1 /*
  2  * Copyright (c) 1997, 2024, 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/classLoaderDataGraph.hpp"
 27 #include "classfile/classLoaderData.inline.hpp"
 28 #include "classfile/javaClasses.inline.hpp"
 29 #include "classfile/stringTable.hpp"
 30 #include "classfile/symbolTable.hpp"
 31 #include "classfile/systemDictionary.hpp"
 32 #include "classfile/vmSymbols.hpp"
 33 #include "code/codeCache.hpp"
 34 #include "compiler/compileBroker.hpp"
 35 #include "compiler/oopMap.hpp"
 36 #include "gc/serial/cardTableRS.hpp"
 37 #include "gc/serial/defNewGeneration.hpp"
 38 #include "gc/serial/serialFullGC.hpp"
 39 #include "gc/serial/serialGcRefProcProxyTask.hpp"
 40 #include "gc/serial/serialHeap.hpp"
 41 #include "gc/serial/serialStringDedup.hpp"
 42 #include "gc/serial/tenuredGeneration.inline.hpp"
 43 #include "gc/shared/classUnloadingContext.hpp"
 44 #include "gc/shared/collectedHeap.inline.hpp"
 45 #include "gc/shared/continuationGCSupport.inline.hpp"
 46 #include "gc/shared/gcHeapSummary.hpp"
 47 #include "gc/shared/gcTimer.hpp"
 48 #include "gc/shared/gcTrace.hpp"
 49 #include "gc/shared/gcTraceTime.inline.hpp"
 50 #include "gc/shared/gc_globals.hpp"
 51 #include "gc/shared/modRefBarrierSet.hpp"
 52 #include "gc/shared/preservedMarks.inline.hpp"
 53 #include "gc/shared/referencePolicy.hpp"
 54 #include "gc/shared/referenceProcessorPhaseTimes.hpp"

 55 #include "gc/shared/space.hpp"
 56 #include "gc/shared/strongRootsScope.hpp"
 57 #include "gc/shared/weakProcessor.hpp"
 58 #include "memory/iterator.inline.hpp"
 59 #include "memory/universe.hpp"
 60 #include "oops/access.inline.hpp"
 61 #include "oops/compressedOops.inline.hpp"
 62 #include "oops/instanceRefKlass.hpp"
 63 #include "oops/markWord.hpp"
 64 #include "oops/methodData.hpp"
 65 #include "oops/objArrayKlass.inline.hpp"
 66 #include "oops/oop.inline.hpp"
 67 #include "oops/typeArrayOop.inline.hpp"
 68 #include "runtime/prefetch.inline.hpp"
 69 #include "utilities/align.hpp"
 70 #include "utilities/copy.hpp"
 71 #include "utilities/events.hpp"
 72 #include "utilities/stack.inline.hpp"
 73 #if INCLUDE_JVMCI
 74 #include "jvmci/jvmci.hpp"
 75 #endif
 76 
 77 Stack<oop, mtGC>              SerialFullGC::_marking_stack;
 78 Stack<ObjArrayTask, mtGC>     SerialFullGC::_objarray_stack;
 79 
 80 PreservedMarksSet       SerialFullGC::_preserved_overflow_stack_set(false /* in_c_heap */);
 81 size_t                  SerialFullGC::_preserved_count = 0;
 82 size_t                  SerialFullGC::_preserved_count_max = 0;
 83 PreservedMark*          SerialFullGC::_preserved_marks = nullptr;
 84 STWGCTimer*             SerialFullGC::_gc_timer        = nullptr;
 85 SerialOldTracer*        SerialFullGC::_gc_tracer       = nullptr;
 86 
 87 AlwaysTrueClosure   SerialFullGC::_always_true_closure;
 88 ReferenceProcessor* SerialFullGC::_ref_processor;
 89 
 90 StringDedup::Requests*  SerialFullGC::_string_dedup_requests = nullptr;
 91 
 92 SerialFullGC::FollowRootClosure  SerialFullGC::follow_root_closure;
 93 
 94 MarkAndPushClosure SerialFullGC::mark_and_push_closure(ClassLoaderData::_claim_stw_fullgc_mark);
 95 CLDToOopClosure    SerialFullGC::follow_cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
 96 CLDToOopClosure    SerialFullGC::adjust_cld_closure(&adjust_pointer_closure, ClassLoaderData::_claim_stw_fullgc_adjust);
 97 
 98 class DeadSpacer : StackObj {
 99   size_t _allowed_deadspace_words;
100   bool _active;
101   ContiguousSpace* _space;
102 
103 public:
104   DeadSpacer(ContiguousSpace* space) : _allowed_deadspace_words(0), _space(space) {
105     size_t ratio = (_space == SerialHeap::heap()->old_gen()->space())
106                    ? MarkSweepDeadRatio : 0;
107     _active = ratio > 0;
108 
109     if (_active) {
110       // We allow some amount of garbage towards the bottom of the space, so
111       // we don't start compacting before there is a significant gain to be made.
112       // Occasionally, we want to ensure a full compaction, which is determined
113       // by the MarkSweepAlwaysCompactCount parameter.
114       if ((SerialHeap::heap()->total_full_collections() % MarkSweepAlwaysCompactCount) != 0) {
115         _allowed_deadspace_words = (space->capacity() * ratio / 100) / HeapWordSize;
116       } else {
117         _active = false;
118       }
119     }
120   }
121 
122   bool insert_deadspace(HeapWord* dead_start, HeapWord* dead_end) {
123     if (!_active) {
124       return false;
125     }
126 
127     size_t dead_length = pointer_delta(dead_end, dead_start);
128     if (_allowed_deadspace_words >= dead_length) {
129       _allowed_deadspace_words -= dead_length;
130       CollectedHeap::fill_with_object(dead_start, dead_length);
131       oop obj = cast_to_oop(dead_start);
132       // obj->set_mark(obj->mark().set_marked());
133 
134       assert(dead_length == obj->size(), "bad filler object size");
135       log_develop_trace(gc, compaction)("Inserting object to dead space: " PTR_FORMAT ", " PTR_FORMAT ", " SIZE_FORMAT "b",
136                                         p2i(dead_start), p2i(dead_end), dead_length * HeapWordSize);
137 
138       return true;
139     } else {
140       _active = false;
141       return false;
142     }
143   }
144 };
145 
146 // Implement the "compaction" part of the mark-compact GC algorithm.
147 class Compacter {
148   // There are four spaces in total, but only the first three can be used after
149   // compact. IOW, old and eden/from must be enough for all live objs
150   static constexpr uint max_num_spaces = 4;
151 
152   struct CompactionSpace {
153     ContiguousSpace* _space;
154     // Will be the new top after compaction is complete.
155     HeapWord* _compaction_top;
156     // The first dead word in this contiguous space. It's an optimization to
157     // skip large chunk of live objects at the beginning.
158     HeapWord* _first_dead;
159 
160     void init(ContiguousSpace* space) {
161       _space = space;
162       _compaction_top = space->bottom();
163       _first_dead = nullptr;
164     }
165   };
166 
167   CompactionSpace _spaces[max_num_spaces];
168   // The num of spaces to be compacted, i.e. containing live objs.
169   uint _num_spaces;
170 
171   uint _index;
172 
173   // Used for BOT update
174   TenuredGeneration* _old_gen;
175 
176   HeapWord* get_compaction_top(uint index) const {
177     return _spaces[index]._compaction_top;
178   }
179 
180   HeapWord* get_first_dead(uint index) const {
181     return _spaces[index]._first_dead;
182   }
183 
184   ContiguousSpace* get_space(uint index) const {
185     return _spaces[index]._space;
186   }
187 
188   void record_first_dead(uint index, HeapWord* first_dead) {
189     assert(_spaces[index]._first_dead == nullptr, "should write only once");
190     _spaces[index]._first_dead = first_dead;
191   }
192 
193   HeapWord* alloc(size_t words) {
194     while (true) {
195       if (words <= pointer_delta(_spaces[_index]._space->end(),
196                                  _spaces[_index]._compaction_top)) {
197         HeapWord* result = _spaces[_index]._compaction_top;
198         _spaces[_index]._compaction_top += words;
199         if (_index == 0) {
200           // old-gen requires BOT update
201           _old_gen->update_for_block(result, result + words);
202         }
203         return result;
204       }
205 
206       // out-of-memory in this space
207       _index++;
208       assert(_index < max_num_spaces - 1, "the last space should not be used");
209     }
210   }
211 
212   static void prefetch_read_scan(void* p) {
213     if (PrefetchScanIntervalInBytes >= 0) {
214       Prefetch::read(p, PrefetchScanIntervalInBytes);
215     }
216   }
217 
218   static void prefetch_write_scan(void* p) {
219     if (PrefetchScanIntervalInBytes >= 0) {
220       Prefetch::write(p, PrefetchScanIntervalInBytes);
221     }
222   }
223 
224   static void prefetch_write_copy(void* p) {
225     if (PrefetchCopyIntervalInBytes >= 0) {
226       Prefetch::write(p, PrefetchCopyIntervalInBytes);
227     }
228   }
229 
230   static void forward_obj(oop obj, HeapWord* new_addr) {
231     prefetch_write_scan(obj);
232     if (cast_from_oop<HeapWord*>(obj) != new_addr) {
233       obj->forward_to(cast_to_oop(new_addr));
234     } else {
235       assert(obj->is_gc_marked(), "inv");
236       // This obj will stay in-place. Fix the markword.
237       obj->init_mark();
238     }
239   }
240 
241   static HeapWord* find_next_live_addr(HeapWord* start, HeapWord* end) {
242     for (HeapWord* i_addr = start; i_addr < end; /* empty */) {
243       prefetch_read_scan(i_addr);
244       oop obj = cast_to_oop(i_addr);
245       if (obj->is_gc_marked()) {
246         return i_addr;
247       }
248       i_addr += obj->size();
249     }
250     return end;
251   };
252 
253   static size_t relocate(HeapWord* addr) {
254     // Prefetch source and destination
255     prefetch_read_scan(addr);
256 
257     oop obj = cast_to_oop(addr);
258     oop new_obj = obj->forwardee();
259     HeapWord* new_addr = cast_from_oop<HeapWord*>(new_obj);
260     assert(addr != new_addr, "inv");
261     prefetch_write_copy(new_addr);
262 
263     size_t obj_size = obj->size();
264     Copy::aligned_conjoint_words(addr, new_addr, obj_size);
265     new_obj->init_mark();
266 
267     return obj_size;
268   }
269 
270 public:
271   explicit Compacter(SerialHeap* heap) {
272     // In this order so that heap is compacted towards old-gen.
273     _spaces[0].init(heap->old_gen()->space());
274     _spaces[1].init(heap->young_gen()->eden());
275     _spaces[2].init(heap->young_gen()->from());
276 
277     bool is_promotion_failed = !heap->young_gen()->to()->is_empty();
278     if (is_promotion_failed) {
279       _spaces[3].init(heap->young_gen()->to());
280       _num_spaces = 4;
281     } else {
282       _num_spaces = 3;
283     }
284     _index = 0;
285     _old_gen = heap->old_gen();
286   }
287 
288   void phase2_calculate_new_addr() {
289     for (uint i = 0; i < _num_spaces; ++i) {
290       ContiguousSpace* space = get_space(i);
291       HeapWord* cur_addr = space->bottom();
292       HeapWord* top = space->top();
293 
294       bool record_first_dead_done = false;
295 
296       DeadSpacer dead_spacer(space);
297 
298       while (cur_addr < top) {
299         oop obj = cast_to_oop(cur_addr);
300         size_t obj_size = obj->size();
301         if (obj->is_gc_marked()) {
302           HeapWord* new_addr = alloc(obj_size);
303           forward_obj(obj, new_addr);
304           cur_addr += obj_size;
305         } else {
306           // Skipping the current known-unmarked obj
307           HeapWord* next_live_addr = find_next_live_addr(cur_addr + obj_size, top);
308           if (dead_spacer.insert_deadspace(cur_addr, next_live_addr)) {
309             // Register space for the filler obj
310             alloc(pointer_delta(next_live_addr, cur_addr));
311           } else {
312             if (!record_first_dead_done) {
313               record_first_dead(i, cur_addr);
314               record_first_dead_done = true;
315             }
316             *(HeapWord**)cur_addr = next_live_addr;
317           }
318           cur_addr = next_live_addr;
319         }
320       }
321 
322       if (!record_first_dead_done) {
323         record_first_dead(i, top);
324       }
325     }
326   }
327 
328   void phase3_adjust_pointers() {
329     for (uint i = 0; i < _num_spaces; ++i) {
330       ContiguousSpace* space = get_space(i);
331       HeapWord* cur_addr = space->bottom();
332       HeapWord* const top = space->top();
333       HeapWord* const first_dead = get_first_dead(i);
334 
335       while (cur_addr < top) {
336         prefetch_write_scan(cur_addr);
337         if (cur_addr < first_dead || cast_to_oop(cur_addr)->is_gc_marked()) {
338           size_t size = cast_to_oop(cur_addr)->oop_iterate_size(&SerialFullGC::adjust_pointer_closure);
339           cur_addr += size;
340         } else {
341           assert(*(HeapWord**)cur_addr > cur_addr, "forward progress");
342           cur_addr = *(HeapWord**)cur_addr;
343         }
344       }
345     }
346   }
347 
348   void phase4_compact() {
349     for (uint i = 0; i < _num_spaces; ++i) {
350       ContiguousSpace* space = get_space(i);
351       HeapWord* cur_addr = space->bottom();
352       HeapWord* top = space->top();
353 
354       // Check if the first obj inside this space is forwarded.
355       if (!cast_to_oop(cur_addr)->is_forwarded()) {
356         // Jump over consecutive (in-place) live-objs-chunk
357         cur_addr = get_first_dead(i);
358       }
359 
360       while (cur_addr < top) {
361         if (!cast_to_oop(cur_addr)->is_forwarded()) {
362           cur_addr = *(HeapWord**) cur_addr;
363           continue;
364         }
365         cur_addr += relocate(cur_addr);
366       }
367 
368       // Reset top and unused memory
369       HeapWord* new_top = get_compaction_top(i);
370       space->set_top(new_top);
371       if (ZapUnusedHeapArea && new_top < top) {
372         space->mangle_unused_area(MemRegion(new_top, top));
373       }
374     }
375   }
376 };
377 
378 template <class T> void SerialFullGC::KeepAliveClosure::do_oop_work(T* p) {
379   mark_and_push(p);
380 }
381 
382 void SerialFullGC::push_objarray(oop obj, size_t index) {
383   ObjArrayTask task(obj, index);
384   assert(task.is_valid(), "bad ObjArrayTask");
385   _objarray_stack.push(task);
386 }
387 
388 void SerialFullGC::follow_array(objArrayOop array) {
389   mark_and_push_closure.do_klass(array->klass());
390   // Don't push empty arrays to avoid unnecessary work.
391   if (array->length() > 0) {
392     SerialFullGC::push_objarray(array, 0);
393   }
394 }
395 
396 void SerialFullGC::follow_object(oop obj) {
397   assert(obj->is_gc_marked(), "should be marked");
398   if (obj->is_objArray()) {
399     // Handle object arrays explicitly to allow them to
400     // be split into chunks if needed.
401     SerialFullGC::follow_array((objArrayOop)obj);
402   } else {
403     obj->oop_iterate(&mark_and_push_closure);
404   }
405 }
406 
407 void SerialFullGC::follow_array_chunk(objArrayOop array, int index) {
408   const int len = array->length();
409   const int beg_index = index;
410   assert(beg_index < len || len == 0, "index too large");
411 
412   const int stride = MIN2(len - beg_index, (int) ObjArrayMarkingStride);
413   const int end_index = beg_index + stride;
414 
415   array->oop_iterate_range(&mark_and_push_closure, beg_index, end_index);
416 
417   if (end_index < len) {
418     SerialFullGC::push_objarray(array, end_index); // Push the continuation.
419   }
420 }
421 
422 void SerialFullGC::follow_stack() {
423   do {
424     while (!_marking_stack.is_empty()) {
425       oop obj = _marking_stack.pop();
426       assert (obj->is_gc_marked(), "p must be marked");
427       follow_object(obj);
428     }
429     // Process ObjArrays one at a time to avoid marking stack bloat.
430     if (!_objarray_stack.is_empty()) {
431       ObjArrayTask task = _objarray_stack.pop();
432       follow_array_chunk(objArrayOop(task.obj()), task.index());
433     }
434   } while (!_marking_stack.is_empty() || !_objarray_stack.is_empty());
435 }
436 
437 SerialFullGC::FollowStackClosure SerialFullGC::follow_stack_closure;
438 
439 void SerialFullGC::FollowStackClosure::do_void() { follow_stack(); }
440 
441 template <class T> void SerialFullGC::follow_root(T* p) {
442   assert(!Universe::heap()->is_in(p),
443          "roots shouldn't be things within the heap");
444   T heap_oop = RawAccess<>::oop_load(p);
445   if (!CompressedOops::is_null(heap_oop)) {
446     oop obj = CompressedOops::decode_not_null(heap_oop);
447     if (!obj->mark().is_marked()) {
448       mark_object(obj);
449       follow_object(obj);
450     }
451   }
452   follow_stack();
453 }
454 
455 void SerialFullGC::FollowRootClosure::do_oop(oop* p)       { follow_root(p); }
456 void SerialFullGC::FollowRootClosure::do_oop(narrowOop* p) { follow_root(p); }
457 
458 // We preserve the mark which should be replaced at the end and the location
459 // that it will go.  Note that the object that this markWord belongs to isn't
460 // currently at that address but it will be after phase4
461 void SerialFullGC::preserve_mark(oop obj, markWord mark) {
462   // We try to store preserved marks in the to space of the new generation since
463   // this is storage which should be available.  Most of the time this should be
464   // sufficient space for the marks we need to preserve but if it isn't we fall
465   // back to using Stacks to keep track of the overflow.
466   if (_preserved_count < _preserved_count_max) {
467     _preserved_marks[_preserved_count++] = PreservedMark(obj, mark);
468   } else {
469     _preserved_overflow_stack_set.get()->push_always(obj, mark);
470   }
471 }
472 
473 void SerialFullGC::phase1_mark(bool clear_all_softrefs) {
474   // Recursively traverse all live objects and mark them
475   GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer);
476 
477   SerialHeap* gch = SerialHeap::heap();
478 
479   ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_mark);
480 
481   ref_processor()->start_discovery(clear_all_softrefs);
482 
483   {
484     StrongRootsScope srs(0);
485 
486     CLDClosure* weak_cld_closure = ClassUnloading ? nullptr : &follow_cld_closure;
487     MarkingNMethodClosure mark_code_closure(&follow_root_closure, !NMethodToOopClosure::FixRelocations, true);
488     gch->process_roots(SerialHeap::SO_None,
489                        &follow_root_closure,
490                        &follow_cld_closure,
491                        weak_cld_closure,
492                        &mark_code_closure);
493   }
494 
495   // Process reference objects found during marking
496   {
497     GCTraceTime(Debug, gc, phases) tm_m("Reference Processing", gc_timer());
498 
499     ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->max_num_queues());
500     SerialGCRefProcProxyTask task(is_alive, keep_alive, follow_stack_closure);
501     const ReferenceProcessorStats& stats = ref_processor()->process_discovered_references(task, pt);
502     pt.print_all_references();
503     gc_tracer()->report_gc_reference_stats(stats);
504   }
505 
506   // This is the point where the entire marking should have completed.
507   assert(_marking_stack.is_empty(), "Marking should have completed");
508 
509   {
510     GCTraceTime(Debug, gc, phases) tm_m("Weak Processing", gc_timer());
511     WeakProcessor::weak_oops_do(&is_alive, &do_nothing_cl);
512   }
513 
514   {
515     GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", gc_timer());
516 
517     ClassUnloadingContext* ctx = ClassUnloadingContext::context();
518 
519     bool unloading_occurred;
520     {
521       CodeCache::UnlinkingScope scope(&is_alive);
522 
523       // Unload classes and purge the SystemDictionary.
524       unloading_occurred = SystemDictionary::do_unloading(gc_timer());
525 
526       // Unload nmethods.
527       CodeCache::do_unloading(unloading_occurred);
528     }
529 
530     {
531       GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", gc_timer());
532       // Release unloaded nmethod's memory.
533       ctx->purge_nmethods();
534     }
535     {
536       GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", gc_timer());
537       gch->prune_unlinked_nmethods();
538     }
539     {
540       GCTraceTime(Debug, gc, phases) t("Free Code Blobs", gc_timer());
541       ctx->free_nmethods();
542     }
543 
544     // Prune dead klasses from subklass/sibling/implementor lists.
545     Klass::clean_weak_klass_links(unloading_occurred);
546 
547     // Clean JVMCI metadata handles.
548     JVMCI_ONLY(JVMCI::do_unloading(unloading_occurred));
549   }
550 
551   {
552     GCTraceTime(Debug, gc, phases) tm_m("Report Object Count", gc_timer());
553     gc_tracer()->report_object_count_after_gc(&is_alive, nullptr);
554   }
555 }
556 
557 void SerialFullGC::allocate_stacks() {
558   void* scratch = nullptr;
559   size_t num_words;
560   DefNewGeneration* young_gen = (DefNewGeneration*)SerialHeap::heap()->young_gen();
561   young_gen->contribute_scratch(scratch, num_words);
562 
563   if (scratch != nullptr) {
564     _preserved_count_max = num_words * HeapWordSize / sizeof(PreservedMark);
565   } else {
566     _preserved_count_max = 0;
567   }
568 
569   _preserved_marks = (PreservedMark*)scratch;
570   _preserved_count = 0;
571 
572   _preserved_overflow_stack_set.init(1);
573 }
574 
575 void SerialFullGC::deallocate_stacks() {
576   if (_preserved_count_max != 0) {
577     DefNewGeneration* young_gen = (DefNewGeneration*)SerialHeap::heap()->young_gen();
578     young_gen->reset_scratch();
579   }
580 
581   _preserved_overflow_stack_set.reclaim();
582   _marking_stack.clear();
583   _objarray_stack.clear(true);
584 }
585 
586 void SerialFullGC::mark_object(oop obj) {
587   if (StringDedup::is_enabled() &&
588       java_lang_String::is_instance(obj) &&
589       SerialStringDedup::is_candidate_from_mark(obj)) {
590     _string_dedup_requests->add(obj);
591   }
592 




593   // some marks may contain information we need to preserve so we store them away
594   // and overwrite the mark.  We'll restore it at the end of serial full GC.
595   markWord mark = obj->mark();
596   obj->set_mark(markWord::prototype().set_marked());
597 
598   ContinuationGCSupport::transform_stack_chunk(obj);
599 
600   if (obj->mark_must_be_preserved(mark)) {
601     preserve_mark(obj, mark);
602   }
603 }
604 
605 template <class T> void SerialFullGC::mark_and_push(T* p) {
606   T heap_oop = RawAccess<>::oop_load(p);
607   if (!CompressedOops::is_null(heap_oop)) {
608     oop obj = CompressedOops::decode_not_null(heap_oop);
609     if (!obj->mark().is_marked()) {
610       mark_object(obj);
611       _marking_stack.push(obj);
612     }
613   }
614 }
615 
616 template <typename T>
617 void MarkAndPushClosure::do_oop_work(T* p)            { SerialFullGC::mark_and_push(p); }
618 void MarkAndPushClosure::do_oop(      oop* p)         { do_oop_work(p); }
619 void MarkAndPushClosure::do_oop(narrowOop* p)         { do_oop_work(p); }
620 
621 template <class T> void SerialFullGC::adjust_pointer(T* p) {
622   T heap_oop = RawAccess<>::oop_load(p);
623   if (!CompressedOops::is_null(heap_oop)) {
624     oop obj = CompressedOops::decode_not_null(heap_oop);
625     assert(Universe::heap()->is_in(obj), "should be in heap");
626 
627     if (obj->is_forwarded()) {
628       oop new_obj = obj->forwardee();
629       assert(is_object_aligned(new_obj), "oop must be aligned");
630       RawAccess<IS_NOT_NULL>::oop_store(p, new_obj);
631     }
632   }
633 }
634 
635 template <typename T>
636 void AdjustPointerClosure::do_oop_work(T* p)           { SerialFullGC::adjust_pointer(p); }
637 inline void AdjustPointerClosure::do_oop(oop* p)       { do_oop_work(p); }
638 inline void AdjustPointerClosure::do_oop(narrowOop* p) { do_oop_work(p); }
639 
640 AdjustPointerClosure SerialFullGC::adjust_pointer_closure;
641 
642 void SerialFullGC::adjust_marks() {
643   // adjust the oops we saved earlier
644   for (size_t i = 0; i < _preserved_count; i++) {
645     PreservedMarks::adjust_preserved_mark(_preserved_marks + i);
646   }
647 
648   // deal with the overflow stack
649   _preserved_overflow_stack_set.get()->adjust_during_full_gc();
650 }
651 
652 void SerialFullGC::restore_marks() {
653   log_trace(gc)("Restoring " SIZE_FORMAT " marks", _preserved_count + _preserved_overflow_stack_set.get()->size());
654 
655   // restore the marks we saved earlier
656   for (size_t i = 0; i < _preserved_count; i++) {
657     _preserved_marks[i].set_mark();
658   }
659 
660   // deal with the overflow
661   _preserved_overflow_stack_set.restore(nullptr);
662 }
663 
664 SerialFullGC::IsAliveClosure   SerialFullGC::is_alive;
665 
666 bool SerialFullGC::IsAliveClosure::do_object_b(oop p) { return p->is_gc_marked(); }
667 
668 SerialFullGC::KeepAliveClosure SerialFullGC::keep_alive;
669 
670 void SerialFullGC::KeepAliveClosure::do_oop(oop* p)       { SerialFullGC::KeepAliveClosure::do_oop_work(p); }
671 void SerialFullGC::KeepAliveClosure::do_oop(narrowOop* p) { SerialFullGC::KeepAliveClosure::do_oop_work(p); }
672 
673 void SerialFullGC::initialize() {
674   SerialFullGC::_gc_timer = new STWGCTimer();
675   SerialFullGC::_gc_tracer = new SerialOldTracer();
676   SerialFullGC::_string_dedup_requests = new StringDedup::Requests();
677 
678   // The Full GC operates on the entire heap so all objects should be subject
679   // to discovery, hence the _always_true_closure.
680   SerialFullGC::_ref_processor = new ReferenceProcessor(&_always_true_closure);
681   mark_and_push_closure.set_ref_discoverer(_ref_processor);
682 }
683 
684 void SerialFullGC::invoke_at_safepoint(bool clear_all_softrefs) {
685   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
686 
687   SerialHeap* gch = SerialHeap::heap();
688 
689   gch->trace_heap_before_gc(_gc_tracer);
690 
691   // Capture used regions for old-gen to reestablish old-to-young invariant
692   // after full-gc.
693   gch->old_gen()->save_used_region();
694 
695   allocate_stacks();
696 
697   phase1_mark(clear_all_softrefs);
698 


699   Compacter compacter{gch};
700 
701   {
702     // Now all live objects are marked, compute the new object addresses.
703     GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer);
704 
705     compacter.phase2_calculate_new_addr();
706   }
707 
708   // Don't add any more derived pointers during phase3
709 #if COMPILER2_OR_JVMCI
710   assert(DerivedPointerTable::is_active(), "Sanity");
711   DerivedPointerTable::set_active(false);
712 #endif
713 
714   {
715     // Adjust the pointers to reflect the new locations
716     GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", gc_timer());
717 
718     ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_adjust);
719 
720     NMethodToOopClosure code_closure(&adjust_pointer_closure, NMethodToOopClosure::FixRelocations);
721     gch->process_roots(SerialHeap::SO_AllCodeCache,
722                        &adjust_pointer_closure,
723                        &adjust_cld_closure,
724                        &adjust_cld_closure,
725                        &code_closure);
726 
727     WeakProcessor::oops_do(&adjust_pointer_closure);
728 
729     adjust_marks();
730     compacter.phase3_adjust_pointers();
731   }
732 
733   {
734     // All pointers are now adjusted, move objects accordingly
735     GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer);
736 
737     compacter.phase4_compact();
738   }
739 
740   restore_marks();
741 


742   deallocate_stacks();
743 
744   SerialFullGC::_string_dedup_requests->flush();
745 
746   bool is_young_gen_empty = (gch->young_gen()->used() == 0);
747   gch->rem_set()->maintain_old_to_young_invariant(gch->old_gen(), is_young_gen_empty);
748 
749   gch->prune_scavengable_nmethods();
750 
751   // Update heap occupancy information which is used as
752   // input to soft ref clearing policy at the next gc.
753   Universe::heap()->update_capacity_and_used_at_gc();
754 
755   // Signal that we have completed a visit to all live objects.
756   Universe::heap()->record_whole_heap_examined_timestamp();
757 
758   gch->trace_heap_after_gc(_gc_tracer);
759 }
--- EOF ---