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/heapRegion.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 (obj->is_forwarded()) {
 46     HeapWord* destination = cast_from_oop<HeapWord*>(_forwarding->forwardee(obj));
 47 
 48     // copy object and reinit its mark
 49     HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
 50     assert(obj_addr != destination, "everything in this pass should be moving");
 51     Copy::aligned_conjoint_words(obj_addr, destination, size);
 52 
 53     // There is no need to transform stack chunks - marking already did that.
 54     cast_to_oop(destination)->init_mark();
 55     assert(cast_to_oop(destination)->klass() != NULL, "should have a class");
 56   }
 57 
 58   // Clear the mark for the compacted object to allow reuse of the
 59   // bitmap without an additional clearing step.
 60   clear_in_bitmap(obj);
 61   return size;
 62 }
 63 
 64 void G1FullGCCompactTask::compact_region(HeapRegion* hr) {
 65   assert(!hr->is_pinned(), "Should be no pinned region in compaction queue");
 66   assert(!hr->is_humongous(), "Should be no humongous regions in compaction queue");
 67 
 68   if (!collector()->is_free(hr->hrm_index())) {
 69     // The compaction closure not only copies the object to the new
 70     // location, but also clears the bitmap for it. This is needed
 71     // for bitmap verification and to be able to use the bitmap
 72     // for evacuation failures in the next young collection. Testing
 73     // showed that it was better overall to clear bit by bit, compared
 74     // to clearing the whole region at the end. This difference was
 75     // clearly seen for regions with few marks.
 76     G1CompactRegionClosure compact(collector()->mark_bitmap());
 77     hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact);
 78   }
 79 
 80   hr->reset_compacted_after_full_gc(_collector->compaction_top(hr));
 81 }
 82 
 83 void G1FullGCCompactTask::work(uint worker_id) {
 84   Ticks start = Ticks::now();
 85   GrowableArray<HeapRegion*>* compaction_queue = collector()->compaction_point(worker_id)->regions();
 86   for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
 87        it != compaction_queue->end();
 88        ++it) {
 89     compact_region(*it);
 90   }
 91 }
 92 
 93 void G1FullGCCompactTask::serial_compaction() {
 94   GCTraceTime(Debug, gc, phases) tm("Phase 4: Serial Compaction", collector()->scope()->timer());
 95   GrowableArray<HeapRegion*>* compaction_queue = collector()->serial_compaction_point()->regions();
 96   for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
 97        it != compaction_queue->end();
 98        ++it) {
 99     compact_region(*it);
100   }
101 }