1 /*
2 * Copyright (c) 2000, 2019, 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.
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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
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23 */
24
25 #ifndef SHARE_GC_SHARED_SPACE_INLINE_HPP
26 #define SHARE_GC_SHARED_SPACE_INLINE_HPP
27
28 #include "gc/shared/space.hpp"
29
30 #include "gc/shared/blockOffsetTable.inline.hpp"
31 #include "gc/shared/collectedHeap.hpp"
32 #include "gc/shared/generation.hpp"
33 #include "gc/shared/genCollectedHeap.hpp"
34 #include "gc/shared/spaceDecorator.hpp"
35 #include "oops/oopsHierarchy.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "runtime/prefetch.inline.hpp"
38 #include "runtime/safepoint.hpp"
39 #if INCLUDE_SERIALGC
40 #include "gc/serial/markSweep.inline.hpp"
41 #endif
42
43 inline HeapWord* Space::block_start(const void* p) {
44 return block_start_const(p);
45 }
46
47 inline HeapWord* OffsetTableContigSpace::allocate(size_t size) {
48 HeapWord* res = ContiguousSpace::allocate(size);
49 if (res != NULL) {
50 _offsets.alloc_block(res, size);
51 }
52 return res;
53 }
54
55 // Because of the requirement of keeping "_offsets" up to date with the
56 // allocations, we sequentialize these with a lock. Therefore, best if
57 // this is used for larger LAB allocations only.
58 inline HeapWord* OffsetTableContigSpace::par_allocate(size_t size) {
59 MutexLocker x(&_par_alloc_lock);
60 // This ought to be just "allocate", because of the lock above, but that
61 // ContiguousSpace::allocate asserts that either the allocating thread
62 // holds the heap lock or it is the VM thread and we're at a safepoint.
63 // The best I (dld) could figure was to put a field in ContiguousSpace
64 // meaning "locking at safepoint taken care of", and set/reset that
65 // here. But this will do for now, especially in light of the comment
66 // above. Perhaps in the future some lock-free manner of keeping the
67 // coordination.
68 HeapWord* res = ContiguousSpace::par_allocate(size);
69 if (res != NULL) {
70 _offsets.alloc_block(res, size);
71 }
72 return res;
73 }
74
75 inline HeapWord*
76 OffsetTableContigSpace::block_start_const(const void* p) const {
77 return _offsets.block_start(p);
78 }
79
80 #if INCLUDE_SERIALGC
81
82 class DeadSpacer : StackObj {
83 size_t _allowed_deadspace_words;
84 bool _active;
85 CompactibleSpace* _space;
86
87 public:
88 DeadSpacer(CompactibleSpace* space) : _allowed_deadspace_words(0), _space(space) {
89 size_t ratio = _space->allowed_dead_ratio();
90 _active = ratio > 0;
91
92 if (_active) {
93 assert(!UseG1GC, "G1 should not be using dead space");
94
95 // We allow some amount of garbage towards the bottom of the space, so
96 // we don't start compacting before there is a significant gain to be made.
97 // Occasionally, we want to ensure a full compaction, which is determined
98 // by the MarkSweepAlwaysCompactCount parameter.
99 if ((MarkSweep::total_invocations() % MarkSweepAlwaysCompactCount) != 0) {
100 _allowed_deadspace_words = (space->capacity() * ratio / 100) / HeapWordSize;
101 } else {
102 _active = false;
103 }
104 }
105 }
106
107
108 bool insert_deadspace(HeapWord* dead_start, HeapWord* dead_end) {
109 if (!_active) {
110 return false;
111 }
112
113 size_t dead_length = pointer_delta(dead_end, dead_start);
114 if (_allowed_deadspace_words >= dead_length) {
115 _allowed_deadspace_words -= dead_length;
116 CollectedHeap::fill_with_object(dead_start, dead_length);
117 oop obj = cast_to_oop(dead_start);
118 obj->set_mark(obj->mark().set_marked());
119
120 assert(dead_length == obj->size(), "bad filler object size");
121 log_develop_trace(gc, compaction)("Inserting object to dead space: " PTR_FORMAT ", " PTR_FORMAT ", " SIZE_FORMAT "b",
122 p2i(dead_start), p2i(dead_end), dead_length * HeapWordSize);
123
124 return true;
125 } else {
126 _active = false;
127 return false;
128 }
129 }
130
131 };
132
133 #ifdef ASSERT
134 template <class SpaceType>
135 inline void CompactibleSpace::verify_up_to_first_dead(SpaceType* space) {
136 HeapWord* cur_obj = space->bottom();
137
138 if (cur_obj < space->_end_of_live && space->_first_dead > cur_obj && !cast_to_oop(cur_obj)->is_gc_marked()) {
139 // we have a chunk of the space which hasn't moved and we've reinitialized
140 // the mark word during the previous pass, so we can't use is_gc_marked for
141 // the traversal.
142 HeapWord* prev_obj = NULL;
143
144 while (cur_obj < space->_first_dead) {
145 size_t size = cast_to_oop(cur_obj)->size();
146 assert(!cast_to_oop(cur_obj)->is_gc_marked(), "should be unmarked (special dense prefix handling)");
147 prev_obj = cur_obj;
148 cur_obj += size;
149 }
150 }
151 }
152 #endif
153
154 template <class SpaceType>
155 inline void CompactibleSpace::clear_empty_region(SpaceType* space) {
156 // Let's remember if we were empty before we did the compaction.
157 bool was_empty = space->used_region().is_empty();
158 // Reset space after compaction is complete
159 space->reset_after_compaction();
160 // We do this clear, below, since it has overloaded meanings for some
161 // space subtypes. For example, OffsetTableContigSpace's that were
162 // compacted into will have had their offset table thresholds updated
163 // continuously, but those that weren't need to have their thresholds
164 // re-initialized. Also mangles unused area for debugging.
165 if (space->used_region().is_empty()) {
166 if (!was_empty) space->clear(SpaceDecorator::Mangle);
167 } else {
168 if (ZapUnusedHeapArea) space->mangle_unused_area();
169 }
170 }
171 #endif // INCLUDE_SERIALGC
172
173 template <typename OopClosureType>
174 void ContiguousSpace::oop_since_save_marks_iterate(OopClosureType* blk) {
175 HeapWord* t;
176 HeapWord* p = saved_mark_word();
177 assert(p != NULL, "expected saved mark");
178
179 const intx interval = PrefetchScanIntervalInBytes;
180 do {
181 t = top();
182 while (p < t) {
183 Prefetch::write(p, interval);
184 debug_only(HeapWord* prev = p);
185 oop m = cast_to_oop(p);
186 p += m->oop_iterate_size(blk);
187 }
188 } while (t < top());
189
190 set_saved_mark_word(p);
191 }
192
193 #endif // SHARE_GC_SHARED_SPACE_INLINE_HPP