1 /*
2 * Copyright (c) 2017, 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 #include "precompiled.hpp"
25 #include "gc/z/zAddressRangeMap.inline.hpp"
26 #include "gc/z/zBarrier.inline.hpp"
27 #include "gc/z/zGlobals.hpp"
28 #include "gc/z/zHeapIterator.hpp"
29 #include "gc/z/zOop.inline.hpp"
30 #include "gc/z/zRootsIterator.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "utilities/bitMap.inline.hpp"
33 #include "utilities/stack.inline.hpp"
34
35 class ZHeapIteratorBitMap : public CHeapObj<mtGC> {
36 private:
37 CHeapBitMap _map;
38
39 public:
40 ZHeapIteratorBitMap(size_t size_in_bits) :
41 _map(size_in_bits) {}
42
43 bool try_set_bit(size_t index) {
44 if (_map.at(index)) {
45 return false;
46 }
47
48 _map.set_bit(index);
49 return true;
50 }
51 };
52
53 class ZHeapIteratorRootOopClosure : public OopClosure {
54 private:
55 ZHeapIterator* const _iter;
56 ObjectClosure* const _cl;
57
58 public:
59 ZHeapIteratorRootOopClosure(ZHeapIterator* iter, ObjectClosure* cl) :
60 _iter(iter),
61 _cl(cl) {}
62
63 virtual void do_oop(oop* p) {
64 // Load barrier needed here for the same reason we
65 // need fixup_partial_loads() in ZHeap::mark_end()
66 const oop obj = ZBarrier::load_barrier_on_oop_field(p);
67 _iter->push(obj);
68 _iter->drain(_cl);
69 }
70
71 virtual void do_oop(narrowOop* p) {
72 ShouldNotReachHere();
73 }
74 };
75
76 class ZHeapIteratorPushOopClosure : public ExtendedOopClosure {
77 private:
78 ZHeapIterator* const _iter;
79 const oop _base;
80
81 public:
82 ZHeapIteratorPushOopClosure(ZHeapIterator* iter, oop base) :
83 _iter(iter),
84 _base(base) {}
85
86 void do_oop_nv(oop* p) {
87 const oop obj = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_load_at(_base, _base->field_offset(p));
88 _iter->push(obj);
89 }
90
91 void do_oop_nv(narrowOop* p) {
92 ShouldNotReachHere();
93 }
94
95 virtual void do_oop(oop* p) {
96 do_oop_nv(p);
97 }
98
99 virtual void do_oop(narrowOop* p) {
100 do_oop_nv(p);
101 }
102
103 #ifdef ASSERT
104 virtual bool should_verify_oops() {
105 return false;
106 }
107 #endif
108 };
109
110 ZHeapIterator::ZHeapIterator() :
111 _visit_stack(),
112 _visit_map() {}
113
114 ZHeapIterator::~ZHeapIterator() {
115 ZVisitMapIterator iter(&_visit_map);
116 for (ZHeapIteratorBitMap* map; iter.next(&map);) {
117 delete map;
118 }
119 }
120
121 size_t ZHeapIterator::object_index_max() const {
122 return ZPageSizeMin >> ZObjectAlignmentSmallShift;
123 }
124
125 size_t ZHeapIterator::object_index(oop obj) const {
126 const uintptr_t addr = ZOop::to_address(obj);
127 const uintptr_t offset = ZAddress::offset(addr);
128 const uintptr_t mask = (1 << ZPageSizeMinShift) - 1;
129 return (offset & mask) >> ZObjectAlignmentSmallShift;
130 }
131
132 ZHeapIteratorBitMap* ZHeapIterator::object_map(oop obj) {
133 const uintptr_t addr = ZOop::to_address(obj);
134 ZHeapIteratorBitMap* map = _visit_map.get(addr);
135 if (map == NULL) {
136 map = new ZHeapIteratorBitMap(object_index_max());
137 _visit_map.put(addr, map);
138 }
139
140 return map;
141 }
142
143 void ZHeapIterator::push(oop obj) {
144 if (obj == NULL) {
145 // Ignore
146 return;
147 }
148
149 ZHeapIteratorBitMap* const map = object_map(obj);
150 const size_t index = object_index(obj);
151 if (!map->try_set_bit(index)) {
152 // Already pushed
153 return;
154 }
155
156 // Push
157 _visit_stack.push(obj);
158 }
159
160 void ZHeapIterator::drain(ObjectClosure* cl) {
161 while (!_visit_stack.is_empty()) {
162 const oop obj = _visit_stack.pop();
163
164 // Visit
165 cl->do_object(obj);
166
167 // Push members to visit
168 ZHeapIteratorPushOopClosure push_cl(this, obj);
169 obj->oop_iterate(&push_cl);
170 }
171 }
172
173 void ZHeapIterator::objects_do(ObjectClosure* cl) {
174 ZHeapIteratorRootOopClosure root_cl(this, cl);
175 ZRootsIterator roots;
176
177 // Follow roots. Note that we also visit the JVMTI weak tag map
178 // as if they where strong roots to make sure we visit all tagged
179 // objects, even those that might now have become unreachable.
180 // If we didn't do this the user would have expected to see
181 // ObjectFree events for unreachable objects in the tag map.
182 roots.oops_do(&root_cl, true /* visit_jvmti_weak_export */);
183 }