1 /*
  2  * Copyright (c) 2001, 2021, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #include "precompiled.hpp"
 26 #include "classfile/classLoaderData.hpp"
 27 #include "classfile/vmClasses.hpp"
 28 #include "gc/shared/allocTracer.hpp"
 29 #include "gc/shared/barrierSet.hpp"
 30 #include "gc/shared/collectedHeap.hpp"
 31 #include "gc/shared/collectedHeap.inline.hpp"
 32 #include "gc/shared/gcLocker.inline.hpp"
 33 #include "gc/shared/gcHeapSummary.hpp"
 34 #include "gc/shared/stringdedup/stringDedup.hpp"
 35 #include "gc/shared/gcTrace.hpp"
 36 #include "gc/shared/gcTraceTime.inline.hpp"
 37 #include "gc/shared/gcVMOperations.hpp"
 38 #include "gc/shared/gcWhen.hpp"
 39 #include "gc/shared/gc_globals.hpp"
 40 #include "gc/shared/memAllocator.hpp"
 41 #include "gc/shared/tlab_globals.hpp"
 42 #include "logging/log.hpp"
 43 #include "logging/logStream.hpp"
 44 #include "memory/classLoaderMetaspace.hpp"
 45 #include "memory/metaspaceUtils.hpp"
 46 #include "memory/resourceArea.hpp"
 47 #include "memory/universe.hpp"
 48 #include "oops/instanceMirrorKlass.hpp"
 49 #include "oops/oop.inline.hpp"
 50 #include "runtime/handles.inline.hpp"
 51 #include "runtime/init.hpp"
 52 #include "runtime/perfData.hpp"
 53 #include "runtime/thread.inline.hpp"
 54 #include "runtime/threadSMR.hpp"
 55 #include "runtime/vmThread.hpp"
 56 #include "services/heapDumper.hpp"
 57 #include "utilities/align.hpp"
 58 #include "utilities/copy.hpp"
 59 #include "utilities/events.hpp"
 60 
 61 class ClassLoaderData;
 62 
 63 size_t CollectedHeap::_filler_array_max_size = 0;
 64 
 65 class GCMessage : public FormatBuffer<1024> {
 66  public:
 67   bool is_before;
 68 };
 69 
 70 template <>
 71 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
 72   st->print_cr("GC heap %s", m.is_before ? "before" : "after");
 73   st->print_raw(m);
 74 }
 75 
 76 class GCHeapLog : public EventLogBase<GCMessage> {
 77  private:
 78   void log_heap(CollectedHeap* heap, bool before);
 79 
 80  public:
 81   GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
 82 
 83   void log_heap_before(CollectedHeap* heap) {
 84     log_heap(heap, true);
 85   }
 86   void log_heap_after(CollectedHeap* heap) {
 87     log_heap(heap, false);
 88   }
 89 };
 90 
 91 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
 92   if (!should_log()) {
 93     return;
 94   }
 95 
 96   double timestamp = fetch_timestamp();
 97   MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag);
 98   int index = compute_log_index();
 99   _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
100   _records[index].timestamp = timestamp;
101   _records[index].data.is_before = before;
102   stringStream st(_records[index].data.buffer(), _records[index].data.size());
103 
104   st.print_cr("{Heap %s GC invocations=%u (full %u):",
105                  before ? "before" : "after",
106                  heap->total_collections(),
107                  heap->total_full_collections());
108 
109   heap->print_on(&st);
110   st.print_cr("}");
111 }
112 
113 ParallelObjectIterator::ParallelObjectIterator(uint thread_num) :
114   _impl(Universe::heap()->parallel_object_iterator(thread_num))
115 {}
116 
117 ParallelObjectIterator::~ParallelObjectIterator() {
118   delete _impl;
119 }
120 
121 void ParallelObjectIterator::object_iterate(ObjectClosure* cl, uint worker_id) {
122   _impl->object_iterate(cl, worker_id);
123 }
124 
125 size_t CollectedHeap::unused() const {
126   MutexLocker ml(Heap_lock);
127   return capacity() - used();
128 }
129 
130 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
131   size_t capacity_in_words = capacity() / HeapWordSize;
132 
133   return VirtualSpaceSummary(
134     _reserved.start(), _reserved.start() + capacity_in_words, _reserved.end());
135 }
136 
137 GCHeapSummary CollectedHeap::create_heap_summary() {
138   VirtualSpaceSummary heap_space = create_heap_space_summary();
139   return GCHeapSummary(heap_space, used());
140 }
141 
142 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
143   const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
144     MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
145   const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
146     MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
147   return MetaspaceSummary(MetaspaceGC::capacity_until_GC(),
148                           MetaspaceUtils::get_combined_statistics(),
149                           ms_chunk_free_list_summary, class_chunk_free_list_summary);
150 }
151 
152 void CollectedHeap::print_heap_before_gc() {
153   LogTarget(Debug, gc, heap) lt;
154   if (lt.is_enabled()) {
155     LogStream ls(lt);
156     ls.print_cr("Heap before GC invocations=%u (full %u):", total_collections(), total_full_collections());
157     ResourceMark rm;
158     print_on(&ls);
159   }
160 
161   if (_gc_heap_log != NULL) {
162     _gc_heap_log->log_heap_before(this);
163   }
164 }
165 
166 void CollectedHeap::print_heap_after_gc() {
167   LogTarget(Debug, gc, heap) lt;
168   if (lt.is_enabled()) {
169     LogStream ls(lt);
170     ls.print_cr("Heap after GC invocations=%u (full %u):", total_collections(), total_full_collections());
171     ResourceMark rm;
172     print_on(&ls);
173   }
174 
175   if (_gc_heap_log != NULL) {
176     _gc_heap_log->log_heap_after(this);
177   }
178 }
179 
180 void CollectedHeap::print() const { print_on(tty); }
181 
182 void CollectedHeap::print_on_error(outputStream* st) const {
183   st->print_cr("Heap:");
184   print_extended_on(st);
185   st->cr();
186 
187   BarrierSet* bs = BarrierSet::barrier_set();
188   if (bs != NULL) {
189     bs->print_on(st);
190   }
191 }
192 
193 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
194   const GCHeapSummary& heap_summary = create_heap_summary();
195   gc_tracer->report_gc_heap_summary(when, heap_summary);
196 
197   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
198   gc_tracer->report_metaspace_summary(when, metaspace_summary);
199 }
200 
201 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
202   trace_heap(GCWhen::BeforeGC, gc_tracer);
203 }
204 
205 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
206   trace_heap(GCWhen::AfterGC, gc_tracer);
207 }
208 
209 // Default implementation, for collectors that don't support the feature.
210 bool CollectedHeap::supports_concurrent_gc_breakpoints() const {
211   return false;
212 }
213 
214 bool CollectedHeap::is_oop(oop object) const {
215   if (!is_object_aligned(object)) {
216     return false;
217   }
218 
219   if (!is_in(object)) {
220     return false;
221   }
222 
223   return true;
224 }
225 
226 // Memory state functions.
227 
228 
229 CollectedHeap::CollectedHeap() :
230   _capacity_at_last_gc(0),
231   _used_at_last_gc(0),
232   _is_gc_active(false),
233   _last_whole_heap_examined_time_ns(os::javaTimeNanos()),
234   _total_collections(0),
235   _total_full_collections(0),
236   _gc_cause(GCCause::_no_gc),
237   _gc_lastcause(GCCause::_no_gc)
238 {
239   const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
240   const size_t elements_per_word = HeapWordSize / sizeof(jint);
241   _filler_array_max_size = align_object_size(filler_array_hdr_size() +
242                                              max_len / elements_per_word);
243 
244   NOT_PRODUCT(_promotion_failure_alot_count = 0;)
245   NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
246 
247   if (UsePerfData) {
248     EXCEPTION_MARK;
249 
250     // create the gc cause jvmstat counters
251     _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
252                              80, GCCause::to_string(_gc_cause), CHECK);
253 
254     _perf_gc_lastcause =
255                 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
256                              80, GCCause::to_string(_gc_lastcause), CHECK);
257   }
258 
259   // Create the ring log
260   if (LogEvents) {
261     _gc_heap_log = new GCHeapLog();
262   } else {
263     _gc_heap_log = NULL;
264   }
265 }
266 
267 // This interface assumes that it's being called by the
268 // vm thread. It collects the heap assuming that the
269 // heap lock is already held and that we are executing in
270 // the context of the vm thread.
271 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
272   Thread* thread = Thread::current();
273   assert(thread->is_VM_thread(), "Precondition#1");
274   assert(Heap_lock->is_locked(), "Precondition#2");
275   GCCauseSetter gcs(this, cause);
276   switch (cause) {
277     case GCCause::_heap_inspection:
278     case GCCause::_heap_dump:
279     case GCCause::_metadata_GC_threshold : {
280       HandleMark hm(thread);
281       do_full_collection(false);        // don't clear all soft refs
282       break;
283     }
284     case GCCause::_archive_time_gc:
285     case GCCause::_metadata_GC_clear_soft_refs: {
286       HandleMark hm(thread);
287       do_full_collection(true);         // do clear all soft refs
288       break;
289     }
290     default:
291       ShouldNotReachHere(); // Unexpected use of this function
292   }
293 }
294 
295 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
296                                                             size_t word_size,
297                                                             Metaspace::MetadataType mdtype) {
298   uint loop_count = 0;
299   uint gc_count = 0;
300   uint full_gc_count = 0;
301 
302   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
303 
304   do {
305     MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
306     if (result != NULL) {
307       return result;
308     }
309 
310     if (GCLocker::is_active_and_needs_gc()) {
311       // If the GCLocker is active, just expand and allocate.
312       // If that does not succeed, wait if this thread is not
313       // in a critical section itself.
314       result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
315       if (result != NULL) {
316         return result;
317       }
318       JavaThread* jthr = JavaThread::current();
319       if (!jthr->in_critical()) {
320         // Wait for JNI critical section to be exited
321         GCLocker::stall_until_clear();
322         // The GC invoked by the last thread leaving the critical
323         // section will be a young collection and a full collection
324         // is (currently) needed for unloading classes so continue
325         // to the next iteration to get a full GC.
326         continue;
327       } else {
328         if (CheckJNICalls) {
329           fatal("Possible deadlock due to allocating while"
330                 " in jni critical section");
331         }
332         return NULL;
333       }
334     }
335 
336     {  // Need lock to get self consistent gc_count's
337       MutexLocker ml(Heap_lock);
338       gc_count      = Universe::heap()->total_collections();
339       full_gc_count = Universe::heap()->total_full_collections();
340     }
341 
342     // Generate a VM operation
343     VM_CollectForMetadataAllocation op(loader_data,
344                                        word_size,
345                                        mdtype,
346                                        gc_count,
347                                        full_gc_count,
348                                        GCCause::_metadata_GC_threshold);
349     VMThread::execute(&op);
350 
351     // If GC was locked out, try again. Check before checking success because the
352     // prologue could have succeeded and the GC still have been locked out.
353     if (op.gc_locked()) {
354       continue;
355     }
356 
357     if (op.prologue_succeeded()) {
358       return op.result();
359     }
360     loop_count++;
361     if ((QueuedAllocationWarningCount > 0) &&
362         (loop_count % QueuedAllocationWarningCount == 0)) {
363       log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
364                             " size=" SIZE_FORMAT, loop_count, word_size);
365     }
366   } while (true);  // Until a GC is done
367 }
368 
369 MemoryUsage CollectedHeap::memory_usage() {
370   return MemoryUsage(InitialHeapSize, used(), capacity(), max_capacity());
371 }
372 
373 void CollectedHeap::set_gc_cause(GCCause::Cause v) {
374   if (UsePerfData) {
375     _gc_lastcause = _gc_cause;
376     _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
377     _perf_gc_cause->set_value(GCCause::to_string(v));
378   }
379   _gc_cause = v;
380 }
381 
382 #ifndef PRODUCT
383 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
384   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
385     // please note mismatch between size (in 32/64 bit words), and ju_addr that always point to a 32 bit word
386     for (juint* ju_addr = reinterpret_cast<juint*>(addr); ju_addr < reinterpret_cast<juint*>(addr + size); ++ju_addr) {
387       assert(*ju_addr == badHeapWordVal, "Found non badHeapWordValue in pre-allocation check");
388     }
389   }
390 }
391 #endif // PRODUCT
392 
393 size_t CollectedHeap::max_tlab_size() const {
394   // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
395   // This restriction could be removed by enabling filling with multiple arrays.
396   // If we compute that the reasonable way as
397   //    header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
398   // we'll overflow on the multiply, so we do the divide first.
399   // We actually lose a little by dividing first,
400   // but that just makes the TLAB  somewhat smaller than the biggest array,
401   // which is fine, since we'll be able to fill that.
402   size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
403               sizeof(jint) *
404               ((juint) max_jint / (size_t) HeapWordSize);
405   return align_down(max_int_size, MinObjAlignment);
406 }
407 
408 size_t CollectedHeap::filler_array_hdr_size() {
409   return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
410 }
411 
412 size_t CollectedHeap::filler_array_min_size() {
413   return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
414 }
415 
416 #ifdef ASSERT
417 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
418 {
419   assert(words >= min_fill_size(), "too small to fill");
420   assert(is_object_aligned(words), "unaligned size");
421 }
422 
423 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
424 {
425   if (ZapFillerObjects && zap) {
426     Copy::fill_to_words(start + filler_array_hdr_size(),
427                         words - filler_array_hdr_size(), 0XDEAFBABE);
428   }
429 }
430 #endif // ASSERT
431 
432 void
433 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
434 {
435   assert(words >= filler_array_min_size(), "too small for an array");
436   assert(words <= filler_array_max_size(), "too big for a single object");
437 
438   const size_t payload_size = words - filler_array_hdr_size();
439   const size_t len = payload_size * HeapWordSize / sizeof(jint);
440   assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
441 
442   ObjArrayAllocator allocator(Universe::intArrayKlassObj(), words, (int)len, /* do_zero */ false);
443   allocator.initialize(start);
444   DEBUG_ONLY(zap_filler_array(start, words, zap);)
445 }
446 
447 void
448 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
449 {
450   assert(words <= filler_array_max_size(), "too big for a single object");
451 
452   if (words >= filler_array_min_size()) {
453     fill_with_array(start, words, zap);
454   } else if (words > 0) {
455     assert(words == min_fill_size(), "unaligned size");
456     ObjAllocator allocator(vmClasses::Object_klass(), words);
457     allocator.initialize(start);
458   }
459 }
460 
461 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
462 {
463   DEBUG_ONLY(fill_args_check(start, words);)
464   HandleMark hm(Thread::current());  // Free handles before leaving.
465   fill_with_object_impl(start, words, zap);
466 }
467 
468 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
469 {
470   DEBUG_ONLY(fill_args_check(start, words);)
471   HandleMark hm(Thread::current());  // Free handles before leaving.
472 
473   // Multiple objects may be required depending on the filler array maximum size. Fill
474   // the range up to that with objects that are filler_array_max_size sized. The
475   // remainder is filled with a single object.
476   const size_t min = min_fill_size();
477   const size_t max = filler_array_max_size();
478   while (words > max) {
479     const size_t cur = (words - max) >= min ? max : max - min;
480     fill_with_array(start, cur, zap);
481     start += cur;
482     words -= cur;
483   }
484 
485   fill_with_object_impl(start, words, zap);
486 }
487 
488 void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
489   CollectedHeap::fill_with_object(start, end, zap);
490 }
491 
492 size_t CollectedHeap::min_dummy_object_size() const {
493   return oopDesc::header_size();
494 }
495 
496 size_t CollectedHeap::tlab_alloc_reserve() const {
497   size_t min_size = min_dummy_object_size();
498   return min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0;
499 }
500 
501 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
502                                            size_t requested_size,
503                                            size_t* actual_size) {
504   guarantee(false, "thread-local allocation buffers not supported");
505   return NULL;
506 }
507 
508 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
509   assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
510          "Should only be called at a safepoint or at start-up");
511 
512   ThreadLocalAllocStats stats;
513 
514   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next();) {
515     BarrierSet::barrier_set()->make_parsable(thread);
516     if (UseTLAB) {
517       if (retire_tlabs) {
518         thread->tlab().retire(&stats);
519       } else {
520         thread->tlab().make_parsable();
521       }
522     }
523   }
524 
525   stats.publish();
526 }
527 
528 void CollectedHeap::resize_all_tlabs() {
529   assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
530          "Should only resize tlabs at safepoint");
531 
532   if (UseTLAB && ResizeTLAB) {
533     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
534       thread->tlab().resize();
535     }
536   }
537 }
538 
539 jlong CollectedHeap::millis_since_last_whole_heap_examined() {
540   return (os::javaTimeNanos() - _last_whole_heap_examined_time_ns) / NANOSECS_PER_MILLISEC;
541 }
542 
543 void CollectedHeap::record_whole_heap_examined_timestamp() {
544   _last_whole_heap_examined_time_ns = os::javaTimeNanos();
545 }
546 
547 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
548   assert(timer != NULL, "timer is null");
549   if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
550     GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
551     HeapDumper::dump_heap();
552   }
553 
554   LogTarget(Trace, gc, classhisto) lt;
555   if (lt.is_enabled()) {
556     GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
557     ResourceMark rm;
558     LogStream ls(lt);
559     VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
560     inspector.doit();
561   }
562 }
563 
564 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
565   full_gc_dump(timer, true);
566 }
567 
568 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
569   full_gc_dump(timer, false);
570 }
571 
572 void CollectedHeap::initialize_reserved_region(const ReservedHeapSpace& rs) {
573   // It is important to do this in a way such that concurrent readers can't
574   // temporarily think something is in the heap.  (Seen this happen in asserts.)
575   _reserved.set_word_size(0);
576   _reserved.set_start((HeapWord*)rs.base());
577   _reserved.set_end((HeapWord*)rs.end());
578 }
579 
580 void CollectedHeap::post_initialize() {
581   StringDedup::initialize();
582   initialize_serviceability();
583 }
584 
585 #ifndef PRODUCT
586 
587 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
588   // Access to count is not atomic; the value does not have to be exact.
589   if (PromotionFailureALot) {
590     const size_t gc_num = total_collections();
591     const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
592     if (elapsed_gcs >= PromotionFailureALotInterval) {
593       // Test for unsigned arithmetic wrap-around.
594       if (++*count >= PromotionFailureALotCount) {
595         *count = 0;
596         return true;
597       }
598     }
599   }
600   return false;
601 }
602 
603 bool CollectedHeap::promotion_should_fail() {
604   return promotion_should_fail(&_promotion_failure_alot_count);
605 }
606 
607 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
608   if (PromotionFailureALot) {
609     _promotion_failure_alot_gc_number = total_collections();
610     *count = 0;
611   }
612 }
613 
614 void CollectedHeap::reset_promotion_should_fail() {
615   reset_promotion_should_fail(&_promotion_failure_alot_count);
616 }
617 
618 #endif  // #ifndef PRODUCT
619 
620 bool CollectedHeap::supports_object_pinning() const {
621   return false;
622 }
623 
624 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) {
625   ShouldNotReachHere();
626   return NULL;
627 }
628 
629 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
630   ShouldNotReachHere();
631 }
632 
633 bool CollectedHeap::is_archived_object(oop object) const {
634   return false;
635 }
636 
637 uint32_t CollectedHeap::hash_oop(oop obj) const {
638   const uintptr_t addr = cast_from_oop<uintptr_t>(obj);
639   return static_cast<uint32_t>(addr >> LogMinObjAlignment);
640 }
641 
642 // It's the caller's responsibility to ensure glitch-freedom
643 // (if required).
644 void CollectedHeap::update_capacity_and_used_at_gc() {
645   _capacity_at_last_gc = capacity();
646   _used_at_last_gc     = used();
647 }