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/fullGCForwarding.inline.hpp"
47 #include "gc/shared/gcHeapSummary.hpp"
48 #include "gc/shared/gcTimer.hpp"
49 #include "gc/shared/gcTrace.hpp"
50 #include "gc/shared/gcTraceTime.inline.hpp"
51 #include "gc/shared/gc_globals.hpp"
52 #include "gc/shared/modRefBarrierSet.hpp"
53 #include "gc/shared/preservedMarks.inline.hpp"
54 #include "gc/shared/referencePolicy.hpp"
55 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
56 #include "gc/shared/space.hpp"
57 #include "gc/shared/strongRootsScope.hpp"
58 #include "gc/shared/weakProcessor.hpp"
59 #include "memory/iterator.inline.hpp"
60 #include "memory/universe.hpp"
61 #include "oops/access.inline.hpp"
62 #include "oops/compressedOops.inline.hpp"
63 #include "oops/instanceRefKlass.hpp"
64 #include "oops/markWord.hpp"
65 #include "oops/methodData.hpp"
66 #include "oops/objArrayKlass.inline.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/typeArrayOop.inline.hpp"
69 #include "runtime/prefetch.inline.hpp"
70 #include "utilities/align.hpp"
71 #include "utilities/copy.hpp"
72 #include "utilities/events.hpp"
73 #include "utilities/stack.inline.hpp"
74 #if INCLUDE_JVMCI
75 #include "jvmci/jvmci.hpp"
76 #endif
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 ((SerialHeap::heap()->total_full_collections() % 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 // Used for BOT update
175 TenuredGeneration* _old_gen;
176
177 HeapWord* get_compaction_top(uint index) const {
178 return _spaces[index]._compaction_top;
179 }
180
181 HeapWord* get_first_dead(uint index) const {
182 return _spaces[index]._first_dead;
183 }
184
185 ContiguousSpace* get_space(uint index) const {
186 return _spaces[index]._space;
187 }
188
189 void record_first_dead(uint index, HeapWord* first_dead) {
190 assert(_spaces[index]._first_dead == nullptr, "should write only once");
191 _spaces[index]._first_dead = first_dead;
192 }
193
194 HeapWord* alloc(size_t old_size, size_t new_size, HeapWord* old_obj) {
195 size_t words = (old_obj == _spaces[_index]._compaction_top) ? old_size : new_size;
196 while (true) {
197 if (words <= pointer_delta(_spaces[_index]._space->end(),
198 _spaces[_index]._compaction_top)) {
199 HeapWord* result = _spaces[_index]._compaction_top;
200 _spaces[_index]._compaction_top += words;
201 if (_index == 0) {
202 // old-gen requires BOT update
203 _old_gen->update_for_block(result, result + words);
204 }
205 return result;
206 }
207
208 // out-of-memory in this space
209 _index++;
210 assert(_index < max_num_spaces - 1, "the last space should not be used");
211 words = (old_obj == _spaces[_index]._compaction_top) ? old_size : new_size;
212 }
213 }
214
215 static void prefetch_read_scan(void* p) {
216 if (PrefetchScanIntervalInBytes >= 0) {
217 Prefetch::read(p, PrefetchScanIntervalInBytes);
218 }
219 }
220
221 static void prefetch_write_scan(void* p) {
222 if (PrefetchScanIntervalInBytes >= 0) {
223 Prefetch::write(p, PrefetchScanIntervalInBytes);
224 }
225 }
226
227 static void prefetch_write_copy(void* p) {
228 if (PrefetchCopyIntervalInBytes >= 0) {
229 Prefetch::write(p, PrefetchCopyIntervalInBytes);
230 }
231 }
232
233 static void forward_obj(oop obj, HeapWord* new_addr) {
234 prefetch_write_scan(obj);
235 if (cast_from_oop<HeapWord*>(obj) != new_addr) {
236 FullGCForwarding::forward_to(obj, cast_to_oop(new_addr));
237 } else {
238 assert(obj->is_gc_marked(), "inv");
239 // This obj will stay in-place. Fix the markword.
240 obj->init_mark();
241 }
242 }
243
244 static HeapWord* find_next_live_addr(HeapWord* start, HeapWord* end) {
245 for (HeapWord* i_addr = start; i_addr < end; /* empty */) {
246 prefetch_read_scan(i_addr);
247 oop obj = cast_to_oop(i_addr);
248 if (obj->is_gc_marked()) {
249 return i_addr;
250 }
251 i_addr += obj->size();
252 }
253 return end;
254 };
255
256 static size_t relocate(HeapWord* addr) {
257 // Prefetch source and destination
258 prefetch_read_scan(addr);
259
260 oop obj = cast_to_oop(addr);
261 oop new_obj = FullGCForwarding::forwardee(obj);
262 HeapWord* new_addr = cast_from_oop<HeapWord*>(new_obj);
263
264 size_t obj_size = obj->size();
265 if (addr != new_addr) {
266 prefetch_write_copy(new_addr);
267 Copy::aligned_conjoint_words(addr, new_addr, obj_size);
268 }
269 new_obj->init_mark();
270 if (addr != new_addr) {
271 new_obj->initialize_hash_if_necessary(obj);
272 }
273
274 return obj_size;
275 }
276
277 public:
278 explicit Compacter(SerialHeap* heap) {
279 // In this order so that heap is compacted towards old-gen.
280 _spaces[0].init(heap->old_gen()->space());
281 _spaces[1].init(heap->young_gen()->eden());
282 _spaces[2].init(heap->young_gen()->from());
283
284 bool is_promotion_failed = !heap->young_gen()->to()->is_empty();
285 if (is_promotion_failed) {
286 _spaces[3].init(heap->young_gen()->to());
287 _num_spaces = 4;
288 } else {
289 _num_spaces = 3;
290 }
291 _index = 0;
292 _old_gen = heap->old_gen();
293 }
294
295 void phase2_calculate_new_addr() {
296 for (uint i = 0; i < _num_spaces; ++i) {
297 ContiguousSpace* space = get_space(i);
298 HeapWord* cur_addr = space->bottom();
299 HeapWord* top = space->top();
300
301 bool record_first_dead_done = false;
302
303 DeadSpacer dead_spacer(space);
304
305 while (cur_addr < top) {
306 oop obj = cast_to_oop(cur_addr);
307 size_t obj_size = obj->size();
308 size_t new_size = obj->copy_size(obj_size, obj->mark());
309 if (obj->is_gc_marked()) {
310 HeapWord* new_addr = alloc(obj_size, new_size, cur_addr);
311 forward_obj(obj, new_addr);
312 assert(obj->size() == obj_size, "size must not change after forwarding");
313 cur_addr += obj_size;
314 } else {
315 // Skipping the current known-unmarked obj
316 HeapWord* next_live_addr = find_next_live_addr(cur_addr + obj_size, top);
317 if (dead_spacer.insert_deadspace(cur_addr, next_live_addr)) {
318 // Register space for the filler obj
319 size_t size = pointer_delta(next_live_addr, cur_addr);
320 alloc(size, size, cur_addr);
321 } else {
322 if (!record_first_dead_done) {
323 record_first_dead(i, cur_addr);
324 record_first_dead_done = true;
325 }
326 *(HeapWord**)cur_addr = next_live_addr;
327 }
328 cur_addr = next_live_addr;
329 }
330 }
331
332 if (!record_first_dead_done) {
333 record_first_dead(i, top);
334 }
335 }
336 }
337
338 void phase3_adjust_pointers() {
339 for (uint i = 0; i < _num_spaces; ++i) {
340 ContiguousSpace* space = get_space(i);
341 HeapWord* cur_addr = space->bottom();
342 HeapWord* const top = space->top();
343 HeapWord* const first_dead = get_first_dead(i);
344
345 while (cur_addr < top) {
346 prefetch_write_scan(cur_addr);
347 if (cur_addr < first_dead || cast_to_oop(cur_addr)->is_gc_marked()) {
348 size_t size = cast_to_oop(cur_addr)->oop_iterate_size(&SerialFullGC::adjust_pointer_closure);
349 cur_addr += size;
350 } else {
351 assert(*(HeapWord**)cur_addr > cur_addr, "forward progress");
352 cur_addr = *(HeapWord**)cur_addr;
353 }
354 }
355 }
356 }
357
358 void phase4_compact() {
359 for (uint i = 0; i < _num_spaces; ++i) {
360 ContiguousSpace* space = get_space(i);
361 HeapWord* cur_addr = space->bottom();
362 HeapWord* top = space->top();
363
364 // Check if the first obj inside this space is forwarded.
365 if (!FullGCForwarding::is_forwarded(cast_to_oop(cur_addr))) {
366 // Jump over consecutive (in-place) live-objs-chunk
367 cur_addr = get_first_dead(i);
368 }
369
370 while (cur_addr < top) {
371 if (!FullGCForwarding::is_forwarded(cast_to_oop(cur_addr))) {
372 cur_addr = *(HeapWord**) cur_addr;
373 continue;
374 }
375 cur_addr += relocate(cur_addr);
376 }
377
378 // Reset top and unused memory
379 HeapWord* new_top = get_compaction_top(i);
380 space->set_top(new_top);
381 if (ZapUnusedHeapArea && new_top < top) {
382 space->mangle_unused_area(MemRegion(new_top, top));
383 }
384 }
385 }
386 };
387
388 template <class T> void SerialFullGC::KeepAliveClosure::do_oop_work(T* p) {
389 mark_and_push(p);
390 }
391
392 void SerialFullGC::push_objarray(oop obj, size_t index) {
393 ObjArrayTask task(obj, index);
394 assert(task.is_valid(), "bad ObjArrayTask");
395 _objarray_stack.push(task);
396 }
397
398 void SerialFullGC::follow_array(objArrayOop array) {
399 mark_and_push_closure.do_klass(array->klass());
400 // Don't push empty arrays to avoid unnecessary work.
401 if (array->length() > 0) {
402 SerialFullGC::push_objarray(array, 0);
403 }
404 }
405
406 void SerialFullGC::follow_object(oop obj) {
407 assert(obj->is_gc_marked(), "should be marked");
408 if (obj->is_objArray()) {
409 // Handle object arrays explicitly to allow them to
410 // be split into chunks if needed.
411 SerialFullGC::follow_array((objArrayOop)obj);
412 } else {
413 obj->oop_iterate(&mark_and_push_closure);
414 }
415 }
416
417 void SerialFullGC::follow_array_chunk(objArrayOop array, int index) {
418 const int len = array->length();
419 const int beg_index = index;
420 assert(beg_index < len || len == 0, "index too large");
421
422 const int stride = MIN2(len - beg_index, (int) ObjArrayMarkingStride);
423 const int end_index = beg_index + stride;
424
425 array->oop_iterate_range(&mark_and_push_closure, beg_index, end_index);
426
427 if (end_index < len) {
428 SerialFullGC::push_objarray(array, end_index); // Push the continuation.
429 }
430 }
431
432 void SerialFullGC::follow_stack() {
433 do {
434 while (!_marking_stack.is_empty()) {
435 oop obj = _marking_stack.pop();
436 assert (obj->is_gc_marked(), "p must be marked");
437 follow_object(obj);
438 }
439 // Process ObjArrays one at a time to avoid marking stack bloat.
440 if (!_objarray_stack.is_empty()) {
441 ObjArrayTask task = _objarray_stack.pop();
442 follow_array_chunk(objArrayOop(task.obj()), task.index());
443 }
444 } while (!_marking_stack.is_empty() || !_objarray_stack.is_empty());
445 }
446
447 SerialFullGC::FollowStackClosure SerialFullGC::follow_stack_closure;
448
449 void SerialFullGC::FollowStackClosure::do_void() { follow_stack(); }
450
451 template <class T> void SerialFullGC::follow_root(T* p) {
452 assert(!Universe::heap()->is_in(p),
453 "roots shouldn't be things within the heap");
454 T heap_oop = RawAccess<>::oop_load(p);
455 if (!CompressedOops::is_null(heap_oop)) {
456 oop obj = CompressedOops::decode_not_null(heap_oop);
457 if (!obj->mark().is_marked()) {
458 mark_object(obj);
459 follow_object(obj);
460 }
461 }
462 follow_stack();
463 }
464
465 void SerialFullGC::FollowRootClosure::do_oop(oop* p) { follow_root(p); }
466 void SerialFullGC::FollowRootClosure::do_oop(narrowOop* p) { follow_root(p); }
467
468 // We preserve the mark which should be replaced at the end and the location
469 // that it will go. Note that the object that this markWord belongs to isn't
470 // currently at that address but it will be after phase4
471 void SerialFullGC::preserve_mark(oop obj, markWord mark) {
472 // We try to store preserved marks in the to space of the new generation since
473 // this is storage which should be available. Most of the time this should be
474 // sufficient space for the marks we need to preserve but if it isn't we fall
475 // back to using Stacks to keep track of the overflow.
476 if (_preserved_count < _preserved_count_max) {
477 _preserved_marks[_preserved_count++] = PreservedMark(obj, mark);
478 } else {
479 _preserved_overflow_stack_set.get()->push_always(obj, mark);
480 }
481 }
482
483 void SerialFullGC::phase1_mark(bool clear_all_softrefs) {
484 // Recursively traverse all live objects and mark them
485 GCTraceTime(Info, gc, phases) tm("Phase 1: Mark live objects", _gc_timer);
486
487 SerialHeap* gch = SerialHeap::heap();
488
489 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_mark);
490
491 ref_processor()->start_discovery(clear_all_softrefs);
492
493 {
494 StrongRootsScope srs(0);
495
496 CLDClosure* weak_cld_closure = ClassUnloading ? nullptr : &follow_cld_closure;
497 MarkingNMethodClosure mark_code_closure(&follow_root_closure, !NMethodToOopClosure::FixRelocations, true);
498 gch->process_roots(SerialHeap::SO_None,
499 &follow_root_closure,
500 &follow_cld_closure,
501 weak_cld_closure,
502 &mark_code_closure);
503 }
504
505 // Process reference objects found during marking
506 {
507 GCTraceTime(Debug, gc, phases) tm_m("Reference Processing", gc_timer());
508
509 ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->max_num_queues());
510 SerialGCRefProcProxyTask task(is_alive, keep_alive, follow_stack_closure);
511 const ReferenceProcessorStats& stats = ref_processor()->process_discovered_references(task, pt);
512 pt.print_all_references();
513 gc_tracer()->report_gc_reference_stats(stats);
514 }
515
516 // This is the point where the entire marking should have completed.
517 assert(_marking_stack.is_empty(), "Marking should have completed");
518
519 {
520 GCTraceTime(Debug, gc, phases) tm_m("Weak Processing", gc_timer());
521 WeakProcessor::weak_oops_do(&is_alive, &do_nothing_cl);
522 }
523
524 {
525 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", gc_timer());
526
527 ClassUnloadingContext* ctx = ClassUnloadingContext::context();
528
529 bool unloading_occurred;
530 {
531 CodeCache::UnlinkingScope scope(&is_alive);
532
533 // Unload classes and purge the SystemDictionary.
534 unloading_occurred = SystemDictionary::do_unloading(gc_timer());
535
536 // Unload nmethods.
537 CodeCache::do_unloading(unloading_occurred);
538 }
539
540 {
541 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", gc_timer());
542 // Release unloaded nmethod's memory.
543 ctx->purge_nmethods();
544 }
545 {
546 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", gc_timer());
547 gch->prune_unlinked_nmethods();
548 }
549 {
550 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", gc_timer());
551 ctx->free_nmethods();
552 }
553
554 // Prune dead klasses from subklass/sibling/implementor lists.
555 Klass::clean_weak_klass_links(unloading_occurred);
556
557 // Clean JVMCI metadata handles.
558 JVMCI_ONLY(JVMCI::do_unloading(unloading_occurred));
559 }
560
561 {
562 GCTraceTime(Debug, gc, phases) tm_m("Report Object Count", gc_timer());
563 gc_tracer()->report_object_count_after_gc(&is_alive, nullptr);
564 }
565 }
566
567 void SerialFullGC::allocate_stacks() {
568 void* scratch = nullptr;
569 size_t num_words;
570 DefNewGeneration* young_gen = (DefNewGeneration*)SerialHeap::heap()->young_gen();
571 young_gen->contribute_scratch(scratch, num_words);
572
573 if (scratch != nullptr) {
574 _preserved_count_max = num_words * HeapWordSize / sizeof(PreservedMark);
575 } else {
576 _preserved_count_max = 0;
577 }
578
579 _preserved_marks = (PreservedMark*)scratch;
580 _preserved_count = 0;
581
582 _preserved_overflow_stack_set.init(1);
583 }
584
585 void SerialFullGC::deallocate_stacks() {
586 if (_preserved_count_max != 0) {
587 DefNewGeneration* young_gen = (DefNewGeneration*)SerialHeap::heap()->young_gen();
588 young_gen->reset_scratch();
589 }
590
591 _preserved_overflow_stack_set.reclaim();
592 _marking_stack.clear();
593 _objarray_stack.clear(true);
594 }
595
596 void SerialFullGC::mark_object(oop obj) {
597 if (StringDedup::is_enabled() &&
598 java_lang_String::is_instance(obj) &&
599 SerialStringDedup::is_candidate_from_mark(obj)) {
600 _string_dedup_requests->add(obj);
601 }
602
603 // some marks may contain information we need to preserve so we store them away
604 // and overwrite the mark. We'll restore it at the end of serial full GC.
605 markWord mark = obj->mark();
606 obj->set_mark(mark.set_marked());
607
608 ContinuationGCSupport::transform_stack_chunk(obj);
609
610 if (obj->mark_must_be_preserved(mark)) {
611 preserve_mark(obj, mark);
612 }
613 }
614
615 template <class T> void SerialFullGC::mark_and_push(T* p) {
616 T heap_oop = RawAccess<>::oop_load(p);
617 if (!CompressedOops::is_null(heap_oop)) {
618 oop obj = CompressedOops::decode_not_null(heap_oop);
619 if (!obj->mark().is_marked()) {
620 mark_object(obj);
621 _marking_stack.push(obj);
622 }
623 }
624 }
625
626 template <typename T>
627 void MarkAndPushClosure::do_oop_work(T* p) { SerialFullGC::mark_and_push(p); }
628 void MarkAndPushClosure::do_oop( oop* p) { do_oop_work(p); }
629 void MarkAndPushClosure::do_oop(narrowOop* p) { do_oop_work(p); }
630
631 template <class T> void SerialFullGC::adjust_pointer(T* p) {
632 T heap_oop = RawAccess<>::oop_load(p);
633 if (!CompressedOops::is_null(heap_oop)) {
634 oop obj = CompressedOops::decode_not_null(heap_oop);
635 assert(Universe::heap()->is_in(obj), "should be in heap");
636
637 if (FullGCForwarding::is_forwarded(obj)) {
638 oop new_obj = FullGCForwarding::forwardee(obj);
639 assert(is_object_aligned(new_obj), "oop must be aligned");
640 RawAccess<IS_NOT_NULL>::oop_store(p, new_obj);
641 }
642 }
643 }
644
645 template <typename T>
646 void AdjustPointerClosure::do_oop_work(T* p) { SerialFullGC::adjust_pointer(p); }
647 inline void AdjustPointerClosure::do_oop(oop* p) { do_oop_work(p); }
648 inline void AdjustPointerClosure::do_oop(narrowOop* p) { do_oop_work(p); }
649
650 AdjustPointerClosure SerialFullGC::adjust_pointer_closure;
651
652 void SerialFullGC::adjust_marks() {
653 // adjust the oops we saved earlier
654 for (size_t i = 0; i < _preserved_count; i++) {
655 PreservedMarks::adjust_preserved_mark(_preserved_marks + i);
656 }
657
658 // deal with the overflow stack
659 _preserved_overflow_stack_set.get()->adjust_during_full_gc();
660 }
661
662 void SerialFullGC::restore_marks() {
663 log_trace(gc)("Restoring " SIZE_FORMAT " marks", _preserved_count + _preserved_overflow_stack_set.get()->size());
664
665 // restore the marks we saved earlier
666 for (size_t i = 0; i < _preserved_count; i++) {
667 _preserved_marks[i].set_mark();
668 }
669
670 // deal with the overflow
671 _preserved_overflow_stack_set.restore(nullptr);
672 }
673
674 SerialFullGC::IsAliveClosure SerialFullGC::is_alive;
675
676 bool SerialFullGC::IsAliveClosure::do_object_b(oop p) { return p->is_gc_marked(); }
677
678 SerialFullGC::KeepAliveClosure SerialFullGC::keep_alive;
679
680 void SerialFullGC::KeepAliveClosure::do_oop(oop* p) { SerialFullGC::KeepAliveClosure::do_oop_work(p); }
681 void SerialFullGC::KeepAliveClosure::do_oop(narrowOop* p) { SerialFullGC::KeepAliveClosure::do_oop_work(p); }
682
683 void SerialFullGC::initialize() {
684 SerialFullGC::_gc_timer = new STWGCTimer();
685 SerialFullGC::_gc_tracer = new SerialOldTracer();
686 SerialFullGC::_string_dedup_requests = new StringDedup::Requests();
687
688 // The Full GC operates on the entire heap so all objects should be subject
689 // to discovery, hence the _always_true_closure.
690 SerialFullGC::_ref_processor = new ReferenceProcessor(&_always_true_closure);
691 mark_and_push_closure.set_ref_discoverer(_ref_processor);
692 }
693
694 void SerialFullGC::invoke_at_safepoint(bool clear_all_softrefs) {
695 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
696
697 SerialHeap* gch = SerialHeap::heap();
698
699 gch->trace_heap_before_gc(_gc_tracer);
700
701 // Capture used regions for old-gen to reestablish old-to-young invariant
702 // after full-gc.
703 gch->old_gen()->save_used_region();
704
705 allocate_stacks();
706
707 phase1_mark(clear_all_softrefs);
708
709 FullGCForwarding::begin();
710
711 Compacter compacter{gch};
712
713 {
714 // Now all live objects are marked, compute the new object addresses.
715 GCTraceTime(Info, gc, phases) tm("Phase 2: Compute new object addresses", _gc_timer);
716
717 compacter.phase2_calculate_new_addr();
718 }
719
720 // Don't add any more derived pointers during phase3
721 #if COMPILER2_OR_JVMCI
722 assert(DerivedPointerTable::is_active(), "Sanity");
723 DerivedPointerTable::set_active(false);
724 #endif
725
726 {
727 // Adjust the pointers to reflect the new locations
728 GCTraceTime(Info, gc, phases) tm("Phase 3: Adjust pointers", gc_timer());
729
730 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_adjust);
731
732 NMethodToOopClosure code_closure(&adjust_pointer_closure, NMethodToOopClosure::FixRelocations);
733 gch->process_roots(SerialHeap::SO_AllCodeCache,
734 &adjust_pointer_closure,
735 &adjust_cld_closure,
736 &adjust_cld_closure,
737 &code_closure);
738
739 WeakProcessor::oops_do(&adjust_pointer_closure);
740
741 adjust_marks();
742 compacter.phase3_adjust_pointers();
743 }
744
745 {
746 // All pointers are now adjusted, move objects accordingly
747 GCTraceTime(Info, gc, phases) tm("Phase 4: Move objects", _gc_timer);
748
749 compacter.phase4_compact();
750 }
751
752 restore_marks();
753
754 FullGCForwarding::end();
755
756 deallocate_stacks();
757
758 SerialFullGC::_string_dedup_requests->flush();
759
760 bool is_young_gen_empty = (gch->young_gen()->used() == 0);
761 gch->rem_set()->maintain_old_to_young_invariant(gch->old_gen(), is_young_gen_empty);
762
763 gch->prune_scavengable_nmethods();
764
765 // Update heap occupancy information which is used as
766 // input to soft ref clearing policy at the next gc.
767 Universe::heap()->update_capacity_and_used_at_gc();
768
769 // Signal that we have completed a visit to all live objects.
770 Universe::heap()->record_whole_heap_examined_timestamp();
771
772 gch->trace_heap_after_gc(_gc_tracer);
773 }