1 /*
  2  * Copyright (c) 2017, 2021, 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/g1FullGCCompactionPoint.hpp"
 27 #include "gc/g1/heapRegion.hpp"
 28 #include "oops/oop.inline.hpp"
 29 #include "utilities/debug.hpp"
 30 
 31 G1FullGCCompactionPoint::G1FullGCCompactionPoint() :
 32     _current_region(NULL),
 33     _compaction_top(NULL) {
 34   _compaction_regions = new (ResourceObj::C_HEAP, mtGC) GrowableArray<HeapRegion*>(32, mtGC);
 35   _compaction_region_iterator = _compaction_regions->begin();
 36 }
 37 
 38 G1FullGCCompactionPoint::~G1FullGCCompactionPoint() {
 39   delete _compaction_regions;
 40 }
 41 
 42 void G1FullGCCompactionPoint::update() {
 43   if (is_initialized()) {
 44     _current_region->set_compaction_top(_compaction_top);
 45   }
 46 }
 47 
 48 void G1FullGCCompactionPoint::initialize_values(bool init_threshold) {
 49   _compaction_top = _current_region->compaction_top();
 50   if (init_threshold) {
 51     _current_region->initialize_bot_threshold();
 52   }
 53 }
 54 
 55 bool G1FullGCCompactionPoint::has_regions() {
 56   return !_compaction_regions->is_empty();
 57 }
 58 
 59 bool G1FullGCCompactionPoint::is_initialized() {
 60   return _current_region != NULL;
 61 }
 62 
 63 void G1FullGCCompactionPoint::initialize(HeapRegion* hr, bool init_threshold) {
 64   _current_region = hr;
 65   initialize_values(init_threshold);
 66 }
 67 
 68 HeapRegion* G1FullGCCompactionPoint::current_region() {
 69   return *_compaction_region_iterator;
 70 }
 71 
 72 HeapRegion* G1FullGCCompactionPoint::next_region() {
 73   HeapRegion* next = *(++_compaction_region_iterator);
 74   assert(next != NULL, "Must return valid region");
 75   return next;
 76 }
 77 
 78 GrowableArray<HeapRegion*>* G1FullGCCompactionPoint::regions() {
 79   return _compaction_regions;
 80 }
 81 
 82 bool G1FullGCCompactionPoint::object_will_fit(size_t size) {
 83   size_t space_left = pointer_delta(_current_region->end(), _compaction_top);
 84   return size <= space_left;
 85 }
 86 
 87 void G1FullGCCompactionPoint::switch_region() {
 88   // Save compaction top in the region.
 89   _current_region->set_compaction_top(_compaction_top);
 90   // Get the next region and re-initialize the values.
 91   _current_region = next_region();
 92   initialize_values(true);
 93 }
 94 
 95 void G1FullGCCompactionPoint::forward(oop object, size_t size) {
 96   assert(_current_region != NULL, "Must have been initialized");
 97 
 98   // Ensure the object fit in the current region.
 99   while (!object_will_fit(size)) {
100     switch_region();
101   }
102 
103   // Store a forwarding pointer if the object should be moved.
104   if (cast_from_oop<HeapWord*>(object) != _compaction_top) {
105     object->forward_to(cast_to_oop(_compaction_top));
106   } else {
107     if (object->forwardee() != NULL) {
108       // Object should not move but mark-word is used so it looks like the
109       // object is forwarded. Need to clear the mark and it's no problem
110       // since it will be restored by preserved marks.
111       object->init_mark();
112     } else {
113       // Make sure object has the correct mark-word set or that it will be
114       // fixed when restoring the preserved marks.
115       assert(object->mark() == object->klass()->prototype_header() || // Correct mark
116              object->mark_must_be_preserved(), // Will be restored by PreservedMarksSet
117              "should have correct prototype obj: " PTR_FORMAT " mark: " PTR_FORMAT " prototype: " PTR_FORMAT,
118              p2i(object), object->mark().value(), object->klass()->prototype_header().value());
119     }
120     assert(object->forwardee() == NULL, "should be forwarded to NULL");
121   }
122 
123   // Update compaction values.
124   _compaction_top += size;
125   _current_region->alloc_block_in_bot(_compaction_top - size, _compaction_top);
126 }
127 
128 void G1FullGCCompactionPoint::add(HeapRegion* hr) {
129   _compaction_regions->append(hr);
130 }
131 
132 HeapRegion* G1FullGCCompactionPoint::remove_last() {
133   return _compaction_regions->pop();
134 }