1 /*
2 * Copyright (c) 1997, 2018, 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 "oops/array.hpp"
29 #include "runtime/handles.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 // A helper class for caching a Method* when the user of the cache
45 // only cares about the latest version of the Method*. This cache safely
46 // interacts with the RedefineClasses API.
47
48 class LatestMethodCache : public CHeapObj<mtClass> {
49 // We save the Klass* and the idnum of Method* in order to get
50 // the current cached Method*.
51 private:
52 Klass* _klass;
53 int _method_idnum;
54
55 public:
56 LatestMethodCache() { _klass = NULL; _method_idnum = -1; }
57 ~LatestMethodCache() { _klass = NULL; _method_idnum = -1; }
58
59 void init(Klass* k, Method* m);
60 Klass* klass() const { return _klass; }
61 int method_idnum() const { return _method_idnum; }
62
63 Method* get_method();
64
65 // CDS support. Replace the klass in this with the archive version
66 // could use this for Enhanced Class Redefinition also.
67 void serialize(SerializeClosure* f) {
68 f->do_ptr((void**)&_klass);
69 }
70 void metaspace_pointers_do(MetaspaceClosure* it);
71 };
72
73
74 // For UseCompressedOops.
75 struct NarrowPtrStruct {
76 // Base address for oop-within-java-object materialization.
77 // NULL if using wide oops or zero based narrow oops.
78 address _base;
79 // Number of shift bits for encoding/decoding narrow ptrs.
80 // 0 if using wide ptrs or zero based unscaled narrow ptrs,
81 // LogMinObjAlignmentInBytes/LogKlassAlignmentInBytes otherwise.
82 int _shift;
83 // Generate code with implicit null checks for narrow ptrs.
84 bool _use_implicit_null_checks;
85 };
86
87 enum VerifyOption {
88 VerifyOption_Default = 0,
89
90 // G1
91 VerifyOption_G1UsePrevMarking = VerifyOption_Default,
92 VerifyOption_G1UseNextMarking = VerifyOption_G1UsePrevMarking + 1,
93 VerifyOption_G1UseFullMarking = VerifyOption_G1UseNextMarking + 1
94 };
95
96 class Universe: AllStatic {
97 // Ugh. Universe is much too friendly.
98 friend class MarkSweep;
99 friend class oopDesc;
100 friend class ClassLoader;
101 friend class SystemDictionary;
102 friend class ReservedHeapSpace;
103 friend class VMStructs;
104 friend class VM_PopulateDumpSharedSpace;
105 friend class Metaspace;
106 friend class MetaspaceShared;
107
108 friend jint universe_init();
109 friend void universe2_init();
110 friend bool universe_post_init();
111 friend void universe_post_module_init();
112
113 private:
114 // Known classes in the VM
115 static Klass* _typeArrayKlassObjs[T_LONG+1];
116 static Klass* _objectArrayKlassObj;
117
118 // Known objects in the VM
119
120 // Primitive objects
121 static oop _int_mirror;
122 static oop _float_mirror;
123 static oop _double_mirror;
124 static oop _byte_mirror;
125 static oop _bool_mirror;
126 static oop _char_mirror;
127 static oop _long_mirror;
128 static oop _short_mirror;
129 static oop _void_mirror;
130
131 static oop _main_thread_group; // Reference to the main thread group object
132 static oop _system_thread_group; // Reference to the system thread group object
133
134 static objArrayOop _the_empty_class_klass_array; // Canonicalized obj array of type java.lang.Class
135 static oop _the_null_sentinel; // A unique object pointer unused except as a sentinel for null.
136 static oop _the_null_string; // A cache of "null" as a Java string
137 static oop _the_min_jint_string; // A cache of "-2147483648" as a Java string
138 static LatestMethodCache* _finalizer_register_cache; // static method for registering finalizable objects
139 static LatestMethodCache* _loader_addClass_cache; // method for registering loaded classes in class loader vector
140 static LatestMethodCache* _pd_implies_cache; // method for checking protection domain attributes
141 static LatestMethodCache* _throw_illegal_access_error_cache; // Unsafe.throwIllegalAccessError() method
142 static LatestMethodCache* _do_stack_walk_cache; // method for stack walker callback
143
144 // preallocated error objects (no backtrace)
145 static oop _out_of_memory_error_java_heap;
146 static oop _out_of_memory_error_metaspace;
147 static oop _out_of_memory_error_class_metaspace;
148 static oop _out_of_memory_error_array_size;
149 static oop _out_of_memory_error_gc_overhead_limit;
150 static oop _out_of_memory_error_realloc_objects;
151 static oop _out_of_memory_error_retry;
152
153 // preallocated cause message for delayed StackOverflowError
154 static oop _delayed_stack_overflow_error_message;
155
156 static Array<int>* _the_empty_int_array; // Canonicalized int array
157 static Array<u2>* _the_empty_short_array; // Canonicalized short array
158 static Array<Klass*>* _the_empty_klass_array; // Canonicalized klass array
159 static Array<InstanceKlass*>* _the_empty_instance_klass_array; // Canonicalized instance klass array
160 static Array<Method*>* _the_empty_method_array; // Canonicalized method array
161
162 static Array<Klass*>* _the_array_interfaces_array;
163
164 // array of preallocated error objects with backtrace
165 static objArrayOop _preallocated_out_of_memory_error_array;
166
167 // number of preallocated error objects available for use
168 static volatile jint _preallocated_out_of_memory_error_avail_count;
169
170 static oop _null_ptr_exception_instance; // preallocated exception object
171 static oop _arithmetic_exception_instance; // preallocated exception object
172 static oop _virtual_machine_error_instance; // preallocated exception object
173 // The object used as an exception dummy when exceptions are thrown for
174 // the vm thread.
175 static oop _vm_exception;
176
177 // References waiting to be transferred to the ReferenceHandler
178 static oop _reference_pending_list;
179
180 // The particular choice of collected heap.
181 static CollectedHeap* _collectedHeap;
182
183 static intptr_t _non_oop_bits;
184
185 // For UseCompressedOops.
186 static struct NarrowPtrStruct _narrow_oop;
187 // For UseCompressedClassPointers.
188 static struct NarrowPtrStruct _narrow_klass;
189 static address _narrow_ptrs_base;
190 // CompressedClassSpaceSize set to 1GB, but appear 3GB away from _narrow_ptrs_base during CDS dump.
191 static uint64_t _narrow_klass_range;
192 // array of dummy objects used with +FullGCAlot
193 debug_only(static objArrayOop _fullgc_alot_dummy_array;)
194 // index of next entry to clear
195 debug_only(static int _fullgc_alot_dummy_next;)
196
197 // Compiler/dispatch support
198 static int _base_vtable_size; // Java vtbl size of klass Object (in words)
199
200 // Initialization
201 static bool _bootstrapping; // true during genesis
202 static bool _module_initialized; // true after call_initPhase2 called
203 static bool _fully_initialized; // true after universe_init and initialize_vtables called
204
205 // the array of preallocated errors with backtraces
206 static objArrayOop preallocated_out_of_memory_errors() { return _preallocated_out_of_memory_error_array; }
207
208 // generate an out of memory error; if possible using an error with preallocated backtrace;
209 // otherwise return the given default error.
210 static oop gen_out_of_memory_error(oop default_err);
211
212 // Historic gc information
213 static size_t _heap_capacity_at_last_gc;
214 static size_t _heap_used_at_last_gc;
215
216 static CollectedHeap* create_heap();
217 static jint initialize_heap();
218 static void initialize_basic_type_mirrors(TRAPS);
219 static void fixup_mirrors(TRAPS);
220
221 static void reinitialize_vtable_of(Klass* k, TRAPS);
222 static void reinitialize_itables(TRAPS);
223 static void compute_base_vtable_size(); // compute vtable size of class Object
224
225 static void genesis(TRAPS); // Create the initial world
226
227 // Mirrors for primitive classes (created eagerly)
228 static oop check_mirror(oop m) {
229 assert(m != NULL, "mirror not initialized");
230 return m;
231 }
232
233 static void set_narrow_oop_base(address base) {
234 assert(UseCompressedOops, "no compressed oops?");
235 _narrow_oop._base = base;
236 }
237 static void set_narrow_klass_base(address base) {
238 assert(UseCompressedClassPointers, "no compressed klass ptrs?");
239 _narrow_klass._base = base;
240 }
241 static void set_narrow_klass_range(uint64_t range) {
242 assert(UseCompressedClassPointers, "no compressed klass ptrs?");
243 _narrow_klass_range = range;
244 }
245 static void set_narrow_oop_use_implicit_null_checks(bool use) {
246 assert(UseCompressedOops, "no compressed ptrs?");
247 _narrow_oop._use_implicit_null_checks = use;
248 }
249
250 // Debugging
251 static int _verify_count; // number of verifies done
252
253 // True during call to verify(). Should only be set/cleared in verify().
254 static bool _verify_in_progress;
255 static long verify_flags;
256
257 static uintptr_t _verify_oop_mask;
258 static uintptr_t _verify_oop_bits;
259
260 static void calculate_verify_data(HeapWord* low_boundary, HeapWord* high_boundary) PRODUCT_RETURN;
261 static void compute_verify_oop_data();
262
263 public:
264 // Known classes in the VM
265 static Klass* boolArrayKlassObj() { return typeArrayKlassObj(T_BOOLEAN); }
266 static Klass* byteArrayKlassObj() { return typeArrayKlassObj(T_BYTE); }
267 static Klass* charArrayKlassObj() { return typeArrayKlassObj(T_CHAR); }
268 static Klass* intArrayKlassObj() { return typeArrayKlassObj(T_INT); }
269 static Klass* shortArrayKlassObj() { return typeArrayKlassObj(T_SHORT); }
270 static Klass* longArrayKlassObj() { return typeArrayKlassObj(T_LONG); }
271 static Klass* floatArrayKlassObj() { return typeArrayKlassObj(T_FLOAT); }
272 static Klass* doubleArrayKlassObj() { return typeArrayKlassObj(T_DOUBLE); }
273
274 static Klass* objectArrayKlassObj() { return _objectArrayKlassObj; }
275
276 static Klass* typeArrayKlassObj(BasicType t) {
277 assert((uint)t >= T_BOOLEAN, "range check for type: %s", type2name(t));
278 assert((uint)t < T_LONG+1, "range check for type: %s", type2name(t));
279 assert(_typeArrayKlassObjs[t] != NULL, "domain check");
280 return _typeArrayKlassObjs[t];
281 }
282
283 // Known objects in the VM
284 static oop int_mirror() { return check_mirror(_int_mirror); }
285 static oop float_mirror() { return check_mirror(_float_mirror); }
286 static oop double_mirror() { return check_mirror(_double_mirror); }
287 static oop byte_mirror() { return check_mirror(_byte_mirror); }
288 static oop bool_mirror() { return check_mirror(_bool_mirror); }
289 static oop char_mirror() { return check_mirror(_char_mirror); }
290 static oop long_mirror() { return check_mirror(_long_mirror); }
291 static oop short_mirror() { return check_mirror(_short_mirror); }
292 static oop void_mirror() { return check_mirror(_void_mirror); }
293
294 static void set_int_mirror(oop m) { _int_mirror = m; }
295 static void set_float_mirror(oop m) { _float_mirror = m; }
296 static void set_double_mirror(oop m) { _double_mirror = m; }
297 static void set_byte_mirror(oop m) { _byte_mirror = m; }
298 static void set_bool_mirror(oop m) { _bool_mirror = m; }
299 static void set_char_mirror(oop m) { _char_mirror = m; }
300 static void set_long_mirror(oop m) { _long_mirror = m; }
301 static void set_short_mirror(oop m) { _short_mirror = m; }
302 static void set_void_mirror(oop m) { _void_mirror = m; }
303
304 // table of same
305 static oop _mirrors[T_VOID+1];
306
307 static oop java_mirror(BasicType t) {
308 assert((uint)t < T_VOID+1, "range check");
309 return check_mirror(_mirrors[t]);
310 }
311 static oop main_thread_group() { return _main_thread_group; }
312 static void set_main_thread_group(oop group) { _main_thread_group = group;}
313
314 static oop system_thread_group() { return _system_thread_group; }
315 static void set_system_thread_group(oop group) { _system_thread_group = group;}
316
317 static objArrayOop the_empty_class_klass_array () { return _the_empty_class_klass_array; }
318 static Array<Klass*>* the_array_interfaces_array() { return _the_array_interfaces_array; }
319 static oop the_null_string() { return _the_null_string; }
320 static oop the_min_jint_string() { return _the_min_jint_string; }
321
322 static Method* finalizer_register_method() { return _finalizer_register_cache->get_method(); }
323 static Method* loader_addClass_method() { return _loader_addClass_cache->get_method(); }
324
325 static Method* protection_domain_implies_method() { return _pd_implies_cache->get_method(); }
326 static Method* throw_illegal_access_error() { return _throw_illegal_access_error_cache->get_method(); }
327
328 static Method* do_stack_walk_method() { return _do_stack_walk_cache->get_method(); }
329
330 static oop the_null_sentinel() { return _the_null_sentinel; }
331 static address the_null_sentinel_addr() { return (address) &_the_null_sentinel; }
332
333 // Function to initialize these
334 static void initialize_known_methods(TRAPS);
335
336 static oop null_ptr_exception_instance() { return _null_ptr_exception_instance; }
337 static oop arithmetic_exception_instance() { return _arithmetic_exception_instance; }
338 static oop virtual_machine_error_instance() { return _virtual_machine_error_instance; }
339 static oop vm_exception() { return _vm_exception; }
340
341 // Reference pending list manipulation. Access is protected by
342 // Heap_lock. The getter, setter and predicate require the caller
343 // owns the lock. Swap is used by parallel non-concurrent reference
344 // processing threads, where some higher level controller owns
345 // Heap_lock, so requires the lock is locked, but not necessarily by
346 // the current thread.
347 static oop reference_pending_list();
348 static void set_reference_pending_list(oop list);
349 static bool has_reference_pending_list();
350 static oop swap_reference_pending_list(oop list);
351
352 static Array<int>* the_empty_int_array() { return _the_empty_int_array; }
353 static Array<u2>* the_empty_short_array() { return _the_empty_short_array; }
354 static Array<Method*>* the_empty_method_array() { return _the_empty_method_array; }
355 static Array<Klass*>* the_empty_klass_array() { return _the_empty_klass_array; }
356 static Array<InstanceKlass*>* the_empty_instance_klass_array() { return _the_empty_instance_klass_array; }
357
358 // OutOfMemoryError support. Returns an error with the required message. The returned error
359 // may or may not have a backtrace. If error has a backtrace then the stack trace is already
360 // filled in.
361 static oop out_of_memory_error_java_heap() { return gen_out_of_memory_error(_out_of_memory_error_java_heap); }
362 static oop out_of_memory_error_metaspace() { return gen_out_of_memory_error(_out_of_memory_error_metaspace); }
363 static oop out_of_memory_error_class_metaspace() { return gen_out_of_memory_error(_out_of_memory_error_class_metaspace); }
364 static oop out_of_memory_error_array_size() { return gen_out_of_memory_error(_out_of_memory_error_array_size); }
365 static oop out_of_memory_error_gc_overhead_limit() { return gen_out_of_memory_error(_out_of_memory_error_gc_overhead_limit); }
366 static oop out_of_memory_error_realloc_objects() { return gen_out_of_memory_error(_out_of_memory_error_realloc_objects); }
367 // Throw default _out_of_memory_error_retry object as it will never propagate out of the VM
368 static oop out_of_memory_error_retry() { return _out_of_memory_error_retry; }
369 static oop delayed_stack_overflow_error_message() { return _delayed_stack_overflow_error_message; }
370
371 // The particular choice of collected heap.
372 static CollectedHeap* heap() { return _collectedHeap; }
373
374 // For UseCompressedOops
375 // Narrow Oop encoding mode:
376 // 0 - Use 32-bits oops without encoding when
377 // NarrowOopHeapBaseMin + heap_size < 4Gb
378 // 1 - Use zero based compressed oops with encoding when
379 // NarrowOopHeapBaseMin + heap_size < 32Gb
380 // 2 - Use compressed oops with disjoint heap base if
381 // base is 32G-aligned and base > 0. This allows certain
382 // optimizations in encoding/decoding.
383 // Disjoint: Bits used in base are disjoint from bits used
384 // for oops ==> oop = (cOop << 3) | base. One can disjoint
385 // the bits of an oop into base and compressed oop.
386 // 3 - Use compressed oops with heap base + encoding.
387 enum NARROW_OOP_MODE {
388 UnscaledNarrowOop = 0,
389 ZeroBasedNarrowOop = 1,
390 DisjointBaseNarrowOop = 2,
391 HeapBasedNarrowOop = 3,
392 AnyNarrowOopMode = 4
393 };
394 static NARROW_OOP_MODE narrow_oop_mode();
395 static const char* narrow_oop_mode_to_string(NARROW_OOP_MODE mode);
396 static char* preferred_heap_base(size_t heap_size, size_t alignment, NARROW_OOP_MODE mode);
397 static char* preferred_metaspace_base(size_t heap_size, NARROW_OOP_MODE mode);
398 static address narrow_oop_base() { return _narrow_oop._base; }
399 // Test whether bits of addr and possible offsets into the heap overlap.
400 static bool is_disjoint_heap_base_address(address addr) {
401 return (((uint64_t)(intptr_t)addr) &
402 (((uint64_t)UCONST64(0xFFFFffffFFFFffff)) >> (32-LogMinObjAlignmentInBytes))) == 0;
403 }
404 // Check for disjoint base compressed oops.
405 static bool narrow_oop_base_disjoint() {
406 return _narrow_oop._base != NULL && is_disjoint_heap_base_address(_narrow_oop._base);
407 }
408 // Check for real heapbased compressed oops.
409 // We must subtract the base as the bits overlap.
410 // If we negate above function, we also get unscaled and zerobased.
411 static bool narrow_oop_base_overlaps() {
412 return _narrow_oop._base != NULL && !is_disjoint_heap_base_address(_narrow_oop._base);
413 }
414 static bool is_narrow_oop_base(void* addr) { return (narrow_oop_base() == (address)addr); }
415 static int narrow_oop_shift() { return _narrow_oop._shift; }
416 static bool narrow_oop_use_implicit_null_checks() { return _narrow_oop._use_implicit_null_checks; }
417
418 // For UseCompressedClassPointers
419 static address narrow_klass_base() { return _narrow_klass._base; }
420 static bool is_narrow_klass_base(void* addr) { return (narrow_klass_base() == (address)addr); }
421 static uint64_t narrow_klass_range() { return _narrow_klass_range; }
422 static int narrow_klass_shift() { return _narrow_klass._shift; }
423 static bool narrow_klass_use_implicit_null_checks() { return _narrow_klass._use_implicit_null_checks; }
424
425 static address* narrow_ptrs_base_addr() { return &_narrow_ptrs_base; }
426 static void set_narrow_ptrs_base(address a) { _narrow_ptrs_base = a; }
427 static address narrow_ptrs_base() { return _narrow_ptrs_base; }
428
429 static void print_compressed_oops_mode(outputStream* st);
430
431 // this is set in vm_version on sparc (and then reset in universe afaict)
432 static void set_narrow_oop_shift(int shift) {
433 _narrow_oop._shift = shift;
434 }
435
436 static void set_narrow_klass_shift(int shift) {
437 assert(shift == 0 || shift == LogKlassAlignmentInBytes, "invalid shift for klass ptrs");
438 _narrow_klass._shift = shift;
439 }
440
441 // Reserve Java heap and determine CompressedOops mode
442 static ReservedSpace reserve_heap(size_t heap_size, size_t alignment);
443
444 // Historic gc information
445 static size_t get_heap_capacity_at_last_gc() { return _heap_capacity_at_last_gc; }
446 static size_t get_heap_free_at_last_gc() { return _heap_capacity_at_last_gc - _heap_used_at_last_gc; }
447 static size_t get_heap_used_at_last_gc() { return _heap_used_at_last_gc; }
448 static void update_heap_info_at_gc();
449
450 // Testers
451 static bool is_bootstrapping() { return _bootstrapping; }
452 static bool is_module_initialized() { return _module_initialized; }
453 static bool is_fully_initialized() { return _fully_initialized; }
454
455 static bool on_page_boundary(void* addr);
456 static bool should_fill_in_stack_trace(Handle throwable);
457 static void check_alignment(uintx size, uintx alignment, const char* name);
458
459 // Iteration
460
461 // Apply "f" to the addresses of all the direct heap pointers maintained
462 // as static fields of "Universe".
463 static void oops_do(OopClosure* f);
464
465 // CDS support
466 static void serialize(SerializeClosure* f);
467
468 // Apply "f" to all klasses for basic types (classes not present in
469 // SystemDictionary).
470 static void basic_type_classes_do(void f(Klass*));
471 static void basic_type_classes_do(KlassClosure* closure);
472 static void metaspace_pointers_do(MetaspaceClosure* it);
473
474 // Debugging
475 enum VERIFY_FLAGS {
476 Verify_Threads = 1,
477 Verify_Heap = 2,
478 Verify_SymbolTable = 4,
479 Verify_StringTable = 8,
480 Verify_CodeCache = 16,
481 Verify_SystemDictionary = 32,
482 Verify_ClassLoaderDataGraph = 64,
483 Verify_MetaspaceUtils = 128,
484 Verify_JNIHandles = 256,
485 Verify_CodeCacheOops = 512,
486 Verify_All = -1
487 };
488 static void initialize_verify_flags();
489 static bool should_verify_subset(uint subset);
490 static bool verify_in_progress() { return _verify_in_progress; }
491 static void verify(VerifyOption option, const char* prefix);
492 static void verify(const char* prefix) {
493 verify(VerifyOption_Default, prefix);
494 }
495 static void verify() {
496 verify("");
497 }
498
499 static int verify_count() { return _verify_count; }
500 static void print_on(outputStream* st);
501 static void print_heap_at_SIGBREAK();
502 static void print_heap_before_gc();
503 static void print_heap_after_gc();
504
505 // Change the number of dummy objects kept reachable by the full gc dummy
506 // array; this should trigger relocation in a sliding compaction collector.
507 debug_only(static bool release_fullgc_alot_dummy();)
508 // The non-oop pattern (see compiledIC.hpp, etc)
509 static void* non_oop_word();
510
511 // Oop verification (see MacroAssembler::verify_oop)
512 static uintptr_t verify_oop_mask() PRODUCT_RETURN0;
513 static uintptr_t verify_oop_bits() PRODUCT_RETURN0;
514 static uintptr_t verify_mark_bits() PRODUCT_RETURN0;
515 static uintptr_t verify_mark_mask() PRODUCT_RETURN0;
516
517 // Compiler support
518 static int base_vtable_size() { return _base_vtable_size; }
519 };
520
521 class DeferredObjAllocEvent : public CHeapObj<mtInternal> {
522 private:
523 oop _oop;
524 size_t _bytesize;
525 jint _arena_id;
526
527 public:
528 DeferredObjAllocEvent(const oop o, const size_t s, const jint id) {
529 _oop = o;
530 _bytesize = s;
531 _arena_id = id;
532 }
533
534 ~DeferredObjAllocEvent() {
535 }
536
537 jint arena_id() { return _arena_id; }
538 size_t bytesize() { return _bytesize; }
539 oop get_oop() { return _oop; }
540 };
541
542 #endif // SHARE_VM_MEMORY_UNIVERSE_HPP