On Wed, Jul 20, 2016 at 12:41 PM, Remi Forax <fo...@univ-mlv.fr> wrote:

> yes, the rewriting part is easy, the question is more how to find the call
> you
> want to rewrite and how to find the bootstrap method and the bootstrap
> arguments associated with that call.
>

At the moment I am using my own non-indy call sites, one per actual site in
the Java code. The call sites are all very straightforward:

sites(context).some_method.call(context, caller, target, args...)

Where sites is a private static method that gets the right box of call
sites, some_method is one of those call sites for calling "some method" and
the call logic does the monomporphic cache.

It should not be hard to see this pattern in code and rewrite it, but it
won't be a simple invokevirtual => invokedynamic.

Charles, given that i will be locked up in a flying box for a little more
> that 10 hours soon,
> if you have precise answers to these two questions, i can write a tool for
> you during that time.
>

What I want is a way to say "take all call sites that look like X and turn
them into indy call sites that do X the right way".


> A fun way to design such filter is to create a class that declares methods
> that uses the @PolymorphicSignature,
> with that the compiler will not try to box the arguments and it will be
> easier to substitute a call to
> a method of this call by an invokedynamic.
>

There's lots of annotations I'd love to play with from java.lang.invoke,
but is there any way to do it without runtime tricks?

FWIW, a contrived benchmark that uses a lot of dynamic calling from Java is
already 3x faster by introducing simple monomorphic caches.

This work is the first step.

* Get dynamic calls from Java caching in SOME way.
* Get dynamic calls from Java using invokedynamic using some tooling. SURE
WISH I COULD EMIT INDY FROM JAVA :-D
* Profile Java-based Ruby core methods and find the worst poly/megamorphic
cases. Move them to Ruby.

Once code is in Ruby, I already have a POC to re-emit the bytecode on a
per-callsite basis. We should also be able to feed expected types into IR
and have it emit specialized versions for e.g. math.

Lots of stuff finally coming together, but Java is the biggest thing
holding me back right now.

- Charlie

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