Trying to understand performance of MethodHandles and LambdaForms in 8u60

[Christopher Berner]

I discovered that jdk 8u60 does a lot of optimizations of MethodHandles
that I didn't expect, so I'm trying to understand what I can expect the VM
to optimize now.

I created this JMH benchmark (
https://gist.github.com/cberner/c141e651cb45288fba24) which tests various
ways of implementing a simple loop.

On 8u40 (https://gist.github.com/cberner/ec8039d1fd972568fe88), the results
show that only the "fast" version, where it's invoking a single static
method, reaches the peak performance.

However, with 8u60 (https://gist.github.com/cberner/b5de95e68e2ba2aa7ca2),
the performance is very different.

1) How does the "boundInvokeExact" version now reach peak performance?
(which uses bindTo to combine the inner part of the loop and the outer
part) Is it that LambdaForms now have extra profiling information, and
bindTo creates a new LambdaForm? I note that the "localBoundInvokeExact"
version is also pretty fast now.

2) Why is the "invokeExact" version faster than the "invokeStatic" version?
I'm quite surprised that getting a MethodHandle to a static method and then
invoking it is faster than just invoking the static method.

3) Why are "multipleInvokeStatic" and "multipleInvokeExact" so slow? I
expected these to be easier to optimize than "boundInvokeExact".

Thanks in advance for any insights!
Christopher