hotspot-dev Digest, Vol 30, Issue 10

[Tim Bell]

Hi Dan:

It is the weekend here, and I am sure others will send more in follow up
messages.  I'll take a crack at it to get you started:

> I have been told that Java 7 JDK will include support for a new "invoke 
> dynamic" opcode.  Is there somewhere I can get info on this?

People tend to sling around JSR numbers without the definition, so for
those (like me :-) without a decoder ring, let me record that Invoke
Dynamic is JSR-000292:

"Supporting Dynamically Typed Languages on the JavaTM Platform"
http://jcp.org/en/jsr/detail?id=292

The initial implementation is already there.  If you want to get down
and read the source, take a look at the first two listed here:

6829144: JSR 292 JVM features need a provisional Java API
http://hg.openjdk.java.net/jdk7/jdk7/jdk/rev/d201987cb76c

6655646: dynamic languages need dynamically linked call sites
http://hg.openjdk.java.net/jdk7/jdk7/hotspot/rev/be93aad57795

For background, start with John Rose and "Notes on an Architecture
for Dynamic Invocation"
http://blogs.sun.com/jrose/entry/notes_on_an_architecture_for

JSR 292 Cookbook talk at last year's JavaOne[TM] conference:
http://cr.openjdk.java.net/~jrose/pres/200906-Cookbook.htm

JVM Language Summit
http://blogs.sun.com/jrose/entry/thursday_at_the_summit
http://openjdk.java.net/projects/mlvm/jvmlangsummit/

> And does anyone know if the Java language will be modified to use this 
> opcode, or is it just for dynamic languages?

As far as I know, mostly the latter.  Having said that, there are a lot
of ideas floating around in the community, so you never know...

HTH-

Tim