8232788: Move biased locking initalization

Reviewed-by: pchilanomate, dholmes

Author: coleenp

src/hotspot/share/classfile/systemDictionary.cpp

@@ -2132,26 +2132,6 @@ void SystemDictionary::update_dictionary(unsigned int d_hash,
   {
     MutexLocker mu1(SystemDictionary_lock, THREAD);
 
-    // See whether biased locking is enabled and if so set it for this
-    // klass.
-    // Note that this must be done past the last potential blocking
-    // point / safepoint. We might enable biased locking lazily using a
-    // VM_Operation to iterate the SystemDictionary and installing the
-    // biasable mark word into each InstanceKlass's prototype header.
-    // To avoid race conditions where we accidentally miss enabling the
-    // optimization for one class in the process of being added to the
-    // dictionary, we must not safepoint after the test of
-    // BiasedLocking::enabled().
-    if (UseBiasedLocking && BiasedLocking::enabled()) {
-      // Set biased locking bit for all loaded classes; it will be
-      // cleared if revocation occurs too often for this type
-      // NOTE that we must only do this when the class is initally
-      // defined, not each time it is referenced from a new class loader
-      if (k->class_loader() == class_loader()) {
-        k->set_prototype_header(markWord::biased_locking_prototype());
-      }
-    }
-
     // Make a new dictionary entry.
     Dictionary* dictionary = loader_data->dictionary();
     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);

src/hotspot/share/oops/instanceKlass.cpp

@@ -69,6 +69,7 @@
 #include "prims/jvmtiThreadState.hpp"
 #include "prims/methodComparator.hpp"
 #include "runtime/atomic.hpp"
+#include "runtime/biasedLocking.hpp"
 #include "runtime/fieldDescriptor.inline.hpp"
 #include "runtime/handles.inline.hpp"
 #include "runtime/javaCalls.hpp"
@@ -456,6 +457,12 @@ InstanceKlass::InstanceKlass(const ClassFileParser& parser, unsigned kind, Klass
   if (Arguments::is_dumping_archive()) {
     SystemDictionaryShared::init_dumptime_info(this);
   }
+
+  // Set biased locking bit for all instances of this class; it will be
+  // cleared if revocation occurs too often for this type
+  if (UseBiasedLocking && BiasedLocking::enabled()) {
+    set_prototype_header(markWord::biased_locking_prototype());
+  }
 }
 
 void InstanceKlass::deallocate_methods(ClassLoaderData* loader_data,
@@ -2408,6 +2415,11 @@ void InstanceKlass::restore_unshareable_info(ClassLoaderData* loader_data, Handl
     // --> see ArrayKlass::complete_create_array_klass()
     array_klasses()->restore_unshareable_info(ClassLoaderData::the_null_class_loader_data(), Handle(), CHECK);
   }
+
+  // Initialize current biased locking state.
+  if (UseBiasedLocking && BiasedLocking::enabled()) {
+    set_prototype_header(markWord::biased_locking_prototype());
+  }
 }
 
 // returns true IFF is_in_error_state() has been changed as a result of this call.

test/hotspot/gtest/oops/test_markOop.cpp test/hotspot/gtest/oops/test_markWord.cpp

@@ -27,6 +27,7 @@
 #include "memory/universe.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/atomic.hpp"
+#include "runtime/biasedLocking.hpp"
 #include "runtime/interfaceSupport.inline.hpp"
 #include "runtime/orderAccess.hpp"
 #include "runtime/os.hpp"
@@ -84,10 +85,14 @@ TEST_VM(markWord, printing) {
   ThreadInVMfromNative invm(THREAD);
   ResourceMark rm(THREAD);
 
+  if (!UseBiasedLocking || !BiasedLocking::enabled()) {
+    // Can't test this with biased locking disabled.
+    return;
+  }
+
   oop obj = SystemDictionary::Byte_klass()->allocate_instance(THREAD);
 
   FlagSetting fs(WizardMode, true);
-  FlagSetting bf(UseBiasedLocking, true);
 
   HandleMark hm(THREAD);
   Handle h_obj(THREAD, obj);