http://cr.openjdk.java.net/~vlivanov/8069591/webrev.00/ https://bugs.openjdk.java.net/browse/JDK-8069591
Overhead of non-inlined MH.invoke/invokeExact calls significantly increased with LambdaForm sharing. The cause is JIT compiler can't produce a single nmethod for the whole MethodHandle chain, so the execution is spread around numerous nmethods (1 per each MethodHandle in the chain). The longer the chain the larger overhead.
The fix is to customize LambdaForms (create a dedicated LambdaForm for a MethodHandle). Per-MethodHandle count is introduced, which is incremented every time a MethodHandle is invoked using MethodHandle.invoke/invokeExact. Once CUSTOMIZE_THRESHOLD is reached for a particular MethodHandle, it's LambdaForm is substituted with a customized one, which has it's MethodHandle embedded. It allows JIT to see actual MethodHandle during compilation and produce more efficient code.
This fix completely recovers Gbemu peak performance to pre-LambdaForm sharing level.
Testing: jck (api/java_lang/invoke), jdk/java/lang/invoke, nashorn tests, nashorn/octane
Thanks! Best regards, Vladimir Ivanov
