RFR: 8154064: JVMTI trace event crashes

[Robbin Ehn]

Hi all,

Please review this bug fix.
Bug: https://bugs.openjdk.java.net/browse/JDK-8154064

Test with tonga. (the 5 crashed tonga test no longer crashes)

Thanks!

/Robbin

diff -r 4823056a5bbd src/share/vm/prims/jvmtiExport.cpp
--- a/src/share/vm/prims/jvmtiExport.cpp        Tue Apr 12 09:08:48 2016 +0000
+++ b/src/share/vm/prims/jvmtiExport.cpp        Wed Apr 13 07:39:50 2016 +0200
@@ -2260,7 +2260,7 @@
     if (env->is_enabled(JVMTI_EVENT_VM_OBJECT_ALLOC)) {
       EVT_TRACE(JVMTI_EVENT_VM_OBJECT_ALLOC, ("JVMTI [%s] Evt vmobject 
alloc sent %s",

JvmtiTrace::safe_get_thread_name(thread),
-                                         object==NULL? "NULL" : 
java_lang_Class::as_Klass(object)->external_name()));
+                                         object==NULL? "NULL" : 
object->klass()->external_name()));

       JvmtiVMObjectAllocEventMark jem(thread, h());
       JvmtiJavaThreadEventTransition jet(thread);