RFR: 8219233: 3x performance drop for some Clojure applications

[David Holmes]

webrev: http://cr.openjdk.java.net/~dholmes/8219233/webrev.v2/
bug: https://bugs.openjdk.java.net/browse/JDK-8219233

We had a bug whereby the callsite to a static method was resolved as 
soon as it was executed, allowing other threads to execute the same code 
and skip the class initialization check. The fix to that was to not do 
the resolution if the target class was not fully initialized. This has a 
consequence that calls to static methods of the current class from the 
<clinit> (including transitively) can't be resolved and effectively 
compiled and so we can take a huge performance hit for those cases 
(which is a rare case and regular benchmarking showed no issue). Clojure 
unfortunately uses a style of coding that is significantly impacted by this.

There is a simple fix for the direct case of calling a static method 
from <clinit>: when we are dealing with the same class then it's okay to 
do the resolution as the current thread must have <clinit> on its 
callstack. No other thread can execute the code being resolved until the 
initial thread completes the static initialization.

Unfortunately that doesn't address the main pattern used by Clojure, but 
we have a subtask open where Vladimir Ivanov continues to look into that 
case. And Claes Redestad has also given coding advice on how to avoid 
the problem in the first place.

Testing: tier 1-3
Microbenchmarking - see bug report.

Thanks,
David
-----