1 /*
  2  * Copyright (c) 2017, 2023, 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 "gc/g1/g1CollectedHeap.hpp"
 27 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
 28 #include "gc/g1/g1FullCollector.inline.hpp"
 29 #include "gc/g1/g1FullGCCompactionPoint.hpp"
 30 #include "gc/g1/g1FullGCCompactTask.hpp"
 31 #include "gc/g1/g1HeapRegion.inline.hpp"
 32 #include "gc/shared/gcTraceTime.inline.hpp"
 33 #include "gc/shared/slidingForwarding.inline.hpp"
 34 #include "logging/log.hpp"
 35 #include "oops/oop.inline.hpp"
 36 #include "utilities/ticks.hpp"
 37 
 38 void G1FullGCCompactTask::G1CompactRegionClosure::clear_in_bitmap(oop obj) {
 39   assert(_bitmap->is_marked(obj), "Should only compact marked objects");
 40   _bitmap->clear(obj);
 41 }
 42 
 43 size_t G1FullGCCompactTask::G1CompactRegionClosure::apply(oop obj) {
 44   size_t size = obj->size();
 45   if (SlidingForwarding::is_forwarded(obj)) {
 46     G1FullGCCompactTask::copy_object_to_new_location(obj);
 47   }
 48 
 49   // Clear the mark for the compacted object to allow reuse of the
 50   // bitmap without an additional clearing step.
 51   clear_in_bitmap(obj);
 52   return size;
 53 }
 54 
 55 void G1FullGCCompactTask::copy_object_to_new_location(oop obj) {
 56   assert(SlidingForwarding::is_forwarded(obj), "Sanity!");
 57   assert(SlidingForwarding::forwardee(obj) != obj, "Object must have a new location");
 58 
 59   size_t size = obj->size();
 60   // Copy object and reinit its mark.
 61   HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
 62   HeapWord* destination = cast_from_oop<HeapWord*>(SlidingForwarding::forwardee(obj));
 63   Copy::aligned_conjoint_words(obj_addr, destination, size);
 64 
 65   // There is no need to transform stack chunks - marking already did that.
 66   cast_to_oop(destination)->init_mark();
 67   assert(cast_to_oop(destination)->klass() != nullptr, "should have a class");
 68 }
 69 
 70 void G1FullGCCompactTask::compact_region(G1HeapRegion* hr) {
 71   assert(!hr->has_pinned_objects(), "Should be no region with pinned objects in compaction queue");
 72   assert(!hr->is_humongous(), "Should be no humongous regions in compaction queue");
 73 
 74   if (!collector()->is_free(hr->hrm_index())) {
 75     // The compaction closure not only copies the object to the new
 76     // location, but also clears the bitmap for it. This is needed
 77     // for bitmap verification and to be able to use the bitmap
 78     // for evacuation failures in the next young collection. Testing
 79     // showed that it was better overall to clear bit by bit, compared
 80     // to clearing the whole region at the end. This difference was
 81     // clearly seen for regions with few marks.
 82     G1CompactRegionClosure compact(collector()->mark_bitmap());
 83     hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact);
 84   }
 85 
 86   hr->reset_compacted_after_full_gc(_collector->compaction_top(hr));
 87 }
 88 
 89 void G1FullGCCompactTask::work(uint worker_id) {
 90   Ticks start = Ticks::now();
 91   GrowableArray<G1HeapRegion*>* compaction_queue = collector()->compaction_point(worker_id)->regions();
 92   for (GrowableArrayIterator<G1HeapRegion*> it = compaction_queue->begin();
 93        it != compaction_queue->end();
 94        ++it) {
 95     compact_region(*it);
 96   }
 97 }
 98 
 99 void G1FullGCCompactTask::serial_compaction() {
100   GCTraceTime(Debug, gc, phases) tm("Phase 4: Serial Compaction", collector()->scope()->timer());
101   GrowableArray<G1HeapRegion*>* compaction_queue = collector()->serial_compaction_point()->regions();
102   for (GrowableArrayIterator<G1HeapRegion*> it = compaction_queue->begin();
103        it != compaction_queue->end();
104        ++it) {
105     compact_region(*it);
106   }
107 }
108 
109 void G1FullGCCompactTask::humongous_compaction() {
110   GCTraceTime(Debug, gc, phases) tm("Phase 4: Humonguous Compaction", collector()->scope()->timer());
111 
112   for (G1HeapRegion* hr : collector()->humongous_compaction_regions()) {
113     assert(collector()->is_compaction_target(hr->hrm_index()), "Sanity");
114     compact_humongous_obj(hr);
115   }
116 }
117 
118 void G1FullGCCompactTask::compact_humongous_obj(G1HeapRegion* src_hr) {
119   assert(src_hr->is_starts_humongous(), "Should be start region of the humongous object");
120 
121   oop obj = cast_to_oop(src_hr->bottom());
122   size_t word_size = obj->size();
123 
124   uint num_regions = (uint)G1CollectedHeap::humongous_obj_size_in_regions(word_size);
125   HeapWord* destination = cast_from_oop<HeapWord*>(SlidingForwarding::forwardee(obj));
126 
127   assert(collector()->mark_bitmap()->is_marked(obj), "Should only compact marked objects");
128   collector()->mark_bitmap()->clear(obj);
129 
130   copy_object_to_new_location(obj);
131 
132   uint dest_start_idx = _g1h->addr_to_region(destination);
133   // Update the metadata for the destination regions.
134   _g1h->set_humongous_metadata(_g1h->region_at(dest_start_idx), num_regions, word_size, false);
135 
136   // Free the source regions that do not overlap with the destination regions.
137   uint src_start_idx = src_hr->hrm_index();
138   free_non_overlapping_regions(src_start_idx, dest_start_idx, num_regions);
139 }
140 
141 void G1FullGCCompactTask::free_non_overlapping_regions(uint src_start_idx, uint dest_start_idx, uint num_regions) {
142   uint dest_end_idx = dest_start_idx + num_regions -1;
143   uint src_end_idx  = src_start_idx + num_regions - 1;
144 
145   uint non_overlapping_start = dest_end_idx < src_start_idx ?
146                                src_start_idx :
147                                dest_end_idx + 1;
148 
149   for (uint i = non_overlapping_start; i <= src_end_idx; ++i) {
150     G1HeapRegion* hr = _g1h->region_at(i);
151     _g1h->free_humongous_region(hr, nullptr);
152   }
153 }
--- EOF ---