1 /*
2 * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2013, 2021, Red Hat, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
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24 */
25
26 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
27 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
28
29 #include "gc/shared/markBitMap.hpp"
30 #include "gc/shared/softRefPolicy.hpp"
31 #include "gc/shared/collectedHeap.hpp"
32 #include "gc/shenandoah/shenandoahAsserts.hpp"
33 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
34 #include "gc/shenandoah/shenandoahLock.hpp"
35 #include "gc/shenandoah/shenandoahEvacOOMHandler.hpp"
36 #include "gc/shenandoah/shenandoahPadding.hpp"
37 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
38 #include "gc/shenandoah/shenandoahUnload.hpp"
39 #include "memory/metaspace.hpp"
40 #include "services/memoryManager.hpp"
41 #include "utilities/globalDefinitions.hpp"
42 #include "utilities/stack.hpp"
43
44 class ConcurrentGCTimer;
45 class ObjectIterateScanRootClosure;
46 class ShenandoahCollectorPolicy;
47 class ShenandoahControlThread;
48 class ShenandoahGCSession;
49 class ShenandoahGCStateResetter;
50 class ShenandoahHeuristics;
51 class ShenandoahMarkingContext;
52 class ShenandoahMode;
53 class ShenandoahPhaseTimings;
54 class ShenandoahHeap;
55 class ShenandoahHeapRegion;
56 class ShenandoahHeapRegionClosure;
57 class ShenandoahCollectionSet;
58 class ShenandoahFreeSet;
59 class ShenandoahConcurrentMark;
60 class ShenandoahFullGC;
61 class ShenandoahMonitoringSupport;
62 class ShenandoahPacer;
63 class ShenandoahReferenceProcessor;
64 class ShenandoahVerifier;
65 class ShenandoahWorkerThreads;
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 override { return "Shenandoah"; }
148 ShenandoahHeap::Name kind() const override { return CollectedHeap::Shenandoah; }
149
150 ShenandoahHeap(ShenandoahCollectorPolicy* policy);
151 jint initialize() override;
152 void post_initialize() override;
153 void initialize_mode();
154 void initialize_heuristics();
155
156 void initialize_serviceability() override;
157
158 void print_on(outputStream* st) const override;
159 void print_extended_on(outputStream *st) const override;
160 void print_tracing_info() const override;
161 void print_heap_regions_on(outputStream* st) const;
162
163 void stop() override;
164
165 void prepare_for_verify() override;
166 void verify(VerifyOption vo) override;
167
168 // WhiteBox testing support.
169 bool supports_concurrent_gc_breakpoints() const override {
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 override;
199 size_t soft_max_capacity() const;
200 size_t initial_capacity() const;
201 size_t capacity() const override;
202 size_t used() const override;
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 ShenandoahWorkerThreads* _workers;
212 ShenandoahWorkerThreads* _safepoint_workers;
213
214 public:
215 uint max_workers();
216 void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
217
218 WorkerThreads* workers() const;
219 WorkerThreads* safepoint_workers() override;
220
221 void gc_threads_do(ThreadClosure* tcl) const override;
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
232 public:
233
234 inline HeapWord* base() const { return _heap_region.start(); }
235
236 inline size_t num_regions() const { return _num_regions; }
237 inline bool is_heap_region_special() { return _heap_region_special; }
238
239 inline ShenandoahHeapRegion* const heap_region_containing(const void* addr) const;
240 inline size_t heap_region_index_containing(const void* addr) const;
241
242 inline ShenandoahHeapRegion* const get_region(size_t region_idx) const;
243
244 void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
245 void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
246
247 // ---------- GC state machinery
248 //
249 // GC state describes the important parts of collector state, that may be
250 // used to make barrier selection decisions in the native and generated code.
251 // Multiple bits can be set at once.
252 //
253 // Important invariant: when GC state is zero, the heap is stable, and no barriers
254 // are required.
255 //
256 public:
257 enum GCStateBitPos {
258 // Heap has forwarded objects: needs LRB barriers.
259 HAS_FORWARDED_BITPOS = 0,
260
261 // Heap is under marking: needs SATB barriers.
262 MARKING_BITPOS = 1,
263
264 // Heap is under evacuation: needs LRB barriers. (Set together with HAS_FORWARDED)
265 EVACUATION_BITPOS = 2,
266
267 // Heap is under updating: needs no additional barriers.
268 UPDATEREFS_BITPOS = 3,
269
270 // Heap is under weak-reference/roots processing: needs weak-LRB barriers.
271 WEAK_ROOTS_BITPOS = 4,
272 };
273
274 enum GCState {
275 STABLE = 0,
276 HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
277 MARKING = 1 << MARKING_BITPOS,
278 EVACUATION = 1 << EVACUATION_BITPOS,
279 UPDATEREFS = 1 << UPDATEREFS_BITPOS,
280 WEAK_ROOTS = 1 << WEAK_ROOTS_BITPOS,
281 };
282
283 private:
284 ShenandoahSharedBitmap _gc_state;
285 ShenandoahSharedFlag _degenerated_gc_in_progress;
286 ShenandoahSharedFlag _full_gc_in_progress;
287 ShenandoahSharedFlag _full_gc_move_in_progress;
288 ShenandoahSharedFlag _progress_last_gc;
289 ShenandoahSharedFlag _concurrent_strong_root_in_progress;
290
291 void set_gc_state_all_threads(char state);
292 void set_gc_state_mask(uint mask, bool value);
293
294 public:
295 char gc_state() const;
296 static address gc_state_addr();
297
298 void set_concurrent_mark_in_progress(bool in_progress);
299 void set_evacuation_in_progress(bool in_progress);
300 void set_update_refs_in_progress(bool in_progress);
301 void set_degenerated_gc_in_progress(bool in_progress);
302 void set_full_gc_in_progress(bool in_progress);
303 void set_full_gc_move_in_progress(bool in_progress);
304 void set_has_forwarded_objects(bool cond);
305 void set_concurrent_strong_root_in_progress(bool cond);
306 void set_concurrent_weak_root_in_progress(bool cond);
307
308 inline bool is_stable() const;
309 inline bool is_idle() const;
310 inline bool is_concurrent_mark_in_progress() const;
311 inline bool is_update_refs_in_progress() const;
312 inline bool is_evacuation_in_progress() const;
313 inline bool is_degenerated_gc_in_progress() const;
314 inline bool is_full_gc_in_progress() const;
315 inline bool is_full_gc_move_in_progress() const;
316 inline bool has_forwarded_objects() const;
317 inline bool is_gc_in_progress_mask(uint mask) const;
318 inline bool is_stw_gc_in_progress() const;
319 inline bool is_concurrent_strong_root_in_progress() const;
320 inline bool is_concurrent_weak_root_in_progress() const;
321
322 private:
323 enum CancelState {
324 // Normal state. GC has not been cancelled and is open for cancellation.
325 // Worker threads can suspend for safepoint.
326 CANCELLABLE,
327
328 // GC has been cancelled. Worker threads can not suspend for
329 // safepoint but must finish their work as soon as possible.
330 CANCELLED,
331
332 // GC has not been cancelled and must not be cancelled. At least
333 // one worker thread checks for pending safepoint and may suspend
334 // if a safepoint is pending.
335 NOT_CANCELLED
336 };
337
338 ShenandoahSharedEnumFlag<CancelState> _cancelled_gc;
339 bool try_cancel_gc();
340
341 public:
342 static address cancelled_gc_addr();
343
344 inline bool cancelled_gc() const;
345 inline bool check_cancelled_gc_and_yield(bool sts_active = true);
346
347 inline void clear_cancelled_gc();
348
349 void cancel_gc(GCCause::Cause cause);
350
351 public:
352 // Elastic heap support
353 void entry_uncommit(double shrink_before, size_t shrink_until);
354 void op_uncommit(double shrink_before, size_t shrink_until);
355
356 private:
357 // GC support
358 // Reset bitmap, prepare regions for new GC cycle
359 void prepare_gc();
360 void prepare_regions_and_collection_set(bool concurrent);
361 // Evacuation
362 void prepare_evacuation(bool concurrent);
363 void evacuate_collection_set(bool concurrent);
364 // Concurrent root processing
365 void prepare_concurrent_roots();
366 void finish_concurrent_roots();
367 // Concurrent class unloading support
368 void do_class_unloading();
369 // Reference updating
370 void prepare_update_heap_references(bool concurrent);
371 void update_heap_references(bool concurrent);
372 // Final update region states
373 void update_heap_region_states(bool concurrent);
374 void rebuild_free_set(bool concurrent);
375
376 void rendezvous_threads();
377 void recycle_trash();
378 public:
379 void notify_gc_progress() { _progress_last_gc.set(); }
380 void notify_gc_no_progress() { _progress_last_gc.unset(); }
381
382 //
383 // Mark support
384 private:
385 ShenandoahControlThread* _control_thread;
386 ShenandoahCollectorPolicy* _shenandoah_policy;
387 ShenandoahMode* _gc_mode;
388 ShenandoahHeuristics* _heuristics;
389 ShenandoahFreeSet* _free_set;
390 ShenandoahPacer* _pacer;
391 ShenandoahVerifier* _verifier;
392
393 ShenandoahPhaseTimings* _phase_timings;
394
395 ShenandoahControlThread* control_thread() { return _control_thread; }
396
397 public:
398 ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
399 ShenandoahMode* mode() const { return _gc_mode; }
400 ShenandoahHeuristics* heuristics() const { return _heuristics; }
401 ShenandoahFreeSet* free_set() const { return _free_set; }
402 ShenandoahPacer* pacer() const { return _pacer; }
403
404 ShenandoahPhaseTimings* phase_timings() const { return _phase_timings; }
405
406 ShenandoahVerifier* verifier();
407
408 // ---------- VM subsystem bindings
409 //
410 private:
411 ShenandoahMonitoringSupport* _monitoring_support;
412 MemoryPool* _memory_pool;
413 GCMemoryManager _stw_memory_manager;
414 GCMemoryManager _cycle_memory_manager;
415 ConcurrentGCTimer* _gc_timer;
416 SoftRefPolicy _soft_ref_policy;
417
418 // For exporting to SA
419 int _log_min_obj_alignment_in_bytes;
420 public:
421 ShenandoahMonitoringSupport* monitoring_support() { return _monitoring_support; }
422 GCMemoryManager* cycle_memory_manager() { return &_cycle_memory_manager; }
423 GCMemoryManager* stw_memory_manager() { return &_stw_memory_manager; }
424 SoftRefPolicy* soft_ref_policy() override { return &_soft_ref_policy; }
425
426 GrowableArray<GCMemoryManager*> memory_managers() override;
427 GrowableArray<MemoryPool*> memory_pools() override;
428 MemoryUsage memory_usage() override;
429 GCTracer* tracer();
430 ConcurrentGCTimer* gc_timer() const;
431
432 // ---------- Reference processing
433 //
434 private:
435 ShenandoahReferenceProcessor* const _ref_processor;
436
437 public:
438 ShenandoahReferenceProcessor* ref_processor() { return _ref_processor; }
439
440 // ---------- Class Unloading
441 //
442 private:
443 ShenandoahSharedFlag _unload_classes;
444 ShenandoahUnload _unloader;
445
446 public:
447 void set_unload_classes(bool uc);
448 bool unload_classes() const;
449
450 // Perform STW class unloading and weak root cleaning
451 void parallel_cleaning(bool full_gc);
452
453 private:
454 void stw_unload_classes(bool full_gc);
455 void stw_process_weak_roots(bool full_gc);
456 void stw_weak_refs(bool full_gc);
457
458 // Heap iteration support
459 void scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops);
460 bool prepare_aux_bitmap_for_iteration();
461 void reclaim_aux_bitmap_for_iteration();
462
463 // ---------- Generic interface hooks
464 // Minor things that super-interface expects us to implement to play nice with
465 // the rest of runtime. Some of the things here are not required to be implemented,
466 // and can be stubbed out.
467 //
468 public:
469 bool is_maximal_no_gc() const override shenandoah_not_implemented_return(false);
470
471 bool is_in(const void* p) const override;
472
473 bool requires_barriers(stackChunkOop obj) const override;
474
475 MemRegion reserved_region() const { return _reserved; }
476 bool is_in_reserved(const void* addr) const { return _reserved.contains(addr); }
477
478 void collect(GCCause::Cause cause) override;
479 void do_full_collection(bool clear_all_soft_refs) override;
480
481 // Used for parsing heap during error printing
482 HeapWord* block_start(const void* addr) const;
483 bool block_is_obj(const HeapWord* addr) const;
484 bool print_location(outputStream* st, void* addr) const override;
485
486 // Used for native heap walkers: heap dumpers, mostly
487 void object_iterate(ObjectClosure* cl) override;
488 // Parallel heap iteration support
489 ParallelObjectIteratorImpl* parallel_object_iterator(uint workers) override;
490
491 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
492 void keep_alive(oop obj) override;
493
494 // ---------- Safepoint interface hooks
495 //
496 public:
497 void safepoint_synchronize_begin() override;
498 void safepoint_synchronize_end() override;
499
500 // ---------- Code roots handling hooks
501 //
502 public:
503 void register_nmethod(nmethod* nm) override;
504 void unregister_nmethod(nmethod* nm) override;
505 void verify_nmethod(nmethod* nm) override {}
506
507 // ---------- Pinning hooks
508 //
509 public:
510 // Shenandoah supports per-object (per-region) pinning
511 void pin_object(JavaThread* thread, oop obj) override;
512 void unpin_object(JavaThread* thread, oop obj) override;
513
514 void sync_pinned_region_status();
515 void assert_pinned_region_status() NOT_DEBUG_RETURN;
516
517 // ---------- Concurrent Stack Processing support
518 //
519 public:
520 bool uses_stack_watermark_barrier() const override { return true; }
521
522 // ---------- Allocation support
523 //
524 private:
525 HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
526 inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
527 HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
528 HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
529
530 public:
531 HeapWord* allocate_memory(ShenandoahAllocRequest& request);
532 HeapWord* mem_allocate(size_t size, bool* what) override;
533 MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
534 size_t size,
535 Metaspace::MetadataType mdtype) override;
536
537 void notify_mutator_alloc_words(size_t words, bool waste);
538
539 HeapWord* allocate_new_tlab(size_t min_size, size_t requested_size, size_t* actual_size) override;
540 size_t tlab_capacity(Thread *thr) const override;
541 size_t unsafe_max_tlab_alloc(Thread *thread) const override;
542 size_t max_tlab_size() const override;
543 size_t tlab_used(Thread* ignored) const override;
544
545 void ensure_parsability(bool retire_labs) override;
546
547 void labs_make_parsable();
548 void tlabs_retire(bool resize);
549 void gclabs_retire(bool resize);
550
551 // ---------- Marking support
552 //
553 private:
554 ShenandoahMarkingContext* _marking_context;
555 MemRegion _bitmap_region;
556 MemRegion _aux_bitmap_region;
557 MarkBitMap _verification_bit_map;
558 MarkBitMap _aux_bit_map;
559
560 size_t _bitmap_size;
561 size_t _bitmap_regions_per_slice;
562 size_t _bitmap_bytes_per_slice;
563
564 size_t _pretouch_heap_page_size;
565 size_t _pretouch_bitmap_page_size;
566
567 bool _bitmap_region_special;
568 bool _aux_bitmap_region_special;
569
570 ShenandoahLiveData** _liveness_cache;
571
572 public:
573 inline ShenandoahMarkingContext* complete_marking_context() const;
574 inline ShenandoahMarkingContext* marking_context() const;
575 inline void mark_complete_marking_context();
576 inline void mark_incomplete_marking_context();
577
578 template<class T>
579 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
580
581 template<class T>
582 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
583
584 template<class T>
585 inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
586
587 void reset_mark_bitmap();
588
589 // SATB barriers hooks
590 inline bool requires_marking(const void* entry) const;
591
592 // Support for bitmap uncommits
593 bool commit_bitmap_slice(ShenandoahHeapRegion *r);
594 bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
595 bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
596
597 // Liveness caching support
598 ShenandoahLiveData* get_liveness_cache(uint worker_id);
599 void flush_liveness_cache(uint worker_id);
600
601 size_t pretouch_heap_page_size() { return _pretouch_heap_page_size; }
602
603 // ---------- Evacuation support
604 //
605 private:
606 ShenandoahCollectionSet* _collection_set;
607 ShenandoahEvacOOMHandler _oom_evac_handler;
608
609 public:
610 static address in_cset_fast_test_addr();
611
612 ShenandoahCollectionSet* collection_set() const { return _collection_set; }
613
614 // Checks if object is in the collection set.
615 inline bool in_collection_set(oop obj) const;
616
617 // Checks if location is in the collection set. Can be interior pointer, not the oop itself.
618 inline bool in_collection_set_loc(void* loc) const;
619
620 // Evacuates object src. Returns the evacuated object, either evacuated
621 // by this thread, or by some other thread.
622 inline oop evacuate_object(oop src, Thread* thread);
623
624 // Call before/after evacuation.
625 inline void enter_evacuation(Thread* t);
626 inline void leave_evacuation(Thread* t);
627
628 // ---------- Helper functions
629 //
630 public:
631 template <class T>
632 inline void conc_update_with_forwarded(T* p);
633
634 template <class T>
635 inline void update_with_forwarded(T* p);
636
637 static inline void atomic_update_oop(oop update, oop* addr, oop compare);
638 static inline void atomic_update_oop(oop update, narrowOop* addr, oop compare);
639 static inline void atomic_update_oop(oop update, narrowOop* addr, narrowOop compare);
640
641 static inline bool atomic_update_oop_check(oop update, oop* addr, oop compare);
642 static inline bool atomic_update_oop_check(oop update, narrowOop* addr, oop compare);
643 static inline bool atomic_update_oop_check(oop update, narrowOop* addr, narrowOop compare);
644
645 static inline void atomic_clear_oop( oop* addr, oop compare);
646 static inline void atomic_clear_oop(narrowOop* addr, oop compare);
647 static inline void atomic_clear_oop(narrowOop* addr, narrowOop compare);
648
649 void trash_humongous_region_at(ShenandoahHeapRegion *r);
650
651 private:
652 void trash_cset_regions();
653
654 // ---------- Testing helpers functions
655 //
656 private:
657 ShenandoahSharedFlag _inject_alloc_failure;
658
659 void try_inject_alloc_failure();
660 bool should_inject_alloc_failure();
661 };
662
663 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP