RFR (XM) 8076579: Popping a stack frame after exception breakpoint sets last method param to exception

[serguei.spitsyn at oracle.com]

Please, review the jdk 9 fix for:
   https://bugs.openjdk.java.net/browse/JDK-8076579


9 hotspot webrev:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8076579-JVMTI-pop.1


Summary:

   This bug is a regression that was introduced but the fix of:
     https://bugs.openjdk.java.net/browse/JDK-7187554

   The bug is in the InterpreterRuntime::member_name_arg_or_null() 
function that
   does not return NULL if there is no invokestatic appendix argument 
(MemberName).
   It is why the _remove_activation_preserving_args is trying to to 
restore unexisting
   appendix argument when a pop instruction is executed by a debugger in 
the debuggee VM.
   The fix is to correctly set NULL in the thread vm_result when it is 
necessary:
     thread->set_vm_result(NULL);


Testing in progress:
   In progress: nsk.jvmti.testlist and nsk.jdi.testlist PopFrame tests, 
JTREG com/sun/jdi tests,
                ad-hog ExceptionBug.java test from the bug report


Thanks,
Serguei