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 /*

  * Copyright (c) 1997, 2013, 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

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

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  */

 #ifndef SHARE_VM_OOPS_INSTANCEKLASS_HPP

 #define SHARE_VM_OOPS_INSTANCEKLASS_HPP

 #include "classfile/classLoaderData.hpp"

 #include "oops/annotations.hpp"

 #include "oops/constMethod.hpp"

 #include "oops/fieldInfo.hpp"

 #include "oops/instanceOop.hpp"

 #include "oops/klassVtable.hpp"

 #include "runtime/atomic.hpp"

 #include "runtime/handles.hpp"

 #include "runtime/os.hpp"

 #include "utilities/accessFlags.hpp"

 #include "utilities/bitMap.inline.hpp"

 #include "utilities/macros.hpp"

 // An InstanceKlass is the VM level representation of a Java class.

 // It contains all information needed for at class at execution runtime.

 //  InstanceKlass layout:

 //    [C++ vtbl pointer           ] Klass

 //    [subtype cache              ] Klass

 //    [instance size              ] Klass

 //    [java mirror                ] Klass

 //    [super                      ] Klass

 //    [access_flags               ] Klass

 //    [name                       ] Klass

 //    [first subklass             ] Klass

 //    [next sibling               ] Klass

 //    [array klasses              ]

 //    [methods                    ]

 //    [local interfaces           ]

 //    [transitive interfaces      ]

 //    [fields                     ]

 //    [constants                  ]

 //    [class loader               ]

 //    [protection domain          ]

 //    [signers                    ]

 //    [source file name           ]

 //    [inner classes              ]

 //    [static field size          ]

 //    [nonstatic field size       ]

 //    [static oop fields size     ]

 //    [nonstatic oop maps size    ]

 //    [has finalize method        ]

 //    [deoptimization mark bit    ]

 //    [initialization state       ]

 //    [initializing thread        ]

 //    [Java vtable length         ]

 //    [oop map cache (stack maps) ]

 //    [EMBEDDED Java vtable             ] size in words = vtable_len

 //    [EMBEDDED nonstatic oop-map blocks] size in words = nonstatic_oop_map_size

 //      The embedded nonstatic oop-map blocks are short pairs (offset, length)

 //      indicating where oops are located in instances of this klass.

 //    [EMBEDDED implementor of the interface] only exist for interface

 //    [EMBEDDED host klass        ] only exist for an anonymous class (JSR 292 enabled)

 // forward declaration for class -- see below for definition

 class SuperTypeClosure;

 class JNIid;

 class jniIdMapBase;

 class BreakpointInfo;

 class fieldDescriptor;

 class DepChange;

 class nmethodBucket;

 class PreviousVersionNode;

 class JvmtiCachedClassFieldMap;

 class MemberNameTable;

 // This is used in iterators below.

 class FieldClosure: public StackObj {

 public:

   virtual void do_field(fieldDescriptor* fd) = 0;

 };

 #ifndef PRODUCT

 // Print fields.

 // If "obj" argument to constructor is NULL, prints static fields, otherwise prints non-static fields.

 class FieldPrinter: public FieldClosure {

    oop _obj;

    outputStream* _st;

  public:

    FieldPrinter(outputStream* st, oop obj = NULL) : _obj(obj), _st(st) {}

    void do_field(fieldDescriptor* fd);

 };

 #endif  // !PRODUCT

 // ValueObjs embedded in klass. Describes where oops are located in instances of

 // this klass.

 class OopMapBlock VALUE_OBJ_CLASS_SPEC {

  public:

   // Byte offset of the first oop mapped by this block.

   int offset() const          { return _offset; }

   void set_offset(int offset) { _offset = offset; }

   // Number of oops in this block.

   uint count() const         { return _count; }

   void set_count(uint count) { _count = count; }

   // sizeof(OopMapBlock) in HeapWords.

   static const int size_in_words() {

     return align_size_up(int(sizeof(OopMapBlock)), HeapWordSize) >>

       LogHeapWordSize;

   }

  private:

   int  _offset;

   uint _count;

 };

 class InstanceKlass: public Klass {

   friend class VMStructs;

   friend class ClassFileParser;

   friend class CompileReplay;

  protected:

   // Constructor

   InstanceKlass(int vtable_len,

                 int itable_len,

                 int static_field_size,

                 int nonstatic_oop_map_size,

                 ReferenceType rt,

                 AccessFlags access_flags,

                 bool is_anonymous);

  public:

   static InstanceKlass* allocate_instance_klass(

                                           ClassLoaderData* loader_data,

                                           int vtable_len,

                                           int itable_len,

                                           int static_field_size,

                                           int nonstatic_oop_map_size,

                                           ReferenceType rt,

                                           AccessFlags access_flags,

                                           Symbol* name,

                                           Klass* super_klass,

                                           bool is_anonymous,

                                           TRAPS);

   InstanceKlass() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }

   // See "The Java Virtual Machine Specification" section 2.16.2-5 for a detailed description

   // of the class loading & initialization procedure, and the use of the states.

   enum ClassState {

     allocated,                          // allocated (but not yet linked)

     loaded,                             // loaded and inserted in class hierarchy (but not linked yet)

     linked,                             // successfully linked/verified (but not initialized yet)

     being_initialized,                  // currently running class initializer

     fully_initialized,                  // initialized (successfull final state)

     initialization_error                // error happened during initialization

   };

   static int number_of_instance_classes() { return _total_instanceKlass_count; }

  private:

   static volatile int _total_instanceKlass_count;

  protected:

   // Protection domain.

   oop             _protection_domain;

   // Class signers.

   objArrayOop     _signers;

   // Lock for (1) initialization; (2) access to the ConstantPool of this class.

   // Must be one per class and it has to be a VM internal object so java code

   // cannot lock it (like the mirror).

   // It has to be an object not a Mutex because it's held through java calls.

   volatile oop    _init_lock;

   // Annotations for this class

   Annotations*    _annotations;

   // Array classes holding elements of this class.

   Klass*          _array_klasses;

   // Constant pool for this class.

   ConstantPool* _constants;

   // The InnerClasses attribute and EnclosingMethod attribute. The

   // _inner_classes is an array of shorts. If the class has InnerClasses

   // attribute, then the _inner_classes array begins with 4-tuples of shorts

   // [inner_class_info_index, outer_class_info_index,

   // inner_name_index, inner_class_access_flags] for the InnerClasses

   // attribute. If the EnclosingMethod attribute exists, it occupies the

   // last two shorts [class_index, method_index] of the array. If only

   // the InnerClasses attribute exists, the _inner_classes array length is

   // number_of_inner_classes * 4. If the class has both InnerClasses

   // and EnclosingMethod attributes the _inner_classes array length is

   // number_of_inner_classes * 4 + enclosing_method_attribute_size.

   Array<jushort>* _inner_classes;

   // Name of source file containing this klass, NULL if not specified.

   Symbol*         _source_file_name;

   // the source debug extension for this klass, NULL if not specified.

   // Specified as UTF-8 string without terminating zero byte in the classfile,

   // it is stored in the instanceklass as a NULL-terminated UTF-8 string

   char*           _source_debug_extension;

   // Generic signature, or null if none.

   Symbol*         _generic_signature;

   // Array name derived from this class which needs unreferencing

   // if this class is unloaded.

   Symbol*         _array_name;

   // Number of heapOopSize words used by non-static fields in this klass

   // (including inherited fields but after header_size()).

   int             _nonstatic_field_size;

   int             _static_field_size;    // number words used by static fields (oop and non-oop) in this klass

   u2              _static_oop_field_count;// number of static oop fields in this klass

   u2              _java_fields_count;    // The number of declared Java fields

   int             _nonstatic_oop_map_size;// size in words of nonstatic oop map blocks

   // _is_marked_dependent can be set concurrently, thus cannot be part of the

   // _misc_flags.

   bool            _is_marked_dependent;  // used for marking during flushing and deoptimization

   enum {

     _misc_rewritten            = 1 << 0, // methods rewritten.

     _misc_has_nonstatic_fields = 1 << 1, // for sizing with UseCompressedOops

     _misc_should_verify_class  = 1 << 2, // allow caching of preverification

     _misc_is_anonymous         = 1 << 3, // has embedded _host_klass field

     _misc_is_contended         = 1 << 4, // marked with contended annotation

     _misc_has_default_methods  = 1 << 5  // class/superclass/implemented interfaces has default methods

   };

   u2              _misc_flags;

   u2              _minor_version;        // minor version number of class file

   u2              _major_version;        // major version number of class file

   Thread*         _init_thread;          // Pointer to current thread doing initialization (to handle recusive initialization)

   int             _vtable_len;           // length of Java vtable (in words)

   int             _itable_len;           // length of Java itable (in words)

   OopMapCache*    volatile _oop_map_cache;   // OopMapCache for all methods in the klass (allocated lazily)

   MemberNameTable* _member_names;        // Member names

   JNIid*          _jni_ids;              // First JNI identifier for static fields in this class

   jmethodID*      _methods_jmethod_ids;  // jmethodIDs corresponding to method_idnum, or NULL if none

   int*            _methods_cached_itable_indices;  // itable_index cache for JNI invoke corresponding to methods idnum, or NULL

   nmethodBucket*  _dependencies;         // list of dependent nmethods

   nmethod*        _osr_nmethods_head;    // Head of list of on-stack replacement nmethods for this class

   BreakpointInfo* _breakpoints;          // bpt lists, managed by Method*

   // Array of interesting part(s) of the previous version(s) of this

   // InstanceKlass. See PreviousVersionWalker below.

   GrowableArray<PreviousVersionNode *>* _previous_versions;

   // JVMTI fields can be moved to their own structure - see 6315920

   unsigned char * _cached_class_file_bytes;       // JVMTI: cached class file, before retransformable agent modified it in CFLH

   jint            _cached_class_file_len;         // JVMTI: length of above

   volatile u2     _idnum_allocated_count;         // JNI/JVMTI: increments with the addition of methods, old ids don't change

   // Class states are defined as ClassState (see above).

   // Place the _init_state here to utilize the unused 2-byte after

   // _idnum_allocated_count.

   u1              _init_state;                    // state of class

   u1              _reference_type;                // reference type

   JvmtiCachedClassFieldMap* _jvmti_cached_class_field_map;  // JVMTI: used during heap iteration

   NOT_PRODUCT(int _verify_count;)  // to avoid redundant verifies

   // Method array.

   Array<Method*>* _methods;

   // Interface (Klass*s) this class declares locally to implement.

   Array<Klass*>* _local_interfaces;

   // Interface (Klass*s) this class implements transitively.

   Array<Klass*>* _transitive_interfaces;

   // Int array containing the original order of method in the class file (for JVMTI).

   Array<int>*     _method_ordering;

   // Instance and static variable information, starts with 6-tuples of shorts

   // [access, name index, sig index, initval index, low_offset, high_offset]

   // for all fields, followed by the generic signature data at the end of

   // the array. Only fields with generic signature attributes have the generic

   // signature data set in the array. The fields array looks like following:

   //

   // f1: [access, name index, sig index, initial value index, low_offset, high_offset]

   // f2: [access, name index, sig index, initial value index, low_offset, high_offset]

   //      ...

   // fn: [access, name index, sig index, initial value index, low_offset, high_offset]

   //     [generic signature index]

   //     [generic signature index]

   //     ...

   Array<u2>*      _fields;

   // embedded Java vtable follows here

   // embedded Java itables follows here

   // embedded static fields follows here

   // embedded nonstatic oop-map blocks follows here

   // embedded implementor of this interface follows here

   //   The embedded implementor only exists if the current klass is an

   //   iterface. The possible values of the implementor fall into following

   //   three cases:

   //     NULL: no implementor.

   //     A Klass* that's not itself: one implementor.

   //     Itsef: more than one implementors.

   // embedded host klass follows here

   //   The embedded host klass only exists in an anonymous class for

   //   dynamic language support (JSR 292 enabled). The host class grants

   //   its access privileges to this class also. The host class is either

   //   named, or a previously loaded anonymous class. A non-anonymous class

   //   or an anonymous class loaded through normal classloading does not

   //   have this embedded field.

   //

   friend class SystemDictionary;

  public:

   bool has_nonstatic_fields() const        {

     return (_misc_flags & _misc_has_nonstatic_fields) != 0;

   }

   void set_has_nonstatic_fields(bool b)    {

     if (b) {

       _misc_flags |= _misc_has_nonstatic_fields;

     } else {

       _misc_flags &= ~_misc_has_nonstatic_fields;

     }

   }

   // field sizes

   int nonstatic_field_size() const         { return _nonstatic_field_size; }

   void set_nonstatic_field_size(int size)  { _nonstatic_field_size = size; }

   int static_field_size() const            { return _static_field_size; }

   void set_static_field_size(int size)     { _static_field_size = size; }

   int static_oop_field_count() const       { return (int)_static_oop_field_count; }

   void set_static_oop_field_count(u2 size) { _static_oop_field_count = size; }

   // Java vtable

   int  vtable_length() const               { return _vtable_len; }

   void set_vtable_length(int len)          { _vtable_len = len; }

   // Java itable

   int  itable_length() const               { return _itable_len; }

   void set_itable_length(int len)          { _itable_len = len; }

   // array klasses

   Klass* array_klasses() const             { return _array_klasses; }

   void set_array_klasses(Klass* k)         { _array_klasses = k; }

   // methods

   Array<Method*>* methods() const          { return _methods; }

   void set_methods(Array<Method*>* a)      { _methods = a; }

   Method* method_with_idnum(int idnum);

   // method ordering

   Array<int>* method_ordering() const     { return _method_ordering; }

   void set_method_ordering(Array<int>* m) { _method_ordering = m; }

   void copy_method_ordering(intArray* m, TRAPS);

   // interfaces

   Array<Klass*>* local_interfaces() const          { return _local_interfaces; }

   void set_local_interfaces(Array<Klass*>* a)      {

     guarantee(_local_interfaces == NULL || a == NULL, "Just checking");

     _local_interfaces = a; }

   Array<Klass*>* transitive_interfaces() const     { return _transitive_interfaces; }

   void set_transitive_interfaces(Array<Klass*>* a) {

     guarantee(_transitive_interfaces == NULL || a == NULL, "Just checking");

     _transitive_interfaces = a;

   }

  private:

   friend class fieldDescriptor;

   FieldInfo* field(int index) const { return FieldInfo::from_field_array(_fields, index); }

  public:

   int     field_offset      (int index) const { return field(index)->offset(); }

   int     field_access_flags(int index) const { return field(index)->access_flags(); }

   Symbol* field_name        (int index) const { return field(index)->name(constants()); }

   Symbol* field_signature   (int index) const { return field(index)->signature(constants()); }

   // Number of Java declared fields

   int java_fields_count() const           { return (int)_java_fields_count; }

   Array<u2>* fields() const            { return _fields; }

   void set_fields(Array<u2>* f, u2 java_fields_count) {

     guarantee(_fields == NULL || f == NULL, "Just checking");

     _fields = f;

     _java_fields_count = java_fields_count;

   }

   // inner classes

   Array<u2>* inner_classes() const       { return _inner_classes; }

   void set_inner_classes(Array<u2>* f)   { _inner_classes = f; }

   enum InnerClassAttributeOffset {

     // From http://mirror.eng/products/jdk/1.1/docs/guide/innerclasses/spec/innerclasses.doc10.html#18814

     inner_class_inner_class_info_offset = 0,

     inner_class_outer_class_info_offset = 1,

     inner_class_inner_name_offset = 2,

     inner_class_access_flags_offset = 3,

     inner_class_next_offset = 4

   };

   enum EnclosingMethodAttributeOffset {

     enclosing_method_class_index_offset = 0,

     enclosing_method_method_index_offset = 1,

     enclosing_method_attribute_size = 2

   };

   // method override check

   bool is_override(methodHandle super_method, Handle targetclassloader, Symbol* targetclassname, TRAPS);

   // package

   bool is_same_class_package(Klass* class2);

   bool is_same_class_package(oop classloader2, Symbol* classname2);

   static bool is_same_class_package(oop class_loader1, Symbol* class_name1, oop class_loader2, Symbol* class_name2);

   // find an enclosing class (defined where original code was, in jvm.cpp!)

   Klass* compute_enclosing_class(bool* inner_is_member, TRAPS) {

     instanceKlassHandle self(THREAD, this);

     return compute_enclosing_class_impl(self, inner_is_member, THREAD);

   }

   static Klass* compute_enclosing_class_impl(instanceKlassHandle self,

                                                bool* inner_is_member, TRAPS);

   // tell if two classes have the same enclosing class (at package level)

   bool is_same_package_member(Klass* class2, TRAPS) {

     instanceKlassHandle self(THREAD, this);

     return is_same_package_member_impl(self, class2, THREAD);

   }

   static bool is_same_package_member_impl(instanceKlassHandle self,

                                           Klass* class2, TRAPS);

   // initialization state

   bool is_loaded() const                   { return _init_state >= loaded; }

   bool is_linked() const                   { return _init_state >= linked; }

   bool is_initialized() const              { return _init_state == fully_initialized; }

   bool is_not_initialized() const          { return _init_state <  being_initialized; }

   bool is_being_initialized() const        { return _init_state == being_initialized; }

   bool is_in_error_state() const           { return _init_state == initialization_error; }

   bool is_reentrant_initialization(Thread *thread)  { return thread == _init_thread; }

   ClassState  init_state()                 { return (ClassState)_init_state; }

   bool is_rewritten() const                { return (_misc_flags & _misc_rewritten) != 0; }

   // defineClass specified verification

   bool should_verify_class() const         {

     return (_misc_flags & _misc_should_verify_class) != 0;

   }

   void set_should_verify_class(bool value) {

     if (value) {

       _misc_flags |= _misc_should_verify_class;

     } else {

       _misc_flags &= ~_misc_should_verify_class;

     }

   }

   // marking

   bool is_marked_dependent() const         { return _is_marked_dependent; }

   void set_is_marked_dependent(bool value) { _is_marked_dependent = value; }

   // initialization (virtuals from Klass)

   bool should_be_initialized() const;  // means that initialize should be called

   void initialize(TRAPS);

   void link_class(TRAPS);

   bool link_class_or_fail(TRAPS); // returns false on failure

   void unlink_class();

   void rewrite_class(TRAPS);

   void link_methods(TRAPS);

   Method* class_initializer();

   // set the class to initialized if no static initializer is present

   void eager_initialize(Thread *thread);

   // reference type

   ReferenceType reference_type() const     { return (ReferenceType)_reference_type; }

   void set_reference_type(ReferenceType t) {

     assert(t == (u1)t, "overflow");

     _reference_type = (u1)t;

   }

   static ByteSize reference_type_offset() { return in_ByteSize(offset_of(InstanceKlass, _reference_type)); }

   // find local field, returns true if found

   bool find_local_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;

   // find field in direct superinterfaces, returns the interface in which the field is defined

   Klass* find_interface_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;

   // find field according to JVM spec 5.4.3.2, returns the klass in which the field is defined

   Klass* find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;

   // find instance or static fields according to JVM spec 5.4.3.2, returns the klass in which the field is defined

   Klass* find_field(Symbol* name, Symbol* sig, bool is_static, fieldDescriptor* fd) const;

   // find a non-static or static field given its offset within the class.

   bool contains_field_offset(int offset) {

     return instanceOopDesc::contains_field_offset(offset, nonstatic_field_size());

   }

   bool find_local_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const;

   bool find_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const;

   // find a local method (returns NULL if not found)

   Method* find_method(Symbol* name, Symbol* signature) const;

   static Method* find_method(Array<Method*>* methods, Symbol* name, Symbol* signature);

   // lookup operation (returns NULL if not found)

   Method* uncached_lookup_method(Symbol* name, Symbol* signature) const;

   // lookup a method in all the interfaces that this class implements

   // (returns NULL if not found)

   Method* lookup_method_in_all_interfaces(Symbol* name, Symbol* signature) const;

   // Find method indices by name.  If a method with the specified name is

   // found the index to the first method is returned, and 'end' is filled in

   // with the index of first non-name-matching method.  If no method is found

   // -1 is returned.

   int find_method_by_name(Symbol* name, int* end);

   static int find_method_by_name(Array<Method*>* methods, Symbol* name, int* end);

   // constant pool

   ConstantPool* constants() const        { return _constants; }

   void set_constants(ConstantPool* c)    { _constants = c; }

   // protection domain

   oop protection_domain()                  { return _protection_domain; }

   void set_protection_domain(oop pd)       { klass_oop_store(&_protection_domain, pd); }

   // host class

   Klass* host_klass() const              {

     Klass** hk = (Klass**)adr_host_klass();

     if (hk == NULL) {

       return NULL;

     } else {

       return *hk;

     }

   }

   void set_host_klass(Klass* host)            {

     assert(is_anonymous(), "not anonymous");

     Klass** addr = (Klass**)adr_host_klass();

     assert(addr != NULL, "no reversed space");

     if (addr != NULL) {

       *addr = host;

     }

   }

   bool is_anonymous() const                {

     return (_misc_flags & _misc_is_anonymous) != 0;

   }

   void set_is_anonymous(bool value)        {

     if (value) {

       _misc_flags |= _misc_is_anonymous;

     } else {

       _misc_flags &= ~_misc_is_anonymous;

     }

   }

   // Oop that keeps the metadata for this class from being unloaded

   // in places where the metadata is stored in other places, like nmethods

   oop klass_holder() const {

     return is_anonymous() ? java_mirror() : class_loader();

   }

   bool is_contended() const                {

     return (_misc_flags & _misc_is_contended) != 0;

   }

   void set_is_contended(bool value)        {

     if (value) {

       _misc_flags |= _misc_is_contended;

     } else {

       _misc_flags &= ~_misc_is_contended;

     }

   }

   // signers

   objArrayOop signers() const              { return _signers; }

   void set_signers(objArrayOop s)          { klass_oop_store((oop*)&_signers, s); }

   // source file name

   Symbol* source_file_name() const         { return _source_file_name; }

   void set_source_file_name(Symbol* n);

   // minor and major version numbers of class file

   u2 minor_version() const                 { return _minor_version; }

   void set_minor_version(u2 minor_version) { _minor_version = minor_version; }

   u2 major_version() const                 { return _major_version; }

   void set_major_version(u2 major_version) { _major_version = major_version; }

   // source debug extension

   char* source_debug_extension() const     { return _source_debug_extension; }

   void set_source_debug_extension(char* array, int length);

   // symbol unloading support (refcount already added)

   Symbol* array_name()                     { return _array_name; }

   void set_array_name(Symbol* name)        { assert(_array_name == NULL  || name == NULL, "name already created"); _array_name = name; }

   // nonstatic oop-map blocks

   static int nonstatic_oop_map_size(unsigned int oop_map_count) {

     return oop_map_count * OopMapBlock::size_in_words();

   }

   unsigned int nonstatic_oop_map_count() const {

     return _nonstatic_oop_map_size / OopMapBlock::size_in_words();

   }

   int nonstatic_oop_map_size() const { return _nonstatic_oop_map_size; }

   void set_nonstatic_oop_map_size(int words) {

     _nonstatic_oop_map_size = words;

   }

   // RedefineClasses() support for previous versions:

   void add_previous_version(instanceKlassHandle ikh, BitMap *emcp_methods,

          int emcp_method_count);

   // If the _previous_versions array is non-NULL, then this klass

   // has been redefined at least once even if we aren't currently

   // tracking a previous version.

   bool has_been_redefined() const { return _previous_versions != NULL; }

   bool has_previous_version() const;

   void init_previous_versions() {

     _previous_versions = NULL;

   }

   GrowableArray<PreviousVersionNode *>* previous_versions() const {

     return _previous_versions;

   }

   static void purge_previous_versions(InstanceKlass* ik);

   // JVMTI: Support for caching a class file before it is modified by an agent that can do retransformation

   void set_cached_class_file(unsigned char *class_file_bytes,

                              jint class_file_len)     { _cached_class_file_len = class_file_len;

                                                         _cached_class_file_bytes = class_file_bytes; }

   jint get_cached_class_file_len()                    { return _cached_class_file_len; }

   unsigned char * get_cached_class_file_bytes()       { return _cached_class_file_bytes; }

   // JVMTI: Support for caching of field indices, types, and offsets

   void set_jvmti_cached_class_field_map(JvmtiCachedClassFieldMap* descriptor) {

     _jvmti_cached_class_field_map = descriptor;

   }

   JvmtiCachedClassFieldMap* jvmti_cached_class_field_map() const {

     return _jvmti_cached_class_field_map;

   }

   bool has_default_methods() const {

     return (_misc_flags & _misc_has_default_methods) != 0;

   }

   void set_has_default_methods(bool b) {

     if (b) {

       _misc_flags |= _misc_has_default_methods;

     } else {

       _misc_flags &= ~_misc_has_default_methods;

     }

   }

   // for adding methods, ConstMethod::UNSET_IDNUM means no more ids available

   inline u2 next_method_idnum();

   void set_initial_method_idnum(u2 value)             { _idnum_allocated_count = value; }

   // generics support

   Symbol* generic_signature() const                   { return _generic_signature; }

   void set_generic_signature(Symbol* sig)             { _generic_signature = sig; }

   u2 enclosing_method_data(int offset);

   u2 enclosing_method_class_index() {

     return enclosing_method_data(enclosing_method_class_index_offset);

   }

   u2 enclosing_method_method_index() {

     return enclosing_method_data(enclosing_method_method_index_offset);

   }

   void set_enclosing_method_indices(u2 class_index,

                                     u2 method_index);

   // jmethodID support

   static jmethodID get_jmethod_id(instanceKlassHandle ik_h,

                      methodHandle method_h);

   static jmethodID get_jmethod_id_fetch_or_update(instanceKlassHandle ik_h,

                      size_t idnum, jmethodID new_id, jmethodID* new_jmeths,

                      jmethodID* to_dealloc_id_p,

                      jmethodID** to_dealloc_jmeths_p);

   static void get_jmethod_id_length_value(jmethodID* cache, size_t idnum,

                 size_t *length_p, jmethodID* id_p);

   jmethodID jmethod_id_or_null(Method* method);

   // cached itable index support

   void set_cached_itable_index(size_t idnum, int index);

   int cached_itable_index(size_t idnum);

   // annotations support

   Annotations* annotations() const          { return _annotations; }

   void set_annotations(Annotations* anno)   { _annotations = anno; }

   AnnotationArray* class_annotations() const {

     return (_annotations != NULL) ? _annotations->class_annotations() : NULL;

   }

   Array<AnnotationArray*>* fields_annotations() const {

     return (_annotations != NULL) ? _annotations->fields_annotations() : NULL;

   }

   AnnotationArray* class_type_annotations() const {

     return (_annotations != NULL) ? _annotations->class_type_annotations() : NULL;

   }

   Array<AnnotationArray*>* fields_type_annotations() const {

     return (_annotations != NULL) ? _annotations->fields_type_annotations() : NULL;

   }

   // allocation

   instanceOop allocate_instance(TRAPS);

   // additional member function to return a handle

   instanceHandle allocate_instance_handle(TRAPS)      { return instanceHandle(THREAD, allocate_instance(THREAD)); }

   objArrayOop allocate_objArray(int n, int length, TRAPS);

   // Helper function

   static instanceOop register_finalizer(instanceOop i, TRAPS);

   // Check whether reflection/jni/jvm code is allowed to instantiate this class;

   // if not, throw either an Error or an Exception.

   virtual void check_valid_for_instantiation(bool throwError, TRAPS);

   // initialization

   void call_class_initializer(TRAPS);

   void set_initialization_state_and_notify(ClassState state, TRAPS);

   // OopMapCache support

   OopMapCache* oop_map_cache()               { return _oop_map_cache; }

   void set_oop_map_cache(OopMapCache *cache) { _oop_map_cache = cache; }

   void mask_for(methodHandle method, int bci, InterpreterOopMap* entry);

   // JNI identifier support (for static fields - for jni performance)

   JNIid* jni_ids()                               { return _jni_ids; }

   void set_jni_ids(JNIid* ids)                   { _jni_ids = ids; }

   JNIid* jni_id_for(int offset);

   // maintenance of deoptimization dependencies

   int mark_dependent_nmethods(DepChange& changes);

   void add_dependent_nmethod(nmethod* nm);

   void remove_dependent_nmethod(nmethod* nm);

   // On-stack replacement support

   nmethod* osr_nmethods_head() const         { return _osr_nmethods_head; };

   void set_osr_nmethods_head(nmethod* h)     { _osr_nmethods_head = h; };

   void add_osr_nmethod(nmethod* n);

   void remove_osr_nmethod(nmethod* n);

   nmethod* lookup_osr_nmethod(Method* const m, int bci, int level, bool match_level) const;

   // Breakpoint support (see methods on Method* for details)

   BreakpointInfo* breakpoints() const       { return _breakpoints; };

   void set_breakpoints(BreakpointInfo* bps) { _breakpoints = bps; };

   // support for stub routines

   static ByteSize init_state_offset()  { return in_ByteSize(offset_of(InstanceKlass, _init_state)); }

   TRACE_DEFINE_OFFSET;

   static ByteSize init_thread_offset() { return in_ByteSize(offset_of(InstanceKlass, _init_thread)); }

   // subclass/subinterface checks

   bool implements_interface(Klass* k) const;

   // Access to the implementor of an interface.

   Klass* implementor() const

   {

     Klass** k = adr_implementor();

     if (k == NULL) {

       return NULL;

     } else {

       return *k;

     }

   }

   void set_implementor(Klass* k) {

     assert(is_interface(), "not interface");

     Klass** addr = adr_implementor();

     assert(addr != NULL, "null addr");

     if (addr != NULL) {

       *addr = k;

     }

   }

   int  nof_implementors() const       {

     Klass* k = implementor();

     if (k == NULL) {

       return 0;

     } else if (k != this) {

       return 1;

     } else {

       return 2;

     }

   }

   void add_implementor(Klass* k);  // k is a new class that implements this interface

   void init_implementor();           // initialize

   // link this class into the implementors list of every interface it implements

   void process_interfaces(Thread *thread);

   // virtual operations from Klass

   bool is_leaf_class() const               { return _subklass == NULL; }

   GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);

   bool compute_is_subtype_of(Klass* k);

   bool can_be_primary_super_slow() const;

   int oop_size(oop obj)  const             { return size_helper(); }

   bool oop_is_instance_slow() const        { return true; }

   // Iterators

   void do_local_static_fields(FieldClosure* cl);

   void do_nonstatic_fields(FieldClosure* cl); // including inherited fields

   void do_local_static_fields(void f(fieldDescriptor*, TRAPS), TRAPS);

   void methods_do(void f(Method* method));

   void array_klasses_do(void f(Klass* k));

   void array_klasses_do(void f(Klass* k, TRAPS), TRAPS);

   void with_array_klasses_do(void f(Klass* k));

   bool super_types_do(SuperTypeClosure* blk);

   // Casting from Klass*

   static InstanceKlass* cast(Klass* k) {

     assert(k->is_klass(), "must be");

     assert(k->oop_is_instance(), "cast to InstanceKlass");

     return (InstanceKlass*) k;

   }

   InstanceKlass* java_super() const {

     return (super() == NULL) ? NULL : cast(super());

   }

   // Sizing (in words)

   static int header_size()            { return align_object_offset(sizeof(InstanceKlass)/HeapWordSize); }

   static int size(int vtable_length, int itable_length,

                   int nonstatic_oop_map_size,

                   bool is_interface, bool is_anonymous) {

     return align_object_size(header_size() +

            align_object_offset(vtable_length) +

            align_object_offset(itable_length) +

            ((is_interface || is_anonymous) ?

              align_object_offset(nonstatic_oop_map_size) :

              nonstatic_oop_map_size) +

            (is_interface ? (int)sizeof(Klass*)/HeapWordSize : 0) +

            (is_anonymous ? (int)sizeof(Klass*)/HeapWordSize : 0));

   }

   int size() const                    { return size(vtable_length(),

                                                itable_length(),

                                                nonstatic_oop_map_size(),

                                                is_interface(),

                                                is_anonymous());

   }

 #if INCLUDE_SERVICES

   virtual void collect_statistics(KlassSizeStats *sz) const;

 #endif

   static int vtable_start_offset()    { return header_size(); }

   static int vtable_length_offset()   { return offset_of(InstanceKlass, _vtable_len) / HeapWordSize; }

   intptr_t* start_of_vtable() const        { return ((intptr_t*)this) + vtable_start_offset(); }

   intptr_t* start_of_itable() const        { return start_of_vtable() + align_object_offset(vtable_length()); }

   int  itable_offset_in_words() const { return start_of_itable() - (intptr_t*)this; }

   intptr_t* end_of_itable() const          { return start_of_itable() + itable_length(); }

   address static_field_addr(int offset);

   OopMapBlock* start_of_nonstatic_oop_maps() const {

     return (OopMapBlock*)(start_of_itable() + align_object_offset(itable_length()));

   }

   Klass** end_of_nonstatic_oop_maps() const {

     return (Klass**)(start_of_nonstatic_oop_maps() +

                      nonstatic_oop_map_count());

   }

   Klass** adr_implementor() const {

     if (is_interface()) {

       return (Klass**)end_of_nonstatic_oop_maps();

     } else {

       return NULL;

     }

   };

   Klass** adr_host_klass() const {

     if (is_anonymous()) {

       Klass** adr_impl = adr_implementor();

       if (adr_impl != NULL) {

         return adr_impl + 1;

       } else {

         return end_of_nonstatic_oop_maps();

       }

     } else {

       return NULL;

     }

   }

   // Allocation profiling support

   juint alloc_size() const            { return _alloc_count * size_helper(); }

   void set_alloc_size(juint n)        {}

   // Use this to return the size of an instance in heap words:

   int size_helper() const {

     return layout_helper_to_size_helper(layout_helper());

   }

   // This bit is initialized in classFileParser.cpp.

   // It is false under any of the following conditions:

   //  - the class is abstract (including any interface)

   //  - the class has a finalizer (if !RegisterFinalizersAtInit)

   //  - the class size is larger than FastAllocateSizeLimit

   //  - the class is java/lang/Class, which cannot be allocated directly

   bool can_be_fastpath_allocated() const {

     return !layout_helper_needs_slow_path(layout_helper());

   }

   // Java vtable/itable

   klassVtable* vtable() const;        // return new klassVtable wrapper

   inline Method* method_at_vtable(int index);

   klassItable* itable() const;        // return new klassItable wrapper

   Method* method_at_itable(Klass* holder, int index, TRAPS);

   // Garbage collection

   virtual void oops_do(OopClosure* cl);

   void oop_follow_contents(oop obj);

   int  oop_adjust_pointers(oop obj);

   void clean_implementors_list(BoolObjectClosure* is_alive);

   void clean_method_data(BoolObjectClosure* is_alive);

   // Explicit metaspace deallocation of fields

   // For RedefineClasses and class file parsing errors, we need to deallocate

   // instanceKlasses and the metadata they point to.

   void deallocate_contents(ClassLoaderData* loader_data);

   static void deallocate_methods(ClassLoaderData* loader_data,

                                  Array<Method*>* methods);

   void static deallocate_interfaces(ClassLoaderData* loader_data,

                                     Klass* super_klass,

                                     Array<Klass*>* local_interfaces,

                                     Array<Klass*>* transitive_interfaces);

   // The constant pool is on stack if any of the methods are executing or

   // referenced by handles.

   bool on_stack() const { return _constants->on_stack(); }

   // callbacks for actions during class unloading

   static void notify_unload_class(InstanceKlass* ik);

   static void release_C_heap_structures(InstanceKlass* ik);

   // Parallel Scavenge and Parallel Old

   PARALLEL_GC_DECLS

   // Naming

   const char* signature_name() const;

   // Iterators

   int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) {

     return oop_oop_iterate_v(obj, blk);

   }

   int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {

     return oop_oop_iterate_v_m(obj, blk, mr);

   }

 #define InstanceKlass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)      \

   int  oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk);           \

   int  oop_oop_iterate##nv_suffix##_m(oop obj, OopClosureType* blk,        \

                                       MemRegion mr);

   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_DECL)

   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_DECL)

 #if INCLUDE_ALL_GCS

 #define InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \

   int  oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* blk);

   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)

   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)

 #endif // INCLUDE_ALL_GCS

   u2 idnum_allocated_count() const      { return _idnum_allocated_count; }

 private:

   // initialization state

 #ifdef ASSERT

   void set_init_state(ClassState state);

 #else

   void set_init_state(ClassState state) { _init_state = (u1)state; }

 #endif

   void set_rewritten()                  { _misc_flags |= _misc_rewritten; }

   void set_init_thread(Thread *thread)  { _init_thread = thread; }

   // The RedefineClasses() API can cause new method idnums to be needed

   // which will cause the caches to grow. Safety requires different

   // cache management logic if the caches can grow instead of just

   // going from NULL to non-NULL.

   bool idnum_can_increment() const      { return has_been_redefined(); }

   jmethodID* methods_jmethod_ids_acquire() const

          { return (jmethodID*)OrderAccess::load_ptr_acquire(&_methods_jmethod_ids); }

   void release_set_methods_jmethod_ids(jmethodID* jmeths)

          { OrderAccess::release_store_ptr(&_methods_jmethod_ids, jmeths); }

   int* methods_cached_itable_indices_acquire() const

          { return (int*)OrderAccess::load_ptr_acquire(&_methods_cached_itable_indices); }

   void release_set_methods_cached_itable_indices(int* indices)

          { OrderAccess::release_store_ptr(&_methods_cached_itable_indices, indices); }

   // Lock during initialization

 public:

   volatile oop init_lock() const     {return _init_lock; }

 private:

   void set_init_lock(oop value) { klass_oop_store(&_init_lock, value); }

   // Offsets for memory management

   oop* adr_protection_domain() const { return (oop*)&this->_protection_domain;}

   oop* adr_signers() const           { return (oop*)&this->_signers;}

   oop* adr_init_lock() const         { return (oop*)&this->_init_lock;}

   // Static methods that are used to implement member methods where an exposed this pointer

   // is needed due to possible GCs

   static bool link_class_impl                           (instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS);

   static bool verify_code                               (instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS);

   static void initialize_impl                           (instanceKlassHandle this_oop, TRAPS);

   static void eager_initialize_impl                     (instanceKlassHandle this_oop);

   static void set_initialization_state_and_notify_impl  (instanceKlassHandle this_oop, ClassState state, TRAPS);

   static void call_class_initializer_impl               (instanceKlassHandle this_oop, TRAPS);

   static Klass* array_klass_impl                      (instanceKlassHandle this_oop, bool or_null, int n, TRAPS);

   static void do_local_static_fields_impl               (instanceKlassHandle this_oop, void f(fieldDescriptor* fd, TRAPS), TRAPS);

   /* jni_id_for_impl for jfieldID only */

   static JNIid* jni_id_for_impl                         (instanceKlassHandle this_oop, int offset);

   // Returns the array class for the n'th dimension

   Klass* array_klass_impl(bool or_null, int n, TRAPS);

   // Returns the array class with this class as element type

   Klass* array_klass_impl(bool or_null, TRAPS);

   // Free CHeap allocated fields.

   void release_C_heap_structures();

 public:

   // CDS support - remove and restore oops from metadata. Oops are not shared.

   virtual void remove_unshareable_info();

   virtual void restore_unshareable_info(TRAPS);

   // jvm support

   jint compute_modifier_flags(TRAPS) const;

   // JSR-292 support

   MemberNameTable* member_names() { return _member_names; }

   void set_member_names(MemberNameTable* member_names) { _member_names = member_names; }

   void add_member_name(Handle member_name);

 public:

   // JVMTI support

   jint jvmti_class_status() const;

  public:

   // Printing

 #ifndef PRODUCT

   void print_on(outputStream* st) const;

 #endif

   void print_value_on(outputStream* st) const;

   void oop_print_value_on(oop obj, outputStream* st);

 #ifndef PRODUCT

   void oop_print_on      (oop obj, outputStream* st);

   void print_dependent_nmethods(bool verbose = false);

   bool is_dependent_nmethod(nmethod* nm);

 #endif

   const char* internal_name() const;

   // Verification

   void verify_on(outputStream* st);

   void oop_verify_on(oop obj, outputStream* st);

 };

 inline Method* InstanceKlass::method_at_vtable(int index)  {

 #ifndef PRODUCT

   assert(index >= 0, "valid vtable index");

   if (DebugVtables) {

     verify_vtable_index(index);

   }

 #endif

   vtableEntry* ve = (vtableEntry*)start_of_vtable();

   return ve[index].method();

 }

 // for adding methods

 // UNSET_IDNUM return means no more ids available

 inline u2 InstanceKlass::next_method_idnum() {

   if (_idnum_allocated_count == ConstMethod::MAX_IDNUM) {

     return ConstMethod::UNSET_IDNUM; // no more ids available

   } else {

     return _idnum_allocated_count++;

   }

 }

 /* JNIid class for jfieldIDs only */

 class JNIid: public CHeapObj<mtClass> {

   friend class VMStructs;

  private:

   Klass*             _holder;

   JNIid*             _next;

   int                _offset;

 #ifdef ASSERT

   bool               _is_static_field_id;

 #endif

  public:

   // Accessors

   Klass* holder() const           { return _holder; }

   int offset() const              { return _offset; }

   JNIid* next()                   { return _next; }

   // Constructor

   JNIid(Klass* holder, int offset, JNIid* next);

   // Identifier lookup

   JNIid* find(int offset);

   bool find_local_field(fieldDescriptor* fd) {

     return InstanceKlass::cast(holder())->find_local_field_from_offset(offset(), true, fd);

   }

   static void deallocate(JNIid* id);

   // Debugging

 #ifdef ASSERT

   bool is_static_field_id() const { return _is_static_field_id; }

   void set_is_static_field_id()   { _is_static_field_id = true; }

 #endif

   void verify(Klass* holder);

 };

 // If breakpoints are more numerous than just JVMTI breakpoints,

 // consider compressing this data structure.

 // It is currently a simple linked list defined in method.hpp.

 class BreakpointInfo;

 // A collection point for interesting information about the previous

 // version(s) of an InstanceKlass. This class uses weak references to

 // the information so that the information may be collected as needed

 // by the system. If the information is shared, then a regular

 // reference must be used because a weak reference would be seen as

 // collectible. A GrowableArray of PreviousVersionNodes is attached

 // to the InstanceKlass as needed. See PreviousVersionWalker below.

 class PreviousVersionNode : public CHeapObj<mtClass> {

  private:

   // A shared ConstantPool is never collected so we'll always have

   // a reference to it so we can update items in the cache. We'll

   // have a weak reference to a non-shared ConstantPool until all

   // of the methods (EMCP or obsolete) have been collected; the

   // non-shared ConstantPool becomes collectible at that point.

   ConstantPool*    _prev_constant_pool;  // regular or weak reference

   bool    _prev_cp_is_weak;     // true if not a shared ConstantPool

   // If the previous version of the InstanceKlass doesn't have any

   // EMCP methods, then _prev_EMCP_methods will be NULL. If all the

   // EMCP methods have been collected, then _prev_EMCP_methods can

   // have a length of zero.

   GrowableArray<Method*>* _prev_EMCP_methods;

 public:

   PreviousVersionNode(ConstantPool* prev_constant_pool, bool prev_cp_is_weak,

     GrowableArray<Method*>* prev_EMCP_methods);

   ~PreviousVersionNode();

   ConstantPool* prev_constant_pool() const {

     return _prev_constant_pool;

   }

   GrowableArray<Method*>* prev_EMCP_methods() const {

     return _prev_EMCP_methods;

   }

 };

 // A Handle-ized version of PreviousVersionNode.

 class PreviousVersionInfo : public ResourceObj {

  private:

   constantPoolHandle   _prev_constant_pool_handle;

   // If the previous version of the InstanceKlass doesn't have any

   // EMCP methods, then _prev_EMCP_methods will be NULL. Since the

   // methods cannot be collected while we hold a handle,

   // _prev_EMCP_methods should never have a length of zero.

   GrowableArray<methodHandle>* _prev_EMCP_method_handles;

 public:

   PreviousVersionInfo(PreviousVersionNode *pv_node);

   ~PreviousVersionInfo();

   constantPoolHandle prev_constant_pool_handle() const {

     return _prev_constant_pool_handle;

   }

   GrowableArray<methodHandle>* prev_EMCP_method_handles() const {

     return _prev_EMCP_method_handles;

   }

 };

 // Helper object for walking previous versions. This helper cleans up

 // the Handles that it allocates when the helper object is destroyed.

 // The PreviousVersionInfo object returned by next_previous_version()

 // is only valid until a subsequent call to next_previous_version() or

 // the helper object is destroyed.

 class PreviousVersionWalker : public StackObj {

  private:

   GrowableArray<PreviousVersionNode *>* _previous_versions;

   int                                   _current_index;

   // Fields for cleaning up when we are done walking the previous versions:

   // A HandleMark for the PreviousVersionInfo handles:

   HandleMark                            _hm;

   // It would be nice to have a ResourceMark field in this helper also,

   // but the ResourceMark code says to be careful to delete handles held

   // in GrowableArrays _before_ deleting the GrowableArray. Since we

   // can't guarantee the order in which the fields are destroyed, we

   // have to let the creator of the PreviousVersionWalker object do

   // the right thing. Also, adding a ResourceMark here causes an

   // include loop.

   // A pointer to the current info object so we can handle the deletes.

   PreviousVersionInfo *                 _current_p;

  public:

   PreviousVersionWalker(InstanceKlass *ik);

   ~PreviousVersionWalker();

   // Return the interesting information for the next previous version

   // of the klass. Returns NULL if there are no more previous versions.

   PreviousVersionInfo* next_previous_version();

 };

 //

 // nmethodBucket is used to record dependent nmethods for

 // deoptimization.  nmethod dependencies are actually <klass, method>

 // pairs but we really only care about the klass part for purposes of

 // finding nmethods which might need to be deoptimized.  Instead of

 // recording the method, a count of how many times a particular nmethod

 // was recorded is kept.  This ensures that any recording errors are

 // noticed since an nmethod should be removed as many times are it's

 // added.

 //

 class nmethodBucket: public CHeapObj<mtClass> {

   friend class VMStructs;

  private:

   nmethod*       _nmethod;

   int            _count;

   nmethodBucket* _next;

  public:

   nmethodBucket(nmethod* nmethod, nmethodBucket* next) {

     _nmethod = nmethod;

     _next = next;

     _count = 1;

   }

   int count()                             { return _count; }

   int increment()                         { _count += 1; return _count; }

   int decrement()                         { _count -= 1; assert(_count >= 0, "don't underflow"); return _count; }

   nmethodBucket* next()                   { return _next; }

   void set_next(nmethodBucket* b)         { _next = b; }

   nmethod* get_nmethod()                  { return _nmethod; }

 };

 // An iterator that's used to access the inner classes indices in the

 // InstanceKlass::_inner_classes array.

 class InnerClassesIterator : public StackObj {

  private:

   Array<jushort>* _inner_classes;

   int _length;

   int _idx;

  public:

   InnerClassesIterator(instanceKlassHandle k) {

     _inner_classes = k->inner_classes();

     if (k->inner_classes() != NULL) {

       _length = _inner_classes->length();

       // The inner class array's length should be the multiple of

       // inner_class_next_offset if it only contains the InnerClasses

       // attribute data, or it should be

       // n*inner_class_next_offset+enclosing_method_attribute_size

       // if it also contains the EnclosingMethod data.

       assert((_length % InstanceKlass::inner_class_next_offset == 0 ||

               _length % InstanceKlass::inner_class_next_offset == InstanceKlass::enclosing_method_attribute_size),

              "just checking");

       // Remove the enclosing_method portion if exists.

       if (_length % InstanceKlass::inner_class_next_offset == InstanceKlass::enclosing_method_attribute_size) {

         _length -= InstanceKlass::enclosing_method_attribute_size;

       }

     } else {

       _length = 0;

     }

     _idx = 0;

   }

   int length() const {

     return _length;

   }

   void next() {

     _idx += InstanceKlass::inner_class_next_offset;

   }

   bool done() const {

     return (_idx >= _length);

   }

   u2 inner_class_info_index() const {

     return _inner_classes->at(

                _idx + InstanceKlass::inner_class_inner_class_info_offset);

   }

   void set_inner_class_info_index(u2 index) {

     _inner_classes->at_put(

                _idx + InstanceKlass::inner_class_inner_class_info_offset, index);

   }

   u2 outer_class_info_index() const {

     return _inner_classes->at(

                _idx + InstanceKlass::inner_class_outer_class_info_offset);

   }

   void set_outer_class_info_index(u2 index) {

     _inner_classes->at_put(

                _idx + InstanceKlass::inner_class_outer_class_info_offset, index);

   }

   u2 inner_name_index() const {

     return _inner_classes->at(

                _idx + InstanceKlass::inner_class_inner_name_offset);

   }

   void set_inner_name_index(u2 index) {

     _inner_classes->at_put(

                _idx + InstanceKlass::inner_class_inner_name_offset, index);

   }

   u2 inner_access_flags() const {

     return _inner_classes->at(

                _idx + InstanceKlass::inner_class_access_flags_offset);

   }

 };

 #endif // SHARE_VM_OOPS_INSTANCEKLASS_HPP