1 /*
   2  * Copyright (c) 1997, 2013, 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_MEMORY_UNIVERSE_HPP
  26 #define SHARE_VM_MEMORY_UNIVERSE_HPP
  27 
  28 #include "runtime/handles.hpp"
  29 #include "utilities/array.hpp"
  30 #include "utilities/growableArray.hpp"
  31 
  32 // Universe is a name space holding known system classes and objects in the VM.
  33 //
  34 // Loaded classes are accessible through the SystemDictionary.
  35 //
  36 // The object heap is allocated and accessed through Universe, and various allocation
  37 // support is provided. Allocation by the interpreter and compiled code is done inline
  38 // and bails out to Scavenge::invoke_and_allocate.
  39 
  40 class CollectedHeap;
  41 class DeferredObjAllocEvent;
  42 
  43 
  44 // Common parts of a Method* cache. This cache safely interacts with
  45 // the RedefineClasses API.
  46 //
  47 class CommonMethodOopCache : public CHeapObj<mtClass> {
  48   // We save the Klass* and the idnum of Method* in order to get
  49   // the current cached Method*.
  50  private:
  51   Klass*                _klass;
  52   int                   _method_idnum;
  53 
  54  public:
  55   CommonMethodOopCache()   { _klass = NULL; _method_idnum = -1; }
  56   ~CommonMethodOopCache()  { _klass = NULL; _method_idnum = -1; }
  57 
  58   void     init(Klass* k, Method* m, TRAPS);
  59   Klass* klass() const         { return _klass; }
  60   int      method_idnum() const  { return _method_idnum; }
  61 
  62   // Enhanced Class Redefinition support
  63   void classes_do(void f(Klass*)) {
  64     f(_klass);
  65   }
  66 
  67   // CDS support.  Replace the klass in this with the archive version
  68   // could use this for Enhanced Class Redefinition also.
  69   void serialize(SerializeClosure* f) {
  70     f->do_ptr((void**)&_klass);
  71   }
  72 };
  73 
  74 
  75 // A helper class for caching a Method* when the user of the cache
  76 // cares about all versions of the Method*.
  77 //
  78 class ActiveMethodOopsCache : public CommonMethodOopCache {
  79   // This subclass adds weak references to older versions of the
  80   // Method* and a query method for a Method*.
  81 
  82  private:
  83   // If the cached Method* has not been redefined, then
  84   // _prev_methods will be NULL. If all of the previous
  85   // versions of the method have been collected, then
  86   // _prev_methods can have a length of zero.
  87   GrowableArray<Method*>* _prev_methods;
  88 
  89  public:
  90   ActiveMethodOopsCache()   { _prev_methods = NULL; }
  91   ~ActiveMethodOopsCache();
  92 
  93   void add_previous_version(Method* method);
  94   bool is_same_method(const Method* method) const;
  95 };
  96 
  97 
  98 // A helper class for caching a Method* when the user of the cache
  99 // only cares about the latest version of the Method*.
 100 //
 101 class LatestMethodOopCache : public CommonMethodOopCache {
 102   // This subclass adds a getter method for the latest Method*.
 103 
 104  public:
 105   Method* get_Method();
 106 };
 107 
 108 // For UseCompressedOops and UseCompressedKlassPointers.
 109 struct NarrowPtrStruct {
 110   // Base address for oop/klass-within-java-object materialization.
 111   // NULL if using wide oops/klasses or zero based narrow oops/klasses.
 112   address _base;
 113   // Number of shift bits for encoding/decoding narrow ptrs.
 114   // 0 if using wide ptrs or zero based unscaled narrow ptrs,
 115   // LogMinObjAlignmentInBytes/LogKlassAlignmentInBytes otherwise.
 116   int     _shift;
 117   // Generate code with implicit null checks for narrow ptrs.
 118   bool    _use_implicit_null_checks;
 119 };
 120 
 121 enum VerifyOption {
 122       VerifyOption_Default = 0,
 123 
 124       // G1
 125       VerifyOption_G1UsePrevMarking = VerifyOption_Default,
 126       VerifyOption_G1UseNextMarking = VerifyOption_G1UsePrevMarking + 1,
 127       VerifyOption_G1UseMarkWord    = VerifyOption_G1UseNextMarking + 1
 128 };
 129 
 130 class Universe: AllStatic {
 131   // Ugh.  Universe is much too friendly.
 132   friend class MarkSweep;
 133   friend class oopDesc;
 134   friend class ClassLoader;
 135   friend class Arguments;
 136   friend class SystemDictionary;
 137   friend class VMStructs;
 138   friend class VM_PopulateDumpSharedSpace;
 139 
 140   friend jint  universe_init();
 141   friend void  universe2_init();
 142   friend bool  universe_post_init();
 143 
 144  private:
 145   // Known classes in the VM
 146   static Klass* _boolArrayKlassObj;
 147   static Klass* _byteArrayKlassObj;
 148   static Klass* _charArrayKlassObj;
 149   static Klass* _intArrayKlassObj;
 150   static Klass* _shortArrayKlassObj;
 151   static Klass* _longArrayKlassObj;
 152   static Klass* _singleArrayKlassObj;
 153   static Klass* _doubleArrayKlassObj;
 154   static Klass* _typeArrayKlassObjs[T_VOID+1];
 155 
 156   static Klass* _objectArrayKlassObj;
 157 
 158   // Known objects in the VM
 159 
 160   // Primitive objects
 161   static oop _int_mirror;
 162   static oop _float_mirror;
 163   static oop _double_mirror;
 164   static oop _byte_mirror;
 165   static oop _bool_mirror;
 166   static oop _char_mirror;
 167   static oop _long_mirror;
 168   static oop _short_mirror;
 169   static oop _void_mirror;
 170 
 171   static oop          _main_thread_group;             // Reference to the main thread group object
 172   static oop          _system_thread_group;           // Reference to the system thread group object
 173 
 174   static objArrayOop  _the_empty_class_klass_array;   // Canonicalized obj array of type java.lang.Class
 175   static oop          _the_null_string;               // A cache of "null" as a Java string
 176   static oop          _the_min_jint_string;          // A cache of "-2147483648" as a Java string
 177   static LatestMethodOopCache* _finalizer_register_cache; // static method for registering finalizable objects
 178   static LatestMethodOopCache* _loader_addClass_cache;    // method for registering loaded classes in class loader vector
 179   static ActiveMethodOopsCache* _reflect_invoke_cache;    // method for security checks
 180   static oop          _out_of_memory_error_java_heap; // preallocated error object (no backtrace)
 181   static oop          _out_of_memory_error_perm_gen;  // preallocated error object (no backtrace)
 182   static oop          _out_of_memory_error_array_size;// preallocated error object (no backtrace)
 183   static oop          _out_of_memory_error_gc_overhead_limit; // preallocated error object (no backtrace)
 184 
 185   static Array<int>*       _the_empty_int_array;    // Canonicalized int array
 186   static Array<u2>*        _the_empty_short_array;  // Canonicalized short array
 187   static Array<Klass*>*  _the_empty_klass_array;  // Canonicalized klass obj array
 188   static Array<Method*>* _the_empty_method_array; // Canonicalized method obj array
 189 
 190   static Array<Klass*>*  _the_array_interfaces_array;
 191 
 192   // array of preallocated error objects with backtrace
 193   static objArrayOop   _preallocated_out_of_memory_error_array;
 194 
 195   // number of preallocated error objects available for use
 196   static volatile jint _preallocated_out_of_memory_error_avail_count;
 197 
 198   static oop          _null_ptr_exception_instance;   // preallocated exception object
 199   static oop          _arithmetic_exception_instance; // preallocated exception object
 200   static oop          _virtual_machine_error_instance; // preallocated exception object
 201   // The object used as an exception dummy when exceptions are thrown for
 202   // the vm thread.
 203   static oop          _vm_exception;
 204 
 205   // The particular choice of collected heap.
 206   static CollectedHeap* _collectedHeap;
 207 
 208   // For UseCompressedOops.
 209   static struct NarrowPtrStruct _narrow_oop;
 210   // For UseCompressedKlassPointers.
 211   static struct NarrowPtrStruct _narrow_klass;
 212   static address _narrow_ptrs_base;
 213 
 214   // Aligned size of the metaspace.
 215   static size_t _class_metaspace_size;
 216 
 217   // array of dummy objects used with +FullGCAlot
 218   debug_only(static objArrayOop _fullgc_alot_dummy_array;)
 219   // index of next entry to clear
 220   debug_only(static int         _fullgc_alot_dummy_next;)
 221 
 222   // Compiler/dispatch support
 223   static int  _base_vtable_size;                      // Java vtbl size of klass Object (in words)
 224 
 225   // Initialization
 226   static bool _bootstrapping;                         // true during genesis
 227   static bool _fully_initialized;                     // true after universe_init and initialize_vtables called
 228 
 229   // the array of preallocated errors with backtraces
 230   static objArrayOop  preallocated_out_of_memory_errors()     { return _preallocated_out_of_memory_error_array; }
 231 
 232   // generate an out of memory error; if possible using an error with preallocated backtrace;
 233   // otherwise return the given default error.
 234   static oop        gen_out_of_memory_error(oop default_err);
 235 
 236   // Historic gc information
 237   static size_t _heap_capacity_at_last_gc;
 238   static size_t _heap_used_at_last_gc;
 239 
 240   static jint initialize_heap();
 241   static void initialize_basic_type_mirrors(TRAPS);
 242   static void fixup_mirrors(TRAPS);
 243 
 244   static void reinitialize_vtable_of(KlassHandle h_k, TRAPS);
 245   static void reinitialize_itables(TRAPS);
 246   static void compute_base_vtable_size();             // compute vtable size of class Object
 247 
 248   static void genesis(TRAPS);                         // Create the initial world
 249 
 250   // Mirrors for primitive classes (created eagerly)
 251   static oop check_mirror(oop m) {
 252     assert(m != NULL, "mirror not initialized");
 253     return m;
 254   }
 255 
 256   // Narrow Oop encoding mode:
 257   // 0 - Use 32-bits oops without encoding when
 258   //     NarrowOopHeapBaseMin + heap_size < 4Gb
 259   // 1 - Use zero based compressed oops with encoding when
 260   //     NarrowOopHeapBaseMin + heap_size < 32Gb
 261   // 2 - Use compressed oops with heap base + encoding.
 262   enum NARROW_OOP_MODE {
 263     UnscaledNarrowOop  = 0,
 264     ZeroBasedNarrowOop = 1,
 265     HeapBasedNarrowOop = 2
 266   };
 267   static char*    preferred_heap_base(size_t heap_size, NARROW_OOP_MODE mode);
 268   static char*    preferred_metaspace_base(size_t heap_size, NARROW_OOP_MODE mode);
 269   static void     set_narrow_oop_base(address base) {
 270     assert(UseCompressedOops, "no compressed oops?");
 271     _narrow_oop._base    = base;
 272   }
 273   static void     set_narrow_klass_base(address base) {
 274     assert(UseCompressedKlassPointers, "no compressed klass ptrs?");
 275     _narrow_klass._base   = base;
 276   }
 277   static void     set_narrow_oop_use_implicit_null_checks(bool use) {
 278     assert(UseCompressedOops, "no compressed ptrs?");
 279     _narrow_oop._use_implicit_null_checks   = use;
 280   }
 281   static bool     reserve_metaspace_helper(bool with_base = false);
 282   static ReservedHeapSpace reserve_heap_metaspace(size_t heap_size, size_t alignment, bool& contiguous);
 283 
 284   static size_t  class_metaspace_size() {
 285     return _class_metaspace_size;
 286   }
 287   static void    set_class_metaspace_size(size_t metaspace_size) {
 288     _class_metaspace_size = metaspace_size;
 289   }
 290 
 291   // Debugging
 292   static int _verify_count;                           // number of verifies done
 293   // True during call to verify().  Should only be set/cleared in verify().
 294   static bool _verify_in_progress;
 295 
 296   static void compute_verify_oop_data();
 297 
 298  public:
 299   // Known classes in the VM
 300   static Klass* boolArrayKlassObj()                 { return _boolArrayKlassObj;   }
 301   static Klass* byteArrayKlassObj()                 { return _byteArrayKlassObj;   }
 302   static Klass* charArrayKlassObj()                 { return _charArrayKlassObj;   }
 303   static Klass* intArrayKlassObj()                  { return _intArrayKlassObj;    }
 304   static Klass* shortArrayKlassObj()                { return _shortArrayKlassObj;  }
 305   static Klass* longArrayKlassObj()                 { return _longArrayKlassObj;   }
 306   static Klass* singleArrayKlassObj()               { return _singleArrayKlassObj; }
 307   static Klass* doubleArrayKlassObj()               { return _doubleArrayKlassObj; }
 308 
 309   static Klass* objectArrayKlassObj() {
 310     return _objectArrayKlassObj;
 311   }
 312 
 313   static Klass* typeArrayKlassObj(BasicType t) {
 314     assert((uint)t < T_VOID+1, err_msg("range check for type: %s", type2name(t)));
 315     assert(_typeArrayKlassObjs[t] != NULL, "domain check");
 316     return _typeArrayKlassObjs[t];
 317   }
 318 
 319   // Known objects in the VM
 320   static oop int_mirror()                   { return check_mirror(_int_mirror); }
 321   static oop float_mirror()                 { return check_mirror(_float_mirror); }
 322   static oop double_mirror()                { return check_mirror(_double_mirror); }
 323   static oop byte_mirror()                  { return check_mirror(_byte_mirror); }
 324   static oop bool_mirror()                  { return check_mirror(_bool_mirror); }
 325   static oop char_mirror()                  { return check_mirror(_char_mirror); }
 326   static oop long_mirror()                  { return check_mirror(_long_mirror); }
 327   static oop short_mirror()                 { return check_mirror(_short_mirror); }
 328   static oop void_mirror()                  { return check_mirror(_void_mirror); }
 329 
 330   // table of same
 331   static oop _mirrors[T_VOID+1];
 332 
 333   static oop java_mirror(BasicType t) {
 334     assert((uint)t < T_VOID+1, "range check");
 335     return check_mirror(_mirrors[t]);
 336   }
 337   static oop      main_thread_group()                 { return _main_thread_group; }
 338   static void set_main_thread_group(oop group)        { _main_thread_group = group;}
 339 
 340   static oop      system_thread_group()               { return _system_thread_group; }
 341   static void set_system_thread_group(oop group)      { _system_thread_group = group;}
 342 
 343   static objArrayOop  the_empty_class_klass_array ()  { return _the_empty_class_klass_array;   }
 344   static Array<Klass*>* the_array_interfaces_array() { return _the_array_interfaces_array;   }
 345   static oop          the_null_string()               { return _the_null_string;               }
 346   static oop          the_min_jint_string()          { return _the_min_jint_string;          }
 347   static Method*      finalizer_register_method()     { return _finalizer_register_cache->get_Method(); }
 348   static Method*      loader_addClass_method()        { return _loader_addClass_cache->get_Method(); }
 349   static ActiveMethodOopsCache* reflect_invoke_cache() { return _reflect_invoke_cache; }
 350   static oop          null_ptr_exception_instance()   { return _null_ptr_exception_instance;   }
 351   static oop          arithmetic_exception_instance() { return _arithmetic_exception_instance; }
 352   static oop          virtual_machine_error_instance() { return _virtual_machine_error_instance; }
 353   static oop          vm_exception()                  { return _vm_exception; }
 354 
 355   static Array<int>*       the_empty_int_array()    { return _the_empty_int_array; }
 356   static Array<u2>*        the_empty_short_array()  { return _the_empty_short_array; }
 357   static Array<Method*>* the_empty_method_array() { return _the_empty_method_array; }
 358   static Array<Klass*>*  the_empty_klass_array()  { return _the_empty_klass_array; }
 359 
 360   // OutOfMemoryError support. Returns an error with the required message. The returned error
 361   // may or may not have a backtrace. If error has a backtrace then the stack trace is already
 362   // filled in.
 363   static oop out_of_memory_error_java_heap()          { return gen_out_of_memory_error(_out_of_memory_error_java_heap);  }
 364   static oop out_of_memory_error_perm_gen()           { return gen_out_of_memory_error(_out_of_memory_error_perm_gen);   }
 365   static oop out_of_memory_error_array_size()         { return gen_out_of_memory_error(_out_of_memory_error_array_size); }
 366   static oop out_of_memory_error_gc_overhead_limit()  { return gen_out_of_memory_error(_out_of_memory_error_gc_overhead_limit);  }
 367 
 368   // Accessors needed for fast allocation
 369   static Klass** boolArrayKlassObj_addr()           { return &_boolArrayKlassObj;   }
 370   static Klass** byteArrayKlassObj_addr()           { return &_byteArrayKlassObj;   }
 371   static Klass** charArrayKlassObj_addr()           { return &_charArrayKlassObj;   }
 372   static Klass** intArrayKlassObj_addr()            { return &_intArrayKlassObj;    }
 373   static Klass** shortArrayKlassObj_addr()          { return &_shortArrayKlassObj;  }
 374   static Klass** longArrayKlassObj_addr()           { return &_longArrayKlassObj;   }
 375   static Klass** singleArrayKlassObj_addr()         { return &_singleArrayKlassObj; }
 376   static Klass** doubleArrayKlassObj_addr()         { return &_doubleArrayKlassObj; }
 377   static Klass** objectArrayKlassObj_addr()         { return &_objectArrayKlassObj; }
 378 
 379   // The particular choice of collected heap.
 380   static CollectedHeap* heap() { return _collectedHeap; }
 381 
 382   // For UseCompressedOops
 383   static address  narrow_oop_base()                       { return  _narrow_oop._base; }
 384   static bool  is_narrow_oop_base(void* addr)             { return (narrow_oop_base() == (address)addr); }
 385   static int      narrow_oop_shift()                      { return  _narrow_oop._shift; }
 386   static bool     narrow_oop_use_implicit_null_checks()   { return  _narrow_oop._use_implicit_null_checks; }
 387 
 388   // For UseCompressedKlassPointers
 389   static address  narrow_klass_base()                     { return  _narrow_klass._base; }
 390   static bool  is_narrow_klass_base(void* addr)           { return (narrow_klass_base() == (address)addr); }
 391   static int      narrow_klass_shift()                    { return  _narrow_klass._shift; }
 392   static bool     narrow_klass_use_implicit_null_checks() { return  _narrow_klass._use_implicit_null_checks; }
 393 
 394   static address* narrow_ptrs_base_addr()                 { return &_narrow_ptrs_base; }
 395   static void     set_narrow_ptrs_base(address a)         { _narrow_ptrs_base = a; }
 396   static address  narrow_ptrs_base()                      { return _narrow_ptrs_base; }
 397 
 398   // this is set in vm_version on sparc (and then reset in universe afaict)
 399   static void     set_narrow_oop_shift(int shift)         {
 400     _narrow_oop._shift   = shift;
 401   }
 402 
 403   static void     set_narrow_klass_shift(int shift)       {
 404     assert(shift == 0 || shift == LogKlassAlignmentInBytes, "invalid shift for klass ptrs");
 405     _narrow_klass._shift   = shift;
 406   }
 407 
 408   // Reserve Java heap and determine CompressedOops mode
 409   static ReservedSpace reserve_heap(size_t heap_size, size_t alignment);
 410 
 411   // Historic gc information
 412   static size_t get_heap_capacity_at_last_gc()         { return _heap_capacity_at_last_gc; }
 413   static size_t get_heap_free_at_last_gc()             { return _heap_capacity_at_last_gc - _heap_used_at_last_gc; }
 414   static size_t get_heap_used_at_last_gc()             { return _heap_used_at_last_gc; }
 415   static void update_heap_info_at_gc();
 416 
 417   // Testers
 418   static bool is_bootstrapping()                      { return _bootstrapping; }
 419   static bool is_fully_initialized()                  { return _fully_initialized; }
 420 
 421   static inline bool element_type_should_be_aligned(BasicType type);
 422   static inline bool field_type_should_be_aligned(BasicType type);
 423   static bool        on_page_boundary(void* addr);
 424   static bool        should_fill_in_stack_trace(Handle throwable);
 425   static void check_alignment(uintx size, uintx alignment, const char* name);
 426 
 427   // Finalizer support.
 428   static void run_finalizers_on_exit();
 429 
 430   // Iteration
 431 
 432   // Apply "f" to the addresses of all the direct heap pointers maintained
 433   // as static fields of "Universe".
 434   static void oops_do(OopClosure* f, bool do_all = false);
 435 
 436   // CDS support
 437   static void serialize(SerializeClosure* f, bool do_all = false);
 438 
 439   // Apply "f" to all klasses for basic types (classes not present in
 440   // SystemDictionary).
 441   static void basic_type_classes_do(void f(Klass*));
 442 
 443   // For sharing -- fill in a list of known vtable pointers.
 444   static void init_self_patching_vtbl_list(void** list, int count);
 445 
 446   // Debugging
 447   static bool verify_in_progress() { return _verify_in_progress; }
 448   static void verify(VerifyOption option, const char* prefix, bool silent = VerifySilently);
 449   static void verify(const char* prefix, bool silent = VerifySilently) {
 450     verify(VerifyOption_Default, prefix, silent);
 451   }
 452   static void verify(bool silent = VerifySilently) {
 453     verify("", silent);
 454   }
 455 
 456   static int  verify_count()       { return _verify_count; }
 457   // The default behavior is to call print_on() on gclog_or_tty.
 458   static void print();
 459   // The extended parameter determines which method on the heap will
 460   // be called: print_on() (extended == false) or print_extended_on()
 461   // (extended == true).
 462   static void print_on(outputStream* st, bool extended = false);
 463   static void print_heap_at_SIGBREAK();
 464   static void print_heap_before_gc() { print_heap_before_gc(gclog_or_tty); }
 465   static void print_heap_after_gc()  { print_heap_after_gc(gclog_or_tty); }
 466   static void print_heap_before_gc(outputStream* st, bool ignore_extended = false);
 467   static void print_heap_after_gc(outputStream* st, bool ignore_extended = false);
 468 
 469   // Change the number of dummy objects kept reachable by the full gc dummy
 470   // array; this should trigger relocation in a sliding compaction collector.
 471   debug_only(static bool release_fullgc_alot_dummy();)
 472   // The non-oop pattern (see compiledIC.hpp, etc)
 473   static void*   non_oop_word();
 474 
 475   // Oop verification (see MacroAssembler::verify_oop)
 476   static uintptr_t verify_oop_mask()          PRODUCT_RETURN0;
 477   static uintptr_t verify_oop_bits()          PRODUCT_RETURN0;
 478   static uintptr_t verify_mark_bits()         PRODUCT_RETURN0;
 479   static uintptr_t verify_mark_mask()         PRODUCT_RETURN0;
 480 
 481   // Flushing and deoptimization
 482   static void flush_dependents_on(instanceKlassHandle dependee);
 483   static void flush_dependents_on(Handle call_site, Handle method_handle);
 484 #ifdef HOTSWAP
 485   // Flushing and deoptimization in case of evolution
 486   static void flush_evol_dependents_on(instanceKlassHandle dependee);
 487 #endif // HOTSWAP
 488   // Support for fullspeed debugging
 489   static void flush_dependents_on_method(methodHandle dependee);
 490 
 491   // Compiler support
 492   static int base_vtable_size()               { return _base_vtable_size; }
 493 };
 494 
 495 class DeferredObjAllocEvent : public CHeapObj<mtInternal> {
 496   private:
 497     oop    _oop;
 498     size_t _bytesize;
 499     jint   _arena_id;
 500 
 501   public:
 502     DeferredObjAllocEvent(const oop o, const size_t s, const jint id) {
 503       _oop      = o;
 504       _bytesize = s;
 505       _arena_id = id;
 506     }
 507 
 508     ~DeferredObjAllocEvent() {
 509     }
 510 
 511     jint   arena_id() { return _arena_id; }
 512     size_t bytesize() { return _bytesize; }
 513     oop    get_oop()  { return _oop; }
 514 };
 515 
 516 #endif // SHARE_VM_MEMORY_UNIVERSE_HPP