About two weeks ago I pushed the remaining changes (6894206, 6893081, 6829187, 6893268) for C2 invokedynamic support on x86 which were integrated into HotSpot 17 b07. Meanwhile HS17b07 has been integrated into JDK 7 b80 and the latter has been released.
With two changesets John Rose pushed lately (6891770, 6914665), which have been integrated into JDK 7 b79, you can run now invokedynamic enabled programs with decent performance. Additionally we tuned inlining heuristics a little (6912063) to be able to use inline-related switches in a product VM and to not count generated MethodHandle adapters.
And here is how it works (gwt is a simple testcase for guardWithTest):
$ java -server -XX:+UnlockExperimentalVMOptions -XX:+EnableMethodHandles -XX:+EnableInvokeDynamic gwt
You can also run JRuby benchmarks, like bench_fractal.rb which prints a nice fractal (we need to tune inlining heuristics a little to get good performance):
$ bin/jruby --server -J-Djruby.compile.invokedynamic=true -J-XX:+UnlockExperimentalVMOptions -J-XX:+EnableMethodHandles -J-XX:+EnableInvokeDynamic -J-XX:InlineSmallCode=2500 -J-XX:MaxInlineSize=50 bench/bench_fractal.rb
(To see the fractal you have to try it yourself :-)
The next thing will be C1 support. I'm currently working on it and it's almost finished.