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