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