Valhalla causes performance slowdown for reflective invocations (due to DelegatingMethodAccessorImpl.invoke and GeneratedMethodAccessor1.invoke were not inlined)

Benchmark location: http://cr.openjdk.java.net/~skuksenko/valhalla/legacy/benchmarks/

Benchmark: reflect.MethodInvoke

Performance difference vs pre-valhalla world is ~20% for invocation of single argument method and 2x times on 6-argument method (doesn't matter if arguments are primitive or reference).

According to profilers data the reason is the following:
 - Call chain for reflective invocation looks as:
org.openjdk.reflect.MethodInvoke.invokeWithSixObjectParams()
  java.lang.reflect.Method.invoke(...)
    jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(...)
      jdk.internal.reflect.GeneratedMethodAccessor1.invoke(...)
        org.openjdk.reflect.MethodInvoke.staticMethodWithSixObjectParams(...)

- In pre-valhalla world all 3 intermediate methods were inlined and final invocation chain in code is:
reflect.MethodInvoke.invokeWithSixObjectParams()
   reflect.MethodInvoke.staticMethodWithSixObjectParams(...)

- In valhalla only Method.invokewas inlined. Final invocation chain is:
org.openjdk.reflect.MethodInvoke.invokeWithSixObjectParams()
  jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(...)
    jdk.internal.reflect.GeneratedMethodAccessor1.invoke(...)
      org.openjdk.reflect.MethodInvoke.staticMethodWithSixObjectParams(...)