still no fun with invokedynamic

[John Rose]

On Sep 11, 2009, at 2:36 AM, Jochen Theodorou wrote:

>> You can also try the backport :)
>> http://code.google.com/p/jvm-language-runtime/source/browse/#svn/ 
>> trunk/invokedynamic-backport
>
> well, I will most probably do, since there is nothing else and the VM
> implementation is hopefully faster than or of equal speed. In
> functionality I trust your backport very much ;)

The backport a great option for experimentation, since it does not  
require a pre-release JVM.  Its performance seems to be comparable to  
the current MLVM JVM.  Basically what you get is a backend that  
performs JRuby-like rewrites of JSR 292 bytecodes.  As we work on code  
quality (JIT optimizer) in the MLVM JVM, I expect that the native JSR  
292 implementations will be decisively faster, since the JSR 292  
version of the code has (potentially) more quasi-static knowledge for  
the JIT optimizer to exploit.

Also, note that the JVM and the JDK are tightly coupled in the JSR 292  
implementations.  At least during JDK7 development, you can't mix and  
match JVMs and JDKs.  The best bet will be to use an JDK7 build  
updated with the current MLVM stuff, when that becomes available.  But  
MLVM will always be ahead of the curve.  I wonder if our friends over  
at EngineYard are making builds from it?  (Hint, hint.)  I know Attila  
Szegedi also has been making MLVM builds and posting the bits.

The other question, of course, is when the MLVM stuff will get into  
the JDK7 builds.  That work has been road-blocked by implementation  
problems in the GC; it's what I've been working on for several weeks  
(plus vacation).  GC extensions are behind many of the crashes we've  
been seeing in the MLVM.  As of last night, I have a set of GC changes  
that pass the JDK7 pre-integration testing, and also begin to support  
the JRuby tests (the benchmarks, actually).  Pushing these into the  
JDK7 pipeline will open the way to committing the other pending MLVM  
changes, so we can get standard builds that are beyond the JavaOne  
preview functionality.

See you at the Summit!
-- John
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