src/share/vm/oops/instanceKlass.hpp

Wed, 23 Feb 2011 11:18:16 -0800

author
kvn
date
Wed, 23 Feb 2011 11:18:16 -0800
changeset 2571
a97fd181b813
parent 2534
e5383553fd4e
child 2638
72dee110246f
permissions
-rw-r--r--

Merge

     1 /*
     2  * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     4  *
     5  * This code is free software; you can redistribute it and/or modify it
     6  * under the terms of the GNU General Public License version 2 only, as
     7  * published by the Free Software Foundation.
     8  *
     9  * This code is distributed in the hope that it will be useful, but WITHOUT
    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    12  * version 2 for more details (a copy is included in the LICENSE file that
    13  * accompanied this code).
    14  *
    15  * You should have received a copy of the GNU General Public License version
    16  * 2 along with this work; if not, write to the Free Software Foundation,
    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
    18  *
    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
    20  * or visit www.oracle.com if you need additional information or have any
    21  * questions.
    22  *
    23  */
    25 #ifndef SHARE_VM_OOPS_INSTANCEKLASS_HPP
    26 #define SHARE_VM_OOPS_INSTANCEKLASS_HPP
    28 #include "oops/constMethodOop.hpp"
    29 #include "oops/constantPoolOop.hpp"
    30 #include "oops/instanceOop.hpp"
    31 #include "oops/klassOop.hpp"
    32 #include "oops/klassVtable.hpp"
    33 #include "oops/objArrayOop.hpp"
    34 #include "runtime/handles.hpp"
    35 #include "runtime/os.hpp"
    36 #include "utilities/accessFlags.hpp"
    37 #include "utilities/bitMap.inline.hpp"
    39 // An instanceKlass is the VM level representation of a Java class.
    40 // It contains all information needed for at class at execution runtime.
    42 //  instanceKlass layout:
    43 //    [header                     ] klassOop
    44 //    [klass pointer              ] klassOop
    45 //    [C++ vtbl pointer           ] Klass
    46 //    [subtype cache              ] Klass
    47 //    [instance size              ] Klass
    48 //    [java mirror                ] Klass
    49 //    [super                      ] Klass
    50 //    [access_flags               ] Klass
    51 //    [name                       ] Klass
    52 //    [first subklass             ] Klass
    53 //    [next sibling               ] Klass
    54 //    [array klasses              ]
    55 //    [methods                    ]
    56 //    [local interfaces           ]
    57 //    [transitive interfaces      ]
    58 //    [number of implementors     ]
    59 //    [implementors               ] klassOop[2]
    60 //    [fields                     ]
    61 //    [constants                  ]
    62 //    [class loader               ]
    63 //    [protection domain          ]
    64 //    [signers                    ]
    65 //    [source file name           ]
    66 //    [inner classes              ]
    67 //    [static field size          ]
    68 //    [nonstatic field size       ]
    69 //    [static oop fields size     ]
    70 //    [nonstatic oop maps size    ]
    71 //    [has finalize method        ]
    72 //    [deoptimization mark bit    ]
    73 //    [initialization state       ]
    74 //    [initializing thread        ]
    75 //    [Java vtable length         ]
    76 //    [oop map cache (stack maps) ]
    77 //    [EMBEDDED Java vtable             ] size in words = vtable_len
    78 //    [EMBEDDED static oop fields       ] size in words = static_oop_fields_size
    79 //    [         static non-oop fields   ] size in words = static_field_size - static_oop_fields_size
    80 //    [EMBEDDED nonstatic oop-map blocks] size in words = nonstatic_oop_map_size
    81 //
    82 //    The embedded nonstatic oop-map blocks are short pairs (offset, length) indicating
    83 //    where oops are located in instances of this klass.
    86 // forward declaration for class -- see below for definition
    87 class SuperTypeClosure;
    88 class JNIid;
    89 class jniIdMapBase;
    90 class BreakpointInfo;
    91 class fieldDescriptor;
    92 class DepChange;
    93 class nmethodBucket;
    94 class PreviousVersionNode;
    95 class JvmtiCachedClassFieldMap;
    97 // This is used in iterators below.
    98 class FieldClosure: public StackObj {
    99 public:
   100   virtual void do_field(fieldDescriptor* fd) = 0;
   101 };
   103 #ifndef PRODUCT
   104 // Print fields.
   105 // If "obj" argument to constructor is NULL, prints static fields, otherwise prints non-static fields.
   106 class FieldPrinter: public FieldClosure {
   107    oop _obj;
   108    outputStream* _st;
   109  public:
   110    FieldPrinter(outputStream* st, oop obj = NULL) : _obj(obj), _st(st) {}
   111    void do_field(fieldDescriptor* fd);
   112 };
   113 #endif  // !PRODUCT
   115 // ValueObjs embedded in klass. Describes where oops are located in instances of
   116 // this klass.
   117 class OopMapBlock VALUE_OBJ_CLASS_SPEC {
   118  public:
   119   // Byte offset of the first oop mapped by this block.
   120   int offset() const          { return _offset; }
   121   void set_offset(int offset) { _offset = offset; }
   123   // Number of oops in this block.
   124   uint count() const         { return _count; }
   125   void set_count(uint count) { _count = count; }
   127   // sizeof(OopMapBlock) in HeapWords.
   128   static const int size_in_words() {
   129     return align_size_up(int(sizeof(OopMapBlock)), HeapWordSize) >>
   130       LogHeapWordSize;
   131   }
   133  private:
   134   int  _offset;
   135   uint _count;
   136 };
   138 class instanceKlass: public Klass {
   139   friend class VMStructs;
   140  public:
   141   // See "The Java Virtual Machine Specification" section 2.16.2-5 for a detailed description
   142   // of the class loading & initialization procedure, and the use of the states.
   143   enum ClassState {
   144     unparsable_by_gc = 0,               // object is not yet parsable by gc. Value of _init_state at object allocation.
   145     allocated,                          // allocated (but not yet linked)
   146     loaded,                             // loaded and inserted in class hierarchy (but not linked yet)
   147     linked,                             // successfully linked/verified (but not initialized yet)
   148     being_initialized,                  // currently running class initializer
   149     fully_initialized,                  // initialized (successfull final state)
   150     initialization_error                // error happened during initialization
   151   };
   153  public:
   154   oop* oop_block_beg() const { return adr_array_klasses(); }
   155   oop* oop_block_end() const { return adr_methods_default_annotations() + 1; }
   157   enum {
   158     implementors_limit = 2              // how many implems can we track?
   159   };
   161  protected:
   162   //
   163   // The oop block.  See comment in klass.hpp before making changes.
   164   //
   166   // Array classes holding elements of this class.
   167   klassOop        _array_klasses;
   168   // Method array.
   169   objArrayOop     _methods;
   170   // Int array containing the original order of method in the class file (for
   171   // JVMTI).
   172   typeArrayOop    _method_ordering;
   173   // Interface (klassOops) this class declares locally to implement.
   174   objArrayOop     _local_interfaces;
   175   // Interface (klassOops) this class implements transitively.
   176   objArrayOop     _transitive_interfaces;
   177   // Instance and static variable information, 5-tuples of shorts [access, name
   178   // index, sig index, initval index, offset].
   179   typeArrayOop    _fields;
   180   // Constant pool for this class.
   181   constantPoolOop _constants;
   182   // Class loader used to load this class, NULL if VM loader used.
   183   oop             _class_loader;
   184   // Protection domain.
   185   oop             _protection_domain;
   186   // Host class, which grants its access privileges to this class also.
   187   // This is only non-null for an anonymous class (AnonymousClasses enabled).
   188   // The host class is either named, or a previously loaded anonymous class.
   189   klassOop        _host_klass;
   190   // Class signers.
   191   objArrayOop     _signers;
   192   // inner_classes attribute.
   193   typeArrayOop    _inner_classes;
   194   // Implementors of this interface (not valid if it overflows)
   195   klassOop        _implementors[implementors_limit];
   196   // invokedynamic bootstrap method (a java.dyn.MethodHandle)
   197   oop             _bootstrap_method;
   198   // Annotations for this class, or null if none.
   199   typeArrayOop    _class_annotations;
   200   // Annotation objects (byte arrays) for fields, or null if no annotations.
   201   // Indices correspond to entries (not indices) in fields array.
   202   objArrayOop     _fields_annotations;
   203   // Annotation objects (byte arrays) for methods, or null if no annotations.
   204   // Index is the idnum, which is initially the same as the methods array index.
   205   objArrayOop     _methods_annotations;
   206   // Annotation objects (byte arrays) for methods' parameters, or null if no
   207   // such annotations.
   208   // Index is the idnum, which is initially the same as the methods array index.
   209   objArrayOop     _methods_parameter_annotations;
   210   // Annotation objects (byte arrays) for methods' default values, or null if no
   211   // such annotations.
   212   // Index is the idnum, which is initially the same as the methods array index.
   213   objArrayOop     _methods_default_annotations;
   215   //
   216   // End of the oop block.
   217   //
   219   // Name of source file containing this klass, NULL if not specified.
   220   Symbol*         _source_file_name;
   221   // the source debug extension for this klass, NULL if not specified.
   222   Symbol*         _source_debug_extension;
   223   // Generic signature, or null if none.
   224   Symbol*         _generic_signature;
   225   // Array name derived from this class which needs unreferencing
   226   // if this class is unloaded.
   227   Symbol*         _array_name;
   229   // Number of heapOopSize words used by non-static fields in this klass
   230   // (including inherited fields but after header_size()).
   231   int             _nonstatic_field_size;
   232   int             _static_field_size;    // number words used by static fields (oop and non-oop) in this klass
   233   int             _static_oop_field_size;// number of static oop fields in this klass
   234   int             _nonstatic_oop_map_size;// size in words of nonstatic oop map blocks
   235   bool            _is_marked_dependent;  // used for marking during flushing and deoptimization
   236   bool            _rewritten;            // methods rewritten.
   237   bool            _has_nonstatic_fields; // for sizing with UseCompressedOops
   238   bool            _should_verify_class;  // allow caching of preverification
   239   u2              _minor_version;        // minor version number of class file
   240   u2              _major_version;        // major version number of class file
   241   ClassState      _init_state;           // state of class
   242   Thread*         _init_thread;          // Pointer to current thread doing initialization (to handle recusive initialization)
   243   int             _vtable_len;           // length of Java vtable (in words)
   244   int             _itable_len;           // length of Java itable (in words)
   245   ReferenceType   _reference_type;       // reference type
   246   OopMapCache*    volatile _oop_map_cache;   // OopMapCache for all methods in the klass (allocated lazily)
   247   JNIid*          _jni_ids;              // First JNI identifier for static fields in this class
   248   jmethodID*      _methods_jmethod_ids;  // jmethodIDs corresponding to method_idnum, or NULL if none
   249   int*            _methods_cached_itable_indices;  // itable_index cache for JNI invoke corresponding to methods idnum, or NULL
   250   nmethodBucket*  _dependencies;         // list of dependent nmethods
   251   nmethod*        _osr_nmethods_head;    // Head of list of on-stack replacement nmethods for this class
   252   BreakpointInfo* _breakpoints;          // bpt lists, managed by methodOop
   253   int             _nof_implementors;     // No of implementors of this interface (zero if not an interface)
   254   // Array of interesting part(s) of the previous version(s) of this
   255   // instanceKlass. See PreviousVersionWalker below.
   256   GrowableArray<PreviousVersionNode *>* _previous_versions;
   257   u2              _enclosing_method_class_index;  // Constant pool index for class of enclosing method, or 0 if none
   258   u2              _enclosing_method_method_index; // Constant pool index for name and type of enclosing method, or 0 if none
   259   // JVMTI fields can be moved to their own structure - see 6315920
   260   unsigned char * _cached_class_file_bytes;       // JVMTI: cached class file, before retransformable agent modified it in CFLH
   261   jint            _cached_class_file_len;         // JVMTI: length of above
   262   JvmtiCachedClassFieldMap* _jvmti_cached_class_field_map;  // JVMTI: used during heap iteration
   263   volatile u2     _idnum_allocated_count;         // JNI/JVMTI: increments with the addition of methods, old ids don't change
   265   // embedded Java vtable follows here
   266   // embedded Java itables follows here
   267   // embedded static fields follows here
   268   // embedded nonstatic oop-map blocks follows here
   270   friend class instanceKlassKlass;
   271   friend class SystemDictionary;
   273  public:
   274   bool has_nonstatic_fields() const        { return _has_nonstatic_fields; }
   275   void set_has_nonstatic_fields(bool b)    { _has_nonstatic_fields = b; }
   277   // field sizes
   278   int nonstatic_field_size() const         { return _nonstatic_field_size; }
   279   void set_nonstatic_field_size(int size)  { _nonstatic_field_size = size; }
   281   int static_field_size() const            { return _static_field_size; }
   282   void set_static_field_size(int size)     { _static_field_size = size; }
   284   int static_oop_field_size() const        { return _static_oop_field_size; }
   285   void set_static_oop_field_size(int size) { _static_oop_field_size = size; }
   287   // Java vtable
   288   int  vtable_length() const               { return _vtable_len; }
   289   void set_vtable_length(int len)          { _vtable_len = len; }
   291   // Java itable
   292   int  itable_length() const               { return _itable_len; }
   293   void set_itable_length(int len)          { _itable_len = len; }
   295   // array klasses
   296   klassOop array_klasses() const           { return _array_klasses; }
   297   void set_array_klasses(klassOop k)       { oop_store_without_check((oop*) &_array_klasses, (oop) k); }
   299   // methods
   300   objArrayOop methods() const              { return _methods; }
   301   void set_methods(objArrayOop a)          { oop_store_without_check((oop*) &_methods, (oop) a); }
   302   methodOop method_with_idnum(int idnum);
   304   // method ordering
   305   typeArrayOop method_ordering() const     { return _method_ordering; }
   306   void set_method_ordering(typeArrayOop m) { oop_store_without_check((oop*) &_method_ordering, (oop) m); }
   308   // interfaces
   309   objArrayOop local_interfaces() const          { return _local_interfaces; }
   310   void set_local_interfaces(objArrayOop a)      { oop_store_without_check((oop*) &_local_interfaces, (oop) a); }
   311   objArrayOop transitive_interfaces() const     { return _transitive_interfaces; }
   312   void set_transitive_interfaces(objArrayOop a) { oop_store_without_check((oop*) &_transitive_interfaces, (oop) a); }
   314   // fields
   315   // Field info extracted from the class file and stored
   316   // as an array of 7 shorts
   317   enum FieldOffset {
   318     access_flags_offset    = 0,
   319     name_index_offset      = 1,
   320     signature_index_offset = 2,
   321     initval_index_offset   = 3,
   322     low_offset             = 4,
   323     high_offset            = 5,
   324     generic_signature_offset = 6,
   325     next_offset            = 7
   326   };
   328   typeArrayOop fields() const              { return _fields; }
   329   int offset_from_fields( int index ) const {
   330     return build_int_from_shorts( fields()->ushort_at(index + low_offset),
   331                                   fields()->ushort_at(index + high_offset) );
   332   }
   334   void set_fields(typeArrayOop f)          { oop_store_without_check((oop*) &_fields, (oop) f); }
   336   // inner classes
   337   typeArrayOop inner_classes() const       { return _inner_classes; }
   338   void set_inner_classes(typeArrayOop f)   { oop_store_without_check((oop*) &_inner_classes, (oop) f); }
   340   enum InnerClassAttributeOffset {
   341     // From http://mirror.eng/products/jdk/1.1/docs/guide/innerclasses/spec/innerclasses.doc10.html#18814
   342     inner_class_inner_class_info_offset = 0,
   343     inner_class_outer_class_info_offset = 1,
   344     inner_class_inner_name_offset = 2,
   345     inner_class_access_flags_offset = 3,
   346     inner_class_next_offset = 4
   347   };
   349   // method override check
   350   bool is_override(methodHandle super_method, Handle targetclassloader, Symbol* targetclassname, TRAPS);
   352   // package
   353   bool is_same_class_package(klassOop class2);
   354   bool is_same_class_package(oop classloader2, Symbol* classname2);
   355   static bool is_same_class_package(oop class_loader1, Symbol* class_name1, oop class_loader2, Symbol* class_name2);
   357   // find an enclosing class (defined where original code was, in jvm.cpp!)
   358   klassOop compute_enclosing_class(bool* inner_is_member, TRAPS) {
   359     instanceKlassHandle self(THREAD, this->as_klassOop());
   360     return compute_enclosing_class_impl(self, inner_is_member, THREAD);
   361   }
   362   static klassOop compute_enclosing_class_impl(instanceKlassHandle self,
   363                                                bool* inner_is_member, TRAPS);
   365   // tell if two classes have the same enclosing class (at package level)
   366   bool is_same_package_member(klassOop class2, TRAPS) {
   367     instanceKlassHandle self(THREAD, this->as_klassOop());
   368     return is_same_package_member_impl(self, class2, THREAD);
   369   }
   370   static bool is_same_package_member_impl(instanceKlassHandle self,
   371                                           klassOop class2, TRAPS);
   373   // initialization state
   374   bool is_loaded() const                   { return _init_state >= loaded; }
   375   bool is_linked() const                   { return _init_state >= linked; }
   376   bool is_initialized() const              { return _init_state == fully_initialized; }
   377   bool is_not_initialized() const          { return _init_state <  being_initialized; }
   378   bool is_being_initialized() const        { return _init_state == being_initialized; }
   379   bool is_in_error_state() const           { return _init_state == initialization_error; }
   380   bool is_reentrant_initialization(Thread *thread)  { return thread == _init_thread; }
   381   int  get_init_state()                    { return _init_state; } // Useful for debugging
   382   bool is_rewritten() const                { return _rewritten; }
   384   // defineClass specified verification
   385   bool should_verify_class() const         { return _should_verify_class; }
   386   void set_should_verify_class(bool value) { _should_verify_class = value; }
   388   // marking
   389   bool is_marked_dependent() const         { return _is_marked_dependent; }
   390   void set_is_marked_dependent(bool value) { _is_marked_dependent = value; }
   392   // initialization (virtuals from Klass)
   393   bool should_be_initialized() const;  // means that initialize should be called
   394   void initialize(TRAPS);
   395   void link_class(TRAPS);
   396   bool link_class_or_fail(TRAPS); // returns false on failure
   397   void unlink_class();
   398   void rewrite_class(TRAPS);
   399   methodOop class_initializer();
   401   // set the class to initialized if no static initializer is present
   402   void eager_initialize(Thread *thread);
   404   // reference type
   405   ReferenceType reference_type() const     { return _reference_type; }
   406   void set_reference_type(ReferenceType t) { _reference_type = t; }
   408   // find local field, returns true if found
   409   bool find_local_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;
   410   // find field in direct superinterfaces, returns the interface in which the field is defined
   411   klassOop find_interface_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;
   412   // find field according to JVM spec 5.4.3.2, returns the klass in which the field is defined
   413   klassOop find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;
   414   // find instance or static fields according to JVM spec 5.4.3.2, returns the klass in which the field is defined
   415   klassOop find_field(Symbol* name, Symbol* sig, bool is_static, fieldDescriptor* fd) const;
   417   // find a non-static or static field given its offset within the class.
   418   bool contains_field_offset(int offset) {
   419     return instanceOopDesc::contains_field_offset(offset, nonstatic_field_size());
   420   }
   422   bool find_local_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const;
   423   bool find_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const;
   425   // find a local method (returns NULL if not found)
   426   methodOop find_method(Symbol* name, Symbol* signature) const;
   427   static methodOop find_method(objArrayOop methods, Symbol* name, Symbol* signature);
   429   // lookup operation (returns NULL if not found)
   430   methodOop uncached_lookup_method(Symbol* name, Symbol* signature) const;
   432   // lookup a method in all the interfaces that this class implements
   433   // (returns NULL if not found)
   434   methodOop lookup_method_in_all_interfaces(Symbol* name, Symbol* signature) const;
   436   // constant pool
   437   constantPoolOop constants() const        { return _constants; }
   438   void set_constants(constantPoolOop c)    { oop_store_without_check((oop*) &_constants, (oop) c); }
   440   // class loader
   441   oop class_loader() const                 { return _class_loader; }
   442   void set_class_loader(oop l)             { oop_store((oop*) &_class_loader, l); }
   444   // protection domain
   445   oop protection_domain()                  { return _protection_domain; }
   446   void set_protection_domain(oop pd)       { oop_store((oop*) &_protection_domain, pd); }
   448   // host class
   449   oop host_klass() const                   { return _host_klass; }
   450   void set_host_klass(oop host)            { oop_store((oop*) &_host_klass, host); }
   451   bool is_anonymous() const                { return _host_klass != NULL; }
   453   // signers
   454   objArrayOop signers() const              { return _signers; }
   455   void set_signers(objArrayOop s)          { oop_store((oop*) &_signers, oop(s)); }
   457   // source file name
   458   Symbol* source_file_name() const         { return _source_file_name; }
   459   void set_source_file_name(Symbol* n);
   461   // minor and major version numbers of class file
   462   u2 minor_version() const                 { return _minor_version; }
   463   void set_minor_version(u2 minor_version) { _minor_version = minor_version; }
   464   u2 major_version() const                 { return _major_version; }
   465   void set_major_version(u2 major_version) { _major_version = major_version; }
   467   // source debug extension
   468   Symbol* source_debug_extension() const   { return _source_debug_extension; }
   469   void set_source_debug_extension(Symbol* n);
   471   // symbol unloading support (refcount already added)
   472   Symbol* array_name()                     { return _array_name; }
   473   void set_array_name(Symbol* name)        { assert(_array_name == NULL, "name already created"); _array_name = name; }
   475   // nonstatic oop-map blocks
   476   static int nonstatic_oop_map_size(unsigned int oop_map_count) {
   477     return oop_map_count * OopMapBlock::size_in_words();
   478   }
   479   unsigned int nonstatic_oop_map_count() const {
   480     return _nonstatic_oop_map_size / OopMapBlock::size_in_words();
   481   }
   482   int nonstatic_oop_map_size() const { return _nonstatic_oop_map_size; }
   483   void set_nonstatic_oop_map_size(int words) {
   484     _nonstatic_oop_map_size = words;
   485   }
   487   // RedefineClasses() support for previous versions:
   488   void add_previous_version(instanceKlassHandle ikh, BitMap *emcp_methods,
   489          int emcp_method_count);
   490   // If the _previous_versions array is non-NULL, then this klass
   491   // has been redefined at least once even if we aren't currently
   492   // tracking a previous version.
   493   bool has_been_redefined() const { return _previous_versions != NULL; }
   494   bool has_previous_version() const;
   495   void init_previous_versions() {
   496     _previous_versions = NULL;
   497   }
   498   GrowableArray<PreviousVersionNode *>* previous_versions() const {
   499     return _previous_versions;
   500   }
   502   // JVMTI: Support for caching a class file before it is modified by an agent that can do retransformation
   503   void set_cached_class_file(unsigned char *class_file_bytes,
   504                              jint class_file_len)     { _cached_class_file_len = class_file_len;
   505                                                         _cached_class_file_bytes = class_file_bytes; }
   506   jint get_cached_class_file_len()                    { return _cached_class_file_len; }
   507   unsigned char * get_cached_class_file_bytes()       { return _cached_class_file_bytes; }
   509   // JVMTI: Support for caching of field indices, types, and offsets
   510   void set_jvmti_cached_class_field_map(JvmtiCachedClassFieldMap* descriptor) {
   511     _jvmti_cached_class_field_map = descriptor;
   512   }
   513   JvmtiCachedClassFieldMap* jvmti_cached_class_field_map() const {
   514     return _jvmti_cached_class_field_map;
   515   }
   517   // for adding methods, constMethodOopDesc::UNSET_IDNUM means no more ids available
   518   inline u2 next_method_idnum();
   519   void set_initial_method_idnum(u2 value)             { _idnum_allocated_count = value; }
   521   // generics support
   522   Symbol* generic_signature() const                   { return _generic_signature; }
   523   void set_generic_signature(Symbol* sig)             { _generic_signature = sig; }
   525   u2 enclosing_method_class_index() const             { return _enclosing_method_class_index; }
   526   u2 enclosing_method_method_index() const            { return _enclosing_method_method_index; }
   527   void set_enclosing_method_indices(u2 class_index,
   528                                     u2 method_index)  { _enclosing_method_class_index  = class_index;
   529                                                         _enclosing_method_method_index = method_index; }
   531   // JSR 292 support
   532   oop bootstrap_method() const                        { return _bootstrap_method; }
   533   void set_bootstrap_method(oop mh)                   { oop_store(&_bootstrap_method, mh); }
   535   // jmethodID support
   536   static jmethodID get_jmethod_id(instanceKlassHandle ik_h,
   537                      methodHandle method_h);
   538   static jmethodID get_jmethod_id_fetch_or_update(instanceKlassHandle ik_h,
   539                      size_t idnum, jmethodID new_id, jmethodID* new_jmeths,
   540                      jmethodID* to_dealloc_id_p,
   541                      jmethodID** to_dealloc_jmeths_p);
   542   static void get_jmethod_id_length_value(jmethodID* cache, size_t idnum,
   543                 size_t *length_p, jmethodID* id_p);
   544   jmethodID jmethod_id_or_null(methodOop method);
   546   // cached itable index support
   547   void set_cached_itable_index(size_t idnum, int index);
   548   int cached_itable_index(size_t idnum);
   550   // annotations support
   551   typeArrayOop class_annotations() const              { return _class_annotations; }
   552   objArrayOop fields_annotations() const              { return _fields_annotations; }
   553   objArrayOop methods_annotations() const             { return _methods_annotations; }
   554   objArrayOop methods_parameter_annotations() const   { return _methods_parameter_annotations; }
   555   objArrayOop methods_default_annotations() const     { return _methods_default_annotations; }
   556   void set_class_annotations(typeArrayOop md)            { oop_store_without_check((oop*)&_class_annotations, (oop)md); }
   557   void set_fields_annotations(objArrayOop md)            { set_annotations(md, &_fields_annotations); }
   558   void set_methods_annotations(objArrayOop md)           { set_annotations(md, &_methods_annotations); }
   559   void set_methods_parameter_annotations(objArrayOop md) { set_annotations(md, &_methods_parameter_annotations); }
   560   void set_methods_default_annotations(objArrayOop md)   { set_annotations(md, &_methods_default_annotations); }
   561   typeArrayOop get_method_annotations_of(int idnum)
   562                                                 { return get_method_annotations_from(idnum, _methods_annotations); }
   563   typeArrayOop get_method_parameter_annotations_of(int idnum)
   564                                                 { return get_method_annotations_from(idnum, _methods_parameter_annotations); }
   565   typeArrayOop get_method_default_annotations_of(int idnum)
   566                                                 { return get_method_annotations_from(idnum, _methods_default_annotations); }
   567   void set_method_annotations_of(int idnum, typeArrayOop anno)
   568                                                 { set_methods_annotations_of(idnum, anno, &_methods_annotations); }
   569   void set_method_parameter_annotations_of(int idnum, typeArrayOop anno)
   570                                                 { set_methods_annotations_of(idnum, anno, &_methods_annotations); }
   571   void set_method_default_annotations_of(int idnum, typeArrayOop anno)
   572                                                 { set_methods_annotations_of(idnum, anno, &_methods_annotations); }
   574   // allocation
   575   DEFINE_ALLOCATE_PERMANENT(instanceKlass);
   576   instanceOop allocate_instance(TRAPS);
   577   instanceOop allocate_permanent_instance(TRAPS);
   579   // additional member function to return a handle
   580   instanceHandle allocate_instance_handle(TRAPS)      { return instanceHandle(THREAD, allocate_instance(THREAD)); }
   582   objArrayOop allocate_objArray(int n, int length, TRAPS);
   583   // Helper function
   584   static instanceOop register_finalizer(instanceOop i, TRAPS);
   586   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
   587   // if not, throw either an Error or an Exception.
   588   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
   590   // initialization
   591   void call_class_initializer(TRAPS);
   592   void set_initialization_state_and_notify(ClassState state, TRAPS);
   594   // OopMapCache support
   595   OopMapCache* oop_map_cache()               { return _oop_map_cache; }
   596   void set_oop_map_cache(OopMapCache *cache) { _oop_map_cache = cache; }
   597   void mask_for(methodHandle method, int bci, InterpreterOopMap* entry);
   599   // JNI identifier support (for static fields - for jni performance)
   600   JNIid* jni_ids()                               { return _jni_ids; }
   601   void set_jni_ids(JNIid* ids)                   { _jni_ids = ids; }
   602   JNIid* jni_id_for(int offset);
   604   // maintenance of deoptimization dependencies
   605   int mark_dependent_nmethods(DepChange& changes);
   606   void add_dependent_nmethod(nmethod* nm);
   607   void remove_dependent_nmethod(nmethod* nm);
   609   // On-stack replacement support
   610   nmethod* osr_nmethods_head() const         { return _osr_nmethods_head; };
   611   void set_osr_nmethods_head(nmethod* h)     { _osr_nmethods_head = h; };
   612   void add_osr_nmethod(nmethod* n);
   613   void remove_osr_nmethod(nmethod* n);
   614   nmethod* lookup_osr_nmethod(const methodOop m, int bci, int level, bool match_level) const;
   616   // Breakpoint support (see methods on methodOop for details)
   617   BreakpointInfo* breakpoints() const       { return _breakpoints; };
   618   void set_breakpoints(BreakpointInfo* bps) { _breakpoints = bps; };
   620   // support for stub routines
   621   static int init_state_offset_in_bytes()    { return offset_of(instanceKlass, _init_state); }
   622   static int init_thread_offset_in_bytes()   { return offset_of(instanceKlass, _init_thread); }
   624   // subclass/subinterface checks
   625   bool implements_interface(klassOop k) const;
   627   // Access to implementors of an interface. We only store the count
   628   // of implementors, and in case, there are only a few
   629   // implementors, we store them in a short list.
   630   // This accessor returns NULL if we walk off the end of the list.
   631   klassOop implementor(int i) const {
   632     return (i < implementors_limit)? _implementors[i]: (klassOop) NULL;
   633   }
   634   int  nof_implementors() const       { return _nof_implementors; }
   635   void add_implementor(klassOop k);  // k is a new class that implements this interface
   636   void init_implementor();           // initialize
   638   // link this class into the implementors list of every interface it implements
   639   void process_interfaces(Thread *thread);
   641   // virtual operations from Klass
   642   bool is_leaf_class() const               { return _subklass == NULL; }
   643   objArrayOop compute_secondary_supers(int num_extra_slots, TRAPS);
   644   bool compute_is_subtype_of(klassOop k);
   645   bool can_be_primary_super_slow() const;
   646   klassOop java_super() const              { return super(); }
   647   int oop_size(oop obj)  const             { return size_helper(); }
   648   int klass_oop_size() const               { return object_size(); }
   649   bool oop_is_instance_slow() const        { return true; }
   651   // Iterators
   652   void do_local_static_fields(FieldClosure* cl);
   653   void do_nonstatic_fields(FieldClosure* cl); // including inherited fields
   654   void do_local_static_fields(void f(fieldDescriptor*, TRAPS), TRAPS);
   656   void methods_do(void f(methodOop method));
   657   void array_klasses_do(void f(klassOop k));
   658   void with_array_klasses_do(void f(klassOop k));
   659   bool super_types_do(SuperTypeClosure* blk);
   661   // Casting from klassOop
   662   static instanceKlass* cast(klassOop k) {
   663     Klass* kp = k->klass_part();
   664     assert(kp->null_vtbl() || kp->oop_is_instance_slow(), "cast to instanceKlass");
   665     return (instanceKlass*) kp;
   666   }
   668   // Sizing (in words)
   669   static int header_size()            { return align_object_offset(oopDesc::header_size() + sizeof(instanceKlass)/HeapWordSize); }
   670   int object_size() const             { return object_size(align_object_offset(vtable_length()) + align_object_offset(itable_length()) + static_field_size() + nonstatic_oop_map_size()); }
   671   static int vtable_start_offset()    { return header_size(); }
   672   static int vtable_length_offset()   { return oopDesc::header_size() + offset_of(instanceKlass, _vtable_len) / HeapWordSize; }
   673   static int object_size(int extra)   { return align_object_size(header_size() + extra); }
   675   intptr_t* start_of_vtable() const        { return ((intptr_t*)as_klassOop()) + vtable_start_offset(); }
   676   intptr_t* start_of_itable() const        { return start_of_vtable() + align_object_offset(vtable_length()); }
   677   int  itable_offset_in_words() const { return start_of_itable() - (intptr_t*)as_klassOop(); }
   679   // Static field offset is an offset into the Heap, should be converted by
   680   // based on UseCompressedOop for traversal
   681   HeapWord* start_of_static_fields() const {
   682     return (HeapWord*)(start_of_itable() + align_object_offset(itable_length()));
   683   }
   685   intptr_t* end_of_itable() const          { return start_of_itable() + itable_length(); }
   687   int offset_of_static_fields() const {
   688     return (intptr_t)start_of_static_fields() - (intptr_t)as_klassOop();
   689   }
   691   OopMapBlock* start_of_nonstatic_oop_maps() const {
   692     return (OopMapBlock*) (start_of_static_fields() + static_field_size());
   693   }
   695   // Allocation profiling support
   696   juint alloc_size() const            { return _alloc_count * size_helper(); }
   697   void set_alloc_size(juint n)        {}
   699   // Use this to return the size of an instance in heap words:
   700   int size_helper() const {
   701     return layout_helper_to_size_helper(layout_helper());
   702   }
   704   // This bit is initialized in classFileParser.cpp.
   705   // It is false under any of the following conditions:
   706   //  - the class is abstract (including any interface)
   707   //  - the class has a finalizer (if !RegisterFinalizersAtInit)
   708   //  - the class size is larger than FastAllocateSizeLimit
   709   //  - the class is java/lang/Class, which cannot be allocated directly
   710   bool can_be_fastpath_allocated() const {
   711     return !layout_helper_needs_slow_path(layout_helper());
   712   }
   714   // Java vtable/itable
   715   klassVtable* vtable() const;        // return new klassVtable wrapper
   716   inline methodOop method_at_vtable(int index);
   717   klassItable* itable() const;        // return new klassItable wrapper
   718   methodOop method_at_itable(klassOop holder, int index, TRAPS);
   720   // Garbage collection
   721   void oop_follow_contents(oop obj);
   722   void follow_static_fields();
   723   void adjust_static_fields();
   724   int  oop_adjust_pointers(oop obj);
   725   bool object_is_parsable() const { return _init_state != unparsable_by_gc; }
   726        // Value of _init_state must be zero (unparsable_by_gc) when klass field is set.
   728   void follow_weak_klass_links(
   729     BoolObjectClosure* is_alive, OopClosure* keep_alive);
   730   void release_C_heap_structures();
   732   // Parallel Scavenge and Parallel Old
   733   PARALLEL_GC_DECLS
   735 #ifndef SERIALGC
   736   // Parallel Scavenge
   737   void push_static_fields(PSPromotionManager* pm);
   739   // Parallel Old
   740   void follow_static_fields(ParCompactionManager* cm);
   741   void copy_static_fields(ParCompactionManager* cm);
   742   void update_static_fields();
   743 #endif // SERIALGC
   745   // Naming
   746   const char* signature_name() const;
   748   // Iterators
   749   int oop_oop_iterate(oop obj, OopClosure* blk) {
   750     return oop_oop_iterate_v(obj, blk);
   751   }
   753   int oop_oop_iterate_m(oop obj, OopClosure* blk, MemRegion mr) {
   754     return oop_oop_iterate_v_m(obj, blk, mr);
   755   }
   757 #define InstanceKlass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)      \
   758   int  oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk);           \
   759   int  oop_oop_iterate##nv_suffix##_m(oop obj, OopClosureType* blk,        \
   760                                       MemRegion mr);
   762   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_DECL)
   763   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_DECL)
   765 #ifndef SERIALGC
   766 #define InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
   767   int  oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* blk);
   769   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
   770   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
   771 #endif // !SERIALGC
   773   void iterate_static_fields(OopClosure* closure);
   774   void iterate_static_fields(OopClosure* closure, MemRegion mr);
   776 private:
   777   // initialization state
   778 #ifdef ASSERT
   779   void set_init_state(ClassState state);
   780 #else
   781   void set_init_state(ClassState state) { _init_state = state; }
   782 #endif
   783   void set_rewritten()                  { _rewritten = true; }
   784   void set_init_thread(Thread *thread)  { _init_thread = thread; }
   786   u2 idnum_allocated_count() const      { return _idnum_allocated_count; }
   787   // The RedefineClasses() API can cause new method idnums to be needed
   788   // which will cause the caches to grow. Safety requires different
   789   // cache management logic if the caches can grow instead of just
   790   // going from NULL to non-NULL.
   791   bool idnum_can_increment() const      { return has_been_redefined(); }
   792   jmethodID* methods_jmethod_ids_acquire() const
   793          { return (jmethodID*)OrderAccess::load_ptr_acquire(&_methods_jmethod_ids); }
   794   void release_set_methods_jmethod_ids(jmethodID* jmeths)
   795          { OrderAccess::release_store_ptr(&_methods_jmethod_ids, jmeths); }
   797   int* methods_cached_itable_indices_acquire() const
   798          { return (int*)OrderAccess::load_ptr_acquire(&_methods_cached_itable_indices); }
   799   void release_set_methods_cached_itable_indices(int* indices)
   800          { OrderAccess::release_store_ptr(&_methods_cached_itable_indices, indices); }
   802   inline typeArrayOop get_method_annotations_from(int idnum, objArrayOop annos);
   803   void set_annotations(objArrayOop md, objArrayOop* md_p)  { oop_store_without_check((oop*)md_p, (oop)md); }
   804   void set_methods_annotations_of(int idnum, typeArrayOop anno, objArrayOop* md_p);
   806   // Offsets for memory management
   807   oop* adr_array_klasses() const     { return (oop*)&this->_array_klasses;}
   808   oop* adr_methods() const           { return (oop*)&this->_methods;}
   809   oop* adr_method_ordering() const   { return (oop*)&this->_method_ordering;}
   810   oop* adr_local_interfaces() const  { return (oop*)&this->_local_interfaces;}
   811   oop* adr_transitive_interfaces() const  { return (oop*)&this->_transitive_interfaces;}
   812   oop* adr_fields() const            { return (oop*)&this->_fields;}
   813   oop* adr_constants() const         { return (oop*)&this->_constants;}
   814   oop* adr_class_loader() const      { return (oop*)&this->_class_loader;}
   815   oop* adr_protection_domain() const { return (oop*)&this->_protection_domain;}
   816   oop* adr_host_klass() const        { return (oop*)&this->_host_klass;}
   817   oop* adr_signers() const           { return (oop*)&this->_signers;}
   818   oop* adr_inner_classes() const     { return (oop*)&this->_inner_classes;}
   819   oop* adr_implementors() const      { return (oop*)&this->_implementors[0];}
   820   oop* adr_bootstrap_method() const  { return (oop*)&this->_bootstrap_method;}
   821   oop* adr_methods_jmethod_ids() const             { return (oop*)&this->_methods_jmethod_ids;}
   822   oop* adr_methods_cached_itable_indices() const   { return (oop*)&this->_methods_cached_itable_indices;}
   823   oop* adr_class_annotations() const   { return (oop*)&this->_class_annotations;}
   824   oop* adr_fields_annotations() const  { return (oop*)&this->_fields_annotations;}
   825   oop* adr_methods_annotations() const { return (oop*)&this->_methods_annotations;}
   826   oop* adr_methods_parameter_annotations() const { return (oop*)&this->_methods_parameter_annotations;}
   827   oop* adr_methods_default_annotations() const { return (oop*)&this->_methods_default_annotations;}
   829   // Static methods that are used to implement member methods where an exposed this pointer
   830   // is needed due to possible GCs
   831   static bool link_class_impl                           (instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS);
   832   static bool verify_code                               (instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS);
   833   static void initialize_impl                           (instanceKlassHandle this_oop, TRAPS);
   834   static void eager_initialize_impl                     (instanceKlassHandle this_oop);
   835   static void set_initialization_state_and_notify_impl  (instanceKlassHandle this_oop, ClassState state, TRAPS);
   836   static void call_class_initializer_impl               (instanceKlassHandle this_oop, TRAPS);
   837   static klassOop array_klass_impl                      (instanceKlassHandle this_oop, bool or_null, int n, TRAPS);
   838   static void do_local_static_fields_impl               (instanceKlassHandle this_oop, void f(fieldDescriptor* fd, TRAPS), TRAPS);
   839   /* jni_id_for_impl for jfieldID only */
   840   static JNIid* jni_id_for_impl                         (instanceKlassHandle this_oop, int offset);
   842   // Returns the array class for the n'th dimension
   843   klassOop array_klass_impl(bool or_null, int n, TRAPS);
   845   // Returns the array class with this class as element type
   846   klassOop array_klass_impl(bool or_null, TRAPS);
   848 public:
   849   // sharing support
   850   virtual void remove_unshareable_info();
   851   virtual void shared_symbols_iterate(SymbolClosure* closure);
   853   // jvm support
   854   jint compute_modifier_flags(TRAPS) const;
   856 public:
   857   // JVMTI support
   858   jint jvmti_class_status() const;
   860  public:
   861   // Printing
   862   void oop_print_value_on(oop obj, outputStream* st);
   863 #ifndef PRODUCT
   864   void oop_print_on      (oop obj, outputStream* st);
   866   void print_dependent_nmethods(bool verbose = false);
   867   bool is_dependent_nmethod(nmethod* nm);
   868 #endif
   870   // Verification
   871   const char* internal_name() const;
   872   void oop_verify_on(oop obj, outputStream* st);
   874 #ifndef PRODUCT
   875   static void verify_class_klass_nonstatic_oop_maps(klassOop k) PRODUCT_RETURN;
   876 #endif
   877 };
   879 inline methodOop instanceKlass::method_at_vtable(int index)  {
   880 #ifndef PRODUCT
   881   assert(index >= 0, "valid vtable index");
   882   if (DebugVtables) {
   883     verify_vtable_index(index);
   884   }
   885 #endif
   886   vtableEntry* ve = (vtableEntry*)start_of_vtable();
   887   return ve[index].method();
   888 }
   890 inline typeArrayOop instanceKlass::get_method_annotations_from(int idnum, objArrayOop annos) {
   891   if (annos == NULL || annos->length() <= idnum) {
   892     return NULL;
   893   }
   894   return typeArrayOop(annos->obj_at(idnum));
   895 }
   897 // for adding methods
   898 // UNSET_IDNUM return means no more ids available
   899 inline u2 instanceKlass::next_method_idnum() {
   900   if (_idnum_allocated_count == constMethodOopDesc::MAX_IDNUM) {
   901     return constMethodOopDesc::UNSET_IDNUM; // no more ids available
   902   } else {
   903     return _idnum_allocated_count++;
   904   }
   905 }
   908 /* JNIid class for jfieldIDs only */
   909 class JNIid: public CHeapObj {
   910   friend class VMStructs;
   911  private:
   912   klassOop           _holder;
   913   JNIid*             _next;
   914   int                _offset;
   915 #ifdef ASSERT
   916   bool               _is_static_field_id;
   917 #endif
   919  public:
   920   // Accessors
   921   klassOop holder() const         { return _holder; }
   922   int offset() const              { return _offset; }
   923   JNIid* next()                   { return _next; }
   924   // Constructor
   925   JNIid(klassOop holder, int offset, JNIid* next);
   926   // Identifier lookup
   927   JNIid* find(int offset);
   929   // Garbage collection support
   930   oop* holder_addr() { return (oop*)&_holder; }
   931   void oops_do(OopClosure* f);
   932   static void deallocate(JNIid* id);
   933   // Debugging
   934 #ifdef ASSERT
   935   bool is_static_field_id() const { return _is_static_field_id; }
   936   void set_is_static_field_id()   { _is_static_field_id = true; }
   937 #endif
   938   void verify(klassOop holder);
   939 };
   942 // If breakpoints are more numerous than just JVMTI breakpoints,
   943 // consider compressing this data structure.
   944 // It is currently a simple linked list defined in methodOop.hpp.
   946 class BreakpointInfo;
   949 // A collection point for interesting information about the previous
   950 // version(s) of an instanceKlass. This class uses weak references to
   951 // the information so that the information may be collected as needed
   952 // by the system. If the information is shared, then a regular
   953 // reference must be used because a weak reference would be seen as
   954 // collectible. A GrowableArray of PreviousVersionNodes is attached
   955 // to the instanceKlass as needed. See PreviousVersionWalker below.
   956 class PreviousVersionNode : public CHeapObj {
   957  private:
   958   // A shared ConstantPool is never collected so we'll always have
   959   // a reference to it so we can update items in the cache. We'll
   960   // have a weak reference to a non-shared ConstantPool until all
   961   // of the methods (EMCP or obsolete) have been collected; the
   962   // non-shared ConstantPool becomes collectible at that point.
   963   jobject _prev_constant_pool;  // regular or weak reference
   964   bool    _prev_cp_is_weak;     // true if not a shared ConstantPool
   966   // If the previous version of the instanceKlass doesn't have any
   967   // EMCP methods, then _prev_EMCP_methods will be NULL. If all the
   968   // EMCP methods have been collected, then _prev_EMCP_methods can
   969   // have a length of zero.
   970   GrowableArray<jweak>* _prev_EMCP_methods;
   972 public:
   973   PreviousVersionNode(jobject prev_constant_pool, bool prev_cp_is_weak,
   974     GrowableArray<jweak>* prev_EMCP_methods);
   975   ~PreviousVersionNode();
   976   jobject prev_constant_pool() const {
   977     return _prev_constant_pool;
   978   }
   979   GrowableArray<jweak>* prev_EMCP_methods() const {
   980     return _prev_EMCP_methods;
   981   }
   982 };
   985 // A Handle-ized version of PreviousVersionNode.
   986 class PreviousVersionInfo : public ResourceObj {
   987  private:
   988   constantPoolHandle   _prev_constant_pool_handle;
   989   // If the previous version of the instanceKlass doesn't have any
   990   // EMCP methods, then _prev_EMCP_methods will be NULL. Since the
   991   // methods cannot be collected while we hold a handle,
   992   // _prev_EMCP_methods should never have a length of zero.
   993   GrowableArray<methodHandle>* _prev_EMCP_method_handles;
   995 public:
   996   PreviousVersionInfo(PreviousVersionNode *pv_node);
   997   ~PreviousVersionInfo();
   998   constantPoolHandle prev_constant_pool_handle() const {
   999     return _prev_constant_pool_handle;
  1001   GrowableArray<methodHandle>* prev_EMCP_method_handles() const {
  1002     return _prev_EMCP_method_handles;
  1004 };
  1007 // Helper object for walking previous versions. This helper cleans up
  1008 // the Handles that it allocates when the helper object is destroyed.
  1009 // The PreviousVersionInfo object returned by next_previous_version()
  1010 // is only valid until a subsequent call to next_previous_version() or
  1011 // the helper object is destroyed.
  1012 class PreviousVersionWalker : public StackObj {
  1013  private:
  1014   GrowableArray<PreviousVersionNode *>* _previous_versions;
  1015   int                                   _current_index;
  1016   // Fields for cleaning up when we are done walking the previous versions:
  1017   // A HandleMark for the PreviousVersionInfo handles:
  1018   HandleMark                            _hm;
  1020   // It would be nice to have a ResourceMark field in this helper also,
  1021   // but the ResourceMark code says to be careful to delete handles held
  1022   // in GrowableArrays _before_ deleting the GrowableArray. Since we
  1023   // can't guarantee the order in which the fields are destroyed, we
  1024   // have to let the creator of the PreviousVersionWalker object do
  1025   // the right thing. Also, adding a ResourceMark here causes an
  1026   // include loop.
  1028   // A pointer to the current info object so we can handle the deletes.
  1029   PreviousVersionInfo *                 _current_p;
  1031  public:
  1032   PreviousVersionWalker(instanceKlass *ik);
  1033   ~PreviousVersionWalker();
  1035   // Return the interesting information for the next previous version
  1036   // of the klass. Returns NULL if there are no more previous versions.
  1037   PreviousVersionInfo* next_previous_version();
  1038 };
  1040 #endif // SHARE_VM_OOPS_INSTANCEKLASS_HPP

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