8192025: Less referential references

Reviewed-by: coleenp, eosterlund, mchung, ahgross, rhalade

src/share/vm/classfile/javaClasses.cpp

 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2679,6 +2679,32 @@ void java_lang_ref_SoftReference::set_clock(jlong value) {
   *offset = value;
 }
 
+// Support for java_lang_ref_ReferenceQueue
+
+oop java_lang_ref_ReferenceQueue::NULL_queue() {
+  InstanceKlass* ik = InstanceKlass::cast(SystemDictionary::ReferenceQueue_klass());
+  oop mirror = ik->java_mirror();
+  return mirror->obj_field(static_NULL_queue_offset);
+}
+
+oop java_lang_ref_ReferenceQueue::ENQUEUED_queue() {
+  InstanceKlass* ik = InstanceKlass::cast(SystemDictionary::ReferenceQueue_klass());
+  oop mirror = ik->java_mirror();
+  return mirror->obj_field(static_ENQUEUED_queue_offset);
+}
+
+void java_lang_ref_ReferenceQueue::compute_offsets() {
+  Klass* k = SystemDictionary::ReferenceQueue_klass();
+  compute_offset(static_NULL_queue_offset,
+                 k,
+                 vmSymbols::referencequeue_null_name(),
+                 vmSymbols::referencequeue_signature());
+  compute_offset(static_ENQUEUED_queue_offset,
+                 k,
+                 vmSymbols::referencequeue_enqueued_name(),
+                 vmSymbols::referencequeue_signature());
+}
+
 // Support for java_lang_invoke_DirectMethodHandle
 
 int java_lang_invoke_DirectMethodHandle::_member_offset;
@@ -3197,6 +3223,8 @@ int java_lang_ref_Reference::discovered_offset;
 int java_lang_ref_Reference::static_lock_offset;
 int java_lang_ref_Reference::static_pending_offset;
 int java_lang_ref_Reference::number_of_fake_oop_fields;
+int java_lang_ref_ReferenceQueue::static_NULL_queue_offset;
+int java_lang_ref_ReferenceQueue::static_ENQUEUED_queue_offset;
 int java_lang_ref_SoftReference::timestamp_offset;
 int java_lang_ref_SoftReference::static_clock_offset;
 int java_lang_ClassLoader::parent_offset;
@@ -3378,6 +3406,8 @@ void JavaClasses::compute_offsets() {
   if (JDK_Version::is_jdk18x_version())
     java_lang_reflect_Parameter::compute_offsets();
 
+  java_lang_ref_ReferenceQueue::compute_offsets();
+
   // generated interpreter code wants to know about the offsets we just computed:
   AbstractAssembler::update_delayed_values();
 }

src/share/vm/classfile/javaClasses.hpp

 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -929,6 +929,12 @@ class java_lang_ref_Reference: AllStatic {
   static HeapWord* discovered_addr(oop ref) {
     return ref->obj_field_addr<HeapWord>(discovered_offset);
   }
+  static inline oop queue(oop ref) {
+    return ref->obj_field(queue_offset);
+  }
+  static inline void set_queue(oop ref, oop value) {
+    return ref->obj_field_put(queue_offset, value);
+  }
   // Accessors for statics
   static oop  pending_list_lock();
   static oop  pending_list();
@@ -962,6 +968,20 @@ class java_lang_ref_SoftReference: public java_lang_ref_Reference {
 };
 
 
+// Interface to java.lang.ref.ReferenceQueue objects
+
+class java_lang_ref_ReferenceQueue: public AllStatic {
+public:
+  static int static_NULL_queue_offset;
+  static int static_ENQUEUED_queue_offset;
+
+  // Accessors
+  static oop NULL_queue();
+  static oop ENQUEUED_queue();
+
+  static void compute_offsets();
+};
+
 // Interface to java.lang.invoke.MethodHandle objects
 
 class MethodHandleEntry;

src/share/vm/classfile/systemDictionary.cpp

 /*
- * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1927,6 +1927,8 @@ void SystemDictionary::initialize_preloaded_classes(TRAPS) {
   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
   InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
 
+  initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(ReferenceQueue_klass), scan, CHECK);
+
   // JSR 292 classes
   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);

src/share/vm/classfile/systemDictionary.hpp

 /*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -130,6 +130,7 @@ class Ticks;
   do_klass(PhantomReference_klass,                      java_lang_ref_PhantomReference,            Pre                 ) \
   do_klass(Cleaner_klass,                               sun_misc_Cleaner,                          Pre                 ) \
   do_klass(Finalizer_klass,                             java_lang_ref_Finalizer,                   Pre                 ) \
+  do_klass(ReferenceQueue_klass,                        java_lang_ref_ReferenceQueue,              Pre                 ) \
                                                                                                                          \
   do_klass(Thread_klass,                                java_lang_Thread,                          Pre                 ) \
   do_klass(ThreadGroup_klass,                           java_lang_ThreadGroup,                     Pre                 ) \

src/share/vm/classfile/vmSymbols.hpp

 /*
- * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -81,6 +81,7 @@
   template(java_lang_ref_PhantomReference,            "java/lang/ref/PhantomReference")           \
   template(sun_misc_Cleaner,                          "sun/misc/Cleaner")                         \
   template(java_lang_ref_Finalizer,                   "java/lang/ref/Finalizer")                  \
+  template(java_lang_ref_ReferenceQueue,              "java/lang/ref/ReferenceQueue")             \
   template(java_lang_reflect_AccessibleObject,        "java/lang/reflect/AccessibleObject")       \
   template(java_lang_reflect_Method,                  "java/lang/reflect/Method")                 \
   template(java_lang_reflect_Constructor,             "java/lang/reflect/Constructor")            \
@@ -417,6 +418,8 @@
   template(getProtectionDomain_name,                  "getProtectionDomain")                      \
   template(getProtectionDomain_signature,             "(Ljava/security/CodeSource;)Ljava/security/ProtectionDomain;") \
   template(url_code_signer_array_void_signature,      "(Ljava/net/URL;[Ljava/security/CodeSigner;)V") \
+  template(referencequeue_null_name,                  "NULL")                                     \
+  template(referencequeue_enqueued_name,              "ENQUEUED")                                 \
                                                                                                   \
   /* non-intrinsic name/signature pairs: */                                                       \
   template(register_method_name,                      "register")                                 \
@@ -508,6 +511,7 @@
   template(class_signature,                           "Ljava/lang/Class;")                                        \
   template(string_signature,                          "Ljava/lang/String;")                                       \
   template(reference_signature,                       "Ljava/lang/ref/Reference;")                                \
+  template(referencequeue_signature,                  "Ljava/lang/ref/ReferenceQueue;")                           \
   template(executable_signature,                      "Ljava/lang/reflect/Executable;")                           \
   template(concurrenthashmap_signature,               "Ljava/util/concurrent/ConcurrentHashMap;")                 \
   template(String_StringBuilder_signature,            "(Ljava/lang/String;)Ljava/lang/StringBuilder;")            \

src/share/vm/oops/klass.cpp

 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -48,6 +48,19 @@
 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
 #endif // INCLUDE_ALL_GCS
 
+bool Klass::is_cloneable() const {
+  return _access_flags.is_cloneable() ||
+         is_subtype_of(SystemDictionary::Cloneable_klass());
+}
+
+void Klass::set_is_cloneable() {
+  if (oop_is_instance() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
+    // Reference cloning should not be intrinsified and always happen in JVM_Clone.
+  } else {
+    _access_flags.set_is_cloneable();
+  }
+}
+
 void Klass::set_name(Symbol* n) {
   _name = n;
   if (_name != NULL) _name->increment_refcount();

src/share/vm/oops/klass.hpp

 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -582,8 +582,8 @@ protected:
   bool has_final_method() const         { return _access_flags.has_final_method(); }
   void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
   void set_has_final_method()           { _access_flags.set_has_final_method(); }
-  bool is_cloneable() const             { return _access_flags.is_cloneable(); }
-  void set_is_cloneable()               { _access_flags.set_is_cloneable(); }
+  bool is_cloneable() const;
+  void set_is_cloneable();
   bool has_vanilla_constructor() const  { return _access_flags.has_vanilla_constructor(); }
   void set_has_vanilla_constructor()    { _access_flags.set_has_vanilla_constructor(); }
   bool has_miranda_methods () const     { return access_flags().has_miranda_methods(); }

src/share/vm/prims/jvm.cpp

 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -38,6 +38,7 @@
 #include "gc_interface/collectedHeap.inline.hpp"
 #include "interpreter/bytecode.hpp"
 #include "memory/oopFactory.hpp"
+#include "memory/referenceType.hpp"
 #include "memory/universe.inline.hpp"
 #include "oops/fieldStreams.hpp"
 #include "oops/instanceKlass.hpp"
@@ -90,6 +91,10 @@
 # include "jvm_bsd.h"
 #endif
 
+#if INCLUDE_ALL_GCS
+#include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
+#endif // INCLUDE_ALL_GCS
+
 #include <errno.h>
 
 #ifndef USDT2
@@ -578,6 +583,28 @@ JVM_ENTRY(void, JVM_MonitorNotifyAll(JNIEnv* env, jobject handle))
 JVM_END
 
 
+static void fixup_cloned_reference(ReferenceType ref_type, oop src, oop clone) {
+  // If G1 is enabled then we need to register a non-null referent
+  // with the SATB barrier.
+#if INCLUDE_ALL_GCS
+  if (UseG1GC) {
+    oop referent = java_lang_ref_Reference::referent(clone);
+    if (referent != NULL) {
+      G1SATBCardTableModRefBS::enqueue(referent);
+    }
+  }
+#endif // INCLUDE_ALL_GCS
+  if ((java_lang_ref_Reference::next(clone) != NULL) ||
+      (java_lang_ref_Reference::queue(clone) == java_lang_ref_ReferenceQueue::ENQUEUED_queue())) {
+    // If the source has been enqueued or is being enqueued, don't
+    // register the clone with a queue.
+    java_lang_ref_Reference::set_queue(clone, java_lang_ref_ReferenceQueue::NULL_queue());
+  }
+  // discovered and next are list links; the clone is not in those lists.
+  java_lang_ref_Reference::set_discovered(clone, NULL);
+  java_lang_ref_Reference::set_next(clone, NULL);
+}
+
 JVM_ENTRY(jobject, JVM_Clone(JNIEnv* env, jobject handle))
   JVMWrapper("JVM_Clone");
   Handle obj(THREAD, JNIHandles::resolve_non_null(handle));
@@ -603,12 +630,17 @@ JVM_ENTRY(jobject, JVM_Clone(JNIEnv* env, jobject handle))
   }
 
   // Make shallow object copy
+  ReferenceType ref_type = REF_NONE;
   const int size = obj->size();
   oop new_obj_oop = NULL;
   if (obj->is_array()) {
     const int length = ((arrayOop)obj())->length();
     new_obj_oop = CollectedHeap::array_allocate(klass, size, length, CHECK_NULL);
   } else {
+    ref_type = InstanceKlass::cast(klass())->reference_type();
+    assert((ref_type == REF_NONE) ==
+           !klass->is_subclass_of(SystemDictionary::Reference_klass()),
+           "invariant");
     new_obj_oop = CollectedHeap::obj_allocate(klass, size, CHECK_NULL);
   }
 
@@ -632,6 +664,12 @@ JVM_ENTRY(jobject, JVM_Clone(JNIEnv* env, jobject handle))
   assert(bs->has_write_region_opt(), "Barrier set does not have write_region");
   bs->write_region(MemRegion((HeapWord*)new_obj_oop, size));
 
+  // If cloning a Reference, set Reference fields to a safe state.
+  // Fixup must be completed before any safepoint.
+  if (ref_type != REF_NONE) {
+    fixup_cloned_reference(ref_type, obj(), new_obj_oop);
+  }
+
   Handle new_obj(THREAD, new_obj_oop);
   // Special handling for MemberNames.  Since they contain Method* metadata, they
   // must be registered so that RedefineClasses can fix metadata contained in them.