CHA for interfaces in C2 compiler

[Vitaly Davidovich]

A heuristic like that would work for most of my cases as well :).

On Wed, Apr 15, 2015 at 10:24 AM, Remi Forax <forax at univ-mlv.fr> wrote:

>
> On 04/15/2015 04:10 PM, Vitaly Davidovich wrote:
>
>> Hi guys,
>>
>> So CHA on classes works nicely in the case of only one subtype loaded.
>> What about interfaces? Currently, it looks like no such
>> optimization/analysis is done.  In my experience, there's a substantial
>> amount of code that exposes an interface via some API, but then loads only
>> implementation of it.  The interface is used instead of abstract class to
>> allow more flexibility in the future.
>>
>> I fully realize that lots of interfaces have more than 1 implementer
>> loaded at runtime, but I also think it's worthwhile to attempt CHA for them.
>>
>> Is this something that's feasible to do? It would require more class
>> loading dependencies to be tracked, but I'm also fine with having this be
>> an extra flag that I can use to enable/disable this optimization.
>>
>> Thoughts?
>>
>> Thanks
>>
>
> I've implemented something like this in a language (which has a special
> syntax for calling Java object).
> To avoid to have too many metadata, I've used a simple heuristic, the idea
> is that an interface with a lot of methods do not have a lot of
> implementations so the runtime only tried to do CHA, using a SwitchPoint,
> if there were more than 3 methods (included) in the interface.
>
> cheers,
> Rémi
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/attachments/20150415/374ab80d/attachment.html>