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/shared/classUnloadingContext.hpp"
43 #include "gc/shared/collectedHeap.inline.hpp"
44 #include "gc/shared/continuationGCSupport.inline.hpp"
45 #include "gc/shared/gcHeapSummary.hpp"
46 #include "gc/shared/gcTimer.hpp"
47 #include "gc/shared/gcTrace.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "gc/shared/gc_globals.hpp"
50 #include "gc/shared/modRefBarrierSet.hpp"
51 #include "gc/shared/preservedMarks.inline.hpp"
52 #include "gc/shared/referencePolicy.hpp"
53 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
54 #include "gc/shared/space.inline.hpp"
55 #include "gc/shared/strongRootsScope.hpp"
56 #include "gc/shared/weakProcessor.hpp"
57 #include "memory/iterator.inline.hpp"
58 #include "memory/universe.hpp"
59 #include "oops/access.inline.hpp"
60 #include "oops/compressedOops.inline.hpp"
61 #include "oops/instanceRefKlass.hpp"
62 #include "oops/markWord.hpp"
63 #include "oops/methodData.hpp"
64 #include "oops/objArrayKlass.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/typeArrayOop.inline.hpp"
67 #include "runtime/prefetch.inline.hpp"
68 #include "utilities/align.hpp"
69 #include "utilities/copy.hpp"
70 #include "utilities/events.hpp"
71 #include "utilities/stack.inline.hpp"
72 #if INCLUDE_JVMCI
73 #include "jvmci/jvmci.hpp"
74 #endif
75
76 uint SerialFullGC::_total_invocations = 0;
77
78 Stack<oop, mtGC> SerialFullGC::_marking_stack;
79 Stack<ObjArrayTask, mtGC> SerialFullGC::_objarray_stack;
80
81 PreservedMarksSet SerialFullGC::_preserved_overflow_stack_set(false /* in_c_heap */);
82 size_t SerialFullGC::_preserved_count = 0;
83 size_t SerialFullGC::_preserved_count_max = 0;
84 PreservedMark* SerialFullGC::_preserved_marks = nullptr;
85 STWGCTimer* SerialFullGC::_gc_timer = nullptr;
86 SerialOldTracer* SerialFullGC::_gc_tracer = nullptr;
87
88 AlwaysTrueClosure SerialFullGC::_always_true_closure;
89 ReferenceProcessor* SerialFullGC::_ref_processor;
90
91 StringDedup::Requests* SerialFullGC::_string_dedup_requests = nullptr;
92
93 SerialFullGC::FollowRootClosure SerialFullGC::follow_root_closure;
94
95 MarkAndPushClosure SerialFullGC::mark_and_push_closure(ClassLoaderData::_claim_stw_fullgc_mark);
96 CLDToOopClosure SerialFullGC::follow_cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
97 CLDToOopClosure SerialFullGC::adjust_cld_closure(&adjust_pointer_closure, ClassLoaderData::_claim_stw_fullgc_adjust);
98
99 class DeadSpacer : StackObj {
100 size_t _allowed_deadspace_words;
101 bool _active;
102 ContiguousSpace* _space;
103
104 public:
105 DeadSpacer(ContiguousSpace* space) : _allowed_deadspace_words(0), _space(space) {
106 size_t ratio = (_space == SerialHeap::heap()->old_gen()->space())
107 ? MarkSweepDeadRatio : 0;
108 _active = ratio > 0;
109
110 if (_active) {
111 // We allow some amount of garbage towards the bottom of the space, so
112 // we don't start compacting before there is a significant gain to be made.
113 // Occasionally, we want to ensure a full compaction, which is determined
114 // by the MarkSweepAlwaysCompactCount parameter.
115 if ((SerialFullGC::total_invocations() % MarkSweepAlwaysCompactCount) != 0) {
116 _allowed_deadspace_words = (space->capacity() * ratio / 100) / HeapWordSize;
117 } else {
118 _active = false;
119 }
120 }
121 }
122
123 bool insert_deadspace(HeapWord* dead_start, HeapWord* dead_end) {
124 if (!_active) {
125 return false;
126 }
127
128 size_t dead_length = pointer_delta(dead_end, dead_start);
129 if (_allowed_deadspace_words >= dead_length) {
130 _allowed_deadspace_words -= dead_length;
131 CollectedHeap::fill_with_object(dead_start, dead_length);
132 oop obj = cast_to_oop(dead_start);
133 // obj->set_mark(obj->mark().set_marked());
134
135 assert(dead_length == obj->size(), "bad filler object size");
136 log_develop_trace(gc, compaction)("Inserting object to dead space: " PTR_FORMAT ", " PTR_FORMAT ", " SIZE_FORMAT "b",
137 p2i(dead_start), p2i(dead_end), dead_length * HeapWordSize);
138
139 return true;
140 } else {
141 _active = false;
142 return false;
143 }
144 }
145 };
146
147 // Implement the "compaction" part of the mark-compact GC algorithm.
148 class Compacter {
149 // There are four spaces in total, but only the first three can be used after
150 // compact. IOW, old and eden/from must be enough for all live objs
151 static constexpr uint max_num_spaces = 4;
152
153 struct CompactionSpace {
154 ContiguousSpace* _space;
155 // Will be the new top after compaction is complete.
156 HeapWord* _compaction_top;
157 // The first dead word in this contiguous space. It's an optimization to
158 // skip large chunk of live objects at the beginning.
159 HeapWord* _first_dead;
160
161 void init(ContiguousSpace* space) {
162 _space = space;
163 _compaction_top = space->bottom();
164 _first_dead = nullptr;
165 }
166 };
167
168 CompactionSpace _spaces[max_num_spaces];
169 // The num of spaces to be compacted, i.e. containing live objs.
170 uint _num_spaces;
171
172 uint _index;
173
174 HeapWord* get_compaction_top(uint index) const {
175 return _spaces[index]._compaction_top;
176 }
177
178 HeapWord* get_first_dead(uint index) const {
179 return _spaces[index]._first_dead;
180 }
181
182 ContiguousSpace* get_space(uint index) const {
183 return _spaces[index]._space;
184 }
185
186 void record_first_dead(uint index, HeapWord* first_dead) {
187 assert(_spaces[index]._first_dead == nullptr, "should write only once");
188 _spaces[index]._first_dead = first_dead;
189 }
190
191 HeapWord* alloc(size_t words) {
192 while (true) {
193 if (words <= pointer_delta(_spaces[_index]._space->end(),
194 _spaces[_index]._compaction_top)) {
195 HeapWord* result = _spaces[_index]._compaction_top;
196 _spaces[_index]._compaction_top += words;
197 if (_index == 0) {
198 // old-gen requires BOT update
199 static_cast<TenuredSpace*>(_spaces[0]._space)->update_for_block(result, result + words);
200 }
201 return result;
202 }
203
204 // out-of-memory in this space
205 _index++;
206 assert(_index < max_num_spaces - 1, "the last space should not be used");
207 }
208 }
209
210 static void prefetch_read_scan(void* p) {
211 if (PrefetchScanIntervalInBytes >= 0) {
212 Prefetch::read(p, PrefetchScanIntervalInBytes);
213 }
214 }
215
216 static void prefetch_write_scan(void* p) {
217 if (PrefetchScanIntervalInBytes >= 0) {
218 Prefetch::write(p, PrefetchScanIntervalInBytes);
219 }
220 }
221
222 static void prefetch_write_copy(void* p) {
223 if (PrefetchCopyIntervalInBytes >= 0) {
224 Prefetch::write(p, PrefetchCopyIntervalInBytes);
225 }
226 }
227
228 static void forward_obj(oop obj, HeapWord* new_addr) {
229 prefetch_write_scan(obj);
230 if (cast_from_oop<HeapWord*>(obj) != new_addr) {
231 obj->forward_to(cast_to_oop(new_addr));
232 } else {
233 assert(obj->is_gc_marked(), "inv");
234 // This obj will stay in-place. Fix the markword.
235 obj->init_mark();
236 }
237 }
238
239 static HeapWord* find_next_live_addr(HeapWord* start, HeapWord* end) {
240 for (HeapWord* i_addr = start; i_addr < end; /* empty */) {
241 prefetch_read_scan(i_addr);
242 oop obj = cast_to_oop(i_addr);
243 if (obj->is_gc_marked()) {
244 return i_addr;
245 }
246 i_addr += obj->size();
247 }
248 return end;
249 };
250
251 static size_t relocate(HeapWord* addr) {
252 // Prefetch source and destination
253 prefetch_read_scan(addr);
254
255 oop obj = cast_to_oop(addr);
256 oop new_obj = obj->forwardee();
257 HeapWord* new_addr = cast_from_oop<HeapWord*>(new_obj);
258 assert(addr != new_addr, "inv");
259 prefetch_write_copy(new_addr);
260
261 size_t obj_size = obj->size();
262 Copy::aligned_conjoint_words(addr, new_addr, obj_size);
263 new_obj->init_mark();
264
265 return obj_size;
266 }
267
268 public:
269 explicit Compacter(SerialHeap* heap) {
270 // In this order so that heap is compacted towards old-gen.
271 _spaces[0].init(heap->old_gen()->space());
272 _spaces[1].init(heap->young_gen()->eden());
273 _spaces[2].init(heap->young_gen()->from());
274
275 bool is_promotion_failed = !heap->young_gen()->to()->is_empty();
276 if (is_promotion_failed) {
277 _spaces[3].init(heap->young_gen()->to());
278 _num_spaces = 4;
279 } else {
280 _num_spaces = 3;
281 }
282 _index = 0;
283 }
284
285 void phase2_calculate_new_addr() {
286 for (uint i = 0; i < _num_spaces; ++i) {
287 ContiguousSpace* space = get_space(i);
288 HeapWord* cur_addr = space->bottom();
289 HeapWord* top = space->top();
290
291 bool record_first_dead_done = false;
292
293 DeadSpacer dead_spacer(space);
294
295 while (cur_addr < top) {
296 oop obj = cast_to_oop(cur_addr);
297 size_t obj_size = obj->size();
298 if (obj->is_gc_marked()) {
299 HeapWord* new_addr = alloc(obj_size);
300 forward_obj(obj, new_addr);
301 cur_addr += obj_size;
302 } else {
303 // Skipping the current known-unmarked obj
304 HeapWord* next_live_addr = find_next_live_addr(cur_addr + obj_size, top);
305 if (dead_spacer.insert_deadspace(cur_addr, next_live_addr)) {
306 // Register space for the filler obj
307 alloc(pointer_delta(next_live_addr, cur_addr));
308 } else {
309 if (!record_first_dead_done) {
310 record_first_dead(i, cur_addr);
311 record_first_dead_done = true;
312 }
313 *(HeapWord**)cur_addr = next_live_addr;
314 }
315 cur_addr = next_live_addr;
316 }
317 }
318
319 if (!record_first_dead_done) {
320 record_first_dead(i, top);
321 }
322 }
323 }
324
325 void phase3_adjust_pointers() {
326 for (uint i = 0; i < _num_spaces; ++i) {
327 ContiguousSpace* space = get_space(i);
328 HeapWord* cur_addr = space->bottom();
329 HeapWord* const top = space->top();
330 HeapWord* const first_dead = get_first_dead(i);
331
332 while (cur_addr < top) {
333 prefetch_write_scan(cur_addr);
334 if (cur_addr < first_dead || cast_to_oop(cur_addr)->is_gc_marked()) {
335 size_t size = cast_to_oop(cur_addr)->oop_iterate_size(&SerialFullGC::adjust_pointer_closure);
336 cur_addr += size;
337 } else {
338 assert(*(HeapWord**)cur_addr > cur_addr, "forward progress");
339 cur_addr = *(HeapWord**)cur_addr;
340 }
341 }
342 }
343 }
344
345 void phase4_compact() {
346 for (uint i = 0; i < _num_spaces; ++i) {
347 ContiguousSpace* space = get_space(i);
348 HeapWord* cur_addr = space->bottom();
349 HeapWord* top = space->top();
350
351 // Check if the first obj inside this space is forwarded.
352 if (!cast_to_oop(cur_addr)->is_forwarded()) {
353 // Jump over consecutive (in-place) live-objs-chunk
354 cur_addr = get_first_dead(i);
355 }
356
357 while (cur_addr < top) {
358 if (!cast_to_oop(cur_addr)->is_forwarded()) {
359 cur_addr = *(HeapWord**) cur_addr;
360 continue;
361 }
362 cur_addr += relocate(cur_addr);
363 }
364
365 // Reset top and unused memory
366 space->set_top(get_compaction_top(i));
367 if (ZapUnusedHeapArea) {
368 space->mangle_unused_area();
369 }
370 }
371 }
372 };
373
374 template <class T> void SerialFullGC::KeepAliveClosure::do_oop_work(T* p) {
375 mark_and_push(p);
376 }
377
378 void SerialFullGC::push_objarray(oop obj, size_t index) {
379 ObjArrayTask task(obj, index);
380 assert(task.is_valid(), "bad ObjArrayTask");
381 _objarray_stack.push(task);
382 }
383
384 void SerialFullGC::follow_array(objArrayOop array) {
385 mark_and_push_closure.do_klass(array->klass());
386 // Don't push empty arrays to avoid unnecessary work.
387 if (array->length() > 0) {
388 SerialFullGC::push_objarray(array, 0);
389 }
390 }
391
392 void SerialFullGC::follow_object(oop obj) {
393 assert(obj->is_gc_marked(), "should be marked");
394 if (obj->is_objArray()) {
395 // Handle object arrays explicitly to allow them to
396 // be split into chunks if needed.
397 SerialFullGC::follow_array((objArrayOop)obj);
398 } else {
399 obj->oop_iterate(&mark_and_push_closure);
400 }
401 }
402
403 void SerialFullGC::follow_array_chunk(objArrayOop array, int index) {
404 const int len = array->length();
405 const int beg_index = index;
406 assert(beg_index < len || len == 0, "index too large");
407
408 const int stride = MIN2(len - beg_index, (int) ObjArrayMarkingStride);
409 const int end_index = beg_index + stride;
410
411 array->oop_iterate_range(&mark_and_push_closure, beg_index, end_index);
412
413 if (end_index < len) {
414 SerialFullGC::push_objarray(array, end_index); // Push the continuation.
415 }
416 }
417
418 void SerialFullGC::follow_stack() {
419 do {
420 while (!_marking_stack.is_empty()) {
421 oop obj = _marking_stack.pop();
422 assert (obj->is_gc_marked(), "p must be marked");
423 follow_object(obj);
424 }
425 // Process ObjArrays one at a time to avoid marking stack bloat.
426 if (!_objarray_stack.is_empty()) {
427 ObjArrayTask task = _objarray_stack.pop();
428 follow_array_chunk(objArrayOop(task.obj()), task.index());
429 }
430 } while (!_marking_stack.is_empty() || !_objarray_stack.is_empty());
431 }
432
433 SerialFullGC::FollowStackClosure SerialFullGC::follow_stack_closure;
434
435 void SerialFullGC::FollowStackClosure::do_void() { follow_stack(); }
436
437 template <class T> void SerialFullGC::follow_root(T* p) {
438 assert(!Universe::heap()->is_in(p),
439 "roots shouldn't be things within the heap");
440 T heap_oop = RawAccess<>::oop_load(p);
441 if (!CompressedOops::is_null(heap_oop)) {
442 oop obj = CompressedOops::decode_not_null(heap_oop);
443 if (!obj->mark().is_marked()) {
444 mark_object(obj);
445 follow_object(obj);
446 }
447 }
448 follow_stack();
449 }
450
451 void SerialFullGC::FollowRootClosure::do_oop(oop* p) { follow_root(p); }
452 void SerialFullGC::FollowRootClosure::do_oop(narrowOop* p) { follow_root(p); }
453
454 // We preserve the mark which should be replaced at the end and the location
455 // that it will go. Note that the object that this markWord belongs to isn't
456 // currently at that address but it will be after phase4
457 void SerialFullGC::preserve_mark(oop obj, markWord mark) {
458 // We try to store preserved marks in the to space of the new generation since
459 // this is storage which should be available. Most of the time this should be
460 // sufficient space for the marks we need to preserve but if it isn't we fall
461 // back to using Stacks to keep track of the overflow.
462 if (_preserved_count < _preserved_count_max) {
463 _preserved_marks[_preserved_count++] = PreservedMark(obj, mark);
464 } else {
465 _preserved_overflow_stack_set.get()->push_always(obj, mark);
466 }
467 }
468
469 void SerialFullGC::phase1_mark(bool clear_all_softrefs) {
470 // Recursively traverse all live objects and mark them
471 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer);
472
473 SerialHeap* gch = SerialHeap::heap();
474
475 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_mark);
476
477 ref_processor()->start_discovery(clear_all_softrefs);
478
479 {
480 StrongRootsScope srs(0);
481
482 CLDClosure* weak_cld_closure = ClassUnloading ? nullptr : &follow_cld_closure;
483 MarkingNMethodClosure mark_code_closure(&follow_root_closure, !NMethodToOopClosure::FixRelocations, true);
484 gch->process_roots(SerialHeap::SO_None,
485 &follow_root_closure,
486 &follow_cld_closure,
487 weak_cld_closure,
488 &mark_code_closure);
489 }
490
491 // Process reference objects found during marking
492 {
493 GCTraceTime(Debug, gc, phases) tm_m("Reference Processing", gc_timer());
494
495 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->max_num_queues());
496 SerialGCRefProcProxyTask task(is_alive, keep_alive, follow_stack_closure);
497 const ReferenceProcessorStats& stats = ref_processor()->process_discovered_references(task, pt);
498 pt.print_all_references();
499 gc_tracer()->report_gc_reference_stats(stats);
500 }
501
502 // This is the point where the entire marking should have completed.
503 assert(_marking_stack.is_empty(), "Marking should have completed");
504
505 {
506 GCTraceTime(Debug, gc, phases) tm_m("Weak Processing", gc_timer());
507 WeakProcessor::weak_oops_do(&is_alive, &do_nothing_cl);
508 }
509
510 {
511 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", gc_timer());
512
513 ClassUnloadingContext* ctx = ClassUnloadingContext::context();
514
515 bool unloading_occurred;
516 {
517 CodeCache::UnlinkingScope scope(&is_alive);
518
519 // Unload classes and purge the SystemDictionary.
520 unloading_occurred = SystemDictionary::do_unloading(gc_timer());
521
522 // Unload nmethods.
523 CodeCache::do_unloading(unloading_occurred);
524 }
525
526 {
527 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", gc_timer());
528 // Release unloaded nmethod's memory.
529 ctx->purge_nmethods();
530 }
531 {
532 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", gc_timer());
533 gch->prune_unlinked_nmethods();
534 }
535 {
536 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", gc_timer());
537 ctx->free_nmethods();
538 }
539
540 // Prune dead klasses from subklass/sibling/implementor lists.
541 Klass::clean_weak_klass_links(unloading_occurred);
542
543 // Clean JVMCI metadata handles.
544 JVMCI_ONLY(JVMCI::do_unloading(unloading_occurred));
545 }
546
547 {
548 GCTraceTime(Debug, gc, phases) tm_m("Report Object Count", gc_timer());
549 gc_tracer()->report_object_count_after_gc(&is_alive, nullptr);
550 }
551 }
552
553 void SerialFullGC::allocate_stacks() {
554 void* scratch = nullptr;
555 size_t num_words;
556 DefNewGeneration* young_gen = (DefNewGeneration*)SerialHeap::heap()->young_gen();
557 young_gen->contribute_scratch(scratch, num_words);
558
559 if (scratch != nullptr) {
560 _preserved_count_max = num_words * HeapWordSize / sizeof(PreservedMark);
561 } else {
562 _preserved_count_max = 0;
563 }
564
565 _preserved_marks = (PreservedMark*)scratch;
566 _preserved_count = 0;
567
568 _preserved_overflow_stack_set.init(1);
569 }
570
571 void SerialFullGC::deallocate_stacks() {
572 if (_preserved_count_max != 0) {
573 DefNewGeneration* young_gen = (DefNewGeneration*)SerialHeap::heap()->young_gen();
574 young_gen->reset_scratch();
575 }
576
577 _preserved_overflow_stack_set.reclaim();
578 _marking_stack.clear();
579 _objarray_stack.clear(true);
580 }
581
582 void SerialFullGC::mark_object(oop obj) {
583 if (StringDedup::is_enabled() &&
584 java_lang_String::is_instance(obj) &&
585 SerialStringDedup::is_candidate_from_mark(obj)) {
586 _string_dedup_requests->add(obj);
587 }
588
589 // some marks may contain information we need to preserve so we store them away
590 // and overwrite the mark. We'll restore it at the end of serial full GC.
591 markWord mark = obj->mark();
592 obj->set_mark(markWord::prototype().set_marked());
593
594 ContinuationGCSupport::transform_stack_chunk(obj);
595
596 if (obj->mark_must_be_preserved(mark)) {
597 preserve_mark(obj, mark);
598 }
599 }
600
601 template <class T> void SerialFullGC::mark_and_push(T* p) {
602 T heap_oop = RawAccess<>::oop_load(p);
603 if (!CompressedOops::is_null(heap_oop)) {
604 oop obj = CompressedOops::decode_not_null(heap_oop);
605 if (!obj->mark().is_marked()) {
606 mark_object(obj);
607 _marking_stack.push(obj);
608 }
609 }
610 }
611
612 template <typename T>
613 void MarkAndPushClosure::do_oop_work(T* p) { SerialFullGC::mark_and_push(p); }
614 void MarkAndPushClosure::do_oop( oop* p) { do_oop_work(p); }
615 void MarkAndPushClosure::do_oop(narrowOop* p) { do_oop_work(p); }
616
617 template <class T> void SerialFullGC::adjust_pointer(T* p) {
618 T heap_oop = RawAccess<>::oop_load(p);
619 if (!CompressedOops::is_null(heap_oop)) {
620 oop obj = CompressedOops::decode_not_null(heap_oop);
621 assert(Universe::heap()->is_in(obj), "should be in heap");
622
623 if (obj->is_forwarded()) {
624 oop new_obj = obj->forwardee();
625 assert(is_object_aligned(new_obj), "oop must be aligned");
626 RawAccess<IS_NOT_NULL>::oop_store(p, new_obj);
627 }
628 }
629 }
630
631 template <typename T>
632 void AdjustPointerClosure::do_oop_work(T* p) { SerialFullGC::adjust_pointer(p); }
633 inline void AdjustPointerClosure::do_oop(oop* p) { do_oop_work(p); }
634 inline void AdjustPointerClosure::do_oop(narrowOop* p) { do_oop_work(p); }
635
636 AdjustPointerClosure SerialFullGC::adjust_pointer_closure;
637
638 void SerialFullGC::adjust_marks() {
639 // adjust the oops we saved earlier
640 for (size_t i = 0; i < _preserved_count; i++) {
641 PreservedMarks::adjust_preserved_mark(_preserved_marks + i);
642 }
643
644 // deal with the overflow stack
645 _preserved_overflow_stack_set.get()->adjust_during_full_gc();
646 }
647
648 void SerialFullGC::restore_marks() {
649 log_trace(gc)("Restoring " SIZE_FORMAT " marks", _preserved_count + _preserved_overflow_stack_set.get()->size());
650
651 // restore the marks we saved earlier
652 for (size_t i = 0; i < _preserved_count; i++) {
653 _preserved_marks[i].set_mark();
654 }
655
656 // deal with the overflow
657 _preserved_overflow_stack_set.restore(nullptr);
658 }
659
660 SerialFullGC::IsAliveClosure SerialFullGC::is_alive;
661
662 bool SerialFullGC::IsAliveClosure::do_object_b(oop p) { return p->is_gc_marked(); }
663
664 SerialFullGC::KeepAliveClosure SerialFullGC::keep_alive;
665
666 void SerialFullGC::KeepAliveClosure::do_oop(oop* p) { SerialFullGC::KeepAliveClosure::do_oop_work(p); }
667 void SerialFullGC::KeepAliveClosure::do_oop(narrowOop* p) { SerialFullGC::KeepAliveClosure::do_oop_work(p); }
668
669 void SerialFullGC::initialize() {
670 SerialFullGC::_gc_timer = new STWGCTimer();
671 SerialFullGC::_gc_tracer = new SerialOldTracer();
672 SerialFullGC::_string_dedup_requests = new StringDedup::Requests();
673
674 // The Full GC operates on the entire heap so all objects should be subject
675 // to discovery, hence the _always_true_closure.
676 SerialFullGC::_ref_processor = new ReferenceProcessor(&_always_true_closure);
677 mark_and_push_closure.set_ref_discoverer(_ref_processor);
678 }
679
680 void SerialFullGC::invoke_at_safepoint(bool clear_all_softrefs) {
681 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
682
683 SerialHeap* gch = SerialHeap::heap();
684 #ifdef ASSERT
685 if (gch->soft_ref_policy()->should_clear_all_soft_refs()) {
686 assert(clear_all_softrefs, "Policy should have been checked earlier");
687 }
688 #endif
689
690 gch->trace_heap_before_gc(_gc_tracer);
691
692 // Increment the invocation count
693 _total_invocations++;
694
695 // Capture used regions for old-gen to reestablish old-to-young invariant
696 // after full-gc.
697 gch->old_gen()->save_used_region();
698
699 allocate_stacks();
700
701 phase1_mark(clear_all_softrefs);
702
703 Compacter compacter{gch};
704
705 {
706 // Now all live objects are marked, compute the new object addresses.
707 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer);
708
709 compacter.phase2_calculate_new_addr();
710 }
711
712 // Don't add any more derived pointers during phase3
713 #if COMPILER2_OR_JVMCI
714 assert(DerivedPointerTable::is_active(), "Sanity");
715 DerivedPointerTable::set_active(false);
716 #endif
717
718 {
719 // Adjust the pointers to reflect the new locations
720 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", gc_timer());
721
722 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_adjust);
723
724 NMethodToOopClosure code_closure(&adjust_pointer_closure, NMethodToOopClosure::FixRelocations);
725 gch->process_roots(SerialHeap::SO_AllCodeCache,
726 &adjust_pointer_closure,
727 &adjust_cld_closure,
728 &adjust_cld_closure,
729 &code_closure);
730
731 WeakProcessor::oops_do(&adjust_pointer_closure);
732
733 adjust_marks();
734 compacter.phase3_adjust_pointers();
735 }
736
737 {
738 // All pointers are now adjusted, move objects accordingly
739 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer);
740
741 compacter.phase4_compact();
742 }
743
744 restore_marks();
745
746 // Set saved marks for allocation profiler (and other things? -- dld)
747 // (Should this be in general part?)
748 gch->save_marks();
749
750 deallocate_stacks();
751
752 SerialFullGC::_string_dedup_requests->flush();
753
754 bool is_young_gen_empty = (gch->young_gen()->used() == 0);
755 gch->rem_set()->maintain_old_to_young_invariant(gch->old_gen(), is_young_gen_empty);
756
757 gch->prune_scavengable_nmethods();
758
759 // Update heap occupancy information which is used as
760 // input to soft ref clearing policy at the next gc.
761 Universe::heap()->update_capacity_and_used_at_gc();
762
763 // Signal that we have completed a visit to all live objects.
764 Universe::heap()->record_whole_heap_examined_timestamp();
765
766 gch->trace_heap_after_gc(_gc_tracer);
767 }