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From Naveen Neelakantam <neela...@uiuc.edu>
Subject Re: [drlvm][jit] abcd and devirtualizer patches was: [OT] Harmony used in accepted research paper
Date Tue, 17 Apr 2007 15:09:18 GMT
Wow!  Thanks for testing it Pavel!

However, should unguard be disabled?  As I understand it, won't most  
virtual calls be devirtualized using the static heuristic during  
first compilation?  It is fairly accurate, but unguard will remove  
the ones that are unprofitable.  This seems intelligent to me.   
Perhaps the profile-based devirtualization code should be modified so  
that it only devirtualizes virtual calls that have been unguarded?

On the other hand, profile-based devirtualization will do the "right"  
thing every time.  So, maybe you are right and we should disable the  
static heuristic and unguard.

What do you think?

Naveen


On Apr 17, 2007, at 8:14 AM, Pavel Ozhdikhin wrote:

> I've tested HARMONY-3630. Profile-guided devirtualizations gives ~2%
> improvement on SPECjbb2005 which is impressive! We should disable  
> unguard
> config before integrating the patch - otherwise we'll devirtualize  
> virtual
> calls twice. Also we should get rid of code duplication in  
> ValueProfiler.cpp.
> I'm going to prepare the patch which includes removing unguard  
> config and
> then we can integrate profile-guided devirt for abstract and  
> virtual calls.
>
> Thanks,
> Pavel
>
>
> On 4/12/07, Pavel Ozhdikhin <pavel.ozhdikhin@gmail.com> wrote:
>>
>> Naveen,
>>
>> It's great! Do you have any data about performance gain/profiling  
>> overhead
>> for profile-guided devirtualization of virtual and abstract calls?  
>> Current
>> agressive devirtualization with unguard pass works pretty well and  
>> it's
>> interesting if we can beat it with value profile.
>>
>> I'm going to play with your patches a bit to better understand the
>> performance overhead/gain implications. I'll comment about the  
>> results here
>> on the dev list.
>>
>> Thanks,
>> Pavel
>>
>>
>>  On 4/12/07, Naveen Neelakantam <neelakan@uiuc.edu> wrote:
>> >
>> > I've uploaded a patch against Egor's ABCD implementation in
>> > HARMONY-1788.   It passes the tests included with HARMONY-2141,
>> > HARMONY-2144 and HARMONY-2147, and removes all but one bounds check
>> > from BidirectionalBubbleSort in HARMONY-1564.  I've also ran the
>> > DaCapo benchmarks using it and it doesn't seem to break anything.
>> >
>> > I've also opened a JIRA issue for my profile-based abstract and
>> > virtual call devirtualization patch: HARMONY-3630.
>> >
>> > Naveen
>> >
>> > On Apr 9, 2007, at 12:23 AM, Pavel Ozhdikhin wrote:
>> >
>> > > Naveen,
>> > >
>> > > Congrartulations! I eager to read your paper - please announce a
>> > > link here
>> > > when it's available.
>> > >
>> > > I'm also looking forward to a new ABCD impementation from Egor  
>> and
>> > > your -
>> > > your both did a lot to make it working, now it's time to make use
>> > > of it in
>> > > Harmony.
>> > >
>> > > Thanks,
>> > > Pavel
>> > >
>> > > On 4/8/07, Naveen Neelakantam < neelakan@uiuc.edu> wrote:
>> > >>
>> > >> Hello all,
>> > >>
>> > >> You might like to hear that a paper which used Apache Harmony  
>> as part
>> > >> of a research infrastructure was accepted to ISCA 2007  
>> (International
>> >
>> > >> Symposium on Computer Architecture).  I will be presenting  
>> this work
>> > >> in San Diego in June and will be sure to include a slide  
>> plugging
>> > >> Harmony.
>> > >>
>> > >> I would like to thank all of the JVM and classlib developers  
>> who made
>> >
>> > >> such an endeavor even possible.  You are doing a wonderful  
>> job, and
>> > >> it is much appreciated!  Please pat yourself on the back.  :-)
>> > >>
>> > >> BTW, in the process of doing this work I helped get Egor  
>> Pasko's ABCD
>> >
>> > >> reimplementation finished, and I added profile-based abstract  
>> call
>> > >> and virtual devirtualization to the code from HARMONY-2012.   
>> I'll
>> > >> post the patches after the weekend.
>> > >>
>> > >> Thanks again,
>> > >> Naveen
>> > >>
>> >
>> >
>>


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