1 /*
2 * Copyright (c) 2011, 2023, 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_OOPS_INSTANCEMIRRORKLASS_HPP
26 #define SHARE_OOPS_INSTANCEMIRRORKLASS_HPP
27
28 #include "classfile/vmClasses.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 KlassKind Kind = InstanceMirrorKlassKind;
49
50 private:
51 static int _offset_of_static_fields;
52
53 InstanceMirrorKlass(const ClassFileParser& parser) : InstanceKlass(parser, Kind) {}
54
55 public:
56 InstanceMirrorKlass();
57
58 static InstanceMirrorKlass* cast(Klass* k) {
59 return const_cast<InstanceMirrorKlass*>(cast(const_cast<const Klass*>(k)));
60 }
61
62 static const InstanceMirrorKlass* cast(const Klass* k) {
63 assert(k->is_mirror_instance_klass(), "cast to InstanceMirrorKlass");
64 return static_cast<const InstanceMirrorKlass*>(k);
65 }
66
67 // Returns the size of the instance including the extra static fields.
68 size_t oop_size(oop obj, markWord mark) const;
69 int hash_offset_in_bytes(oop obj) const;
70
71 // Static field offset is an offset into the Heap, should be converted by
72 // based on UseCompressedOop for traversal
73 static HeapWord* start_of_static_fields(oop obj) {
74 return (HeapWord*)(cast_from_oop<intptr_t>(obj) + offset_of_static_fields());
75 }
76
77 static void init_offset_of_static_fields() {
78 // Cache the offset of the static fields in the Class instance
79 assert(_offset_of_static_fields == 0, "once");
80 _offset_of_static_fields = InstanceMirrorKlass::cast(vmClasses::Class_klass())->size_helper() << LogHeapWordSize;
81 }
82
83 static int offset_of_static_fields() {
84 return _offset_of_static_fields;
85 }
86
87 int compute_static_oop_field_count(oop obj);
88
89 // Given a Klass return the size of the instance
90 size_t instance_size(Klass* k);
91
92 // allocation
93 instanceOop allocate_instance(Klass* k, bool extend, TRAPS);
94
95 static void serialize_offsets(class SerializeClosure* f) NOT_CDS_RETURN;
96
97 // Oop fields (and metadata) iterators
98 //
99 // The InstanceMirrorKlass iterators also visit the hidden Klass pointer.
100
101 // Iterate over the static fields.
102 template <typename T, class OopClosureType>
103 inline void oop_oop_iterate_statics(oop obj, OopClosureType* closure);
104
105 // Forward iteration
106 // Iterate over the oop fields and metadata.
107 template <typename T, class OopClosureType>
108 inline void oop_oop_iterate(oop obj, OopClosureType* closure);
109
110 // Reverse iteration
111 // Iterate over the oop fields and metadata.
112 template <typename T, class OopClosureType>
113 inline void oop_oop_iterate_reverse(oop obj, OopClosureType* closure);
114
115 // Bounded range iteration
116 // Iterate over the oop fields and metadata.
117 template <typename T, class OopClosureType>
118 inline void oop_oop_iterate_bounded(oop obj, OopClosureType* closure, MemRegion mr);
119
120 private:
121
122 // Iterate over the static fields.
123 template <typename T, class OopClosureType>
124 inline void oop_oop_iterate_statics_bounded(oop obj, OopClosureType* closure, MemRegion mr);
125 };
126
127 #endif // SHARE_OOPS_INSTANCEMIRRORKLASS_HPP