I've figured out how to do this the "old" way, by generating
>> interfaces for each class that has e.g. a foo field, and casting to that
>> interface every time I compile a get_foo() invocation.  This works, and
>> its
>> reasonably performant, but using invokedynamic seems like it would be a
>> more
>> elegant and flexible solution.
>>
>>
>>
>> ___
>> mlvm-dev mailing list
>> mlvm-dev@openjdk.java.net
>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
>>
>>
>
> --
> Jochen "blackdrag" Theodorou
> blog: http://blackdragsview.blogspot.com/
>
>
> ___
> 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


Re: invokedynamic and subclasses

2015-06-24 Thread Jochen Theodorou

Hi Mike,

First of all, the bootstrap method does not have to be in the same 
class. In Groovy we have for example one bootstrap method for all 
classes only. It is part of the runtime then you could say.



We do it like this. We have two bootstrap methods in the Groovy runtime 
(you don't need to have them in the class). The first one is normally 
called and will produce a handle to call the second one. I tend to call 
the first one the static bootstrapper and the second one the dynamic 
bootstrapper. The dynamic bootstrapper will be called like a method 
(takes an Object[]), thus I will have all the arguments of the call as 
well as the receiver. This I can use to identify runtime classes and 
produce a new handle that fits my needs and replaces the first one. This 
method also is a fallback. The installed handle usually has to be 
guarded (like first call with B, second with C), and we use the dynamic 
bootstrapper as fallback. Of course you can easily check more cases and 
implement a polymorphic inline cache.


Of course that implies, that if the dynamic bootstrapper is called it 
will also have to do the first execution of the target (like getting the 
value of the field foo). We use (part of) the produced method handle for 
this. And of course the callsite will have to be mutable then


Does this help you out? It works quite good for Groovy.

bye blackdrag

Am 24.06.2015 14:19, schrieb Mike Jarmy:

I've been experimenting with invokedynamic in a compiler for a dynamic
language
that I'm working on, and I've run into a problem that I'm having difficulty
solving.

Let's say I have a class called A (Java syntax used for clarity):

 public class A {
 }

And another called B, that is a subclass of A:

 public class B extends A {
 public Value foo;
 public Value bar;
 }

There will be lots of other subclasses of A as well (let's call them C,
D, E,
etc), some of which will have a field called foo, and some of which
won't. The
class A will never have any fields -- its sole purpose is to be the base
class
of everything else.

I have been able to successfully use a static bootstrap method in B, so
that I
can compile a call to invokedynamic on the imaginary method get_foo() of an
instance of B, and then reroute the call inside B's bootstrap method via
MethodHandles.Lookup.findGetter(), and finally return the current value
of foo.
So far, so good.

However, at the place where I am compiling the invokedynamic instruction, I
have no idea if the target is a B, C, D, or what.  All I know is that it
must
be an A.

So what I really want to be able to do (I think) is to use a static
bootstrap
method in A. I want get_foo() to succeed for every invokedynamic call to an
instance of A who's *subclass* really does have a field called foo.

Unfortunately there doesn't seem to be a way to make A do what I want. I
understand why that is -- foo doesn't exist in A, so there is no way to
create
a findGetter() call.  But I'm hoping there might be some clever way to do it
anyway.  I've tried all kinds of different approaches (making yet another
invokedynamic call from inside A, etc, etc) but I can't come up with
anything
that works.

Any ideas?

By the way, I've figured out how to do this the "old" way, by generating
interfaces for each class that has e.g. a foo field, and casting to that
interface every time I compile a get_foo() invocation.  This works, and its
reasonably performant, but using invokedynamic seems like it would be a more
elegant and flexible solution.



___
mlvm-dev mailing list
mlvm-dev@openjdk.java.net
http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev




--
Jochen "blackdrag" Theodorou
blog: http://blackdragsview.blogspot.com/

___
mlvm-dev mailing list
mlvm-dev@openjdk.java.net
http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev


Re: invokedynamic and subclasses

2015-06-24 Thread Mike Jarmy
Thanks guys, the cookbook is just the kind of thing I was looking for.

On Wed, Jun 24, 2015 at 9:53 AM, Rémi Forax  wrote:

> Hi Mike,
> i've compiled a small list of patterns,
>   https://code.google.com/p/jsr292-cookbook/
>
> take a look to the first inlining cache example.
>
> cheers,
> Rémi
>
> Le 24 juin 2015 14:19:32 CEST, Mike Jarmy  a écrit :
> >I've been experimenting with invokedynamic in a compiler for a dynamic
> >language
> >that I'm working on, and I've run into a problem that I'm having
> >difficulty
> >solving.
> >
> >Let's say I have a class called A (Java syntax used for clarity):
> >
> >public class A {
> >}
> >
> >And another called B, that is a subclass of A:
> >
> >public class B extends A {
> >public Value foo;
> >public Value bar;
> >}
> >
> >There will be lots of other subclasses of A as well (let's call them C,
> >D,
> >E,
> >etc), some of which will have a field called foo, and some of which
> >won't.
> >The
> >class A will never have any fields -- its sole purpose is to be the
> >base
> >class
> >of everything else.
> >
> >I have been able to successfully use a static bootstrap method in B, so
> >that I
> >can compile a call to invokedynamic on the imaginary method get_foo()
> >of an
> >instance of B, and then reroute the call inside B's bootstrap method
> >via
> >MethodHandles.Lookup.findGetter(), and finally return the current value
> >of
> >foo.
> >So far, so good.
> >
> >However, at the place where I am compiling the invokedynamic
> >instruction, I
> >have no idea if the target is a B, C, D, or what.  All I know is that
> >it
> >must
> >be an A.
> >
> >So what I really want to be able to do (I think) is to use a static
> >bootstrap
> >method in A. I want get_foo() to succeed for every invokedynamic call
> >to an
> >instance of A who's *subclass* really does have a field called foo.
> >
> >Unfortunately there doesn't seem to be a way to make A do what I want.
> >I
> >understand why that is -- foo doesn't exist in A, so there is no way to
> >create
> >a findGetter() call.  But I'm hoping there might be some clever way to
> >do it
> >anyway.  I've tried all kinds of different approaches (making yet
> >another
> >invokedynamic call from inside A, etc, etc) but I can't come up with
> >anything
> >that works.
> >
> >Any ideas?
> >
> >By the way, I've figured out how to do this the "old" way, by
> >generating
> >interfaces for each class that has e.g. a foo field, and casting to
> >that
> >interface every time I compile a get_foo() invocation.  This works, and
> >its
> >reasonably performant, but using invokedynamic seems like it would be a
> >more
> >elegant and flexible solution.
> >
> >
> >
> >
> >___
> >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


Re: invokedynamic and subclasses

2015-06-24 Thread Rémi Forax
Hi Mike, 
i've compiled a small list of patterns,
  https://code.google.com/p/jsr292-cookbook/

take a look to the first inlining cache example.

cheers,
Rémi 

Le 24 juin 2015 14:19:32 CEST, Mike Jarmy  a écrit :
>I've been experimenting with invokedynamic in a compiler for a dynamic
>language
>that I'm working on, and I've run into a problem that I'm having
>difficulty
>solving.
>
>Let's say I have a class called A (Java syntax used for clarity):
>
>public class A {
>}
>
>And another called B, that is a subclass of A:
>
>public class B extends A {
>public Value foo;
>public Value bar;
>}
>
>There will be lots of other subclasses of A as well (let's call them C,
>D,
>E,
>etc), some of which will have a field called foo, and some of which
>won't.
>The
>class A will never have any fields -- its sole purpose is to be the
>base
>class
>of everything else.
>
>I have been able to successfully use a static bootstrap method in B, so
>that I
>can compile a call to invokedynamic on the imaginary method get_foo()
>of an
>instance of B, and then reroute the call inside B's bootstrap method
>via
>MethodHandles.Lookup.findGetter(), and finally return the current value
>of
>foo.
>So far, so good.
>
>However, at the place where I am compiling the invokedynamic
>instruction, I
>have no idea if the target is a B, C, D, or what.  All I know is that
>it
>must
>be an A.
>
>So what I really want to be able to do (I think) is to use a static
>bootstrap
>method in A. I want get_foo() to succeed for every invokedynamic call
>to an
>instance of A who's *subclass* really does have a field called foo.
>
>Unfortunately there doesn't seem to be a way to make A do what I want.
>I
>understand why that is -- foo doesn't exist in A, so there is no way to
>create
>a findGetter() call.  But I'm hoping there might be some clever way to
>do it
>anyway.  I've tried all kinds of different approaches (making yet
>another
>invokedynamic call from inside A, etc, etc) but I can't come up with
>anything
>that works.
>
>Any ideas?
>
>By the way, I've figured out how to do this the "old" way, by
>generating
>interfaces for each class that has e.g. a foo field, and casting to
>that
>interface every time I compile a get_foo() invocation.  This works, and
>its
>reasonably performant, but using invokedynamic seems like it would be a
>more
>elegant and flexible solution.
>
>
>
>
>___
>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


Re: invokedynamic and subclasses

2015-06-24 Thread MacGregor, Duncan (GE Energy Management)
Okay, this is just the sort of thing invokeDynamic is designed for.

Where you want to call get_foo() you should use an invokeDynaimc instruction 
that will create a MutableCallSite. You should set the target of this to be a 
lookup method that can find the appropriate get_foo() method, and possibly 
install that as a target. I highly recommend looking at Remi’s JSR 292 cookbook 
(https://code.google.com/p/jsr292-cookbook/) for some simple examples of how to 
do this sort of thing.

Hope this helps set you off in the right direction,

Duncan.

From: mlvm-dev 
mailto:mlvm-dev-boun...@openjdk.java.net>> 
on behalf of Mike Jarmy mailto:mja...@gmail.com>>
Reply-To: Da Vinci Machine Project 
mailto:mlvm-dev@openjdk.java.net>>
Date: Wednesday, 24 June 2015 13:19
To: Da Vinci Machine Project 
mailto:mlvm-dev@openjdk.java.net>>
Subject: invokedynamic and subclasses

I've been experimenting with invokedynamic in a compiler for a dynamic language
that I'm working on, and I've run into a problem that I'm having difficulty
solving.

Let's say I have a class called A (Java syntax used for clarity):

public class A {
}

And another called B, that is a subclass of A:

public class B extends A {
public Value foo;
public Value bar;
}

There will be lots of other subclasses of A as well (let's call them C, D, E,
etc), some of which will have a field called foo, and some of which won't. The
class A will never have any fields -- its sole purpose is to be the base class
of everything else.

I have been able to successfully use a static bootstrap method in B, so that I
can compile a call to invokedynamic on the imaginary method get_foo() of an
instance of B, and then reroute the call inside B's bootstrap method via
MethodHandles.Lookup.findGetter(), and finally return the current value of foo.
So far, so good.

However, at the place where I am compiling the invokedynamic instruction, I
have no idea if the target is a B, C, D, or what.  All I know is that it must
be an A.

So what I really want to be able to do (I think) is to use a static bootstrap
method in A. I want get_foo() to succeed for every invokedynamic call to an
instance of A who's *subclass* really does have a field called foo.

Unfortunately there doesn't seem to be a way to make A do what I want. I
understand why that is -- foo doesn't exist in A, so there is no way to create
a findGetter() call.  But I'm hoping there might be some clever way to do it
anyway.  I've tried all kinds of different approaches (making yet another
invokedynamic call from inside A, etc, etc) but I can't come up with anything
that works.

Any ideas?

By the way, I've figured out how to do this the "old" way, by generating
interfaces for each class that has e.g. a foo field, and casting to that
interface every time I compile a get_foo() invocation.  This works, and its
reasonably performant, but using invokedynamic seems like it would be a more
elegant and flexible solution.



___
mlvm-dev mailing list
mlvm-dev@openjdk.java.net
http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev


invokedynamic and subclasses

2015-06-24 Thread Mike Jarmy
I've been experimenting with invokedynamic in a compiler for a dynamic
language
that I'm working on, and I've run into a problem that I'm having difficulty
solving.

Let's say I have a class called A (Java syntax used for clarity):

public class A {
}

And another called B, that is a subclass of A:

public class B extends A {
public Value foo;
public Value bar;
}

There will be lots of other subclasses of A as well (let's call them C, D,
E,
etc), some of which will have a field called foo, and some of which won't.
The
class A will never have any fields -- its sole purpose is to be the base
class
of everything else.

I have been able to successfully use a static bootstrap method in B, so
that I
can compile a call to invokedynamic on the imaginary method get_foo() of an
instance of B, and then reroute the call inside B's bootstrap method via
MethodHandles.Lookup.findGetter(), and finally return the current value of
foo.
So far, so good.

However, at the place where I am compiling the invokedynamic instruction, I
have no idea if the target is a B, C, D, or what.  All I know is that it
must
be an A.

So what I really want to be able to do (I think) is to use a static
bootstrap
method in A. I want get_foo() to succeed for every invokedynamic call to an
instance of A who's *subclass* really does have a field called foo.

Unfortunately there doesn't seem to be a way to make A do what I want. I
understand why that is -- foo doesn't exist in A, so there is no way to
create
a findGetter() call.  But I'm hoping there might be some clever way to do it
anyway.  I've tried all kinds of different approaches (making yet another
invokedynamic call from inside A, etc, etc) but I can't come up with
anything
that works.

Any ideas?

By the way, I've figured out how to do this the "old" way, by generating
interfaces for each class that has e.g. a foo field, and casting to that
interface every time I compile a get_foo() invocation.  This works, and its
reasonably performant, but using invokedynamic seems like it would be a more
elegant and flexible solution.
___
mlvm-dev mailing list
mlvm-dev@openjdk.java.net
http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev