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
21 * questions.
22 *
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 InstanceKlass;
45
46 public:
47 static const KlassKind Kind = InstanceMirrorKlassKind;
48
49 private:
50 static int _offset_of_static_fields;
51
52 InstanceMirrorKlass(const ClassFileParser& parser) : InstanceKlass(parser, Kind) {}
53
54 template <class OopClosureType>
55 inline void do_metadata(oop obj, OopClosureType* closure);
56
57 public:
58 InstanceMirrorKlass();
59
60 static InstanceMirrorKlass* cast(Klass* k) {
61 return const_cast<InstanceMirrorKlass*>(cast(const_cast<const Klass*>(k)));
62 }
63
64 static const InstanceMirrorKlass* cast(const Klass* k) {
65 assert(k->is_mirror_instance_klass(), "cast to InstanceMirrorKlass");
66 return static_cast<const InstanceMirrorKlass*>(k);
67 }
68
69 // Returns the size of the instance including the extra static fields.
70 size_t oop_size(oop obj, markWord mark) const;
71 int hash_offset_in_bytes(oop obj, markWord m) const;
72
73 // Static field offset is an offset into the Heap, should be converted by
74 // based on UseCompressedOop for traversal
75 static HeapWord* start_of_static_fields(oop obj) {
76 return (HeapWord*)(cast_from_oop<intptr_t>(obj) + offset_of_static_fields());
77 }
78
79 static void init_offset_of_static_fields() {
80 // Cache the offset of the static fields in the Class instance
81 assert(_offset_of_static_fields == 0, "once");
82 _offset_of_static_fields = InstanceMirrorKlass::cast(vmClasses::Class_klass())->size_helper() << LogHeapWordSize;
83 }
84
85 static int offset_of_static_fields() {
86 return _offset_of_static_fields;
87 }
88
89 int compute_static_oop_field_count(oop obj);
90
91 // Given a Klass return the size of the instance
92 size_t instance_size(Klass* k);
93
94 // allocation
95 instanceOop allocate_instance(Klass* k, bool extend, TRAPS);
96
97 static void serialize_offsets(class SerializeClosure* f) NOT_CDS_RETURN;
98
99 // Oop fields (and metadata) iterators
100 //
101 // The InstanceMirrorKlass iterators also visit the hidden Klass pointer.
102
103 // Iterate over the static fields.
104 template <typename T, class OopClosureType>
105 inline void oop_oop_iterate_statics(oop obj, OopClosureType* closure);
106
107 // Forward iteration
108 // Iterate over the oop fields and metadata.
109 template <typename T, class OopClosureType>
110 inline void oop_oop_iterate(oop obj, OopClosureType* closure);
111
112 // Reverse iteration
113 // Iterate over the oop fields and metadata.
114 template <typename T, class OopClosureType>
115 inline void oop_oop_iterate_reverse(oop obj, OopClosureType* closure);
116
117 // Bounded range iteration
118 // Iterate over the oop fields and metadata.
119 template <typename T, class OopClosureType>
120 inline void oop_oop_iterate_bounded(oop obj, OopClosureType* closure, MemRegion mr);
121
122 private:
123
124 // Iterate over the static fields.
125 template <typename T, class OopClosureType>
126 inline void oop_oop_iterate_statics_bounded(oop obj, OopClosureType* closure, MemRegion mr);
127 };
128
129 #endif // SHARE_OOPS_INSTANCEMIRRORKLASS_HPP