1 /*
2 * Copyright (c) 2013, 2021, Red Hat, Inc. 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_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
27
28 #include "gc/shared/markBitMap.hpp"
29 #include "gc/shared/softRefPolicy.hpp"
30 #include "gc/shared/collectedHeap.hpp"
31 #include "gc/shenandoah/shenandoahAsserts.hpp"
32 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
33 #include "gc/shenandoah/shenandoahLock.hpp"
34 #include "gc/shenandoah/shenandoahEvacOOMHandler.hpp"
35 #include "gc/shenandoah/shenandoahPadding.hpp"
36 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
37 #include "gc/shenandoah/shenandoahUnload.hpp"
38 #include "memory/metaspace.hpp"
39 #include "services/memoryManager.hpp"
40 #include "utilities/globalDefinitions.hpp"
41 #include "utilities/stack.hpp"
42
43 class ConcurrentGCTimer;
44 class ObjectIterateScanRootClosure;
45 class ShenandoahCollectorPolicy;
46 class ShenandoahControlThread;
47 class ShenandoahGCSession;
48 class ShenandoahGCStateResetter;
49 class ShenandoahHeuristics;
50 class ShenandoahMarkingContext;
51 class ShenandoahMode;
52 class ShenandoahPhaseTimings;
53 class ShenandoahHeap;
54 class ShenandoahHeapRegion;
55 class ShenandoahHeapRegionClosure;
56 class ShenandoahCollectionSet;
57 class ShenandoahFreeSet;
58 class ShenandoahConcurrentMark;
59 class ShenandoahFullGC;
60 class ShenandoahMonitoringSupport;
61 class ShenandoahPacer;
62 class ShenandoahReferenceProcessor;
63 class ShenandoahVerifier;
64 class ShenandoahWorkGang;
65 class SlidingForwarding;
66 class VMStructs;
67
68 // Used for buffering per-region liveness data.
69 // Needed since ShenandoahHeapRegion uses atomics to update liveness.
70 // The ShenandoahHeap array has max-workers elements, each of which is an array of
71 // uint16_t * max_regions. The choice of uint16_t is not accidental:
72 // there is a tradeoff between static/dynamic footprint that translates
73 // into cache pressure (which is already high during marking), and
74 // too many atomic updates. uint32_t is too large, uint8_t is too small.
75 typedef uint16_t ShenandoahLiveData;
76 #define SHENANDOAH_LIVEDATA_MAX ((ShenandoahLiveData)-1)
77
78 class ShenandoahRegionIterator : public StackObj {
79 private:
80 ShenandoahHeap* _heap;
81
82 shenandoah_padding(0);
83 volatile size_t _index;
84 shenandoah_padding(1);
85
86 // No implicit copying: iterators should be passed by reference to capture the state
87 NONCOPYABLE(ShenandoahRegionIterator);
88
89 public:
90 ShenandoahRegionIterator();
91 ShenandoahRegionIterator(ShenandoahHeap* heap);
92
93 // Reset iterator to default state
94 void reset();
95
96 // Returns next region, or NULL if there are no more regions.
97 // This is multi-thread-safe.
98 inline ShenandoahHeapRegion* next();
99
100 // This is *not* MT safe. However, in the absence of multithreaded access, it
101 // can be used to determine if there is more work to do.
102 bool has_next() const;
103 };
104
105 class ShenandoahHeapRegionClosure : public StackObj {
106 public:
107 virtual void heap_region_do(ShenandoahHeapRegion* r) = 0;
108 virtual bool is_thread_safe() { return false; }
109 };
110
111 typedef ShenandoahLock ShenandoahHeapLock;
112 typedef ShenandoahLocker ShenandoahHeapLocker;
113 typedef Stack<oop, mtGC> ShenandoahScanObjectStack;
114
115 // Shenandoah GC is low-pause concurrent GC that uses Brooks forwarding pointers
116 // to encode forwarding data. See BrooksPointer for details on forwarding data encoding.
117 // See ShenandoahControlThread for GC cycle structure.
118 //
119 class ShenandoahHeap : public CollectedHeap {
120 friend class ShenandoahAsserts;
121 friend class VMStructs;
122 friend class ShenandoahGCSession;
123 friend class ShenandoahGCStateResetter;
124 friend class ShenandoahParallelObjectIterator;
125 friend class ShenandoahSafepoint;
126 // Supported GC
127 friend class ShenandoahConcurrentGC;
128 friend class ShenandoahDegenGC;
129 friend class ShenandoahFullGC;
130 friend class ShenandoahUnload;
131
132 // ---------- Locks that guard important data structures in Heap
133 //
134 private:
135 ShenandoahHeapLock _lock;
136
137 public:
138 ShenandoahHeapLock* lock() {
139 return &_lock;
140 }
141
142 // ---------- Initialization, termination, identification, printing routines
143 //
144 public:
145 static ShenandoahHeap* heap();
146
147 const char* name() const { return "Shenandoah"; }
148 ShenandoahHeap::Name kind() const { return CollectedHeap::Shenandoah; }
149
150 ShenandoahHeap(ShenandoahCollectorPolicy* policy);
151 jint initialize();
152 void post_initialize();
153 void initialize_mode();
154 void initialize_heuristics();
155
156 void initialize_serviceability();
157
158 void print_on(outputStream* st) const;
159 void print_extended_on(outputStream *st) const;
160 void print_tracing_info() const;
161 void print_heap_regions_on(outputStream* st) const;
162
163 void stop();
164
165 void prepare_for_verify();
166 void verify(VerifyOption vo);
167
168 // WhiteBox testing support.
169 bool supports_concurrent_gc_breakpoints() const {
170 return true;
171 }
172
173 // ---------- Heap counters and metrics
174 //
175 private:
176 size_t _initial_size;
177 size_t _minimum_size;
178 volatile size_t _soft_max_size;
179 shenandoah_padding(0);
180 volatile size_t _used;
181 volatile size_t _committed;
182 volatile size_t _bytes_allocated_since_gc_start;
183 shenandoah_padding(1);
184
185 public:
186 void increase_used(size_t bytes);
187 void decrease_used(size_t bytes);
188 void set_used(size_t bytes);
189
190 void increase_committed(size_t bytes);
191 void decrease_committed(size_t bytes);
192 void increase_allocated(size_t bytes);
193
194 size_t bytes_allocated_since_gc_start();
195 void reset_bytes_allocated_since_gc_start();
196
197 size_t min_capacity() const;
198 size_t max_capacity() const;
199 size_t soft_max_capacity() const;
200 size_t initial_capacity() const;
201 size_t capacity() const;
202 size_t used() const;
203 size_t committed() const;
204
205 void set_soft_max_capacity(size_t v);
206
207 // ---------- Workers handling
208 //
209 private:
210 uint _max_workers;
211 ShenandoahWorkGang* _workers;
212 ShenandoahWorkGang* _safepoint_workers;
213
214 public:
215 uint max_workers();
216 void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
217
218 WorkGang* workers() const;
219 WorkGang* safepoint_workers();
220
221 void gc_threads_do(ThreadClosure* tcl) const;
222
223 // ---------- Heap regions handling machinery
224 //
225 private:
226 MemRegion _heap_region;
227 bool _heap_region_special;
228 size_t _num_regions;
229 ShenandoahHeapRegion** _regions;
230 ShenandoahRegionIterator _update_refs_iterator;
231 SlidingForwarding* _forwarding;
232
233 public:
234
235 inline HeapWord* base() const { return _heap_region.start(); }
236
237 inline size_t num_regions() const { return _num_regions; }
238 inline bool is_heap_region_special() { return _heap_region_special; }
239
240 inline ShenandoahHeapRegion* const heap_region_containing(const void* addr) const;
241 inline size_t heap_region_index_containing(const void* addr) const;
242
243 inline ShenandoahHeapRegion* const get_region(size_t region_idx) const;
244
245 void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
246 void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
247
248 SlidingForwarding* forwarding() const { return _forwarding; }
249
250 // ---------- GC state machinery
251 //
252 // GC state describes the important parts of collector state, that may be
253 // used to make barrier selection decisions in the native and generated code.
254 // Multiple bits can be set at once.
255 //
256 // Important invariant: when GC state is zero, the heap is stable, and no barriers
257 // are required.
258 //
259 public:
260 enum GCStateBitPos {
261 // Heap has forwarded objects: needs LRB barriers.
262 HAS_FORWARDED_BITPOS = 0,
263
264 // Heap is under marking: needs SATB barriers.
265 MARKING_BITPOS = 1,
266
267 // Heap is under evacuation: needs LRB barriers. (Set together with HAS_FORWARDED)
268 EVACUATION_BITPOS = 2,
269
270 // Heap is under updating: needs no additional barriers.
271 UPDATEREFS_BITPOS = 3,
272
273 // Heap is under weak-reference/roots processing: needs weak-LRB barriers.
274 WEAK_ROOTS_BITPOS = 4,
275 };
276
277 enum GCState {
278 STABLE = 0,
279 HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
280 MARKING = 1 << MARKING_BITPOS,
281 EVACUATION = 1 << EVACUATION_BITPOS,
282 UPDATEREFS = 1 << UPDATEREFS_BITPOS,
283 WEAK_ROOTS = 1 << WEAK_ROOTS_BITPOS,
284 };
285
286 private:
287 ShenandoahSharedBitmap _gc_state;
288 ShenandoahSharedFlag _degenerated_gc_in_progress;
289 ShenandoahSharedFlag _full_gc_in_progress;
290 ShenandoahSharedFlag _full_gc_move_in_progress;
291 ShenandoahSharedFlag _progress_last_gc;
292 ShenandoahSharedFlag _concurrent_strong_root_in_progress;
293
294 void set_gc_state_all_threads(char state);
295 void set_gc_state_mask(uint mask, bool value);
296
297 public:
298 char gc_state() const;
299 static address gc_state_addr();
300
301 void set_concurrent_mark_in_progress(bool in_progress);
302 void set_evacuation_in_progress(bool in_progress);
303 void set_update_refs_in_progress(bool in_progress);
304 void set_degenerated_gc_in_progress(bool in_progress);
305 void set_full_gc_in_progress(bool in_progress);
306 void set_full_gc_move_in_progress(bool in_progress);
307 void set_has_forwarded_objects(bool cond);
308 void set_concurrent_strong_root_in_progress(bool cond);
309 void set_concurrent_weak_root_in_progress(bool cond);
310
311 inline bool is_stable() const;
312 inline bool is_idle() const;
313 inline bool is_concurrent_mark_in_progress() const;
314 inline bool is_update_refs_in_progress() const;
315 inline bool is_evacuation_in_progress() const;
316 inline bool is_degenerated_gc_in_progress() const;
317 inline bool is_full_gc_in_progress() const;
318 inline bool is_full_gc_move_in_progress() const;
319 inline bool has_forwarded_objects() const;
320 inline bool is_gc_in_progress_mask(uint mask) const;
321 inline bool is_stw_gc_in_progress() const;
322 inline bool is_concurrent_strong_root_in_progress() const;
323 inline bool is_concurrent_weak_root_in_progress() const;
324
325 private:
326 enum CancelState {
327 // Normal state. GC has not been cancelled and is open for cancellation.
328 // Worker threads can suspend for safepoint.
329 CANCELLABLE,
330
331 // GC has been cancelled. Worker threads can not suspend for
332 // safepoint but must finish their work as soon as possible.
333 CANCELLED,
334
335 // GC has not been cancelled and must not be cancelled. At least
336 // one worker thread checks for pending safepoint and may suspend
337 // if a safepoint is pending.
338 NOT_CANCELLED
339 };
340
341 ShenandoahSharedEnumFlag<CancelState> _cancelled_gc;
342 bool try_cancel_gc();
343
344 public:
345 static address cancelled_gc_addr();
346
347 inline bool cancelled_gc() const;
348 inline bool check_cancelled_gc_and_yield(bool sts_active = true);
349
350 inline void clear_cancelled_gc();
351
352 void cancel_gc(GCCause::Cause cause);
353
354 public:
355 // Elastic heap support
356 void entry_uncommit(double shrink_before, size_t shrink_until);
357 void op_uncommit(double shrink_before, size_t shrink_until);
358
359 private:
360 // GC support
361 // Reset bitmap, prepare regions for new GC cycle
362 void prepare_gc();
363 void prepare_regions_and_collection_set(bool concurrent);
364 // Evacuation
365 void prepare_evacuation(bool concurrent);
366 void evacuate_collection_set(bool concurrent);
367 // Concurrent root processing
368 void prepare_concurrent_roots();
369 void finish_concurrent_roots();
370 // Concurrent class unloading support
371 void do_class_unloading();
372 // Reference updating
373 void prepare_update_heap_references(bool concurrent);
374 void update_heap_references(bool concurrent);
375 // Final update region states
376 void update_heap_region_states(bool concurrent);
377 void rebuild_free_set(bool concurrent);
378
379 void rendezvous_threads();
380 void recycle_trash();
381 public:
382 void notify_gc_progress() { _progress_last_gc.set(); }
383 void notify_gc_no_progress() { _progress_last_gc.unset(); }
384
385 //
386 // Mark support
387 private:
388 ShenandoahControlThread* _control_thread;
389 ShenandoahCollectorPolicy* _shenandoah_policy;
390 ShenandoahMode* _gc_mode;
391 ShenandoahHeuristics* _heuristics;
392 ShenandoahFreeSet* _free_set;
393 ShenandoahPacer* _pacer;
394 ShenandoahVerifier* _verifier;
395
396 ShenandoahPhaseTimings* _phase_timings;
397
398 ShenandoahControlThread* control_thread() { return _control_thread; }
399
400 public:
401 ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
402 ShenandoahMode* mode() const { return _gc_mode; }
403 ShenandoahHeuristics* heuristics() const { return _heuristics; }
404 ShenandoahFreeSet* free_set() const { return _free_set; }
405 ShenandoahPacer* pacer() const { return _pacer; }
406
407 ShenandoahPhaseTimings* phase_timings() const { return _phase_timings; }
408
409 ShenandoahVerifier* verifier();
410
411 // ---------- VM subsystem bindings
412 //
413 private:
414 ShenandoahMonitoringSupport* _monitoring_support;
415 MemoryPool* _memory_pool;
416 GCMemoryManager _stw_memory_manager;
417 GCMemoryManager _cycle_memory_manager;
418 ConcurrentGCTimer* _gc_timer;
419 SoftRefPolicy _soft_ref_policy;
420
421 // For exporting to SA
422 int _log_min_obj_alignment_in_bytes;
423 public:
424 ShenandoahMonitoringSupport* monitoring_support() { return _monitoring_support; }
425 GCMemoryManager* cycle_memory_manager() { return &_cycle_memory_manager; }
426 GCMemoryManager* stw_memory_manager() { return &_stw_memory_manager; }
427 SoftRefPolicy* soft_ref_policy() { return &_soft_ref_policy; }
428
429 GrowableArray<GCMemoryManager*> memory_managers();
430 GrowableArray<MemoryPool*> memory_pools();
431 MemoryUsage memory_usage();
432 GCTracer* tracer();
433 ConcurrentGCTimer* gc_timer() const;
434
435 // ---------- Reference processing
436 //
437 private:
438 ShenandoahReferenceProcessor* const _ref_processor;
439
440 public:
441 ShenandoahReferenceProcessor* ref_processor() { return _ref_processor; }
442
443 // ---------- Class Unloading
444 //
445 private:
446 ShenandoahSharedFlag _unload_classes;
447 ShenandoahUnload _unloader;
448
449 public:
450 void set_unload_classes(bool uc);
451 bool unload_classes() const;
452
453 // Perform STW class unloading and weak root cleaning
454 void parallel_cleaning(bool full_gc);
455
456 private:
457 void stw_unload_classes(bool full_gc);
458 void stw_process_weak_roots(bool full_gc);
459 void stw_weak_refs(bool full_gc);
460
461 // Heap iteration support
462 void scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops);
463 bool prepare_aux_bitmap_for_iteration();
464 void reclaim_aux_bitmap_for_iteration();
465
466 // ---------- Generic interface hooks
467 // Minor things that super-interface expects us to implement to play nice with
468 // the rest of runtime. Some of the things here are not required to be implemented,
469 // and can be stubbed out.
470 //
471 public:
472 AdaptiveSizePolicy* size_policy() shenandoah_not_implemented_return(NULL);
473 bool is_maximal_no_gc() const shenandoah_not_implemented_return(false);
474
475 bool is_in(const void* p) const;
476
477 MemRegion reserved_region() const { return _reserved; }
478 bool is_in_reserved(const void* addr) const { return _reserved.contains(addr); }
479
480 void collect(GCCause::Cause cause);
481 void do_full_collection(bool clear_all_soft_refs);
482
483 // Used for parsing heap during error printing
484 HeapWord* block_start(const void* addr) const;
485 bool block_is_obj(const HeapWord* addr) const;
486 bool print_location(outputStream* st, void* addr) const;
487
488 // Used for native heap walkers: heap dumpers, mostly
489 void object_iterate(ObjectClosure* cl);
490 // Parallel heap iteration support
491 virtual ParallelObjectIterator* parallel_object_iterator(uint workers);
492
493 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
494 void keep_alive(oop obj);
495
496 // ---------- Safepoint interface hooks
497 //
498 public:
499 void safepoint_synchronize_begin();
500 void safepoint_synchronize_end();
501
502 // ---------- Code roots handling hooks
503 //
504 public:
505 void register_nmethod(nmethod* nm);
506 void unregister_nmethod(nmethod* nm);
507 void flush_nmethod(nmethod* nm);
508 void verify_nmethod(nmethod* nm) {}
509
510 // ---------- Pinning hooks
511 //
512 public:
513 // Shenandoah supports per-object (per-region) pinning
514 bool supports_object_pinning() const { return true; }
515
516 oop pin_object(JavaThread* thread, oop obj);
517 void unpin_object(JavaThread* thread, oop obj);
518
519 void sync_pinned_region_status();
520 void assert_pinned_region_status() NOT_DEBUG_RETURN;
521
522 // ---------- Concurrent Stack Processing support
523 //
524 public:
525 bool uses_stack_watermark_barrier() const { return true; }
526
527 // ---------- Allocation support
528 //
529 private:
530 HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
531 inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
532 HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
533 HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
534
535 public:
536 HeapWord* allocate_memory(ShenandoahAllocRequest& request);
537 HeapWord* mem_allocate(size_t size, bool* what);
538 MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
539 size_t size,
540 Metaspace::MetadataType mdtype);
541
542 void notify_mutator_alloc_words(size_t words, bool waste);
543
544 HeapWord* allocate_new_tlab(size_t min_size, size_t requested_size, size_t* actual_size);
545 size_t tlab_capacity(Thread *thr) const;
546 size_t unsafe_max_tlab_alloc(Thread *thread) const;
547 size_t max_tlab_size() const;
548 size_t tlab_used(Thread* ignored) const;
549
550 void ensure_parsability(bool retire_labs);
551
552 void labs_make_parsable();
553 void tlabs_retire(bool resize);
554 void gclabs_retire(bool resize);
555
556 // ---------- Marking support
557 //
558 private:
559 ShenandoahMarkingContext* _marking_context;
560 MemRegion _bitmap_region;
561 MemRegion _aux_bitmap_region;
562 MarkBitMap _verification_bit_map;
563 MarkBitMap _aux_bit_map;
564
565 size_t _bitmap_size;
566 size_t _bitmap_regions_per_slice;
567 size_t _bitmap_bytes_per_slice;
568
569 size_t _pretouch_heap_page_size;
570 size_t _pretouch_bitmap_page_size;
571
572 bool _bitmap_region_special;
573 bool _aux_bitmap_region_special;
574
575 ShenandoahLiveData** _liveness_cache;
576
577 public:
578 inline ShenandoahMarkingContext* complete_marking_context() const;
579 inline ShenandoahMarkingContext* marking_context() const;
580 inline void mark_complete_marking_context();
581 inline void mark_incomplete_marking_context();
582
583 template<class T>
584 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
585
586 template<class T>
587 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
588
589 template<class T>
590 inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
591
592 void reset_mark_bitmap();
593
594 // SATB barriers hooks
595 inline bool requires_marking(const void* entry) const;
596
597 // Support for bitmap uncommits
598 bool commit_bitmap_slice(ShenandoahHeapRegion *r);
599 bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
600 bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
601
602 // Liveness caching support
603 ShenandoahLiveData* get_liveness_cache(uint worker_id);
604 void flush_liveness_cache(uint worker_id);
605
606 size_t pretouch_heap_page_size() { return _pretouch_heap_page_size; }
607
608 // ---------- Evacuation support
609 //
610 private:
611 ShenandoahCollectionSet* _collection_set;
612 ShenandoahEvacOOMHandler _oom_evac_handler;
613
614 public:
615 static address in_cset_fast_test_addr();
616
617 ShenandoahCollectionSet* collection_set() const { return _collection_set; }
618
619 // Checks if object is in the collection set.
620 inline bool in_collection_set(oop obj) const;
621
622 // Checks if location is in the collection set. Can be interior pointer, not the oop itself.
623 inline bool in_collection_set_loc(void* loc) const;
624
625 // Evacuates object src. Returns the evacuated object, either evacuated
626 // by this thread, or by some other thread.
627 inline oop evacuate_object(oop src, Thread* thread);
628
629 // Call before/after evacuation.
630 inline void enter_evacuation(Thread* t);
631 inline void leave_evacuation(Thread* t);
632
633 // ---------- Helper functions
634 //
635 public:
636 template <class T>
637 inline void conc_update_with_forwarded(T* p);
638
639 template <class T>
640 inline void update_with_forwarded(T* p);
641
642 static inline oop cas_oop(oop n, narrowOop* addr, oop c);
643 static inline oop cas_oop(oop n, oop* addr, oop c);
644 static inline oop cas_oop(oop n, narrowOop* addr, narrowOop c);
645
646 void trash_humongous_region_at(ShenandoahHeapRegion *r);
647
648 private:
649 void trash_cset_regions();
650
651 // ---------- Testing helpers functions
652 //
653 private:
654 ShenandoahSharedFlag _inject_alloc_failure;
655
656 void try_inject_alloc_failure();
657 bool should_inject_alloc_failure();
658 };
659
660 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP