1 /*
2 * Copyright (c) 2011, 2018, 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.
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23 */
24
25 #ifndef SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP
26 #define SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP
27
28 #include "classfile/systemDictionary.hpp"
29 #include "oops/instanceKlass.hpp"
30 #include "runtime/handles.hpp"
31 #include "utilities/macros.hpp"
32
33 class ClassFileParser;
34
35 // An InstanceMirrorKlass is a specialized InstanceKlass for
36 // java.lang.Class instances. These instances are special because
37 // they contain the static fields of the class in addition to the
38 // normal fields of Class. This means they are variable sized
39 // instances and need special logic for computing their size and for
40 // iteration of their oops.
41
42
43 class InstanceMirrorKlass: public InstanceKlass {
44 friend class VMStructs;
45 friend class InstanceKlass;
46
47 public:
48 static const KlassID ID = InstanceMirrorKlassID;
49
50 private:
51 static int _offset_of_static_fields;
52
53 InstanceMirrorKlass(const ClassFileParser& parser) : InstanceKlass(parser, InstanceKlass::_misc_kind_mirror, ID) {}
54
55 public:
56 InstanceMirrorKlass() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }
57
58 // Casting from Klass*
59 static InstanceMirrorKlass* cast(Klass* k) {
60 assert(InstanceKlass::cast(k)->is_mirror_instance_klass(),
61 "cast to InstanceMirrorKlass");
62 return static_cast<InstanceMirrorKlass*>(k);
63 }
64
65 // Returns the size of the instance including the extra static fields.
66 virtual int oop_size(oop obj) const;
67
68 // Static field offset is an offset into the Heap, should be converted by
69 // based on UseCompressedOop for traversal
70 static HeapWord* start_of_static_fields(oop obj) {
71 return (HeapWord*)(cast_from_oop<intptr_t>(obj) + offset_of_static_fields());
72 }
73
74 static void init_offset_of_static_fields() {
75 // Cache the offset of the static fields in the Class instance
76 assert(_offset_of_static_fields == 0, "once");
77 _offset_of_static_fields = InstanceMirrorKlass::cast(SystemDictionary::Class_klass())->size_helper() << LogHeapWordSize;
78 }
79
80 static int offset_of_static_fields() {
81 return _offset_of_static_fields;
82 }
83
84 int compute_static_oop_field_count(oop obj);
85
86 // Given a Klass return the size of the instance
87 int instance_size(Klass* k);
88
89 // allocation
90 instanceOop allocate_instance(Klass* k, TRAPS);
91
92 // GC specific object visitors
93 //
94 #if INCLUDE_PARALLELGC
95 // Parallel Compact
96 void oop_pc_follow_contents(oop obj, ParCompactionManager* cm);
97 void oop_pc_update_pointers(oop obj, ParCompactionManager* cm);
98 #endif
99
100 static void serialize_offsets(class SerializeClosure* f) NOT_CDS_RETURN;
101
102 // Oop fields (and metadata) iterators
103 //
104 // The InstanceMirrorKlass iterators also visit the hidden Klass pointer.
105
106 // Iterate over the static fields.
107 template <typename T, class OopClosureType>
108 inline void oop_oop_iterate_statics(oop obj, OopClosureType* closure);
109
110 // Forward iteration
111 // Iterate over the oop fields and metadata.
112 template <typename T, class OopClosureType>
113 inline void oop_oop_iterate(oop obj, OopClosureType* closure);
114
115 // Reverse iteration
116 // Iterate over the oop fields and metadata.
117 template <typename T, class OopClosureType>
118 inline void oop_oop_iterate_reverse(oop obj, OopClosureType* closure);
119
120 // Bounded range iteration
121 // Iterate over the oop fields and metadata.
122 template <typename T, class OopClosureType>
123 inline void oop_oop_iterate_bounded(oop obj, OopClosureType* closure, MemRegion mr);
124
125 private:
126
127 // Iterate over the static fields.
128 template <typename T, class OopClosureType>
129 inline void oop_oop_iterate_statics_bounded(oop obj, OopClosureType* closure, MemRegion mr);
130 };
131
132 #endif // SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP