1 /*
   2  * Copyright (c) 2015, 2019, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
  25 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
  26 
  27 #include "classfile/javaClasses.inline.hpp"
  28 #include "gc/shared/markBitMap.inline.hpp"
  29 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
  30 #include "gc/shared/suspendibleThreadSet.hpp"
  31 #include "gc/shenandoah/shenandoahAsserts.hpp"
  32 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
  33 #include "gc/shenandoah/shenandoahBrooksPointer.inline.hpp"
  34 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
  35 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
  36 #include "gc/shenandoah/shenandoahHeap.hpp"
  37 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
  38 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
  39 #include "gc/shenandoah/shenandoahControlThread.hpp"
  40 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  41 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
  42 #include "oops/oop.inline.hpp"
  43 #include "runtime/atomic.hpp"
  44 #include "runtime/prefetch.inline.hpp"
  45 #include "runtime/thread.hpp"
  46 #include "utilities/copy.hpp"
  47 #include "utilities/globalDefinitions.hpp"
  48 
  49 template <class T>
  50 void ShenandoahUpdateRefsClosure::do_oop_work(T* p) {
  51   T o = RawAccess<>::oop_load(p);
  52   if (!CompressedOops::is_null(o)) {
  53     oop obj = CompressedOops::decode_not_null(o);
  54     _heap->update_with_forwarded_not_null(p, obj);
  55   }
  56 }
  57 
  58 void ShenandoahUpdateRefsClosure::do_oop(oop* p)       { do_oop_work(p); }
  59 void ShenandoahUpdateRefsClosure::do_oop(narrowOop* p) { do_oop_work(p); }
  60 
  61 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {
  62   size_t new_index = Atomic::add((size_t) 1, &_index);
  63   // get_region() provides the bounds-check and returns NULL on OOB.
  64   return _heap->get_region(new_index - 1);
  65 }
  66 
  67 inline bool ShenandoahHeap::has_forwarded_objects() const {
  68   return _gc_state.is_set(HAS_FORWARDED);
  69 }
  70 
  71 inline WorkGang* ShenandoahHeap::workers() const {
  72   return _workers;
  73 }
  74 
  75 inline WorkGang* ShenandoahHeap::get_safepoint_workers() {
  76   return _safepoint_workers;
  77 }
  78 
  79 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
  80   uintptr_t region_start = ((uintptr_t) addr);
  81   uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
  82   assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
  83   return index;
  84 }
  85 
  86 inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {
  87   size_t index = heap_region_index_containing(addr);
  88   ShenandoahHeapRegion* const result = get_region(index);
  89   assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
  90   return result;
  91 }
  92 
  93 template <class T>
  94 inline oop ShenandoahHeap::update_with_forwarded_not_null(T* p, oop obj) {
  95   if (in_collection_set(obj)) {
  96     shenandoah_assert_forwarded_except(p, obj, is_full_gc_in_progress() || cancelled_gc() || is_degenerated_gc_in_progress());
  97     obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
  98     RawAccess<IS_NOT_NULL>::oop_store(p, obj);
  99   }
 100 #ifdef ASSERT
 101   else {
 102     shenandoah_assert_not_forwarded(p, obj);
 103   }
 104 #endif
 105   return obj;
 106 }
 107 
 108 template <class T>
 109 inline oop ShenandoahHeap::maybe_update_with_forwarded(T* p) {
 110   T o = RawAccess<>::oop_load(p);
 111   if (!CompressedOops::is_null(o)) {
 112     oop obj = CompressedOops::decode_not_null(o);
 113     return maybe_update_with_forwarded_not_null(p, obj);
 114   } else {
 115     return NULL;
 116   }
 117 }
 118 
 119 template <class T>
 120 inline oop ShenandoahHeap::evac_update_with_forwarded(T* p) {
 121   T o = RawAccess<>::oop_load(p);
 122   if (!CompressedOops::is_null(o)) {
 123     oop heap_oop = CompressedOops::decode_not_null(o);
 124     if (in_collection_set(heap_oop)) {
 125       oop forwarded_oop = ShenandoahBarrierSet::resolve_forwarded_not_null(heap_oop);
 126       if (oopDesc::equals_raw(forwarded_oop, heap_oop)) {
 127         forwarded_oop = evacuate_object(heap_oop, Thread::current());
 128       }
 129       oop prev = atomic_compare_exchange_oop(forwarded_oop, p, heap_oop);
 130       if (oopDesc::equals_raw(prev, heap_oop)) {
 131         return forwarded_oop;
 132       } else {
 133         return NULL;
 134       }
 135     }
 136     return heap_oop;
 137   } else {
 138     return NULL;
 139   }
 140 }
 141 
 142 inline oop ShenandoahHeap::atomic_compare_exchange_oop(oop n, oop* addr, oop c) {
 143   return (oop) Atomic::cmpxchg(n, addr, c);
 144 }
 145 
 146 inline oop ShenandoahHeap::atomic_compare_exchange_oop(oop n, narrowOop* addr, oop c) {
 147   narrowOop cmp = CompressedOops::encode(c);
 148   narrowOop val = CompressedOops::encode(n);
 149   return CompressedOops::decode((narrowOop) Atomic::cmpxchg(val, addr, cmp));
 150 }
 151 
 152 template <class T>
 153 inline oop ShenandoahHeap::maybe_update_with_forwarded_not_null(T* p, oop heap_oop) {
 154   shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || is_full_gc_in_progress() || is_degenerated_gc_in_progress());
 155   shenandoah_assert_correct(p, heap_oop);
 156 
 157   if (in_collection_set(heap_oop)) {
 158     oop forwarded_oop = ShenandoahBarrierSet::resolve_forwarded_not_null(heap_oop);
 159     if (oopDesc::equals_raw(forwarded_oop, heap_oop)) {
 160       // E.g. during evacuation.
 161       return forwarded_oop;
 162     }
 163 
 164     shenandoah_assert_forwarded_except(p, heap_oop, is_full_gc_in_progress() || is_degenerated_gc_in_progress());
 165     shenandoah_assert_not_in_cset_except(p, forwarded_oop, cancelled_gc());
 166 
 167     // If this fails, another thread wrote to p before us, it will be logged in SATB and the
 168     // reference be updated later.
 169     oop result = atomic_compare_exchange_oop(forwarded_oop, p, heap_oop);
 170 
 171     if (oopDesc::equals_raw(result, heap_oop)) { // CAS successful.
 172       return forwarded_oop;
 173     } else {
 174       // Note: we used to assert the following here. This doesn't work because sometimes, during
 175       // marking/updating-refs, it can happen that a Java thread beats us with an arraycopy,
 176       // which first copies the array, which potentially contains from-space refs, and only afterwards
 177       // updates all from-space refs to to-space refs, which leaves a short window where the new array
 178       // elements can be from-space.
 179       // assert(CompressedOops::is_null(result) ||
 180       //        oopDesc::equals_raw(result, ShenandoahBarrierSet::resolve_oop_static_not_null(result)),
 181       //       "expect not forwarded");
 182       return NULL;
 183     }
 184   } else {
 185     shenandoah_assert_not_forwarded(p, heap_oop);
 186     return heap_oop;
 187   }
 188 }
 189 
 190 inline bool ShenandoahHeap::cancelled_gc() const {
 191   return _cancelled_gc.get() == CANCELLED;
 192 }
 193 
 194 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {
 195   if (! (sts_active && ShenandoahSuspendibleWorkers)) {
 196     return cancelled_gc();
 197   }
 198 
 199   jbyte prev = _cancelled_gc.cmpxchg(NOT_CANCELLED, CANCELLABLE);
 200   if (prev == CANCELLABLE || prev == NOT_CANCELLED) {
 201     if (SuspendibleThreadSet::should_yield()) {
 202       SuspendibleThreadSet::yield();
 203     }
 204 
 205     // Back to CANCELLABLE. The thread that poked NOT_CANCELLED first gets
 206     // to restore to CANCELLABLE.
 207     if (prev == CANCELLABLE) {
 208       _cancelled_gc.set(CANCELLABLE);
 209     }
 210     return false;
 211   } else {
 212     return true;
 213   }
 214 }
 215 
 216 inline void ShenandoahHeap::clear_cancelled_gc() {
 217   _cancelled_gc.set(CANCELLABLE);
 218   _oom_evac_handler.clear();
 219 }
 220 
 221 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
 222   assert(UseTLAB, "TLABs should be enabled");
 223 
 224   PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
 225   if (gclab == NULL) {
 226     assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
 227            "Performance: thread should have GCLAB: %s", thread->name());
 228     // No GCLABs in this thread, fallback to shared allocation
 229     return NULL;
 230   }
 231   HeapWord* obj = gclab->allocate(size);
 232   if (obj != NULL) {
 233     return obj;
 234   }
 235   // Otherwise...
 236   return allocate_from_gclab_slow(thread, size);
 237 }
 238 
 239 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
 240   if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
 241     // This thread went through the OOM during evac protocol and it is safe to return
 242     // the forward pointer. It must not attempt to evacuate any more.
 243     return ShenandoahBarrierSet::resolve_forwarded(p);
 244   }
 245 
 246   assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
 247 
 248   size_t size_no_fwdptr = (size_t) p->size();
 249   size_t size_with_fwdptr = size_no_fwdptr + ShenandoahBrooksPointer::word_size();
 250 
 251   assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
 252 
 253   bool alloc_from_gclab = true;
 254   HeapWord* filler = NULL;
 255 
 256 #ifdef ASSERT
 257   if (ShenandoahOOMDuringEvacALot &&
 258       (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
 259         filler = NULL;
 260   } else {
 261 #endif
 262     if (UseTLAB) {
 263       filler = allocate_from_gclab(thread, size_with_fwdptr);
 264     }
 265     if (filler == NULL) {
 266       ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size_with_fwdptr);
 267       filler = allocate_memory(req);
 268       alloc_from_gclab = false;
 269     }
 270 #ifdef ASSERT
 271   }
 272 #endif
 273 
 274   if (filler == NULL) {
 275     control_thread()->handle_alloc_failure_evac(size_with_fwdptr);
 276 
 277     _oom_evac_handler.handle_out_of_memory_during_evacuation();
 278 
 279     return ShenandoahBarrierSet::resolve_forwarded(p);
 280   }
 281 
 282   // Copy the object and initialize its forwarding ptr:
 283   HeapWord* copy = filler + ShenandoahBrooksPointer::word_size();
 284   oop copy_val = oop(copy);
 285 
 286   Copy::aligned_disjoint_words((HeapWord*) p, copy, size_no_fwdptr);
 287   ShenandoahBrooksPointer::initialize(oop(copy));
 288 
 289   // Try to install the new forwarding pointer.
 290   oop result = ShenandoahBrooksPointer::try_update_forwardee(p, copy_val);
 291 
 292   if (oopDesc::equals_raw(result, p)) {
 293     // Successfully evacuated. Our copy is now the public one!
 294     shenandoah_assert_correct(NULL, copy_val);
 295     return copy_val;
 296   }  else {
 297     // Failed to evacuate. We need to deal with the object that is left behind. Since this
 298     // new allocation is certainly after TAMS, it will be considered live in the next cycle.
 299     // But if it happens to contain references to evacuated regions, those references would
 300     // not get updated for this stale copy during this cycle, and we will crash while scanning
 301     // it the next cycle.
 302     //
 303     // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
 304     // object will overwrite this stale copy, or the filler object on LAB retirement will
 305     // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
 306     // have to explicitly overwrite the copy with the filler object. With that overwrite,
 307     // we have to keep the fwdptr initialized and pointing to our (stale) copy.
 308     if (alloc_from_gclab) {
 309       ShenandoahThreadLocalData::gclab(thread)->undo_allocation(filler, size_with_fwdptr);
 310     } else {
 311       fill_with_object(copy, size_no_fwdptr);
 312     }
 313     shenandoah_assert_correct(NULL, copy_val);
 314     shenandoah_assert_correct(NULL, result);
 315     return result;
 316   }
 317 }
 318 
 319 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
 320   return !_marking_context->is_marked(oop(entry));
 321 }
 322 
 323 template <class T>
 324 inline bool ShenandoahHeap::in_collection_set(T p) const {
 325   HeapWord* obj = (HeapWord*) p;
 326   assert(collection_set() != NULL, "Sanity");
 327   assert(is_in(obj), "should be in heap");
 328 
 329   return collection_set()->is_in(obj);
 330 }
 331 
 332 inline bool ShenandoahHeap::is_stable() const {
 333   return _gc_state.is_clear();
 334 }
 335 
 336 inline bool ShenandoahHeap::is_idle() const {
 337   return _gc_state.is_unset(MARKING | EVACUATION | UPDATEREFS | TRAVERSAL);
 338 }
 339 
 340 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
 341   return _gc_state.is_set(MARKING);
 342 }
 343 
 344 inline bool ShenandoahHeap::is_concurrent_traversal_in_progress() const {
 345   return _gc_state.is_set(TRAVERSAL);
 346 }
 347 
 348 inline bool ShenandoahHeap::is_evacuation_in_progress() const {
 349   return _gc_state.is_set(EVACUATION);
 350 }
 351 
 352 inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const {
 353   return _gc_state.is_set(mask);
 354 }
 355 
 356 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
 357   return _degenerated_gc_in_progress.is_set();
 358 }
 359 
 360 inline bool ShenandoahHeap::is_full_gc_in_progress() const {
 361   return _full_gc_in_progress.is_set();
 362 }
 363 
 364 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {
 365   return _full_gc_move_in_progress.is_set();
 366 }
 367 
 368 inline bool ShenandoahHeap::is_update_refs_in_progress() const {
 369   return _gc_state.is_set(UPDATEREFS);
 370 }
 371 
 372 template<class T>
 373 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
 374   marked_object_iterate(region, cl, region->top());
 375 }
 376 
 377 template<class T>
 378 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
 379   assert(ShenandoahBrooksPointer::word_offset() < 0, "skip_delta calculation below assumes the forwarding ptr is before obj");
 380   assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
 381 
 382   ShenandoahMarkingContext* const ctx = complete_marking_context();
 383   assert(ctx->is_complete(), "sanity");
 384 
 385   MarkBitMap* mark_bit_map = ctx->mark_bit_map();
 386   HeapWord* tams = ctx->top_at_mark_start(region);
 387 
 388   size_t skip_bitmap_delta = ShenandoahBrooksPointer::word_size() + 1;
 389   size_t skip_objsize_delta = ShenandoahBrooksPointer::word_size() /* + actual obj.size() below */;
 390   HeapWord* start = region->bottom() + ShenandoahBrooksPointer::word_size();
 391   HeapWord* end = MIN2(tams + ShenandoahBrooksPointer::word_size(), region->end());
 392 
 393   // Step 1. Scan below the TAMS based on bitmap data.
 394   HeapWord* limit_bitmap = MIN2(limit, tams);
 395 
 396   // Try to scan the initial candidate. If the candidate is above the TAMS, it would
 397   // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.
 398   HeapWord* cb = mark_bit_map->get_next_marked_addr(start, end);
 399 
 400   intx dist = ShenandoahMarkScanPrefetch;
 401   if (dist > 0) {
 402     // Batched scan that prefetches the oop data, anticipating the access to
 403     // either header, oop field, or forwarding pointer. Not that we cannot
 404     // touch anything in oop, while it still being prefetched to get enough
 405     // time for prefetch to work. This is why we try to scan the bitmap linearly,
 406     // disregarding the object size. However, since we know forwarding pointer
 407     // preceeds the object, we can skip over it. Once we cannot trust the bitmap,
 408     // there is no point for prefetching the oop contents, as oop->size() will
 409     // touch it prematurely.
 410 
 411     // No variable-length arrays in standard C++, have enough slots to fit
 412     // the prefetch distance.
 413     static const int SLOT_COUNT = 256;
 414     guarantee(dist <= SLOT_COUNT, "adjust slot count");
 415     HeapWord* slots[SLOT_COUNT];
 416 
 417     int avail;
 418     do {
 419       avail = 0;
 420       for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {
 421         Prefetch::read(cb, ShenandoahBrooksPointer::byte_offset());
 422         slots[avail++] = cb;
 423         cb += skip_bitmap_delta;
 424         if (cb < limit_bitmap) {
 425           cb = mark_bit_map->get_next_marked_addr(cb, limit_bitmap);
 426         }
 427       }
 428 
 429       for (int c = 0; c < avail; c++) {
 430         assert (slots[c] < tams,  "only objects below TAMS here: "  PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));
 431         assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));
 432         oop obj = oop(slots[c]);
 433         assert(oopDesc::is_oop(obj), "sanity");
 434         assert(ctx->is_marked(obj), "object expected to be marked");
 435         cl->do_object(obj);
 436       }
 437     } while (avail > 0);
 438   } else {
 439     while (cb < limit_bitmap) {
 440       assert (cb < tams,  "only objects below TAMS here: "  PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));
 441       assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));
 442       oop obj = oop(cb);
 443       assert(oopDesc::is_oop(obj), "sanity");
 444       assert(ctx->is_marked(obj), "object expected to be marked");
 445       cl->do_object(obj);
 446       cb += skip_bitmap_delta;
 447       if (cb < limit_bitmap) {
 448         cb = mark_bit_map->get_next_marked_addr(cb, limit_bitmap);
 449       }
 450     }
 451   }
 452 
 453   // Step 2. Accurate size-based traversal, happens past the TAMS.
 454   // This restarts the scan at TAMS, which makes sure we traverse all objects,
 455   // regardless of what happened at Step 1.
 456   HeapWord* cs = tams + ShenandoahBrooksPointer::word_size();
 457   while (cs < limit) {
 458     assert (cs > tams,  "only objects past TAMS here: "   PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));
 459     assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));
 460     oop obj = oop(cs);
 461     assert(oopDesc::is_oop(obj), "sanity");
 462     assert(ctx->is_marked(obj), "object expected to be marked");
 463     int size = obj->size();
 464     cl->do_object(obj);
 465     cs += size + skip_objsize_delta;
 466   }
 467 }
 468 
 469 template <class T>
 470 class ShenandoahObjectToOopClosure : public ObjectClosure {
 471   T* _cl;
 472 public:
 473   ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}
 474 
 475   void do_object(oop obj) {
 476     obj->oop_iterate(_cl);
 477   }
 478 };
 479 
 480 template <class T>
 481 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {
 482   T* _cl;
 483   MemRegion _bounds;
 484 public:
 485   ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :
 486     _cl(cl), _bounds(bottom, top) {}
 487 
 488   void do_object(oop obj) {
 489     obj->oop_iterate(_cl, _bounds);
 490   }
 491 };
 492 
 493 template<class T>
 494 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {
 495   if (region->is_humongous()) {
 496     HeapWord* bottom = region->bottom();
 497     if (top > bottom) {
 498       region = region->humongous_start_region();
 499       ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);
 500       marked_object_iterate(region, &objs);
 501     }
 502   } else {
 503     ShenandoahObjectToOopClosure<T> objs(cl);
 504     marked_object_iterate(region, &objs, top);
 505   }
 506 }
 507 
 508 inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {
 509   if (region_idx < _num_regions) {
 510     return _regions[region_idx];
 511   } else {
 512     return NULL;
 513   }
 514 }
 515 
 516 inline void ShenandoahHeap::mark_complete_marking_context() {
 517   _marking_context->mark_complete();
 518 }
 519 
 520 inline void ShenandoahHeap::mark_incomplete_marking_context() {
 521   _marking_context->mark_incomplete();
 522 }
 523 
 524 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
 525   assert (_marking_context->is_complete()," sanity");
 526   return _marking_context;
 527 }
 528 
 529 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
 530   return _marking_context;
 531 }
 532 
 533 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP