src/share/vm/oops/instanceKlass.hpp

Thu, 13 Jan 2011 22:15:41 -0800

author
never
date
Thu, 13 Jan 2011 22:15:41 -0800
changeset 2462
8012aa3ccede
parent 2314
f95d63e2154a
child 2497
3582bf76420e
permissions
-rw-r--r--

4926272: methodOopDesc::method_from_bcp is unsafe
Reviewed-by: coleenp, jrose, kvn, dcubed

     1 /*
     2  * Copyright (c) 1997, 2010, 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   // Name of source file containing this klass, NULL if not specified.
   193   symbolOop       _source_file_name;
   194   // the source debug extension for this klass, NULL if not specified.
   195   symbolOop       _source_debug_extension;
   196   // inner_classes attribute.
   197   typeArrayOop    _inner_classes;
   198   // Implementors of this interface (not valid if it overflows)
   199   klassOop        _implementors[implementors_limit];
   200   // Generic signature, or null if none.
   201   symbolOop       _generic_signature;
   202   // invokedynamic bootstrap method (a java.dyn.MethodHandle)
   203   oop             _bootstrap_method;
   204   // Annotations for this class, or null if none.
   205   typeArrayOop    _class_annotations;
   206   // Annotation objects (byte arrays) for fields, or null if no annotations.
   207   // Indices correspond to entries (not indices) in fields array.
   208   objArrayOop     _fields_annotations;
   209   // Annotation objects (byte arrays) for methods, or null if no annotations.
   210   // Index is the idnum, which is initially the same as the methods array index.
   211   objArrayOop     _methods_annotations;
   212   // Annotation objects (byte arrays) for methods' parameters, or null if no
   213   // such annotations.
   214   // Index is the idnum, which is initially the same as the methods array index.
   215   objArrayOop     _methods_parameter_annotations;
   216   // Annotation objects (byte arrays) for methods' default values, or null if no
   217   // such annotations.
   218   // Index is the idnum, which is initially the same as the methods array index.
   219   objArrayOop     _methods_default_annotations;
   221   //
   222   // End of the oop block.
   223   //
   225   // Number of heapOopSize words used by non-static fields in this klass
   226   // (including inherited fields but after header_size()).
   227   int             _nonstatic_field_size;
   228   int             _static_field_size;    // number words used by static fields (oop and non-oop) in this klass
   229   int             _static_oop_field_size;// number of static oop fields in this klass
   230   int             _nonstatic_oop_map_size;// size in words of nonstatic oop map blocks
   231   bool            _is_marked_dependent;  // used for marking during flushing and deoptimization
   232   bool            _rewritten;            // methods rewritten.
   233   bool            _has_nonstatic_fields; // for sizing with UseCompressedOops
   234   bool            _should_verify_class;  // allow caching of preverification
   235   u2              _minor_version;        // minor version number of class file
   236   u2              _major_version;        // major version number of class file
   237   ClassState      _init_state;           // state of class
   238   Thread*         _init_thread;          // Pointer to current thread doing initialization (to handle recusive initialization)
   239   int             _vtable_len;           // length of Java vtable (in words)
   240   int             _itable_len;           // length of Java itable (in words)
   241   ReferenceType   _reference_type;       // reference type
   242   OopMapCache*    volatile _oop_map_cache;   // OopMapCache for all methods in the klass (allocated lazily)
   243   JNIid*          _jni_ids;              // First JNI identifier for static fields in this class
   244   jmethodID*      _methods_jmethod_ids;  // jmethodIDs corresponding to method_idnum, or NULL if none
   245   int*            _methods_cached_itable_indices;  // itable_index cache for JNI invoke corresponding to methods idnum, or NULL
   246   nmethodBucket*  _dependencies;         // list of dependent nmethods
   247   nmethod*        _osr_nmethods_head;    // Head of list of on-stack replacement nmethods for this class
   248   BreakpointInfo* _breakpoints;          // bpt lists, managed by methodOop
   249   int             _nof_implementors;     // No of implementors of this interface (zero if not an interface)
   250   // Array of interesting part(s) of the previous version(s) of this
   251   // instanceKlass. See PreviousVersionWalker below.
   252   GrowableArray<PreviousVersionNode *>* _previous_versions;
   253   u2              _enclosing_method_class_index;  // Constant pool index for class of enclosing method, or 0 if none
   254   u2              _enclosing_method_method_index; // Constant pool index for name and type of enclosing method, or 0 if none
   255   // JVMTI fields can be moved to their own structure - see 6315920
   256   unsigned char * _cached_class_file_bytes;       // JVMTI: cached class file, before retransformable agent modified it in CFLH
   257   jint            _cached_class_file_len;         // JVMTI: length of above
   258   JvmtiCachedClassFieldMap* _jvmti_cached_class_field_map;  // JVMTI: used during heap iteration
   259   volatile u2     _idnum_allocated_count;         // JNI/JVMTI: increments with the addition of methods, old ids don't change
   261   // embedded Java vtable follows here
   262   // embedded Java itables follows here
   263   // embedded static fields follows here
   264   // embedded nonstatic oop-map blocks follows here
   266   friend class instanceKlassKlass;
   267   friend class SystemDictionary;
   269  public:
   270   bool has_nonstatic_fields() const        { return _has_nonstatic_fields; }
   271   void set_has_nonstatic_fields(bool b)    { _has_nonstatic_fields = b; }
   273   // field sizes
   274   int nonstatic_field_size() const         { return _nonstatic_field_size; }
   275   void set_nonstatic_field_size(int size)  { _nonstatic_field_size = size; }
   277   int static_field_size() const            { return _static_field_size; }
   278   void set_static_field_size(int size)     { _static_field_size = size; }
   280   int static_oop_field_size() const        { return _static_oop_field_size; }
   281   void set_static_oop_field_size(int size) { _static_oop_field_size = size; }
   283   // Java vtable
   284   int  vtable_length() const               { return _vtable_len; }
   285   void set_vtable_length(int len)          { _vtable_len = len; }
   287   // Java itable
   288   int  itable_length() const               { return _itable_len; }
   289   void set_itable_length(int len)          { _itable_len = len; }
   291   // array klasses
   292   klassOop array_klasses() const           { return _array_klasses; }
   293   void set_array_klasses(klassOop k)       { oop_store_without_check((oop*) &_array_klasses, (oop) k); }
   295   // methods
   296   objArrayOop methods() const              { return _methods; }
   297   void set_methods(objArrayOop a)          { oop_store_without_check((oop*) &_methods, (oop) a); }
   298   methodOop method_with_idnum(int idnum);
   300   // method ordering
   301   typeArrayOop method_ordering() const     { return _method_ordering; }
   302   void set_method_ordering(typeArrayOop m) { oop_store_without_check((oop*) &_method_ordering, (oop) m); }
   304   // interfaces
   305   objArrayOop local_interfaces() const          { return _local_interfaces; }
   306   void set_local_interfaces(objArrayOop a)      { oop_store_without_check((oop*) &_local_interfaces, (oop) a); }
   307   objArrayOop transitive_interfaces() const     { return _transitive_interfaces; }
   308   void set_transitive_interfaces(objArrayOop a) { oop_store_without_check((oop*) &_transitive_interfaces, (oop) a); }
   310   // fields
   311   // Field info extracted from the class file and stored
   312   // as an array of 7 shorts
   313   enum FieldOffset {
   314     access_flags_offset    = 0,
   315     name_index_offset      = 1,
   316     signature_index_offset = 2,
   317     initval_index_offset   = 3,
   318     low_offset             = 4,
   319     high_offset            = 5,
   320     generic_signature_offset = 6,
   321     next_offset            = 7
   322   };
   324   typeArrayOop fields() const              { return _fields; }
   325   int offset_from_fields( int index ) const {
   326     return build_int_from_shorts( fields()->ushort_at(index + low_offset),
   327                                   fields()->ushort_at(index + high_offset) );
   328   }
   330   void set_fields(typeArrayOop f)          { oop_store_without_check((oop*) &_fields, (oop) f); }
   332   // inner classes
   333   typeArrayOop inner_classes() const       { return _inner_classes; }
   334   void set_inner_classes(typeArrayOop f)   { oop_store_without_check((oop*) &_inner_classes, (oop) f); }
   336   enum InnerClassAttributeOffset {
   337     // From http://mirror.eng/products/jdk/1.1/docs/guide/innerclasses/spec/innerclasses.doc10.html#18814
   338     inner_class_inner_class_info_offset = 0,
   339     inner_class_outer_class_info_offset = 1,
   340     inner_class_inner_name_offset = 2,
   341     inner_class_access_flags_offset = 3,
   342     inner_class_next_offset = 4
   343   };
   345   // method override check
   346   bool is_override(methodHandle super_method, Handle targetclassloader, symbolHandle targetclassname, TRAPS);
   348   // package
   349   bool is_same_class_package(klassOop class2);
   350   bool is_same_class_package(oop classloader2, symbolOop classname2);
   351   static bool is_same_class_package(oop class_loader1, symbolOop class_name1, oop class_loader2, symbolOop class_name2);
   353   // find an enclosing class (defined where original code was, in jvm.cpp!)
   354   klassOop compute_enclosing_class(bool* inner_is_member, TRAPS) {
   355     instanceKlassHandle self(THREAD, this->as_klassOop());
   356     return compute_enclosing_class_impl(self, inner_is_member, THREAD);
   357   }
   358   static klassOop compute_enclosing_class_impl(instanceKlassHandle self,
   359                                                bool* inner_is_member, TRAPS);
   361   // tell if two classes have the same enclosing class (at package level)
   362   bool is_same_package_member(klassOop class2, TRAPS) {
   363     instanceKlassHandle self(THREAD, this->as_klassOop());
   364     return is_same_package_member_impl(self, class2, THREAD);
   365   }
   366   static bool is_same_package_member_impl(instanceKlassHandle self,
   367                                           klassOop class2, TRAPS);
   369   // initialization state
   370   bool is_loaded() const                   { return _init_state >= loaded; }
   371   bool is_linked() const                   { return _init_state >= linked; }
   372   bool is_initialized() const              { return _init_state == fully_initialized; }
   373   bool is_not_initialized() const          { return _init_state <  being_initialized; }
   374   bool is_being_initialized() const        { return _init_state == being_initialized; }
   375   bool is_in_error_state() const           { return _init_state == initialization_error; }
   376   bool is_reentrant_initialization(Thread *thread)  { return thread == _init_thread; }
   377   int  get_init_state()                    { return _init_state; } // Useful for debugging
   378   bool is_rewritten() const                { return _rewritten; }
   380   // defineClass specified verification
   381   bool should_verify_class() const         { return _should_verify_class; }
   382   void set_should_verify_class(bool value) { _should_verify_class = value; }
   384   // marking
   385   bool is_marked_dependent() const         { return _is_marked_dependent; }
   386   void set_is_marked_dependent(bool value) { _is_marked_dependent = value; }
   388   // initialization (virtuals from Klass)
   389   bool should_be_initialized() const;  // means that initialize should be called
   390   void initialize(TRAPS);
   391   void link_class(TRAPS);
   392   bool link_class_or_fail(TRAPS); // returns false on failure
   393   void unlink_class();
   394   void rewrite_class(TRAPS);
   395   methodOop class_initializer();
   397   // set the class to initialized if no static initializer is present
   398   void eager_initialize(Thread *thread);
   400   // reference type
   401   ReferenceType reference_type() const     { return _reference_type; }
   402   void set_reference_type(ReferenceType t) { _reference_type = t; }
   404   // find local field, returns true if found
   405   bool find_local_field(symbolOop name, symbolOop sig, fieldDescriptor* fd) const;
   406   // find field in direct superinterfaces, returns the interface in which the field is defined
   407   klassOop find_interface_field(symbolOop name, symbolOop sig, fieldDescriptor* fd) const;
   408   // find field according to JVM spec 5.4.3.2, returns the klass in which the field is defined
   409   klassOop find_field(symbolOop name, symbolOop sig, fieldDescriptor* fd) const;
   410   // find instance or static fields according to JVM spec 5.4.3.2, returns the klass in which the field is defined
   411   klassOop find_field(symbolOop name, symbolOop sig, bool is_static, fieldDescriptor* fd) const;
   413   // find a non-static or static field given its offset within the class.
   414   bool contains_field_offset(int offset) {
   415     return instanceOopDesc::contains_field_offset(offset, nonstatic_field_size());
   416   }
   418   bool find_local_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const;
   419   bool find_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const;
   421   // find a local method (returns NULL if not found)
   422   methodOop find_method(symbolOop name, symbolOop signature) const;
   423   static methodOop find_method(objArrayOop methods, symbolOop name, symbolOop signature);
   425   // lookup operation (returns NULL if not found)
   426   methodOop uncached_lookup_method(symbolOop name, symbolOop signature) const;
   428   // lookup a method in all the interfaces that this class implements
   429   // (returns NULL if not found)
   430   methodOop lookup_method_in_all_interfaces(symbolOop name, symbolOop signature) const;
   432   // constant pool
   433   constantPoolOop constants() const        { return _constants; }
   434   void set_constants(constantPoolOop c)    { oop_store_without_check((oop*) &_constants, (oop) c); }
   436   // class loader
   437   oop class_loader() const                 { return _class_loader; }
   438   void set_class_loader(oop l)             { oop_store((oop*) &_class_loader, l); }
   440   // protection domain
   441   oop protection_domain()                  { return _protection_domain; }
   442   void set_protection_domain(oop pd)       { oop_store((oop*) &_protection_domain, pd); }
   444   // host class
   445   oop host_klass() const                   { return _host_klass; }
   446   void set_host_klass(oop host)            { oop_store((oop*) &_host_klass, host); }
   447   bool is_anonymous() const                { return _host_klass != NULL; }
   449   // signers
   450   objArrayOop signers() const              { return _signers; }
   451   void set_signers(objArrayOop s)          { oop_store((oop*) &_signers, oop(s)); }
   453   // source file name
   454   symbolOop source_file_name() const       { return _source_file_name; }
   455   void set_source_file_name(symbolOop n)   { oop_store_without_check((oop*) &_source_file_name, (oop) n); }
   457   // minor and major version numbers of class file
   458   u2 minor_version() const                 { return _minor_version; }
   459   void set_minor_version(u2 minor_version) { _minor_version = minor_version; }
   460   u2 major_version() const                 { return _major_version; }
   461   void set_major_version(u2 major_version) { _major_version = major_version; }
   463   // source debug extension
   464   symbolOop source_debug_extension() const    { return _source_debug_extension; }
   465   void set_source_debug_extension(symbolOop n){ oop_store_without_check((oop*) &_source_debug_extension, (oop) n); }
   467   // nonstatic oop-map blocks
   468   static int nonstatic_oop_map_size(unsigned int oop_map_count) {
   469     return oop_map_count * OopMapBlock::size_in_words();
   470   }
   471   unsigned int nonstatic_oop_map_count() const {
   472     return _nonstatic_oop_map_size / OopMapBlock::size_in_words();
   473   }
   474   int nonstatic_oop_map_size() const { return _nonstatic_oop_map_size; }
   475   void set_nonstatic_oop_map_size(int words) {
   476     _nonstatic_oop_map_size = words;
   477   }
   479   // RedefineClasses() support for previous versions:
   480   void add_previous_version(instanceKlassHandle ikh, BitMap *emcp_methods,
   481          int emcp_method_count);
   482   // If the _previous_versions array is non-NULL, then this klass
   483   // has been redefined at least once even if we aren't currently
   484   // tracking a previous version.
   485   bool has_been_redefined() const { return _previous_versions != NULL; }
   486   bool has_previous_version() const;
   487   void init_previous_versions() {
   488     _previous_versions = NULL;
   489   }
   490   GrowableArray<PreviousVersionNode *>* previous_versions() const {
   491     return _previous_versions;
   492   }
   494   // JVMTI: Support for caching a class file before it is modified by an agent that can do retransformation
   495   void set_cached_class_file(unsigned char *class_file_bytes,
   496                              jint class_file_len)     { _cached_class_file_len = class_file_len;
   497                                                         _cached_class_file_bytes = class_file_bytes; }
   498   jint get_cached_class_file_len()                    { return _cached_class_file_len; }
   499   unsigned char * get_cached_class_file_bytes()       { return _cached_class_file_bytes; }
   501   // JVMTI: Support for caching of field indices, types, and offsets
   502   void set_jvmti_cached_class_field_map(JvmtiCachedClassFieldMap* descriptor) {
   503     _jvmti_cached_class_field_map = descriptor;
   504   }
   505   JvmtiCachedClassFieldMap* jvmti_cached_class_field_map() const {
   506     return _jvmti_cached_class_field_map;
   507   }
   509   // for adding methods, constMethodOopDesc::UNSET_IDNUM means no more ids available
   510   inline u2 next_method_idnum();
   511   void set_initial_method_idnum(u2 value)             { _idnum_allocated_count = value; }
   513   // generics support
   514   symbolOop generic_signature() const                 { return _generic_signature; }
   515   void set_generic_signature(symbolOop sig)           { oop_store_without_check((oop*)&_generic_signature, (oop)sig); }
   516   u2 enclosing_method_class_index() const             { return _enclosing_method_class_index; }
   517   u2 enclosing_method_method_index() const            { return _enclosing_method_method_index; }
   518   void set_enclosing_method_indices(u2 class_index,
   519                                     u2 method_index)  { _enclosing_method_class_index  = class_index;
   520                                                         _enclosing_method_method_index = method_index; }
   522   // JSR 292 support
   523   oop bootstrap_method() const                        { return _bootstrap_method; }
   524   void set_bootstrap_method(oop mh)                   { oop_store(&_bootstrap_method, mh); }
   526   // jmethodID support
   527   static jmethodID get_jmethod_id(instanceKlassHandle ik_h,
   528                      methodHandle method_h);
   529   static jmethodID get_jmethod_id_fetch_or_update(instanceKlassHandle ik_h,
   530                      size_t idnum, jmethodID new_id, jmethodID* new_jmeths,
   531                      jmethodID* to_dealloc_id_p,
   532                      jmethodID** to_dealloc_jmeths_p);
   533   static void get_jmethod_id_length_value(jmethodID* cache, size_t idnum,
   534                 size_t *length_p, jmethodID* id_p);
   535   jmethodID jmethod_id_or_null(methodOop method);
   537   // cached itable index support
   538   void set_cached_itable_index(size_t idnum, int index);
   539   int cached_itable_index(size_t idnum);
   541   // annotations support
   542   typeArrayOop class_annotations() const              { return _class_annotations; }
   543   objArrayOop fields_annotations() const              { return _fields_annotations; }
   544   objArrayOop methods_annotations() const             { return _methods_annotations; }
   545   objArrayOop methods_parameter_annotations() const   { return _methods_parameter_annotations; }
   546   objArrayOop methods_default_annotations() const     { return _methods_default_annotations; }
   547   void set_class_annotations(typeArrayOop md)            { oop_store_without_check((oop*)&_class_annotations, (oop)md); }
   548   void set_fields_annotations(objArrayOop md)            { set_annotations(md, &_fields_annotations); }
   549   void set_methods_annotations(objArrayOop md)           { set_annotations(md, &_methods_annotations); }
   550   void set_methods_parameter_annotations(objArrayOop md) { set_annotations(md, &_methods_parameter_annotations); }
   551   void set_methods_default_annotations(objArrayOop md)   { set_annotations(md, &_methods_default_annotations); }
   552   typeArrayOop get_method_annotations_of(int idnum)
   553                                                 { return get_method_annotations_from(idnum, _methods_annotations); }
   554   typeArrayOop get_method_parameter_annotations_of(int idnum)
   555                                                 { return get_method_annotations_from(idnum, _methods_parameter_annotations); }
   556   typeArrayOop get_method_default_annotations_of(int idnum)
   557                                                 { return get_method_annotations_from(idnum, _methods_default_annotations); }
   558   void set_method_annotations_of(int idnum, typeArrayOop anno)
   559                                                 { set_methods_annotations_of(idnum, anno, &_methods_annotations); }
   560   void set_method_parameter_annotations_of(int idnum, typeArrayOop anno)
   561                                                 { set_methods_annotations_of(idnum, anno, &_methods_annotations); }
   562   void set_method_default_annotations_of(int idnum, typeArrayOop anno)
   563                                                 { set_methods_annotations_of(idnum, anno, &_methods_annotations); }
   565   // allocation
   566   DEFINE_ALLOCATE_PERMANENT(instanceKlass);
   567   instanceOop allocate_instance(TRAPS);
   568   instanceOop allocate_permanent_instance(TRAPS);
   570   // additional member function to return a handle
   571   instanceHandle allocate_instance_handle(TRAPS)      { return instanceHandle(THREAD, allocate_instance(THREAD)); }
   573   objArrayOop allocate_objArray(int n, int length, TRAPS);
   574   // Helper function
   575   static instanceOop register_finalizer(instanceOop i, TRAPS);
   577   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
   578   // if not, throw either an Error or an Exception.
   579   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
   581   // initialization
   582   void call_class_initializer(TRAPS);
   583   void set_initialization_state_and_notify(ClassState state, TRAPS);
   585   // OopMapCache support
   586   OopMapCache* oop_map_cache()               { return _oop_map_cache; }
   587   void set_oop_map_cache(OopMapCache *cache) { _oop_map_cache = cache; }
   588   void mask_for(methodHandle method, int bci, InterpreterOopMap* entry);
   590   // JNI identifier support (for static fields - for jni performance)
   591   JNIid* jni_ids()                               { return _jni_ids; }
   592   void set_jni_ids(JNIid* ids)                   { _jni_ids = ids; }
   593   JNIid* jni_id_for(int offset);
   595   // maintenance of deoptimization dependencies
   596   int mark_dependent_nmethods(DepChange& changes);
   597   void add_dependent_nmethod(nmethod* nm);
   598   void remove_dependent_nmethod(nmethod* nm);
   600   // On-stack replacement support
   601   nmethod* osr_nmethods_head() const         { return _osr_nmethods_head; };
   602   void set_osr_nmethods_head(nmethod* h)     { _osr_nmethods_head = h; };
   603   void add_osr_nmethod(nmethod* n);
   604   void remove_osr_nmethod(nmethod* n);
   605   nmethod* lookup_osr_nmethod(const methodOop m, int bci, int level, bool match_level) const;
   607   // Breakpoint support (see methods on methodOop for details)
   608   BreakpointInfo* breakpoints() const       { return _breakpoints; };
   609   void set_breakpoints(BreakpointInfo* bps) { _breakpoints = bps; };
   611   // support for stub routines
   612   static int init_state_offset_in_bytes()    { return offset_of(instanceKlass, _init_state); }
   613   static int init_thread_offset_in_bytes()   { return offset_of(instanceKlass, _init_thread); }
   615   // subclass/subinterface checks
   616   bool implements_interface(klassOop k) const;
   618   // Access to implementors of an interface. We only store the count
   619   // of implementors, and in case, there are only a few
   620   // implementors, we store them in a short list.
   621   // This accessor returns NULL if we walk off the end of the list.
   622   klassOop implementor(int i) const {
   623     return (i < implementors_limit)? _implementors[i]: (klassOop) NULL;
   624   }
   625   int  nof_implementors() const       { return _nof_implementors; }
   626   void add_implementor(klassOop k);  // k is a new class that implements this interface
   627   void init_implementor();           // initialize
   629   // link this class into the implementors list of every interface it implements
   630   void process_interfaces(Thread *thread);
   632   // virtual operations from Klass
   633   bool is_leaf_class() const               { return _subklass == NULL; }
   634   objArrayOop compute_secondary_supers(int num_extra_slots, TRAPS);
   635   bool compute_is_subtype_of(klassOop k);
   636   bool can_be_primary_super_slow() const;
   637   klassOop java_super() const              { return super(); }
   638   int oop_size(oop obj)  const             { return size_helper(); }
   639   int klass_oop_size() const               { return object_size(); }
   640   bool oop_is_instance_slow() const        { return true; }
   642   // Iterators
   643   void do_local_static_fields(FieldClosure* cl);
   644   void do_nonstatic_fields(FieldClosure* cl); // including inherited fields
   645   void do_local_static_fields(void f(fieldDescriptor*, TRAPS), TRAPS);
   647   void methods_do(void f(methodOop method));
   648   void array_klasses_do(void f(klassOop k));
   649   void with_array_klasses_do(void f(klassOop k));
   650   bool super_types_do(SuperTypeClosure* blk);
   652   // Casting from klassOop
   653   static instanceKlass* cast(klassOop k) {
   654     Klass* kp = k->klass_part();
   655     assert(kp->null_vtbl() || kp->oop_is_instance_slow(), "cast to instanceKlass");
   656     return (instanceKlass*) kp;
   657   }
   659   // Sizing (in words)
   660   static int header_size()            { return align_object_offset(oopDesc::header_size() + sizeof(instanceKlass)/HeapWordSize); }
   661   int object_size() const             { return object_size(align_object_offset(vtable_length()) + align_object_offset(itable_length()) + static_field_size() + nonstatic_oop_map_size()); }
   662   static int vtable_start_offset()    { return header_size(); }
   663   static int vtable_length_offset()   { return oopDesc::header_size() + offset_of(instanceKlass, _vtable_len) / HeapWordSize; }
   664   static int object_size(int extra)   { return align_object_size(header_size() + extra); }
   666   intptr_t* start_of_vtable() const        { return ((intptr_t*)as_klassOop()) + vtable_start_offset(); }
   667   intptr_t* start_of_itable() const        { return start_of_vtable() + align_object_offset(vtable_length()); }
   668   int  itable_offset_in_words() const { return start_of_itable() - (intptr_t*)as_klassOop(); }
   670   // Static field offset is an offset into the Heap, should be converted by
   671   // based on UseCompressedOop for traversal
   672   HeapWord* start_of_static_fields() const {
   673     return (HeapWord*)(start_of_itable() + align_object_offset(itable_length()));
   674   }
   676   intptr_t* end_of_itable() const          { return start_of_itable() + itable_length(); }
   678   int offset_of_static_fields() const {
   679     return (intptr_t)start_of_static_fields() - (intptr_t)as_klassOop();
   680   }
   682   OopMapBlock* start_of_nonstatic_oop_maps() const {
   683     return (OopMapBlock*) (start_of_static_fields() + static_field_size());
   684   }
   686   // Allocation profiling support
   687   juint alloc_size() const            { return _alloc_count * size_helper(); }
   688   void set_alloc_size(juint n)        {}
   690   // Use this to return the size of an instance in heap words:
   691   int size_helper() const {
   692     return layout_helper_to_size_helper(layout_helper());
   693   }
   695   // This bit is initialized in classFileParser.cpp.
   696   // It is false under any of the following conditions:
   697   //  - the class is abstract (including any interface)
   698   //  - the class has a finalizer (if !RegisterFinalizersAtInit)
   699   //  - the class size is larger than FastAllocateSizeLimit
   700   //  - the class is java/lang/Class, which cannot be allocated directly
   701   bool can_be_fastpath_allocated() const {
   702     return !layout_helper_needs_slow_path(layout_helper());
   703   }
   705   // Java vtable/itable
   706   klassVtable* vtable() const;        // return new klassVtable wrapper
   707   inline methodOop method_at_vtable(int index);
   708   klassItable* itable() const;        // return new klassItable wrapper
   709   methodOop method_at_itable(klassOop holder, int index, TRAPS);
   711   // Garbage collection
   712   void oop_follow_contents(oop obj);
   713   void follow_static_fields();
   714   void adjust_static_fields();
   715   int  oop_adjust_pointers(oop obj);
   716   bool object_is_parsable() const { return _init_state != unparsable_by_gc; }
   717        // Value of _init_state must be zero (unparsable_by_gc) when klass field is set.
   719   void follow_weak_klass_links(
   720     BoolObjectClosure* is_alive, OopClosure* keep_alive);
   721   void release_C_heap_structures();
   723   // Parallel Scavenge and Parallel Old
   724   PARALLEL_GC_DECLS
   726 #ifndef SERIALGC
   727   // Parallel Scavenge
   728   void push_static_fields(PSPromotionManager* pm);
   730   // Parallel Old
   731   void follow_static_fields(ParCompactionManager* cm);
   732   void copy_static_fields(ParCompactionManager* cm);
   733   void update_static_fields();
   734   void update_static_fields(HeapWord* beg_addr, HeapWord* end_addr);
   735 #endif // SERIALGC
   737   // Naming
   738   const char* signature_name() const;
   740   // Iterators
   741   int oop_oop_iterate(oop obj, OopClosure* blk) {
   742     return oop_oop_iterate_v(obj, blk);
   743   }
   745   int oop_oop_iterate_m(oop obj, OopClosure* blk, MemRegion mr) {
   746     return oop_oop_iterate_v_m(obj, blk, mr);
   747   }
   749 #define InstanceKlass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)      \
   750   int  oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk);           \
   751   int  oop_oop_iterate##nv_suffix##_m(oop obj, OopClosureType* blk,        \
   752                                       MemRegion mr);
   754   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_DECL)
   755   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_DECL)
   757 #ifndef SERIALGC
   758 #define InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
   759   int  oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* blk);
   761   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
   762   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
   763 #endif // !SERIALGC
   765   void iterate_static_fields(OopClosure* closure);
   766   void iterate_static_fields(OopClosure* closure, MemRegion mr);
   768 private:
   769   // initialization state
   770 #ifdef ASSERT
   771   void set_init_state(ClassState state);
   772 #else
   773   void set_init_state(ClassState state) { _init_state = state; }
   774 #endif
   775   void set_rewritten()                  { _rewritten = true; }
   776   void set_init_thread(Thread *thread)  { _init_thread = thread; }
   778   u2 idnum_allocated_count() const      { return _idnum_allocated_count; }
   779   // The RedefineClasses() API can cause new method idnums to be needed
   780   // which will cause the caches to grow. Safety requires different
   781   // cache management logic if the caches can grow instead of just
   782   // going from NULL to non-NULL.
   783   bool idnum_can_increment() const      { return has_been_redefined(); }
   784   jmethodID* methods_jmethod_ids_acquire() const
   785          { return (jmethodID*)OrderAccess::load_ptr_acquire(&_methods_jmethod_ids); }
   786   void release_set_methods_jmethod_ids(jmethodID* jmeths)
   787          { OrderAccess::release_store_ptr(&_methods_jmethod_ids, jmeths); }
   789   int* methods_cached_itable_indices_acquire() const
   790          { return (int*)OrderAccess::load_ptr_acquire(&_methods_cached_itable_indices); }
   791   void release_set_methods_cached_itable_indices(int* indices)
   792          { OrderAccess::release_store_ptr(&_methods_cached_itable_indices, indices); }
   794   inline typeArrayOop get_method_annotations_from(int idnum, objArrayOop annos);
   795   void set_annotations(objArrayOop md, objArrayOop* md_p)  { oop_store_without_check((oop*)md_p, (oop)md); }
   796   void set_methods_annotations_of(int idnum, typeArrayOop anno, objArrayOop* md_p);
   798   // Offsets for memory management
   799   oop* adr_array_klasses() const     { return (oop*)&this->_array_klasses;}
   800   oop* adr_methods() const           { return (oop*)&this->_methods;}
   801   oop* adr_method_ordering() const   { return (oop*)&this->_method_ordering;}
   802   oop* adr_local_interfaces() const  { return (oop*)&this->_local_interfaces;}
   803   oop* adr_transitive_interfaces() const  { return (oop*)&this->_transitive_interfaces;}
   804   oop* adr_fields() const            { return (oop*)&this->_fields;}
   805   oop* adr_constants() const         { return (oop*)&this->_constants;}
   806   oop* adr_class_loader() const      { return (oop*)&this->_class_loader;}
   807   oop* adr_protection_domain() const { return (oop*)&this->_protection_domain;}
   808   oop* adr_host_klass() const        { return (oop*)&this->_host_klass;}
   809   oop* adr_signers() const           { return (oop*)&this->_signers;}
   810   oop* adr_source_file_name() const  { return (oop*)&this->_source_file_name;}
   811   oop* adr_source_debug_extension() const { return (oop*)&this->_source_debug_extension;}
   812   oop* adr_inner_classes() const     { return (oop*)&this->_inner_classes;}
   813   oop* adr_implementors() const      { return (oop*)&this->_implementors[0];}
   814   oop* adr_generic_signature() const { return (oop*)&this->_generic_signature;}
   815   oop* adr_bootstrap_method() const  { return (oop*)&this->_bootstrap_method;}
   816   oop* adr_methods_jmethod_ids() const             { return (oop*)&this->_methods_jmethod_ids;}
   817   oop* adr_methods_cached_itable_indices() const   { return (oop*)&this->_methods_cached_itable_indices;}
   818   oop* adr_class_annotations() const   { return (oop*)&this->_class_annotations;}
   819   oop* adr_fields_annotations() const  { return (oop*)&this->_fields_annotations;}
   820   oop* adr_methods_annotations() const { return (oop*)&this->_methods_annotations;}
   821   oop* adr_methods_parameter_annotations() const { return (oop*)&this->_methods_parameter_annotations;}
   822   oop* adr_methods_default_annotations() const { return (oop*)&this->_methods_default_annotations;}
   824   // Static methods that are used to implement member methods where an exposed this pointer
   825   // is needed due to possible GCs
   826   static bool link_class_impl                           (instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS);
   827   static bool verify_code                               (instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS);
   828   static void initialize_impl                           (instanceKlassHandle this_oop, TRAPS);
   829   static void eager_initialize_impl                     (instanceKlassHandle this_oop);
   830   static void set_initialization_state_and_notify_impl  (instanceKlassHandle this_oop, ClassState state, TRAPS);
   831   static void call_class_initializer_impl               (instanceKlassHandle this_oop, TRAPS);
   832   static klassOop array_klass_impl                      (instanceKlassHandle this_oop, bool or_null, int n, TRAPS);
   833   static void do_local_static_fields_impl               (instanceKlassHandle this_oop, void f(fieldDescriptor* fd, TRAPS), TRAPS);
   834   /* jni_id_for_impl for jfieldID only */
   835   static JNIid* jni_id_for_impl                         (instanceKlassHandle this_oop, int offset);
   837   // Returns the array class for the n'th dimension
   838   klassOop array_klass_impl(bool or_null, int n, TRAPS);
   840   // Returns the array class with this class as element type
   841   klassOop array_klass_impl(bool or_null, TRAPS);
   843 public:
   844   // sharing support
   845   virtual void remove_unshareable_info();
   846   void field_names_and_sigs_iterate(OopClosure* closure);
   848   // jvm support
   849   jint compute_modifier_flags(TRAPS) const;
   851 public:
   852   // JVMTI support
   853   jint jvmti_class_status() const;
   855  public:
   856   // Printing
   857   void oop_print_value_on(oop obj, outputStream* st);
   858 #ifndef PRODUCT
   859   void oop_print_on      (oop obj, outputStream* st);
   861   void print_dependent_nmethods(bool verbose = false);
   862   bool is_dependent_nmethod(nmethod* nm);
   863 #endif
   865   // Verification
   866   const char* internal_name() const;
   867   void oop_verify_on(oop obj, outputStream* st);
   869 #ifndef PRODUCT
   870   static void verify_class_klass_nonstatic_oop_maps(klassOop k) PRODUCT_RETURN;
   871 #endif
   872 };
   874 inline methodOop instanceKlass::method_at_vtable(int index)  {
   875 #ifndef PRODUCT
   876   assert(index >= 0, "valid vtable index");
   877   if (DebugVtables) {
   878     verify_vtable_index(index);
   879   }
   880 #endif
   881   vtableEntry* ve = (vtableEntry*)start_of_vtable();
   882   return ve[index].method();
   883 }
   885 inline typeArrayOop instanceKlass::get_method_annotations_from(int idnum, objArrayOop annos) {
   886   if (annos == NULL || annos->length() <= idnum) {
   887     return NULL;
   888   }
   889   return typeArrayOop(annos->obj_at(idnum));
   890 }
   892 // for adding methods
   893 // UNSET_IDNUM return means no more ids available
   894 inline u2 instanceKlass::next_method_idnum() {
   895   if (_idnum_allocated_count == constMethodOopDesc::MAX_IDNUM) {
   896     return constMethodOopDesc::UNSET_IDNUM; // no more ids available
   897   } else {
   898     return _idnum_allocated_count++;
   899   }
   900 }
   903 /* JNIid class for jfieldIDs only */
   904 class JNIid: public CHeapObj {
   905   friend class VMStructs;
   906  private:
   907   klassOop           _holder;
   908   JNIid*             _next;
   909   int                _offset;
   910 #ifdef ASSERT
   911   bool               _is_static_field_id;
   912 #endif
   914  public:
   915   // Accessors
   916   klassOop holder() const         { return _holder; }
   917   int offset() const              { return _offset; }
   918   JNIid* next()                   { return _next; }
   919   // Constructor
   920   JNIid(klassOop holder, int offset, JNIid* next);
   921   // Identifier lookup
   922   JNIid* find(int offset);
   924   // Garbage collection support
   925   oop* holder_addr() { return (oop*)&_holder; }
   926   void oops_do(OopClosure* f);
   927   static void deallocate(JNIid* id);
   928   // Debugging
   929 #ifdef ASSERT
   930   bool is_static_field_id() const { return _is_static_field_id; }
   931   void set_is_static_field_id()   { _is_static_field_id = true; }
   932 #endif
   933   void verify(klassOop holder);
   934 };
   937 // If breakpoints are more numerous than just JVMTI breakpoints,
   938 // consider compressing this data structure.
   939 // It is currently a simple linked list defined in methodOop.hpp.
   941 class BreakpointInfo;
   944 // A collection point for interesting information about the previous
   945 // version(s) of an instanceKlass. This class uses weak references to
   946 // the information so that the information may be collected as needed
   947 // by the system. If the information is shared, then a regular
   948 // reference must be used because a weak reference would be seen as
   949 // collectible. A GrowableArray of PreviousVersionNodes is attached
   950 // to the instanceKlass as needed. See PreviousVersionWalker below.
   951 class PreviousVersionNode : public CHeapObj {
   952  private:
   953   // A shared ConstantPool is never collected so we'll always have
   954   // a reference to it so we can update items in the cache. We'll
   955   // have a weak reference to a non-shared ConstantPool until all
   956   // of the methods (EMCP or obsolete) have been collected; the
   957   // non-shared ConstantPool becomes collectible at that point.
   958   jobject _prev_constant_pool;  // regular or weak reference
   959   bool    _prev_cp_is_weak;     // true if not a shared ConstantPool
   961   // If the previous version of the instanceKlass doesn't have any
   962   // EMCP methods, then _prev_EMCP_methods will be NULL. If all the
   963   // EMCP methods have been collected, then _prev_EMCP_methods can
   964   // have a length of zero.
   965   GrowableArray<jweak>* _prev_EMCP_methods;
   967 public:
   968   PreviousVersionNode(jobject prev_constant_pool, bool prev_cp_is_weak,
   969     GrowableArray<jweak>* prev_EMCP_methods);
   970   ~PreviousVersionNode();
   971   jobject prev_constant_pool() const {
   972     return _prev_constant_pool;
   973   }
   974   GrowableArray<jweak>* prev_EMCP_methods() const {
   975     return _prev_EMCP_methods;
   976   }
   977 };
   980 // A Handle-ized version of PreviousVersionNode.
   981 class PreviousVersionInfo : public ResourceObj {
   982  private:
   983   constantPoolHandle   _prev_constant_pool_handle;
   984   // If the previous version of the instanceKlass doesn't have any
   985   // EMCP methods, then _prev_EMCP_methods will be NULL. Since the
   986   // methods cannot be collected while we hold a handle,
   987   // _prev_EMCP_methods should never have a length of zero.
   988   GrowableArray<methodHandle>* _prev_EMCP_method_handles;
   990 public:
   991   PreviousVersionInfo(PreviousVersionNode *pv_node);
   992   ~PreviousVersionInfo();
   993   constantPoolHandle prev_constant_pool_handle() const {
   994     return _prev_constant_pool_handle;
   995   }
   996   GrowableArray<methodHandle>* prev_EMCP_method_handles() const {
   997     return _prev_EMCP_method_handles;
   998   }
   999 };
  1002 // Helper object for walking previous versions. This helper cleans up
  1003 // the Handles that it allocates when the helper object is destroyed.
  1004 // The PreviousVersionInfo object returned by next_previous_version()
  1005 // is only valid until a subsequent call to next_previous_version() or
  1006 // the helper object is destroyed.
  1007 class PreviousVersionWalker : public StackObj {
  1008  private:
  1009   GrowableArray<PreviousVersionNode *>* _previous_versions;
  1010   int                                   _current_index;
  1011   // Fields for cleaning up when we are done walking the previous versions:
  1012   // A HandleMark for the PreviousVersionInfo handles:
  1013   HandleMark                            _hm;
  1015   // It would be nice to have a ResourceMark field in this helper also,
  1016   // but the ResourceMark code says to be careful to delete handles held
  1017   // in GrowableArrays _before_ deleting the GrowableArray. Since we
  1018   // can't guarantee the order in which the fields are destroyed, we
  1019   // have to let the creator of the PreviousVersionWalker object do
  1020   // the right thing. Also, adding a ResourceMark here causes an
  1021   // include loop.
  1023   // A pointer to the current info object so we can handle the deletes.
  1024   PreviousVersionInfo *                 _current_p;
  1026  public:
  1027   PreviousVersionWalker(instanceKlass *ik);
  1028   ~PreviousVersionWalker();
  1030   // Return the interesting information for the next previous version
  1031   // of the klass. Returns NULL if there are no more previous versions.
  1032   PreviousVersionInfo* next_previous_version();
  1033 };
  1035 #endif // SHARE_VM_OOPS_INSTANCEKLASS_HPP

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