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  */
  24 
  25 #ifndef SHARE_VM_OOPS_INSTANCEKLASS_HPP
  26 #define SHARE_VM_OOPS_INSTANCEKLASS_HPP
  27 
  28 #include "oops/constMethodOop.hpp"
  29 #include "oops/constantPoolOop.hpp"
  30 #include "oops/fieldInfo.hpp"
  31 #include "oops/instanceOop.hpp"
  32 #include "oops/klassOop.hpp"
  33 #include "oops/klassVtable.hpp"
  34 #include "oops/objArrayOop.hpp"
  35 #include "runtime/handles.hpp"
  36 #include "runtime/os.hpp"
  37 #include "utilities/accessFlags.hpp"
  38 #include "utilities/bitMap.inline.hpp"
  39 
  40 // An instanceKlass is the VM level representation of a Java class.
  41 // It contains all information needed for at class at execution runtime.
  42 
  43 //  instanceKlass layout:
  44 //    [header                     ] klassOop
  45 //    [klass pointer              ] klassOop
  46 //    [C++ vtbl pointer           ] Klass
  47 //    [subtype cache              ] Klass
  48 //    [instance size              ] Klass
  49 //    [java mirror                ] Klass
  50 //    [super                      ] Klass
  51 //    [access_flags               ] Klass
  52 //    [name                       ] Klass
  53 //    [first subklass             ] Klass
  54 //    [next sibling               ] Klass
  55 //    [array klasses              ]
  56 //    [methods                    ]
  57 //    [local interfaces           ]
  58 //    [transitive interfaces      ]
  59 //    [number of implementors     ]
  60 //    [implementors               ] klassOop[2]
  61 //    [fields                     ]
  62 //    [constants                  ]
  63 //    [class loader               ]
  64 //    [protection domain          ]
  65 //    [signers                    ]
  66 //    [source file name           ]
  67 //    [inner classes              ]
  68 //    [static field size          ]
  69 //    [nonstatic field size       ]
  70 //    [static oop fields size     ]
  71 //    [nonstatic oop maps size    ]
  72 //    [has finalize method        ]
  73 //    [deoptimization mark bit    ]
  74 //    [initialization state       ]
  75 //    [initializing thread        ]
  76 //    [Java vtable length         ]
  77 //    [oop map cache (stack maps) ]
  78 //    [EMBEDDED Java vtable             ] size in words = vtable_len
  79 //    [EMBEDDED nonstatic oop-map blocks] size in words = nonstatic_oop_map_size
  80 //
  81 //    The embedded nonstatic oop-map blocks are short pairs (offset, length) indicating
  82 //    where oops are located in instances of this klass.
  83 
  84 
  85 // forward declaration for class -- see below for definition
  86 class SuperTypeClosure;
  87 class JNIid;
  88 class jniIdMapBase;
  89 class BreakpointInfo;
  90 class fieldDescriptor;
  91 class DepChange;
  92 class nmethodBucket;
  93 class PreviousVersionNode;
  94 class JvmtiCachedClassFieldMap;
  95 
  96 // This is used in iterators below.
  97 class FieldClosure: public StackObj {
  98 public:
  99   virtual void do_field(fieldDescriptor* fd) = 0;
 100 };
 101 
 102 #ifndef PRODUCT
 103 // Print fields.
 104 // If "obj" argument to constructor is NULL, prints static fields, otherwise prints non-static fields.
 105 class FieldPrinter: public FieldClosure {
 106    oop _obj;
 107    outputStream* _st;
 108  public:
 109    FieldPrinter(outputStream* st, oop obj = NULL) : _obj(obj), _st(st) {}
 110    void do_field(fieldDescriptor* fd);
 111 };
 112 #endif  // !PRODUCT
 113 
 114 // ValueObjs embedded in klass. Describes where oops are located in instances of
 115 // this klass.
 116 class OopMapBlock VALUE_OBJ_CLASS_SPEC {
 117  public:
 118   // Byte offset of the first oop mapped by this block.
 119   int offset() const          { return _offset; }
 120   void set_offset(int offset) { _offset = offset; }
 121 
 122   // Number of oops in this block.
 123   uint count() const         { return _count; }
 124   void set_count(uint count) { _count = count; }
 125 
 126   // sizeof(OopMapBlock) in HeapWords.
 127   static const int size_in_words() {
 128     return align_size_up(int(sizeof(OopMapBlock)), HeapWordSize) >>
 129       LogHeapWordSize;
 130   }
 131 
 132  private:
 133   int  _offset;
 134   uint _count;
 135 };
 136 
 137 class instanceKlass: public Klass {
 138   friend class VMStructs;
 139  public:
 140   // See "The Java Virtual Machine Specification" section 2.16.2-5 for a detailed description
 141   // of the class loading & initialization procedure, and the use of the states.
 142   enum ClassState {
 143     unparsable_by_gc = 0,               // object is not yet parsable by gc. Value of _init_state at object allocation.
 144     allocated,                          // allocated (but not yet linked)
 145     loaded,                             // loaded and inserted in class hierarchy (but not linked yet)
 146     linked,                             // successfully linked/verified (but not initialized yet)
 147     being_initialized,                  // currently running class initializer
 148     fully_initialized,                  // initialized (successfull final state)
 149     initialization_error                // error happened during initialization
 150   };
 151 
 152  public:
 153   oop* oop_block_beg() const { return adr_array_klasses(); }
 154   oop* oop_block_end() const { return adr_methods_default_annotations() + 1; }
 155 
 156   enum {
 157     implementors_limit = 2              // how many implems can we track?
 158   };
 159 
 160  protected:
 161   //
 162   // The oop block.  See comment in klass.hpp before making changes.
 163   //
 164 
 165   // Array classes holding elements of this class.
 166   klassOop        _array_klasses;
 167   // Method array.
 168   objArrayOop     _methods;
 169   // Int array containing the original order of method in the class file (for
 170   // JVMTI).
 171   typeArrayOop    _method_ordering;
 172   // Interface (klassOops) this class declares locally to implement.
 173   objArrayOop     _local_interfaces;
 174   // Interface (klassOops) this class implements transitively.
 175   objArrayOop     _transitive_interfaces;
 176   // Instance and static variable information, 5-tuples of shorts [access, name
 177   // index, sig index, initval index, offset].
 178   typeArrayOop    _fields;
 179   // Constant pool for this class.
 180   constantPoolOop _constants;
 181   // Class loader used to load this class, NULL if VM loader used.
 182   oop             _class_loader;
 183   // Protection domain.
 184   oop             _protection_domain;
 185   // Host class, which grants its access privileges to this class also.
 186   // This is only non-null for an anonymous class (JSR 292 enabled).
 187   // The host class is either named, or a previously loaded anonymous class.
 188   klassOop        _host_klass;
 189   // Class signers.
 190   objArrayOop     _signers;
 191   // The InnerClasses attribute and EnclosingMethod attribute. The 
 192   // _inner_classes is an array of shorts. If the class has InnerClasses 
 193   // attribute, then the _inner_classes array begins with 4-tuples of shorts
 194   // [inner_class_info_index, outer_class_info_index,
 195   // inner_name_index, inner_class_access_flags] for the InnerClasses
 196   // attribute. If the EnclosingMethod attribute exists, it occupies the
 197   // last two shorts [class_index, method_index] of the array. If only
 198   // the InnerClasses attribute exists, the _inner_classes array length is
 199   // number_of_inner_classes * 4. If the class has both InnerClasses 
 200   // and EnclosingMethod attributes the _inner_classes array length is 
 201   // number_of_inner_classes * 4 + enclosing_method_attribute_size.
 202   typeArrayOop    _inner_classes;
 203   // Implementors of this interface (not valid if it overflows)
 204   klassOop        _implementors[implementors_limit];
 205   // Annotations for this class, or null if none.
 206   typeArrayOop    _class_annotations;
 207   // Annotation objects (byte arrays) for fields, or null if no annotations.
 208   // Indices correspond to entries (not indices) in fields array.
 209   objArrayOop     _fields_annotations;
 210   // Annotation objects (byte arrays) for methods, or null if no annotations.
 211   // Index is the idnum, which is initially the same as the methods array index.
 212   objArrayOop     _methods_annotations;
 213   // Annotation objects (byte arrays) for methods' parameters, or null if no
 214   // such annotations.
 215   // Index is the idnum, which is initially the same as the methods array index.
 216   objArrayOop     _methods_parameter_annotations;
 217   // Annotation objects (byte arrays) for methods' default values, or null if no
 218   // such annotations.
 219   // Index is the idnum, which is initially the same as the methods array index.
 220   objArrayOop     _methods_default_annotations;
 221 
 222   //
 223   // End of the oop block.
 224   //
 225 
 226   // Name of source file containing this klass, NULL if not specified.
 227   Symbol*         _source_file_name;
 228   // the source debug extension for this klass, NULL if not specified.
 229   Symbol*         _source_debug_extension;
 230   // Generic signature, or null if none.
 231   Symbol*         _generic_signature;
 232   // Array name derived from this class which needs unreferencing
 233   // if this class is unloaded.
 234   Symbol*         _array_name;
 235 
 236   // Number of heapOopSize words used by non-static fields in this klass
 237   // (including inherited fields but after header_size()).
 238   int             _nonstatic_field_size;
 239   int             _static_field_size;    // number words used by static fields (oop and non-oop) in this klass
 240   u2              _static_oop_field_count;// number of static oop fields in this klass
 241   u2              _java_fields_count;    // The number of declared Java fields
 242   int             _nonstatic_oop_map_size;// size in words of nonstatic oop map blocks
 243 
 244   bool            _is_marked_dependent;  // used for marking during flushing and deoptimization
 245   bool            _rewritten;            // methods rewritten.
 246   bool            _has_nonstatic_fields; // for sizing with UseCompressedOops
 247   bool            _should_verify_class;  // allow caching of preverification
 248   u2              _minor_version;        // minor version number of class file
 249   u2              _major_version;        // major version number of class file
 250   Thread*         _init_thread;          // Pointer to current thread doing initialization (to handle recusive initialization)
 251   int             _vtable_len;           // length of Java vtable (in words)
 252   int             _itable_len;           // length of Java itable (in words)
 253   OopMapCache*    volatile _oop_map_cache;   // OopMapCache for all methods in the klass (allocated lazily)
 254   JNIid*          _jni_ids;              // First JNI identifier for static fields in this class
 255   jmethodID*      _methods_jmethod_ids;  // jmethodIDs corresponding to method_idnum, or NULL if none
 256   int*            _methods_cached_itable_indices;  // itable_index cache for JNI invoke corresponding to methods idnum, or NULL
 257   nmethodBucket*  _dependencies;         // list of dependent nmethods
 258   nmethod*        _osr_nmethods_head;    // Head of list of on-stack replacement nmethods for this class
 259   BreakpointInfo* _breakpoints;          // bpt lists, managed by methodOop
 260   int             _nof_implementors;     // No of implementors of this interface (zero if not an interface)
 261   // Array of interesting part(s) of the previous version(s) of this
 262   // instanceKlass. See PreviousVersionWalker below.
 263   GrowableArray<PreviousVersionNode *>* _previous_versions;
 264   // JVMTI fields can be moved to their own structure - see 6315920
 265   unsigned char * _cached_class_file_bytes;       // JVMTI: cached class file, before retransformable agent modified it in CFLH
 266   jint            _cached_class_file_len;         // JVMTI: length of above
 267   JvmtiCachedClassFieldMap* _jvmti_cached_class_field_map;  // JVMTI: used during heap iteration
 268   volatile u2     _idnum_allocated_count;         // JNI/JVMTI: increments with the addition of methods, old ids don't change
 269 
 270   // Class states are defined as ClassState (see above).
 271   // Place the _init_state here to utilize the unused 2-byte after
 272   // _idnum_allocated_count.
 273   u1              _init_state;                    // state of class
 274 
 275   u1              _reference_type;                // reference type
 276 
 277   // embedded Java vtable follows here
 278   // embedded Java itables follows here
 279   // embedded static fields follows here
 280   // embedded nonstatic oop-map blocks follows here
 281 
 282   friend class instanceKlassKlass;
 283   friend class SystemDictionary;
 284 
 285  public:
 286   bool has_nonstatic_fields() const        { return _has_nonstatic_fields; }
 287   void set_has_nonstatic_fields(bool b)    { _has_nonstatic_fields = b; }
 288 
 289   // field sizes
 290   int nonstatic_field_size() const         { return _nonstatic_field_size; }
 291   void set_nonstatic_field_size(int size)  { _nonstatic_field_size = size; }
 292 
 293   int static_field_size() const            { return _static_field_size; }
 294   void set_static_field_size(int size)     { _static_field_size = size; }
 295 
 296   int static_oop_field_count() const       { return (int)_static_oop_field_count; }
 297   void set_static_oop_field_count(u2 size) { _static_oop_field_count = size; }
 298 
 299   // Java vtable
 300   int  vtable_length() const               { return _vtable_len; }
 301   void set_vtable_length(int len)          { _vtable_len = len; }
 302 
 303   // Java itable
 304   int  itable_length() const               { return _itable_len; }
 305   void set_itable_length(int len)          { _itable_len = len; }
 306 
 307   // array klasses
 308   klassOop array_klasses() const           { return _array_klasses; }
 309   void set_array_klasses(klassOop k)       { oop_store_without_check((oop*) &_array_klasses, (oop) k); }
 310 
 311   // methods
 312   objArrayOop methods() const              { return _methods; }
 313   void set_methods(objArrayOop a)          { oop_store_without_check((oop*) &_methods, (oop) a); }
 314   methodOop method_with_idnum(int idnum);
 315 
 316   // method ordering
 317   typeArrayOop method_ordering() const     { return _method_ordering; }
 318   void set_method_ordering(typeArrayOop m) { oop_store_without_check((oop*) &_method_ordering, (oop) m); }
 319 
 320   // interfaces
 321   objArrayOop local_interfaces() const          { return _local_interfaces; }
 322   void set_local_interfaces(objArrayOop a)      { oop_store_without_check((oop*) &_local_interfaces, (oop) a); }
 323   objArrayOop transitive_interfaces() const     { return _transitive_interfaces; }
 324   void set_transitive_interfaces(objArrayOop a) { oop_store_without_check((oop*) &_transitive_interfaces, (oop) a); }
 325 
 326  private:
 327   friend class fieldDescriptor;
 328   FieldInfo* field(int index) const { return FieldInfo::from_field_array(_fields, index); }
 329 
 330  public:
 331   int     field_offset      (int index) const { return field(index)->offset(); }
 332   int     field_access_flags(int index) const { return field(index)->access_flags(); }
 333   Symbol* field_name        (int index) const { return field(index)->name(constants()); }
 334   Symbol* field_signature   (int index) const { return field(index)->signature(constants()); }
 335 
 336   // Number of Java declared fields
 337   int java_fields_count() const           { return (int)_java_fields_count; }
 338 
 339   // Number of fields including any injected fields
 340   int all_fields_count() const            { return _fields->length() / sizeof(FieldInfo::field_slots); }
 341 
 342   typeArrayOop fields() const              { return _fields; }
 343 
 344   void set_fields(typeArrayOop f, u2 java_fields_count) {
 345     oop_store_without_check((oop*) &_fields, (oop) f);
 346     _java_fields_count = java_fields_count;
 347   }
 348 
 349   // inner classes
 350   typeArrayOop inner_classes() const       { return _inner_classes; }
 351   void set_inner_classes(typeArrayOop f)   { oop_store_without_check((oop*) &_inner_classes, (oop) f); }
 352 
 353   enum InnerClassAttributeOffset {
 354     // From http://mirror.eng/products/jdk/1.1/docs/guide/innerclasses/spec/innerclasses.doc10.html#18814
 355     inner_class_inner_class_info_offset = 0,
 356     inner_class_outer_class_info_offset = 1,
 357     inner_class_inner_name_offset = 2,
 358     inner_class_access_flags_offset = 3,
 359     inner_class_next_offset = 4
 360   };
 361 
 362   enum EnclosingMethodAttributeOffset {
 363     enclosing_method_class_index_offset = 0,
 364     enclosing_method_method_index_offset = 1,
 365     enclosing_method_attribute_size = 2
 366   };
 367 
 368   // method override check
 369   bool is_override(methodHandle super_method, Handle targetclassloader, Symbol* targetclassname, TRAPS);
 370 
 371   // package
 372   bool is_same_class_package(klassOop class2);
 373   bool is_same_class_package(oop classloader2, Symbol* classname2);
 374   static bool is_same_class_package(oop class_loader1, Symbol* class_name1, oop class_loader2, Symbol* class_name2);
 375 
 376   // find an enclosing class (defined where original code was, in jvm.cpp!)
 377   klassOop compute_enclosing_class(bool* inner_is_member, TRAPS) {
 378     instanceKlassHandle self(THREAD, this->as_klassOop());
 379     return compute_enclosing_class_impl(self, inner_is_member, THREAD);
 380   }
 381   static klassOop compute_enclosing_class_impl(instanceKlassHandle self,
 382                                                bool* inner_is_member, TRAPS);
 383 
 384   // tell if two classes have the same enclosing class (at package level)
 385   bool is_same_package_member(klassOop class2, TRAPS) {
 386     instanceKlassHandle self(THREAD, this->as_klassOop());
 387     return is_same_package_member_impl(self, class2, THREAD);
 388   }
 389   static bool is_same_package_member_impl(instanceKlassHandle self,
 390                                           klassOop class2, TRAPS);
 391 
 392   // initialization state
 393   bool is_loaded() const                   { return _init_state >= loaded; }
 394   bool is_linked() const                   { return _init_state >= linked; }
 395   bool is_initialized() const              { return _init_state == fully_initialized; }
 396   bool is_not_initialized() const          { return _init_state <  being_initialized; }
 397   bool is_being_initialized() const        { return _init_state == being_initialized; }
 398   bool is_in_error_state() const           { return _init_state == initialization_error; }
 399   bool is_reentrant_initialization(Thread *thread)  { return thread == _init_thread; }
 400   ClassState  init_state()                 { return (ClassState)_init_state; }
 401   bool is_rewritten() const                { return _rewritten; }
 402 
 403   // defineClass specified verification
 404   bool should_verify_class() const         { return _should_verify_class; }
 405   void set_should_verify_class(bool value) { _should_verify_class = value; }
 406 
 407   // marking
 408   bool is_marked_dependent() const         { return _is_marked_dependent; }
 409   void set_is_marked_dependent(bool value) { _is_marked_dependent = value; }
 410 
 411   // initialization (virtuals from Klass)
 412   bool should_be_initialized() const;  // means that initialize should be called
 413   void initialize(TRAPS);
 414   void link_class(TRAPS);
 415   bool link_class_or_fail(TRAPS); // returns false on failure
 416   void unlink_class();
 417   void rewrite_class(TRAPS);
 418   void relocate_and_link_methods(TRAPS);
 419   methodOop class_initializer();
 420 
 421   // set the class to initialized if no static initializer is present
 422   void eager_initialize(Thread *thread);
 423 
 424   // reference type
 425   ReferenceType reference_type() const     { return (ReferenceType)_reference_type; }
 426   void set_reference_type(ReferenceType t) {
 427     assert(t == (u1)t, "overflow");
 428     _reference_type = (u1)t;
 429   }
 430 
 431   static ByteSize reference_type_offset() { return in_ByteSize(sizeof(klassOopDesc) + offset_of(instanceKlass, _reference_type)); }
 432 
 433   // find local field, returns true if found
 434   bool find_local_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;
 435   // find field in direct superinterfaces, returns the interface in which the field is defined
 436   klassOop find_interface_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;
 437   // find field according to JVM spec 5.4.3.2, returns the klass in which the field is defined
 438   klassOop find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;
 439   // find instance or static fields according to JVM spec 5.4.3.2, returns the klass in which the field is defined
 440   klassOop find_field(Symbol* name, Symbol* sig, bool is_static, fieldDescriptor* fd) const;
 441 
 442   // find a non-static or static field given its offset within the class.
 443   bool contains_field_offset(int offset) {
 444     return instanceOopDesc::contains_field_offset(offset, nonstatic_field_size());
 445   }
 446 
 447   bool find_local_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const;
 448   bool find_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const;
 449 
 450   // find a local method (returns NULL if not found)
 451   methodOop find_method(Symbol* name, Symbol* signature) const;
 452   static methodOop find_method(objArrayOop methods, Symbol* name, Symbol* signature);
 453 
 454   // lookup operation (returns NULL if not found)
 455   methodOop uncached_lookup_method(Symbol* name, Symbol* signature) const;
 456 
 457   // lookup a method in all the interfaces that this class implements
 458   // (returns NULL if not found)
 459   methodOop lookup_method_in_all_interfaces(Symbol* name, Symbol* signature) const;
 460 
 461   // constant pool
 462   constantPoolOop constants() const        { return _constants; }
 463   void set_constants(constantPoolOop c)    { oop_store_without_check((oop*) &_constants, (oop) c); }
 464 
 465   // class loader
 466   oop class_loader() const                 { return _class_loader; }
 467   void set_class_loader(oop l)             { oop_store((oop*) &_class_loader, l); }
 468 
 469   // protection domain
 470   oop protection_domain()                  { return _protection_domain; }
 471   void set_protection_domain(oop pd)       { oop_store((oop*) &_protection_domain, pd); }
 472 
 473   // host class
 474   oop host_klass() const                   { return _host_klass; }
 475   void set_host_klass(oop host)            { oop_store((oop*) &_host_klass, host); }
 476   bool is_anonymous() const                { return _host_klass != NULL; }
 477 
 478   // signers
 479   objArrayOop signers() const              { return _signers; }
 480   void set_signers(objArrayOop s)          { oop_store((oop*) &_signers, oop(s)); }
 481 
 482   // source file name
 483   Symbol* source_file_name() const         { return _source_file_name; }
 484   void set_source_file_name(Symbol* n);
 485 
 486   // minor and major version numbers of class file
 487   u2 minor_version() const                 { return _minor_version; }
 488   void set_minor_version(u2 minor_version) { _minor_version = minor_version; }
 489   u2 major_version() const                 { return _major_version; }
 490   void set_major_version(u2 major_version) { _major_version = major_version; }
 491 
 492   // source debug extension
 493   Symbol* source_debug_extension() const   { return _source_debug_extension; }
 494   void set_source_debug_extension(Symbol* n);
 495 
 496   // symbol unloading support (refcount already added)
 497   Symbol* array_name()                     { return _array_name; }
 498   void set_array_name(Symbol* name)        { assert(_array_name == NULL, "name already created"); _array_name = name; }
 499 
 500   // nonstatic oop-map blocks
 501   static int nonstatic_oop_map_size(unsigned int oop_map_count) {
 502     return oop_map_count * OopMapBlock::size_in_words();
 503   }
 504   unsigned int nonstatic_oop_map_count() const {
 505     return _nonstatic_oop_map_size / OopMapBlock::size_in_words();
 506   }
 507   int nonstatic_oop_map_size() const { return _nonstatic_oop_map_size; }
 508   void set_nonstatic_oop_map_size(int words) {
 509     _nonstatic_oop_map_size = words;
 510   }
 511 
 512   // RedefineClasses() support for previous versions:
 513   void add_previous_version(instanceKlassHandle ikh, BitMap *emcp_methods,
 514          int emcp_method_count);
 515   // If the _previous_versions array is non-NULL, then this klass
 516   // has been redefined at least once even if we aren't currently
 517   // tracking a previous version.
 518   bool has_been_redefined() const { return _previous_versions != NULL; }
 519   bool has_previous_version() const;
 520   void init_previous_versions() {
 521     _previous_versions = NULL;
 522   }
 523   GrowableArray<PreviousVersionNode *>* previous_versions() const {
 524     return _previous_versions;
 525   }
 526 
 527   // JVMTI: Support for caching a class file before it is modified by an agent that can do retransformation
 528   void set_cached_class_file(unsigned char *class_file_bytes,
 529                              jint class_file_len)     { _cached_class_file_len = class_file_len;
 530                                                         _cached_class_file_bytes = class_file_bytes; }
 531   jint get_cached_class_file_len()                    { return _cached_class_file_len; }
 532   unsigned char * get_cached_class_file_bytes()       { return _cached_class_file_bytes; }
 533 
 534   // JVMTI: Support for caching of field indices, types, and offsets
 535   void set_jvmti_cached_class_field_map(JvmtiCachedClassFieldMap* descriptor) {
 536     _jvmti_cached_class_field_map = descriptor;
 537   }
 538   JvmtiCachedClassFieldMap* jvmti_cached_class_field_map() const {
 539     return _jvmti_cached_class_field_map;
 540   }
 541 
 542   // for adding methods, constMethodOopDesc::UNSET_IDNUM means no more ids available
 543   inline u2 next_method_idnum();
 544   void set_initial_method_idnum(u2 value)             { _idnum_allocated_count = value; }
 545 
 546   // generics support
 547   Symbol* generic_signature() const                   { return _generic_signature; }
 548   void set_generic_signature(Symbol* sig)             { _generic_signature = sig; }
 549 
 550   u2 enclosing_method_data(int offset);
 551   u2 enclosing_method_class_index() {
 552     return enclosing_method_data(enclosing_method_class_index_offset);
 553   }
 554   u2 enclosing_method_method_index() {
 555     return enclosing_method_data(enclosing_method_method_index_offset);
 556   }
 557   void set_enclosing_method_indices(u2 class_index,
 558                                     u2 method_index);
 559 
 560   // jmethodID support
 561   static jmethodID get_jmethod_id(instanceKlassHandle ik_h,
 562                      methodHandle method_h);
 563   static jmethodID get_jmethod_id_fetch_or_update(instanceKlassHandle ik_h,
 564                      size_t idnum, jmethodID new_id, jmethodID* new_jmeths,
 565                      jmethodID* to_dealloc_id_p,
 566                      jmethodID** to_dealloc_jmeths_p);
 567   static void get_jmethod_id_length_value(jmethodID* cache, size_t idnum,
 568                 size_t *length_p, jmethodID* id_p);
 569   jmethodID jmethod_id_or_null(methodOop method);
 570 
 571   // cached itable index support
 572   void set_cached_itable_index(size_t idnum, int index);
 573   int cached_itable_index(size_t idnum);
 574 
 575   // annotations support
 576   typeArrayOop class_annotations() const              { return _class_annotations; }
 577   objArrayOop fields_annotations() const              { return _fields_annotations; }
 578   objArrayOop methods_annotations() const             { return _methods_annotations; }
 579   objArrayOop methods_parameter_annotations() const   { return _methods_parameter_annotations; }
 580   objArrayOop methods_default_annotations() const     { return _methods_default_annotations; }
 581   void set_class_annotations(typeArrayOop md)            { oop_store_without_check((oop*)&_class_annotations, (oop)md); }
 582   void set_fields_annotations(objArrayOop md)            { set_annotations(md, &_fields_annotations); }
 583   void set_methods_annotations(objArrayOop md)           { set_annotations(md, &_methods_annotations); }
 584   void set_methods_parameter_annotations(objArrayOop md) { set_annotations(md, &_methods_parameter_annotations); }
 585   void set_methods_default_annotations(objArrayOop md)   { set_annotations(md, &_methods_default_annotations); }
 586   typeArrayOop get_method_annotations_of(int idnum)
 587                                                 { return get_method_annotations_from(idnum, _methods_annotations); }
 588   typeArrayOop get_method_parameter_annotations_of(int idnum)
 589                                                 { return get_method_annotations_from(idnum, _methods_parameter_annotations); }
 590   typeArrayOop get_method_default_annotations_of(int idnum)
 591                                                 { return get_method_annotations_from(idnum, _methods_default_annotations); }
 592   void set_method_annotations_of(int idnum, typeArrayOop anno)
 593                                                 { set_methods_annotations_of(idnum, anno, &_methods_annotations); }
 594   void set_method_parameter_annotations_of(int idnum, typeArrayOop anno)
 595                                                 { set_methods_annotations_of(idnum, anno, &_methods_parameter_annotations); }
 596   void set_method_default_annotations_of(int idnum, typeArrayOop anno)
 597                                                 { set_methods_annotations_of(idnum, anno, &_methods_default_annotations); }
 598 
 599   // allocation
 600   DEFINE_ALLOCATE_PERMANENT(instanceKlass);
 601   instanceOop allocate_instance(TRAPS);
 602   instanceOop allocate_permanent_instance(TRAPS);
 603 
 604   // additional member function to return a handle
 605   instanceHandle allocate_instance_handle(TRAPS)      { return instanceHandle(THREAD, allocate_instance(THREAD)); }
 606 
 607   objArrayOop allocate_objArray(int n, int length, TRAPS);
 608   // Helper function
 609   static instanceOop register_finalizer(instanceOop i, TRAPS);
 610 
 611   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
 612   // if not, throw either an Error or an Exception.
 613   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
 614 
 615   // initialization
 616   void call_class_initializer(TRAPS);
 617   void set_initialization_state_and_notify(ClassState state, TRAPS);
 618 
 619   // OopMapCache support
 620   OopMapCache* oop_map_cache()               { return _oop_map_cache; }
 621   void set_oop_map_cache(OopMapCache *cache) { _oop_map_cache = cache; }
 622   void mask_for(methodHandle method, int bci, InterpreterOopMap* entry);
 623 
 624   // JNI identifier support (for static fields - for jni performance)
 625   JNIid* jni_ids()                               { return _jni_ids; }
 626   void set_jni_ids(JNIid* ids)                   { _jni_ids = ids; }
 627   JNIid* jni_id_for(int offset);
 628 
 629   // maintenance of deoptimization dependencies
 630   int mark_dependent_nmethods(DepChange& changes);
 631   void add_dependent_nmethod(nmethod* nm);
 632   void remove_dependent_nmethod(nmethod* nm);
 633 
 634   // On-stack replacement support
 635   nmethod* osr_nmethods_head() const         { return _osr_nmethods_head; };
 636   void set_osr_nmethods_head(nmethod* h)     { _osr_nmethods_head = h; };
 637   void add_osr_nmethod(nmethod* n);
 638   void remove_osr_nmethod(nmethod* n);
 639   nmethod* lookup_osr_nmethod(const methodOop m, int bci, int level, bool match_level) const;
 640 
 641   // Breakpoint support (see methods on methodOop for details)
 642   BreakpointInfo* breakpoints() const       { return _breakpoints; };
 643   void set_breakpoints(BreakpointInfo* bps) { _breakpoints = bps; };
 644 
 645   // support for stub routines
 646   static ByteSize init_state_offset()  { return in_ByteSize(sizeof(klassOopDesc) + offset_of(instanceKlass, _init_state)); }
 647   static ByteSize init_thread_offset() { return in_ByteSize(sizeof(klassOopDesc) + offset_of(instanceKlass, _init_thread)); }
 648 
 649   // subclass/subinterface checks
 650   bool implements_interface(klassOop k) const;
 651 
 652   // Access to implementors of an interface. We only store the count
 653   // of implementors, and in case, there are only a few
 654   // implementors, we store them in a short list.
 655   // This accessor returns NULL if we walk off the end of the list.
 656   klassOop implementor(int i) const {
 657     return (i < implementors_limit)? _implementors[i]: (klassOop) NULL;
 658   }
 659   int  nof_implementors() const       { return _nof_implementors; }
 660   void add_implementor(klassOop k);  // k is a new class that implements this interface
 661   void init_implementor();           // initialize
 662 
 663   // link this class into the implementors list of every interface it implements
 664   void process_interfaces(Thread *thread);
 665 
 666   // virtual operations from Klass
 667   bool is_leaf_class() const               { return _subklass == NULL; }
 668   objArrayOop compute_secondary_supers(int num_extra_slots, TRAPS);
 669   bool compute_is_subtype_of(klassOop k);
 670   bool can_be_primary_super_slow() const;
 671   klassOop java_super() const              { return super(); }
 672   int oop_size(oop obj)  const             { return size_helper(); }
 673   int klass_oop_size() const               { return object_size(); }
 674   bool oop_is_instance_slow() const        { return true; }
 675 
 676   // Iterators
 677   void do_local_static_fields(FieldClosure* cl);
 678   void do_nonstatic_fields(FieldClosure* cl); // including inherited fields
 679   void do_local_static_fields(void f(fieldDescriptor*, TRAPS), TRAPS);
 680 
 681   void methods_do(void f(methodOop method));
 682   void array_klasses_do(void f(klassOop k));
 683   void with_array_klasses_do(void f(klassOop k));
 684   bool super_types_do(SuperTypeClosure* blk);
 685 
 686   // Casting from klassOop
 687   static instanceKlass* cast(klassOop k) {
 688     assert(k->is_klass(), "must be");
 689     Klass* kp = k->klass_part();
 690     assert(kp->null_vtbl() || kp->oop_is_instance_slow(), "cast to instanceKlass");
 691     return (instanceKlass*) kp;
 692   }
 693 
 694   // Sizing (in words)
 695   static int header_size()            { return align_object_offset(oopDesc::header_size() + sizeof(instanceKlass)/HeapWordSize); }
 696   int object_size() const             { return object_size(align_object_offset(vtable_length()) + align_object_offset(itable_length()) + nonstatic_oop_map_size()); }
 697   static int vtable_start_offset()    { return header_size(); }
 698   static int vtable_length_offset()   { return oopDesc::header_size() + offset_of(instanceKlass, _vtable_len) / HeapWordSize; }
 699   static int object_size(int extra)   { return align_object_size(header_size() + extra); }
 700 
 701   intptr_t* start_of_vtable() const        { return ((intptr_t*)as_klassOop()) + vtable_start_offset(); }
 702   intptr_t* start_of_itable() const        { return start_of_vtable() + align_object_offset(vtable_length()); }
 703   int  itable_offset_in_words() const { return start_of_itable() - (intptr_t*)as_klassOop(); }
 704 
 705   intptr_t* end_of_itable() const          { return start_of_itable() + itable_length(); }
 706 
 707   address static_field_addr(int offset);
 708 
 709   OopMapBlock* start_of_nonstatic_oop_maps() const {
 710     return (OopMapBlock*)(start_of_itable() + align_object_offset(itable_length()));
 711   }
 712 
 713   // Allocation profiling support
 714   juint alloc_size() const            { return _alloc_count * size_helper(); }
 715   void set_alloc_size(juint n)        {}
 716 
 717   // Use this to return the size of an instance in heap words:
 718   int size_helper() const {
 719     return layout_helper_to_size_helper(layout_helper());
 720   }
 721 
 722   // This bit is initialized in classFileParser.cpp.
 723   // It is false under any of the following conditions:
 724   //  - the class is abstract (including any interface)
 725   //  - the class has a finalizer (if !RegisterFinalizersAtInit)
 726   //  - the class size is larger than FastAllocateSizeLimit
 727   //  - the class is java/lang/Class, which cannot be allocated directly
 728   bool can_be_fastpath_allocated() const {
 729     return !layout_helper_needs_slow_path(layout_helper());
 730   }
 731 
 732   // Java vtable/itable
 733   klassVtable* vtable() const;        // return new klassVtable wrapper
 734   inline methodOop method_at_vtable(int index);
 735   klassItable* itable() const;        // return new klassItable wrapper
 736   methodOop method_at_itable(klassOop holder, int index, TRAPS);
 737 
 738   // Garbage collection
 739   void oop_follow_contents(oop obj);
 740   int  oop_adjust_pointers(oop obj);
 741   bool object_is_parsable() const { return _init_state != unparsable_by_gc; }
 742        // Value of _init_state must be zero (unparsable_by_gc) when klass field is set.
 743 
 744   void follow_weak_klass_links(
 745     BoolObjectClosure* is_alive, OopClosure* keep_alive);
 746   void release_C_heap_structures();
 747 
 748   // Parallel Scavenge and Parallel Old
 749   PARALLEL_GC_DECLS
 750 
 751   // Naming
 752   const char* signature_name() const;
 753 
 754   // Iterators
 755   int oop_oop_iterate(oop obj, OopClosure* blk) {
 756     return oop_oop_iterate_v(obj, blk);
 757   }
 758 
 759   int oop_oop_iterate_m(oop obj, OopClosure* blk, MemRegion mr) {
 760     return oop_oop_iterate_v_m(obj, blk, mr);
 761   }
 762 
 763 #define InstanceKlass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)      \
 764   int  oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk);           \
 765   int  oop_oop_iterate##nv_suffix##_m(oop obj, OopClosureType* blk,        \
 766                                       MemRegion mr);
 767 
 768   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_DECL)
 769   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_DECL)
 770 
 771 #ifndef SERIALGC
 772 #define InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
 773   int  oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* blk);
 774 
 775   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 776   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 777 #endif // !SERIALGC
 778 
 779 private:
 780   // initialization state
 781 #ifdef ASSERT
 782   void set_init_state(ClassState state);
 783 #else
 784   void set_init_state(ClassState state) { _init_state = (u1)state; }
 785 #endif
 786   void set_rewritten()                  { _rewritten = true; }
 787   void set_init_thread(Thread *thread)  { _init_thread = thread; }
 788 
 789   u2 idnum_allocated_count() const      { return _idnum_allocated_count; }
 790   // The RedefineClasses() API can cause new method idnums to be needed
 791   // which will cause the caches to grow. Safety requires different
 792   // cache management logic if the caches can grow instead of just
 793   // going from NULL to non-NULL.
 794   bool idnum_can_increment() const      { return has_been_redefined(); }
 795   jmethodID* methods_jmethod_ids_acquire() const
 796          { return (jmethodID*)OrderAccess::load_ptr_acquire(&_methods_jmethod_ids); }
 797   void release_set_methods_jmethod_ids(jmethodID* jmeths)
 798          { OrderAccess::release_store_ptr(&_methods_jmethod_ids, jmeths); }
 799 
 800   int* methods_cached_itable_indices_acquire() const
 801          { return (int*)OrderAccess::load_ptr_acquire(&_methods_cached_itable_indices); }
 802   void release_set_methods_cached_itable_indices(int* indices)
 803          { OrderAccess::release_store_ptr(&_methods_cached_itable_indices, indices); }
 804 
 805   inline typeArrayOop get_method_annotations_from(int idnum, objArrayOop annos);
 806   void set_annotations(objArrayOop md, objArrayOop* md_p)  { oop_store_without_check((oop*)md_p, (oop)md); }
 807   void set_methods_annotations_of(int idnum, typeArrayOop anno, objArrayOop* md_p);
 808 
 809   // Offsets for memory management
 810   oop* adr_array_klasses() const     { return (oop*)&this->_array_klasses;}
 811   oop* adr_methods() const           { return (oop*)&this->_methods;}
 812   oop* adr_method_ordering() const   { return (oop*)&this->_method_ordering;}
 813   oop* adr_local_interfaces() const  { return (oop*)&this->_local_interfaces;}
 814   oop* adr_transitive_interfaces() const  { return (oop*)&this->_transitive_interfaces;}
 815   oop* adr_fields() const            { return (oop*)&this->_fields;}
 816   oop* adr_constants() const         { return (oop*)&this->_constants;}
 817   oop* adr_class_loader() const      { return (oop*)&this->_class_loader;}
 818   oop* adr_protection_domain() const { return (oop*)&this->_protection_domain;}
 819   oop* adr_host_klass() const        { return (oop*)&this->_host_klass;}
 820   oop* adr_signers() const           { return (oop*)&this->_signers;}
 821   oop* adr_inner_classes() const     { return (oop*)&this->_inner_classes;}
 822   oop* adr_implementors() const      { return (oop*)&this->_implementors[0];}
 823   oop* adr_methods_jmethod_ids() const             { return (oop*)&this->_methods_jmethod_ids;}
 824   oop* adr_methods_cached_itable_indices() const   { return (oop*)&this->_methods_cached_itable_indices;}
 825   oop* adr_class_annotations() const   { return (oop*)&this->_class_annotations;}
 826   oop* adr_fields_annotations() const  { return (oop*)&this->_fields_annotations;}
 827   oop* adr_methods_annotations() const { return (oop*)&this->_methods_annotations;}
 828   oop* adr_methods_parameter_annotations() const { return (oop*)&this->_methods_parameter_annotations;}
 829   oop* adr_methods_default_annotations() const { return (oop*)&this->_methods_default_annotations;}
 830 
 831   // Static methods that are used to implement member methods where an exposed this pointer
 832   // is needed due to possible GCs
 833   static bool link_class_impl                           (instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS);
 834   static bool verify_code                               (instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS);
 835   static void initialize_impl                           (instanceKlassHandle this_oop, TRAPS);
 836   static void eager_initialize_impl                     (instanceKlassHandle this_oop);
 837   static void set_initialization_state_and_notify_impl  (instanceKlassHandle this_oop, ClassState state, TRAPS);
 838   static void call_class_initializer_impl               (instanceKlassHandle this_oop, TRAPS);
 839   static klassOop array_klass_impl                      (instanceKlassHandle this_oop, bool or_null, int n, TRAPS);
 840   static void do_local_static_fields_impl               (instanceKlassHandle this_oop, void f(fieldDescriptor* fd, TRAPS), TRAPS);
 841   /* jni_id_for_impl for jfieldID only */
 842   static JNIid* jni_id_for_impl                         (instanceKlassHandle this_oop, int offset);
 843 
 844   // Returns the array class for the n'th dimension
 845   klassOop array_klass_impl(bool or_null, int n, TRAPS);
 846 
 847   // Returns the array class with this class as element type
 848   klassOop array_klass_impl(bool or_null, TRAPS);
 849 
 850 public:
 851   // sharing support
 852   virtual void remove_unshareable_info();
 853   virtual void shared_symbols_iterate(SymbolClosure* closure);
 854 
 855   // jvm support
 856   jint compute_modifier_flags(TRAPS) const;
 857 
 858 public:
 859   // JVMTI support
 860   jint jvmti_class_status() const;
 861 
 862  public:
 863   // Printing
 864   void oop_print_value_on(oop obj, outputStream* st);
 865 #ifndef PRODUCT
 866   void oop_print_on      (oop obj, outputStream* st);
 867 
 868   void print_dependent_nmethods(bool verbose = false);
 869   bool is_dependent_nmethod(nmethod* nm);
 870 #endif
 871 
 872   // Verification
 873   const char* internal_name() const;
 874   void oop_verify_on(oop obj, outputStream* st);
 875 };
 876 
 877 inline methodOop instanceKlass::method_at_vtable(int index)  {
 878 #ifndef PRODUCT
 879   assert(index >= 0, "valid vtable index");
 880   if (DebugVtables) {
 881     verify_vtable_index(index);
 882   }
 883 #endif
 884   vtableEntry* ve = (vtableEntry*)start_of_vtable();
 885   return ve[index].method();
 886 }
 887 
 888 inline typeArrayOop instanceKlass::get_method_annotations_from(int idnum, objArrayOop annos) {
 889   if (annos == NULL || annos->length() <= idnum) {
 890     return NULL;
 891   }
 892   return typeArrayOop(annos->obj_at(idnum));
 893 }
 894 
 895 // for adding methods
 896 // UNSET_IDNUM return means no more ids available
 897 inline u2 instanceKlass::next_method_idnum() {
 898   if (_idnum_allocated_count == constMethodOopDesc::MAX_IDNUM) {
 899     return constMethodOopDesc::UNSET_IDNUM; // no more ids available
 900   } else {
 901     return _idnum_allocated_count++;
 902   }
 903 }
 904 
 905 
 906 /* JNIid class for jfieldIDs only */
 907 class JNIid: public CHeapObj {
 908   friend class VMStructs;
 909  private:
 910   klassOop           _holder;
 911   JNIid*             _next;
 912   int                _offset;
 913 #ifdef ASSERT
 914   bool               _is_static_field_id;
 915 #endif
 916 
 917  public:
 918   // Accessors
 919   klassOop holder() const         { return _holder; }
 920   int offset() const              { return _offset; }
 921   JNIid* next()                   { return _next; }
 922   // Constructor
 923   JNIid(klassOop holder, int offset, JNIid* next);
 924   // Identifier lookup
 925   JNIid* find(int offset);
 926 
 927   bool find_local_field(fieldDescriptor* fd) {
 928     return instanceKlass::cast(holder())->find_local_field_from_offset(offset(), true, fd);
 929   }
 930 
 931   // Garbage collection support
 932   oop* holder_addr() { return (oop*)&_holder; }
 933   void oops_do(OopClosure* f);
 934   static void deallocate(JNIid* id);
 935   // Debugging
 936 #ifdef ASSERT
 937   bool is_static_field_id() const { return _is_static_field_id; }
 938   void set_is_static_field_id()   { _is_static_field_id = true; }
 939 #endif
 940   void verify(klassOop holder);
 941 };
 942 
 943 
 944 // If breakpoints are more numerous than just JVMTI breakpoints,
 945 // consider compressing this data structure.
 946 // It is currently a simple linked list defined in methodOop.hpp.
 947 
 948 class BreakpointInfo;
 949 
 950 
 951 // A collection point for interesting information about the previous
 952 // version(s) of an instanceKlass. This class uses weak references to
 953 // the information so that the information may be collected as needed
 954 // by the system. If the information is shared, then a regular
 955 // reference must be used because a weak reference would be seen as
 956 // collectible. A GrowableArray of PreviousVersionNodes is attached
 957 // to the instanceKlass as needed. See PreviousVersionWalker below.
 958 class PreviousVersionNode : public CHeapObj {
 959  private:
 960   // A shared ConstantPool is never collected so we'll always have
 961   // a reference to it so we can update items in the cache. We'll
 962   // have a weak reference to a non-shared ConstantPool until all
 963   // of the methods (EMCP or obsolete) have been collected; the
 964   // non-shared ConstantPool becomes collectible at that point.
 965   jobject _prev_constant_pool;  // regular or weak reference
 966   bool    _prev_cp_is_weak;     // true if not a shared ConstantPool
 967 
 968   // If the previous version of the instanceKlass doesn't have any
 969   // EMCP methods, then _prev_EMCP_methods will be NULL. If all the
 970   // EMCP methods have been collected, then _prev_EMCP_methods can
 971   // have a length of zero.
 972   GrowableArray<jweak>* _prev_EMCP_methods;
 973 
 974 public:
 975   PreviousVersionNode(jobject prev_constant_pool, bool prev_cp_is_weak,
 976     GrowableArray<jweak>* prev_EMCP_methods);
 977   ~PreviousVersionNode();
 978   jobject prev_constant_pool() const {
 979     return _prev_constant_pool;
 980   }
 981   GrowableArray<jweak>* prev_EMCP_methods() const {
 982     return _prev_EMCP_methods;
 983   }
 984 };
 985 
 986 
 987 // A Handle-ized version of PreviousVersionNode.
 988 class PreviousVersionInfo : public ResourceObj {
 989  private:
 990   constantPoolHandle   _prev_constant_pool_handle;
 991   // If the previous version of the instanceKlass doesn't have any
 992   // EMCP methods, then _prev_EMCP_methods will be NULL. Since the
 993   // methods cannot be collected while we hold a handle,
 994   // _prev_EMCP_methods should never have a length of zero.
 995   GrowableArray<methodHandle>* _prev_EMCP_method_handles;
 996 
 997 public:
 998   PreviousVersionInfo(PreviousVersionNode *pv_node);
 999   ~PreviousVersionInfo();
1000   constantPoolHandle prev_constant_pool_handle() const {
1001     return _prev_constant_pool_handle;
1002   }
1003   GrowableArray<methodHandle>* prev_EMCP_method_handles() const {
1004     return _prev_EMCP_method_handles;
1005   }
1006 };
1007 
1008 
1009 // Helper object for walking previous versions. This helper cleans up
1010 // the Handles that it allocates when the helper object is destroyed.
1011 // The PreviousVersionInfo object returned by next_previous_version()
1012 // is only valid until a subsequent call to next_previous_version() or
1013 // the helper object is destroyed.
1014 class PreviousVersionWalker : public StackObj {
1015  private:
1016   GrowableArray<PreviousVersionNode *>* _previous_versions;
1017   int                                   _current_index;
1018   // Fields for cleaning up when we are done walking the previous versions:
1019   // A HandleMark for the PreviousVersionInfo handles:
1020   HandleMark                            _hm;
1021 
1022   // It would be nice to have a ResourceMark field in this helper also,
1023   // but the ResourceMark code says to be careful to delete handles held
1024   // in GrowableArrays _before_ deleting the GrowableArray. Since we
1025   // can't guarantee the order in which the fields are destroyed, we
1026   // have to let the creator of the PreviousVersionWalker object do
1027   // the right thing. Also, adding a ResourceMark here causes an
1028   // include loop.
1029 
1030   // A pointer to the current info object so we can handle the deletes.
1031   PreviousVersionInfo *                 _current_p;
1032 
1033  public:
1034   PreviousVersionWalker(instanceKlass *ik);
1035   ~PreviousVersionWalker();
1036 
1037   // Return the interesting information for the next previous version
1038   // of the klass. Returns NULL if there are no more previous versions.
1039   PreviousVersionInfo* next_previous_version();
1040 };
1041 
1042 
1043 //
1044 // nmethodBucket is used to record dependent nmethods for
1045 // deoptimization.  nmethod dependencies are actually <klass, method>
1046 // pairs but we really only care about the klass part for purposes of
1047 // finding nmethods which might need to be deoptimized.  Instead of
1048 // recording the method, a count of how many times a particular nmethod
1049 // was recorded is kept.  This ensures that any recording errors are
1050 // noticed since an nmethod should be removed as many times are it's
1051 // added.
1052 //
1053 class nmethodBucket: public CHeapObj {
1054   friend class VMStructs;
1055  private:
1056   nmethod*       _nmethod;
1057   int            _count;
1058   nmethodBucket* _next;
1059 
1060  public:
1061   nmethodBucket(nmethod* nmethod, nmethodBucket* next) {
1062     _nmethod = nmethod;
1063     _next = next;
1064     _count = 1;
1065   }
1066   int count()                             { return _count; }
1067   int increment()                         { _count += 1; return _count; }
1068   int decrement()                         { _count -= 1; assert(_count >= 0, "don't underflow"); return _count; }
1069   nmethodBucket* next()                   { return _next; }
1070   void set_next(nmethodBucket* b)         { _next = b; }
1071   nmethod* get_nmethod()                  { return _nmethod; }
1072 };
1073 
1074 #endif // SHARE_VM_OOPS_INSTANCEKLASS_HPP