1 /*
  2  * Copyright (c) 2015, 2020, 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.
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 24 
 25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
 26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
 27 
 28 #include "gc/shenandoah/shenandoahHeap.hpp"
 29 
 30 #include "classfile/javaClasses.inline.hpp"
 31 #include "gc/shared/markBitMap.inline.hpp"
 32 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
 33 #include "gc/shared/continuationGCSupport.inline.hpp"
 34 #include "gc/shared/suspendibleThreadSet.hpp"
 35 #include "gc/shared/tlab_globals.hpp"
 36 #include "gc/shenandoah/shenandoahAsserts.hpp"
 37 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
 38 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
 39 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
 40 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
 41 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
 42 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
 43 #include "gc/shenandoah/shenandoahControlThread.hpp"
 44 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
 45 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
 46 #include "oops/compressedOops.inline.hpp"
 47 #include "oops/oop.inline.hpp"
 48 #include "runtime/atomic.hpp"
 49 #include "runtime/javaThread.hpp"
 50 #include "runtime/prefetch.inline.hpp"
 51 #include "utilities/copy.hpp"
 52 #include "utilities/globalDefinitions.hpp"
 53 
 54 inline ShenandoahHeap* ShenandoahHeap::heap() {
 55   return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
 56 }
 57 
 58 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {
 59   size_t new_index = Atomic::add(&_index, (size_t) 1, memory_order_relaxed);
 60   // get_region() provides the bounds-check and returns null on OOB.
 61   return _heap->get_region(new_index - 1);
 62 }
 63 
 64 inline bool ShenandoahHeap::has_forwarded_objects() const {
 65   return _gc_state.is_set(HAS_FORWARDED);
 66 }
 67 
 68 inline WorkerThreads* ShenandoahHeap::workers() const {
 69   return _workers;
 70 }
 71 
 72 inline WorkerThreads* ShenandoahHeap::safepoint_workers() {
 73   return _safepoint_workers;
 74 }
 75 
 76 inline void ShenandoahHeap::notify_gc_progress() {
 77   Atomic::store(&_gc_no_progress_count, (size_t) 0);
 78 
 79 }
 80 inline void ShenandoahHeap::notify_gc_no_progress() {
 81   Atomic::inc(&_gc_no_progress_count);
 82 }
 83 
 84 inline size_t ShenandoahHeap::get_gc_no_progress_count() const {
 85   return Atomic::load(&_gc_no_progress_count);
 86 }
 87 
 88 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
 89   uintptr_t region_start = ((uintptr_t) addr);
 90   uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
 91   assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
 92   return index;
 93 }
 94 
 95 inline ShenandoahHeapRegion* ShenandoahHeap::heap_region_containing(const void* addr) const {
 96   size_t index = heap_region_index_containing(addr);
 97   ShenandoahHeapRegion* const result = get_region(index);
 98   assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
 99   return result;
100 }
101 
102 inline void ShenandoahHeap::enter_evacuation(Thread* t) {
103   _oom_evac_handler.enter_evacuation(t);
104 }
105 
106 inline void ShenandoahHeap::leave_evacuation(Thread* t) {
107   _oom_evac_handler.leave_evacuation(t);
108 }
109 
110 template <class T>
111 inline void ShenandoahHeap::update_with_forwarded(T* p) {
112   T o = RawAccess<>::oop_load(p);
113   if (!CompressedOops::is_null(o)) {
114     oop obj = CompressedOops::decode_not_null(o);
115     if (in_collection_set(obj)) {
116       // Corner case: when evacuation fails, there are objects in collection
117       // set that are not really forwarded. We can still go and try and update them
118       // (uselessly) to simplify the common path.
119       shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
120       oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
121       shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
122 
123       // Unconditionally store the update: no concurrent updates expected.
124       RawAccess<IS_NOT_NULL>::oop_store(p, fwd);
125     }
126   }
127 }
128 
129 template <class T>
130 inline void ShenandoahHeap::conc_update_with_forwarded(T* p) {
131   T o = RawAccess<>::oop_load(p);
132   if (!CompressedOops::is_null(o)) {
133     oop obj = CompressedOops::decode_not_null(o);
134     if (in_collection_set(obj)) {
135       // Corner case: when evacuation fails, there are objects in collection
136       // set that are not really forwarded. We can still go and try CAS-update them
137       // (uselessly) to simplify the common path.
138       shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
139       oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
140       shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
141 
142       // Sanity check: we should not be updating the cset regions themselves,
143       // unless we are recovering from the evacuation failure.
144       shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || cancelled_gc());
145 
146       // Either we succeed in updating the reference, or something else gets in our way.
147       // We don't care if that is another concurrent GC update, or another mutator update.
148       atomic_update_oop(fwd, p, obj);
149     }
150   }
151 }
152 
153 // Atomic updates of heap location. This is only expected to work with updating the same
154 // logical object with its forwardee. The reason why we need stronger-than-relaxed memory
155 // ordering has to do with coordination with GC barriers and mutator accesses.
156 //
157 // In essence, stronger CAS access is required to maintain the transitive chains that mutator
158 // accesses build by themselves. To illustrate this point, consider the following example.
159 //
160 // Suppose "o" is the object that has a field "x" and the reference to "o" is stored
161 // to field at "addr", which happens to be Java volatile field. Normally, the accesses to volatile
162 // field at "addr" would be matched with release/acquire barriers. This changes when GC moves
163 // the object under mutator feet.
164 //
165 // Thread 1 (Java)
166 //         // --- previous access starts here
167 //         ...
168 //   T1.1: store(&o.x, 1, mo_relaxed)
169 //   T1.2: store(&addr, o, mo_release) // volatile store
170 //
171 //         // --- new access starts here
172 //         // LRB: copy and install the new copy to fwdptr
173 //   T1.3: var copy = copy(o)
174 //   T1.4: cas(&fwd, t, copy, mo_release) // pointer-mediated publication
175 //         <access continues>
176 //
177 // Thread 2 (GC updater)
178 //   T2.1: var f = load(&fwd, mo_{consume|acquire}) // pointer-mediated acquisition
179 //   T2.2: cas(&addr, o, f, mo_release) // this method
180 //
181 // Thread 3 (Java)
182 //   T3.1: var o = load(&addr, mo_acquire) // volatile read
183 //   T3.2: if (o != null)
184 //   T3.3:   var r = load(&o.x, mo_relaxed)
185 //
186 // r is guaranteed to contain "1".
187 //
188 // Without GC involvement, there is synchronizes-with edge from T1.2 to T3.1,
189 // which guarantees this. With GC involvement, when LRB copies the object and
190 // another thread updates the reference to it, we need to have the transitive edge
191 // from T1.4 to T2.1 (that one is guaranteed by forwarding accesses), plus the edge
192 // from T2.2 to T3.1 (which is brought by this CAS).
193 //
194 // Note that we do not need to "acquire" in these methods, because we do not read the
195 // failure witnesses contents on any path, and "release" is enough.
196 //
197 
198 inline void ShenandoahHeap::atomic_update_oop(oop update, oop* addr, oop compare) {
199   assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
200   Atomic::cmpxchg(addr, compare, update, memory_order_release);
201 }
202 
203 inline void ShenandoahHeap::atomic_update_oop(oop update, narrowOop* addr, narrowOop compare) {
204   assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
205   narrowOop u = CompressedOops::encode(update);
206   Atomic::cmpxchg(addr, compare, u, memory_order_release);
207 }
208 
209 inline void ShenandoahHeap::atomic_update_oop(oop update, narrowOop* addr, oop compare) {
210   assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
211   narrowOop c = CompressedOops::encode(compare);
212   narrowOop u = CompressedOops::encode(update);
213   Atomic::cmpxchg(addr, c, u, memory_order_release);
214 }
215 
216 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, oop* addr, oop compare) {
217   assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
218   return (oop) Atomic::cmpxchg(addr, compare, update, memory_order_release) == compare;
219 }
220 
221 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, narrowOop* addr, narrowOop compare) {
222   assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
223   narrowOop u = CompressedOops::encode(update);
224   return (narrowOop) Atomic::cmpxchg(addr, compare, u, memory_order_release) == compare;
225 }
226 
227 inline bool ShenandoahHeap::atomic_update_oop_check(oop update, narrowOop* addr, oop compare) {
228   assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
229   narrowOop c = CompressedOops::encode(compare);
230   narrowOop u = CompressedOops::encode(update);
231   return CompressedOops::decode(Atomic::cmpxchg(addr, c, u, memory_order_release)) == compare;
232 }
233 
234 // The memory ordering discussion above does not apply for methods that store nulls:
235 // then, there is no transitive reads in mutator (as we see nulls), and we can do
236 // relaxed memory ordering there.
237 
238 inline void ShenandoahHeap::atomic_clear_oop(oop* addr, oop compare) {
239   assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
240   Atomic::cmpxchg(addr, compare, oop(), memory_order_relaxed);
241 }
242 
243 inline void ShenandoahHeap::atomic_clear_oop(narrowOop* addr, oop compare) {
244   assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
245   narrowOop cmp = CompressedOops::encode(compare);
246   Atomic::cmpxchg(addr, cmp, narrowOop(), memory_order_relaxed);
247 }
248 
249 inline void ShenandoahHeap::atomic_clear_oop(narrowOop* addr, narrowOop compare) {
250   assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
251   Atomic::cmpxchg(addr, compare, narrowOop(), memory_order_relaxed);
252 }
253 
254 inline bool ShenandoahHeap::cancelled_gc() const {
255   return _cancelled_gc.get() == CANCELLED;
256 }
257 
258 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {
259   if (sts_active && ShenandoahSuspendibleWorkers && !cancelled_gc()) {
260     if (SuspendibleThreadSet::should_yield()) {
261       SuspendibleThreadSet::yield();
262     }
263   }
264   return cancelled_gc();
265 }
266 
267 inline void ShenandoahHeap::clear_cancelled_gc() {
268   _cancelled_gc.set(CANCELLABLE);
269   _oom_evac_handler.clear();
270 }
271 
272 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
273   assert(UseTLAB, "TLABs should be enabled");
274 
275   PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
276   if (gclab == nullptr) {
277     assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
278            "Performance: thread should have GCLAB: %s", thread->name());
279     // No GCLABs in this thread, fallback to shared allocation
280     return nullptr;
281   }
282   HeapWord* obj = gclab->allocate(size);
283   if (obj != nullptr) {
284     return obj;
285   }
286   // Otherwise...
287   return allocate_from_gclab_slow(thread, size);
288 }
289 
290 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
291   if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
292     // This thread went through the OOM during evac protocol and it is safe to return
293     // the forward pointer. It must not attempt to evacuate any more.
294     return ShenandoahBarrierSet::resolve_forwarded(p);
295   }
296 
297   assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
298 
299   size_t size = p->size();
300 
301   assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
302 
303   bool alloc_from_gclab = true;
304   HeapWord* copy = nullptr;
305 
306 #ifdef ASSERT
307   if (ShenandoahOOMDuringEvacALot &&
308       (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
309         copy = nullptr;
310   } else {
311 #endif
312     if (UseTLAB) {
313       copy = allocate_from_gclab(thread, size);
314     }
315     if (copy == nullptr) {
316       ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);
317       copy = allocate_memory(req);
318       alloc_from_gclab = false;
319     }
320 #ifdef ASSERT
321   }
322 #endif
323 
324   if (copy == nullptr) {
325     control_thread()->handle_alloc_failure_evac(size);
326 
327     _oom_evac_handler.handle_out_of_memory_during_evacuation();
328 
329     return ShenandoahBarrierSet::resolve_forwarded(p);
330   }
331 
332   // Copy the object:
333   Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
334 
335   // Try to install the new forwarding pointer.
336   oop copy_val = cast_to_oop(copy);
337   ContinuationGCSupport::relativize_stack_chunk(copy_val);
338 
339   oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
340   if (result == copy_val) {
341     // Successfully evacuated. Our copy is now the public one!
342     shenandoah_assert_correct(nullptr, copy_val);
343     return copy_val;
344   }  else {
345     // Failed to evacuate. We need to deal with the object that is left behind. Since this
346     // new allocation is certainly after TAMS, it will be considered live in the next cycle.
347     // But if it happens to contain references to evacuated regions, those references would
348     // not get updated for this stale copy during this cycle, and we will crash while scanning
349     // it the next cycle.
350     //
351     // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
352     // object will overwrite this stale copy, or the filler object on LAB retirement will
353     // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
354     // have to explicitly overwrite the copy with the filler object. With that overwrite,
355     // we have to keep the fwdptr initialized and pointing to our (stale) copy.
356     if (alloc_from_gclab) {
357       ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
358     } else {
359       fill_with_object(copy, size);
360       shenandoah_assert_correct(nullptr, copy_val);
361     }
362     shenandoah_assert_correct(nullptr, result);
363     return result;
364   }
365 }
366 
367 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
368   oop obj = cast_to_oop(entry);
369   return !_marking_context->is_marked_strong(obj);
370 }
371 
372 inline bool ShenandoahHeap::in_collection_set(oop p) const {
373   assert(collection_set() != nullptr, "Sanity");
374   return collection_set()->is_in(p);
375 }
376 
377 inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
378   assert(collection_set() != nullptr, "Sanity");
379   return collection_set()->is_in_loc(p);
380 }
381 
382 inline bool ShenandoahHeap::is_stable() const {
383   return _gc_state.is_clear();
384 }
385 
386 inline bool ShenandoahHeap::is_idle() const {
387   return _gc_state.is_unset(MARKING | EVACUATION | UPDATEREFS);
388 }
389 
390 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
391   return _gc_state.is_set(MARKING);
392 }
393 
394 inline bool ShenandoahHeap::is_evacuation_in_progress() const {
395   return _gc_state.is_set(EVACUATION);
396 }
397 
398 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
399   return _degenerated_gc_in_progress.is_set();
400 }
401 
402 inline bool ShenandoahHeap::is_full_gc_in_progress() const {
403   return _full_gc_in_progress.is_set();
404 }
405 
406 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {
407   return _full_gc_move_in_progress.is_set();
408 }
409 
410 inline bool ShenandoahHeap::is_update_refs_in_progress() const {
411   return _gc_state.is_set(UPDATEREFS);
412 }
413 
414 inline bool ShenandoahHeap::is_stw_gc_in_progress() const {
415   return is_full_gc_in_progress() || is_degenerated_gc_in_progress();
416 }
417 
418 inline bool ShenandoahHeap::is_concurrent_strong_root_in_progress() const {
419   return _concurrent_strong_root_in_progress.is_set();
420 }
421 
422 inline bool ShenandoahHeap::is_concurrent_weak_root_in_progress() const {
423   return _gc_state.is_set(WEAK_ROOTS);
424 }
425 
426 template<class T>
427 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
428   marked_object_iterate(region, cl, region->top());
429 }
430 
431 template<class T>
432 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
433   assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
434 
435   ShenandoahMarkingContext* const ctx = complete_marking_context();
436   assert(ctx->is_complete(), "sanity");
437 
438   HeapWord* tams = ctx->top_at_mark_start(region);
439 
440   size_t skip_bitmap_delta = 1;
441   HeapWord* start = region->bottom();
442   HeapWord* end = MIN2(tams, region->end());
443 
444   // Step 1. Scan below the TAMS based on bitmap data.
445   HeapWord* limit_bitmap = MIN2(limit, tams);
446 
447   // Try to scan the initial candidate. If the candidate is above the TAMS, it would
448   // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.
449   HeapWord* cb = ctx->get_next_marked_addr(start, end);
450 
451   intx dist = ShenandoahMarkScanPrefetch;
452   if (dist > 0) {
453     // Batched scan that prefetches the oop data, anticipating the access to
454     // either header, oop field, or forwarding pointer. Not that we cannot
455     // touch anything in oop, while it still being prefetched to get enough
456     // time for prefetch to work. This is why we try to scan the bitmap linearly,
457     // disregarding the object size. However, since we know forwarding pointer
458     // precedes the object, we can skip over it. Once we cannot trust the bitmap,
459     // there is no point for prefetching the oop contents, as oop->size() will
460     // touch it prematurely.
461 
462     // No variable-length arrays in standard C++, have enough slots to fit
463     // the prefetch distance.
464     static const int SLOT_COUNT = 256;
465     guarantee(dist <= SLOT_COUNT, "adjust slot count");
466     HeapWord* slots[SLOT_COUNT];
467 
468     int avail;
469     do {
470       avail = 0;
471       for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {
472         Prefetch::read(cb, oopDesc::mark_offset_in_bytes());
473         slots[avail++] = cb;
474         cb += skip_bitmap_delta;
475         if (cb < limit_bitmap) {
476           cb = ctx->get_next_marked_addr(cb, limit_bitmap);
477         }
478       }
479 
480       for (int c = 0; c < avail; c++) {
481         assert (slots[c] < tams,  "only objects below TAMS here: "  PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));
482         assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));
483         oop obj = cast_to_oop(slots[c]);
484         assert(oopDesc::is_oop(obj), "sanity");
485         assert(ctx->is_marked(obj), "object expected to be marked");
486         cl->do_object(obj);
487       }
488     } while (avail > 0);
489   } else {
490     while (cb < limit_bitmap) {
491       assert (cb < tams,  "only objects below TAMS here: "  PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));
492       assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));
493       oop obj = cast_to_oop(cb);
494       assert(oopDesc::is_oop(obj), "sanity");
495       assert(ctx->is_marked(obj), "object expected to be marked");
496       cl->do_object(obj);
497       cb += skip_bitmap_delta;
498       if (cb < limit_bitmap) {
499         cb = ctx->get_next_marked_addr(cb, limit_bitmap);
500       }
501     }
502   }
503 
504   // Step 2. Accurate size-based traversal, happens past the TAMS.
505   // This restarts the scan at TAMS, which makes sure we traverse all objects,
506   // regardless of what happened at Step 1.
507   HeapWord* cs = tams;
508   while (cs < limit) {
509     assert (cs >= tams, "only objects past TAMS here: "   PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));
510     assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));
511     oop obj = cast_to_oop(cs);
512     assert(oopDesc::is_oop(obj), "sanity");
513     assert(ctx->is_marked(obj), "object expected to be marked");
514     size_t size = obj->size();
515     cl->do_object(obj);
516     cs += size;
517   }
518 }
519 
520 template <class T>
521 class ShenandoahObjectToOopClosure : public ObjectClosure {
522   T* _cl;
523 public:
524   ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}
525 
526   void do_object(oop obj) {
527     obj->oop_iterate(_cl);
528   }
529 };
530 
531 template <class T>
532 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {
533   T* _cl;
534   MemRegion _bounds;
535 public:
536   ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :
537     _cl(cl), _bounds(bottom, top) {}
538 
539   void do_object(oop obj) {
540     obj->oop_iterate(_cl, _bounds);
541   }
542 };
543 
544 template<class T>
545 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {
546   if (region->is_humongous()) {
547     HeapWord* bottom = region->bottom();
548     if (top > bottom) {
549       region = region->humongous_start_region();
550       ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);
551       marked_object_iterate(region, &objs);
552     }
553   } else {
554     ShenandoahObjectToOopClosure<T> objs(cl);
555     marked_object_iterate(region, &objs, top);
556   }
557 }
558 
559 inline ShenandoahHeapRegion* ShenandoahHeap::get_region(size_t region_idx) const {
560   if (region_idx < _num_regions) {
561     return _regions[region_idx];
562   } else {
563     return nullptr;
564   }
565 }
566 
567 inline void ShenandoahHeap::mark_complete_marking_context() {
568   _marking_context->mark_complete();
569 }
570 
571 inline void ShenandoahHeap::mark_incomplete_marking_context() {
572   _marking_context->mark_incomplete();
573 }
574 
575 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
576   assert (_marking_context->is_complete()," sanity");
577   return _marking_context;
578 }
579 
580 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
581   return _marking_context;
582 }
583 
584 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP