1 /*
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  3  * Copyright (c) 2013, 2021, Red Hat, Inc. All rights reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  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).
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 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
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 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/heuristics/shenandoahSpaceInfo.hpp"
 33 #include "gc/shenandoah/shenandoahAsserts.hpp"
 34 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
 35 #include "gc/shenandoah/shenandoahLock.hpp"
 36 #include "gc/shenandoah/shenandoahEvacOOMHandler.hpp"
 37 #include "gc/shenandoah/shenandoahPadding.hpp"
 38 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
 39 #include "gc/shenandoah/shenandoahUnload.hpp"
 40 #include "memory/metaspace.hpp"
 41 #include "services/memoryManager.hpp"
 42 #include "utilities/globalDefinitions.hpp"
 43 #include "utilities/stack.hpp"
 44 
 45 class ConcurrentGCTimer;
 46 class ObjectIterateScanRootClosure;
 47 class ShenandoahCollectorPolicy;
 48 class ShenandoahControlThread;
 49 class ShenandoahGCSession;
 50 class ShenandoahGCStateResetter;
 51 class ShenandoahHeuristics;
 52 class ShenandoahMarkingContext;
 53 class ShenandoahMode;
 54 class ShenandoahPhaseTimings;
 55 class ShenandoahHeap;
 56 class ShenandoahHeapRegion;
 57 class ShenandoahHeapRegionClosure;
 58 class ShenandoahCollectionSet;
 59 class ShenandoahFreeSet;
 60 class ShenandoahConcurrentMark;
 61 class ShenandoahFullGC;
 62 class ShenandoahMonitoringSupport;
 63 class ShenandoahPacer;
 64 class ShenandoahReferenceProcessor;
 65 class ShenandoahVerifier;
 66 class ShenandoahWorkerThreads;
 67 class VMStructs;
 68 
 69 // Used for buffering per-region liveness data.
 70 // Needed since ShenandoahHeapRegion uses atomics to update liveness.
 71 // The ShenandoahHeap array has max-workers elements, each of which is an array of
 72 // uint16_t * max_regions. The choice of uint16_t is not accidental:
 73 // there is a tradeoff between static/dynamic footprint that translates
 74 // into cache pressure (which is already high during marking), and
 75 // too many atomic updates. uint32_t is too large, uint8_t is too small.
 76 typedef uint16_t ShenandoahLiveData;
 77 #define SHENANDOAH_LIVEDATA_MAX ((ShenandoahLiveData)-1)
 78 
 79 class ShenandoahRegionIterator : public StackObj {
 80 private:
 81   ShenandoahHeap* _heap;
 82 
 83   shenandoah_padding(0);
 84   volatile size_t _index;
 85   shenandoah_padding(1);
 86 
 87   // No implicit copying: iterators should be passed by reference to capture the state
 88   NONCOPYABLE(ShenandoahRegionIterator);
 89 
 90 public:
 91   ShenandoahRegionIterator();
 92   ShenandoahRegionIterator(ShenandoahHeap* heap);
 93 
 94   // Reset iterator to default state
 95   void reset();
 96 
 97   // Returns next region, or null if there are no more regions.
 98   // This is multi-thread-safe.
 99   inline ShenandoahHeapRegion* next();
100 
101   // This is *not* MT safe. However, in the absence of multithreaded access, it
102   // can be used to determine if there is more work to do.
103   bool has_next() const;
104 };
105 
106 class ShenandoahHeapRegionClosure : public StackObj {
107 public:
108   virtual void heap_region_do(ShenandoahHeapRegion* r) = 0;
109   virtual bool is_thread_safe() { return false; }
110 };
111 
112 typedef ShenandoahLock    ShenandoahHeapLock;
113 typedef ShenandoahLocker  ShenandoahHeapLocker;
114 typedef Stack<oop, mtGC>  ShenandoahScanObjectStack;
115 
116 // Shenandoah GC is low-pause concurrent GC that uses Brooks forwarding pointers
117 // to encode forwarding data. See BrooksPointer for details on forwarding data encoding.
118 // See ShenandoahControlThread for GC cycle structure.
119 //
120 class ShenandoahHeap : public CollectedHeap, public ShenandoahSpaceInfo {
121   friend class ShenandoahAsserts;
122   friend class VMStructs;
123   friend class ShenandoahGCSession;
124   friend class ShenandoahGCStateResetter;
125   friend class ShenandoahParallelObjectIterator;
126   friend class ShenandoahSafepoint;
127 
128   // Supported GC
129   friend class ShenandoahConcurrentGC;
130   friend class ShenandoahDegenGC;
131   friend class ShenandoahFullGC;
132   friend class ShenandoahUnload;
133 
134 // ---------- Locks that guard important data structures in Heap
135 //
136 private:
137   ShenandoahHeapLock _lock;
138 
139 public:
140   ShenandoahHeapLock* lock() {
141     return &_lock;
142   }
143 
144 // ---------- Initialization, termination, identification, printing routines
145 //
146 public:
147   static ShenandoahHeap* heap();
148 
149   const char* name()          const override { return "Shenandoah"; }
150   ShenandoahHeap::Name kind() const override { return CollectedHeap::Shenandoah; }
151 
152   ShenandoahHeap(ShenandoahCollectorPolicy* policy);
153   jint initialize() override;
154   void post_initialize() override;
155   void initialize_mode();
156   void initialize_heuristics();
157 
158   void initialize_serviceability() override;
159 
160   void print_on(outputStream* st)              const override;
161   void print_extended_on(outputStream *st)     const override;
162   void print_tracing_info()                    const override;
163   void print_heap_regions_on(outputStream* st) const;
164 
165   void stop() override;
166 
167   void prepare_for_verify() override;
168   void verify(VerifyOption vo) override;
169 
170 // WhiteBox testing support.
171   bool supports_concurrent_gc_breakpoints() const override {
172     return true;
173   }
174 
175 // ---------- Heap counters and metrics
176 //
177 private:
178            size_t _initial_size;
179            size_t _minimum_size;
180   volatile size_t _soft_max_size;
181   shenandoah_padding(0);
182   volatile size_t _used;
183   volatile size_t _committed;
184   volatile size_t _bytes_allocated_since_gc_start;
185   shenandoah_padding(1);
186 
187 public:
188   void increase_used(size_t bytes);
189   void decrease_used(size_t bytes);
190   void set_used(size_t bytes);
191 
192   void increase_committed(size_t bytes);
193   void decrease_committed(size_t bytes);
194   void increase_allocated(size_t bytes);
195 
196   size_t bytes_allocated_since_gc_start() const override;
197   void reset_bytes_allocated_since_gc_start();
198 
199   size_t min_capacity()      const;
200   size_t max_capacity()      const override;
201   size_t soft_max_capacity() const override;
202   size_t initial_capacity()  const;
203   size_t capacity()          const override;
204   size_t used()              const override;
205   size_t committed()         const;
206   size_t available()         const override;
207 
208   void set_soft_max_capacity(size_t v);
209 
210 // ---------- Periodic Tasks
211 //
212 private:
213   void notify_heap_changed();
214 
215 public:
216   void set_forced_counters_update(bool value);
217   void handle_force_counters_update();
218 
219 // ---------- Workers handling
220 //
221 private:
222   uint _max_workers;
223   ShenandoahWorkerThreads* _workers;
224   ShenandoahWorkerThreads* _safepoint_workers;
225 
226 public:
227   uint max_workers();
228   void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
229 
230   WorkerThreads* workers() const;
231   WorkerThreads* safepoint_workers() override;
232 
233   void gc_threads_do(ThreadClosure* tcl) const override;
234 
235 // ---------- Heap regions handling machinery
236 //
237 private:
238   MemRegion _heap_region;
239   bool      _heap_region_special;
240   size_t    _num_regions;
241   ShenandoahHeapRegion** _regions;
242   ShenandoahRegionIterator _update_refs_iterator;
243 
244 public:
245 
246   inline HeapWord* base() const { return _heap_region.start(); }
247 
248   inline size_t num_regions() const { return _num_regions; }
249   inline bool is_heap_region_special() { return _heap_region_special; }
250 
251   inline ShenandoahHeapRegion* heap_region_containing(const void* addr) const;
252   inline size_t heap_region_index_containing(const void* addr) const;
253 
254   inline ShenandoahHeapRegion* get_region(size_t region_idx) const;
255 
256   void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
257   void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
258 
259 // ---------- GC state machinery
260 //
261 // GC state describes the important parts of collector state, that may be
262 // used to make barrier selection decisions in the native and generated code.
263 // Multiple bits can be set at once.
264 //
265 // Important invariant: when GC state is zero, the heap is stable, and no barriers
266 // are required.
267 //
268 public:
269   enum GCStateBitPos {
270     // Heap has forwarded objects: needs LRB barriers.
271     HAS_FORWARDED_BITPOS   = 0,
272 
273     // Heap is under marking: needs SATB barriers.
274     MARKING_BITPOS    = 1,
275 
276     // Heap is under evacuation: needs LRB barriers. (Set together with HAS_FORWARDED)
277     EVACUATION_BITPOS = 2,
278 
279     // Heap is under updating: needs no additional barriers.
280     UPDATEREFS_BITPOS = 3,
281 
282     // Heap is under weak-reference/roots processing: needs weak-LRB barriers.
283     WEAK_ROOTS_BITPOS  = 4,
284   };
285 
286   enum GCState {
287     STABLE        = 0,
288     HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
289     MARKING       = 1 << MARKING_BITPOS,
290     EVACUATION    = 1 << EVACUATION_BITPOS,
291     UPDATEREFS    = 1 << UPDATEREFS_BITPOS,
292     WEAK_ROOTS    = 1 << WEAK_ROOTS_BITPOS,
293   };
294 
295 private:
296   bool _gc_state_changed;
297   ShenandoahSharedBitmap _gc_state;
298 
299   // tracks if new regions have been allocated or retired since last check
300   ShenandoahSharedFlag   _heap_changed;
301   ShenandoahSharedFlag   _degenerated_gc_in_progress;
302   ShenandoahSharedFlag   _full_gc_in_progress;
303   ShenandoahSharedFlag   _full_gc_move_in_progress;
304   ShenandoahSharedFlag   _concurrent_strong_root_in_progress;
305 
306   size_t _gc_no_progress_count;
307 
308   // This updates the singlular, global gc state. This must happen on a safepoint.
309   void set_gc_state(uint mask, bool value);
310 
311 public:
312   char gc_state() const;
313 
314   // This copies the global gc state into a thread local variable for java threads.
315   // It is primarily intended to support quick access at barriers.
316   void propagate_gc_state_to_java_threads();
317 
318   // This is public to support assertions that the state hasn't been changed off of
319   // a safepoint and that any changes were propagated to java threads after the safepoint.
320   bool has_gc_state_changed() const { return _gc_state_changed; }
321 
322   // Returns true if allocations have occurred in new regions or if regions have been
323   // uncommitted since the previous calls. This call will reset the flag to false.
324   bool has_changed() {
325     return _heap_changed.try_unset();
326   }
327 
328   void set_concurrent_mark_in_progress(bool in_progress);
329   void set_evacuation_in_progress(bool in_progress);
330   void set_update_refs_in_progress(bool in_progress);
331   void set_degenerated_gc_in_progress(bool in_progress);
332   void set_full_gc_in_progress(bool in_progress);
333   void set_full_gc_move_in_progress(bool in_progress);
334   void set_has_forwarded_objects(bool cond);
335   void set_concurrent_strong_root_in_progress(bool cond);
336   void set_concurrent_weak_root_in_progress(bool cond);
337 
338   inline bool is_stable() const;
339   inline bool is_idle() const;
340   inline bool is_concurrent_mark_in_progress() const;
341   inline bool is_update_refs_in_progress() const;
342   inline bool is_evacuation_in_progress() const;
343   inline bool is_degenerated_gc_in_progress() const;
344   inline bool is_full_gc_in_progress() const;
345   inline bool is_full_gc_move_in_progress() const;
346   inline bool has_forwarded_objects() const;
347 
348   inline bool is_stw_gc_in_progress() const;
349   inline bool is_concurrent_strong_root_in_progress() const;
350   inline bool is_concurrent_weak_root_in_progress() const;
351 
352 private:
353   enum CancelState {
354     // Normal state. GC has not been cancelled and is open for cancellation.
355     // Worker threads can suspend for safepoint.
356     CANCELLABLE,
357 
358     // GC has been cancelled. Worker threads can not suspend for
359     // safepoint but must finish their work as soon as possible.
360     CANCELLED
361   };
362 
363   ShenandoahSharedEnumFlag<CancelState> _cancelled_gc;
364   bool try_cancel_gc();
365 
366 public:
367 
368   inline bool cancelled_gc() const;
369   inline bool check_cancelled_gc_and_yield(bool sts_active = true);
370 
371   inline void clear_cancelled_gc();
372 
373   void cancel_gc(GCCause::Cause cause);
374 
375 public:
376   // These will uncommit empty regions if heap::committed > shrink_until
377   // and there exists at least one region which was made empty before shrink_before.
378   void maybe_uncommit(double shrink_before, size_t shrink_until);
379   void op_uncommit(double shrink_before, size_t shrink_until);
380 
381   // Returns true if the soft maximum heap has been changed using management APIs.
382   bool check_soft_max_changed();
383 
384 private:
385   // GC support
386   // Reset bitmap, prepare regions for new GC cycle
387   void prepare_gc();
388   void prepare_regions_and_collection_set(bool concurrent);
389   // Evacuation
390   void evacuate_collection_set(bool concurrent);
391   // Concurrent root processing
392   void prepare_concurrent_roots();
393   void finish_concurrent_roots();
394   // Concurrent class unloading support
395   void do_class_unloading();
396   // Reference updating
397   void prepare_update_heap_references(bool concurrent);
398   void update_heap_references(bool concurrent);
399   // Final update region states
400   void update_heap_region_states(bool concurrent);
401   void rebuild_free_set(bool concurrent);
402 
403   void rendezvous_threads(const char* name);
404   void recycle_trash();
405 public:
406   void notify_gc_progress();
407   void notify_gc_no_progress();
408   size_t get_gc_no_progress_count() const;
409 
410 //
411 // Mark support
412 private:
413   ShenandoahControlThread*   _control_thread;
414   ShenandoahCollectorPolicy* _shenandoah_policy;
415   ShenandoahMode*            _gc_mode;
416   ShenandoahHeuristics*      _heuristics;
417   ShenandoahFreeSet*         _free_set;
418   ShenandoahPacer*           _pacer;
419   ShenandoahVerifier*        _verifier;
420 
421   ShenandoahPhaseTimings*    _phase_timings;
422 
423   ShenandoahControlThread*   control_thread()          { return _control_thread;    }
424 
425 public:
426   ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
427   ShenandoahMode*            mode()              const { return _gc_mode;           }
428   ShenandoahHeuristics*      heuristics()        const { return _heuristics;        }
429   ShenandoahFreeSet*         free_set()          const { return _free_set;          }
430   ShenandoahPacer*           pacer()             const { return _pacer;             }
431 
432   ShenandoahPhaseTimings*    phase_timings()     const { return _phase_timings;     }
433 
434   ShenandoahVerifier*        verifier();
435 
436 // ---------- VM subsystem bindings
437 //
438 private:
439   ShenandoahMonitoringSupport* _monitoring_support;
440   MemoryPool*                  _memory_pool;
441   GCMemoryManager              _stw_memory_manager;
442   GCMemoryManager              _cycle_memory_manager;
443   ConcurrentGCTimer*           _gc_timer;
444   // For exporting to SA
445   int                          _log_min_obj_alignment_in_bytes;
446 public:
447   ShenandoahMonitoringSupport* monitoring_support()          { return _monitoring_support;    }
448   GCMemoryManager* cycle_memory_manager()                    { return &_cycle_memory_manager; }
449   GCMemoryManager* stw_memory_manager()                      { return &_stw_memory_manager;   }
450 
451   GrowableArray<GCMemoryManager*> memory_managers() override;
452   GrowableArray<MemoryPool*> memory_pools() override;
453   MemoryUsage memory_usage() override;
454   GCTracer* tracer();
455   ConcurrentGCTimer* gc_timer() const;
456 
457 // ---------- Reference processing
458 //
459 private:
460   ShenandoahReferenceProcessor* const _ref_processor;
461 
462 public:
463   ShenandoahReferenceProcessor* ref_processor() { return _ref_processor; }
464 
465 // ---------- Class Unloading
466 //
467 private:
468   ShenandoahSharedFlag _unload_classes;
469   ShenandoahUnload     _unloader;
470 
471 public:
472   void set_unload_classes(bool uc);
473   bool unload_classes() const;
474 
475   // Perform STW class unloading and weak root cleaning
476   void parallel_cleaning(bool full_gc);
477 
478 private:
479   void stw_unload_classes(bool full_gc);
480   void stw_process_weak_roots(bool full_gc);
481   void stw_weak_refs(bool full_gc);
482 
483   // Heap iteration support
484   void scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops);
485   bool prepare_aux_bitmap_for_iteration();
486   void reclaim_aux_bitmap_for_iteration();
487 
488 // ---------- Generic interface hooks
489 // Minor things that super-interface expects us to implement to play nice with
490 // the rest of runtime. Some of the things here are not required to be implemented,
491 // and can be stubbed out.
492 //
493 public:
494   bool is_maximal_no_gc() const override shenandoah_not_implemented_return(false);
495 
496   // Check the pointer is in active part of Java heap.
497   // Use is_in_reserved to check if object is within heap bounds.
498   bool is_in(const void* p) const override;
499 
500   bool requires_barriers(stackChunkOop obj) const override;
501 
502   MemRegion reserved_region() const { return _reserved; }
503   bool is_in_reserved(const void* addr) const { return _reserved.contains(addr); }
504 
505   void collect(GCCause::Cause cause) override;
506   void do_full_collection(bool clear_all_soft_refs) override;
507 
508   // Used for parsing heap during error printing
509   HeapWord* block_start(const void* addr) const;
510   bool block_is_obj(const HeapWord* addr) const;
511   bool print_location(outputStream* st, void* addr) const override;
512 
513   // Used for native heap walkers: heap dumpers, mostly
514   void object_iterate(ObjectClosure* cl) override;
515   // Parallel heap iteration support
516   ParallelObjectIteratorImpl* parallel_object_iterator(uint workers) override;
517 
518   // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
519   void keep_alive(oop obj) override;
520 
521 // ---------- Safepoint interface hooks
522 //
523 public:
524   void safepoint_synchronize_begin() override;
525   void safepoint_synchronize_end() override;
526 
527 // ---------- Code roots handling hooks
528 //
529 public:
530   void register_nmethod(nmethod* nm) override;
531   void unregister_nmethod(nmethod* nm) override;
532   void verify_nmethod(nmethod* nm) override {}
533 
534 // ---------- Pinning hooks
535 //
536 public:
537   // Shenandoah supports per-object (per-region) pinning
538   void pin_object(JavaThread* thread, oop obj) override;
539   void unpin_object(JavaThread* thread, oop obj) override;
540 
541   void sync_pinned_region_status();
542   void assert_pinned_region_status() NOT_DEBUG_RETURN;
543 
544 // ---------- CDS archive support
545 
546   bool can_load_archived_objects() const override { return UseCompressedOops; }
547   HeapWord* allocate_loaded_archive_space(size_t size) override;
548   void complete_loaded_archive_space(MemRegion archive_space) override;
549 
550 // ---------- Allocation support
551 //
552 private:
553   HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
554   inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
555   HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
556   HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
557 
558 public:
559   HeapWord* allocate_memory(ShenandoahAllocRequest& request);
560   HeapWord* mem_allocate(size_t size, bool* what) override;
561   MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
562                                                size_t size,
563                                                Metaspace::MetadataType mdtype) override;
564 
565   void notify_mutator_alloc_words(size_t words, bool waste);
566 
567   HeapWord* allocate_new_tlab(size_t min_size, size_t requested_size, size_t* actual_size) override;
568   size_t tlab_capacity(Thread *thr) const override;
569   size_t unsafe_max_tlab_alloc(Thread *thread) const override;
570   size_t max_tlab_size() const override;
571   size_t tlab_used(Thread* ignored) const override;
572 
573   void ensure_parsability(bool retire_labs) override;
574 
575   void labs_make_parsable();
576   void tlabs_retire(bool resize);
577   void gclabs_retire(bool resize);
578 
579 // ---------- Marking support
580 //
581 private:
582   ShenandoahMarkingContext* _marking_context;
583   MemRegion  _bitmap_region;
584   MemRegion  _aux_bitmap_region;
585   MarkBitMap _verification_bit_map;
586   MarkBitMap _aux_bit_map;
587 
588   size_t _bitmap_size;
589   size_t _bitmap_regions_per_slice;
590   size_t _bitmap_bytes_per_slice;
591 
592   size_t _pretouch_heap_page_size;
593   size_t _pretouch_bitmap_page_size;
594 
595   bool _bitmap_region_special;
596   bool _aux_bitmap_region_special;
597 
598   ShenandoahLiveData** _liveness_cache;
599 
600 public:
601   inline ShenandoahMarkingContext* complete_marking_context() const;
602   inline ShenandoahMarkingContext* marking_context() const;
603   inline void mark_complete_marking_context();
604   inline void mark_incomplete_marking_context();
605 
606   template<class T>
607   inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
608 
609   template<class T>
610   inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
611 
612   template<class T>
613   inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
614 
615   void reset_mark_bitmap();
616 
617   // SATB barriers hooks
618   inline bool requires_marking(const void* entry) const;
619 
620   // Support for bitmap uncommits
621   bool commit_bitmap_slice(ShenandoahHeapRegion *r);
622   bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
623   bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
624 
625   // Liveness caching support
626   ShenandoahLiveData* get_liveness_cache(uint worker_id);
627   void flush_liveness_cache(uint worker_id);
628 
629   size_t pretouch_heap_page_size() { return _pretouch_heap_page_size; }
630 
631 // ---------- Evacuation support
632 //
633 private:
634   ShenandoahCollectionSet* _collection_set;
635   ShenandoahEvacOOMHandler _oom_evac_handler;
636 
637 public:
638   static address in_cset_fast_test_addr();
639 
640   ShenandoahCollectionSet* collection_set() const { return _collection_set; }
641 
642   // Checks if object is in the collection set.
643   inline bool in_collection_set(oop obj) const;
644 
645   // Checks if location is in the collection set. Can be interior pointer, not the oop itself.
646   inline bool in_collection_set_loc(void* loc) const;
647 
648   // Evacuates object src. Returns the evacuated object, either evacuated
649   // by this thread, or by some other thread.
650   oop evacuate_object(oop src, Thread* thread);
651 
652   // Call before/after evacuation.
653   inline void enter_evacuation(Thread* t);
654   inline void leave_evacuation(Thread* t);
655 
656 // ---------- Helper functions
657 //
658 public:
659   template <class T>
660   inline void conc_update_with_forwarded(T* p);
661 
662   template <class T>
663   inline void update_with_forwarded(T* p);
664 
665   static inline void atomic_update_oop(oop update,       oop* addr,       oop compare);
666   static inline void atomic_update_oop(oop update, narrowOop* addr,       oop compare);
667   static inline void atomic_update_oop(oop update, narrowOop* addr, narrowOop compare);
668 
669   static inline bool atomic_update_oop_check(oop update,       oop* addr,       oop compare);
670   static inline bool atomic_update_oop_check(oop update, narrowOop* addr,       oop compare);
671   static inline bool atomic_update_oop_check(oop update, narrowOop* addr, narrowOop compare);
672 
673   static inline void atomic_clear_oop(      oop* addr,       oop compare);
674   static inline void atomic_clear_oop(narrowOop* addr,       oop compare);
675   static inline void atomic_clear_oop(narrowOop* addr, narrowOop compare);
676 
677   void trash_humongous_region_at(ShenandoahHeapRegion *r);
678 
679 private:
680   void trash_cset_regions();
681 
682 // ---------- Testing helpers functions
683 //
684 private:
685   ShenandoahSharedFlag _inject_alloc_failure;
686 
687   void try_inject_alloc_failure();
688   bool should_inject_alloc_failure();
689 };
690 
691 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP