1 /* 2 * Copyright (c) 2017, 2025, 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 "gc/g1/g1CollectedHeap.hpp" 26 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp" 27 #include "gc/g1/g1FullCollector.inline.hpp" 28 #include "gc/g1/g1FullGCCompactionPoint.hpp" 29 #include "gc/g1/g1FullGCCompactTask.hpp" 30 #include "gc/g1/g1HeapRegion.inline.hpp" 31 #include "gc/shared/fullGCForwarding.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 (FullGCForwarding::is_forwarded(obj)) { 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(FullGCForwarding::is_forwarded(obj), "Sanity!"); 56 assert(FullGCForwarding::forwardee(obj) != 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*>(FullGCForwarding::forwardee(obj)); 62 assert(obj_addr != destination, "only copy actually-moving objects"); 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 cast_to_oop(destination)->initialize_hash_if_necessary(obj); 68 assert(cast_to_oop(destination)->klass() != nullptr, "should have a class"); 69 } 70 71 void G1FullGCCompactTask::compact_region(G1HeapRegion* hr) { 72 assert(!hr->has_pinned_objects(), "Should be no region with pinned objects in compaction queue"); 73 assert(!hr->is_humongous(), "Should be no humongous regions in compaction queue"); 74 75 if (!collector()->is_free(hr->hrm_index())) { 76 // The compaction closure not only copies the object to the new 77 // location, but also clears the bitmap for it. This is needed 78 // for bitmap verification and to be able to use the bitmap 79 // for evacuation failures in the next young collection. Testing 80 // showed that it was better overall to clear bit by bit, compared 81 // to clearing the whole region at the end. This difference was 82 // clearly seen for regions with few marks. 83 G1CompactRegionClosure compact(collector()->mark_bitmap()); 84 hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact); 85 } 86 87 hr->reset_compacted_after_full_gc(_collector->compaction_top(hr)); 88 } 89 90 void G1FullGCCompactTask::work(uint worker_id) { 91 Ticks start = Ticks::now(); 92 GrowableArray<G1HeapRegion*>* compaction_queue = collector()->compaction_point(worker_id)->regions(); 93 for (GrowableArrayIterator<G1HeapRegion*> it = compaction_queue->begin(); 94 it != compaction_queue->end(); 95 ++it) { 96 compact_region(*it); 97 } 98 } 99 100 void G1FullGCCompactTask::serial_compaction() { 101 GCTraceTime(Debug, gc, phases) tm("Phase 4: Serial Compaction", collector()->scope()->timer()); 102 GrowableArray<G1HeapRegion*>* compaction_queue = collector()->serial_compaction_point()->regions(); 103 for (GrowableArrayIterator<G1HeapRegion*> it = compaction_queue->begin(); 104 it != compaction_queue->end(); 105 ++it) { 106 compact_region(*it); 107 } 108 } 109 110 void G1FullGCCompactTask::humongous_compaction() { 111 GCTraceTime(Debug, gc, phases) tm("Phase 4: Humonguous Compaction", collector()->scope()->timer()); 112 113 for (G1HeapRegion* hr : collector()->humongous_compaction_regions()) { 114 assert(collector()->is_compaction_target(hr->hrm_index()), "Sanity"); 115 compact_humongous_obj(hr); 116 } 117 } 118 119 void G1FullGCCompactTask::compact_humongous_obj(G1HeapRegion* src_hr) { 120 assert(src_hr->is_starts_humongous(), "Should be start region of the humongous object"); 121 122 oop obj = cast_to_oop(src_hr->bottom()); 123 size_t word_size = obj->size(); 124 125 uint num_regions = (uint)G1CollectedHeap::humongous_obj_size_in_regions(word_size); 126 HeapWord* destination = cast_from_oop<HeapWord*>(FullGCForwarding::forwardee(obj)); 127 128 assert(collector()->mark_bitmap()->is_marked(obj), "Should only compact marked objects"); 129 collector()->mark_bitmap()->clear(obj); 130 131 copy_object_to_new_location(obj); 132 133 uint dest_start_idx = _g1h->addr_to_region(destination); 134 // Update the metadata for the destination regions. 135 _g1h->set_humongous_metadata(_g1h->region_at(dest_start_idx), num_regions, word_size, false); 136 137 // Free the source regions that do not overlap with the destination regions. 138 uint src_start_idx = src_hr->hrm_index(); 139 free_non_overlapping_regions(src_start_idx, dest_start_idx, num_regions); 140 } 141 142 void G1FullGCCompactTask::free_non_overlapping_regions(uint src_start_idx, uint dest_start_idx, uint num_regions) { 143 uint dest_end_idx = dest_start_idx + num_regions -1; 144 uint src_end_idx = src_start_idx + num_regions - 1; 145 146 uint non_overlapping_start = dest_end_idx < src_start_idx ? 147 src_start_idx : 148 dest_end_idx + 1; 149 150 for (uint i = non_overlapping_start; i <= src_end_idx; ++i) { 151 G1HeapRegion* hr = _g1h->region_at(i); 152 _g1h->free_humongous_region(hr, nullptr); 153 } 154 }