1 /*
2 * Copyright (c) 2011, 2026, 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_OOPS_FIELDSTREAMS_HPP
26 #define SHARE_OOPS_FIELDSTREAMS_HPP
27
28 #include "oops/fieldInfo.hpp"
29 #include "oops/instanceKlass.hpp"
30 #include "runtime/fieldDescriptor.hpp"
31
32 // The is the base class for iteration over the fields array
33 // describing the declared fields in the class. Several subclasses
34 // are provided depending on the kind of iteration required. The
35 // JavaFieldStream is for iterating over regular Java fields and it
36 // generally the preferred iterator. InternalFieldStream only
37 // iterates over fields that have been injected by the JVM.
38 // AllFieldStream exposes all fields and should only be used in rare
39 // cases.
40 // HierarchicalFieldStream allows to also iterate over fields of supertypes.
41 class FieldStreamBase : public StackObj {
42 protected:
43 const Array<u1>* _fieldinfo_stream;
44 FieldInfoReader _reader;
45 constantPoolHandle _constants;
46 int _index;
47 int _limit;
48
49 FieldInfo _fi_buf;
50 fieldDescriptor _fd_buf;
51
52 FieldInfo const * field() const {
53 assert(!done(), "no more fields");
54 return &_fi_buf;
55 }
56
57 inline FieldStreamBase(const Array<u1>* fieldinfo_stream, ConstantPool* constants, int start, int limit);
58
59 inline FieldStreamBase(const Array<u1>* fieldinfo_stream, ConstantPool* constants);
60
61 private:
62 void initialize() {
63 int java_fields_count;
64 int injected_fields_count;
65 _reader.read_field_counts(&java_fields_count, &injected_fields_count);
66 if (_limit < _index) {
67 _limit = java_fields_count + injected_fields_count;
68 }
69 assert(_limit <= java_fields_count + injected_fields_count, "Safety check");
70 if (_index < _limit) {
71 if (_index != 0) {
72 _reader.skip_to_field_info(_index);
73 }
74 _reader.read_field_info(_fi_buf);
75 }
76 }
77
78 public:
79 inline FieldStreamBase(InstanceKlass* klass);
80
81 // accessors
82 int index() const { return _index; }
83 InstanceKlass* field_holder() const { return _constants->pool_holder(); }
84
85 void next() {
86 _index += 1;
87 if (done()) return;
88 _reader.read_field_info(_fi_buf);
89 }
90 bool done() const { return _index >= _limit; }
91
92 // Accessors for current field
93 AccessFlags access_flags() const {
94 return field()->access_flags();
95 }
96
97 FieldInfo::FieldFlags field_flags() const {
98 return field()->field_flags();
99 }
100
101 Symbol* name() const {
102 return field()->name(_constants());
103 }
104
105 Symbol* signature() const {
106 return field()->signature(_constants());
107 }
108
109 Symbol* generic_signature() const {
110 if (field()->field_flags().is_generic()) {
111 return _constants->symbol_at(field()->generic_signature_index());
112 } else {
113 return nullptr;
114 }
115 }
116
117 int offset() const {
118 return field()->offset();
119 }
120
121 bool is_contended() const {
122 return field()->is_contended();
123 }
124
125 int contended_group() const {
126 return field()->contended_group();
127 }
128
129 // Convenient methods
130
131 const FieldInfo& to_FieldInfo() const {
132 return _fi_buf;
133 }
134
135 int num_total_fields() const {
136 return FieldInfoStream::num_total_fields(_fieldinfo_stream);
137 }
138
139 // bridge to a heavier API:
140 fieldDescriptor& field_descriptor() const {
141 fieldDescriptor& field = const_cast<fieldDescriptor&>(_fd_buf);
142 field.reinitialize(field_holder(), to_FieldInfo());
143 return field;
144 }
145 };
146
147 // Iterate over only the Java fields
148 class JavaFieldStream : public FieldStreamBase {
149 Array<u1>* _search_table;
150
151 public:
152 JavaFieldStream(const InstanceKlass* k): FieldStreamBase(k->fieldinfo_stream(), k->constants(), 0, k->java_fields_count()),
153 _search_table(k->fieldinfo_search_table()) {}
154
155 u2 name_index() const {
156 assert(!field()->field_flags().is_injected(), "regular only");
157 return field()->name_index();
158 }
159
160 u2 signature_index() const {
161 assert(!field()->field_flags().is_injected(), "regular only");
162 return field()->signature_index();
163 }
164
165 u2 generic_signature_index() const {
166 assert(!field()->field_flags().is_injected(), "regular only");
167 if (field()->field_flags().is_generic()) {
168 return field()->generic_signature_index();
169 }
170 return 0;
171 }
172
173 u2 initval_index() const {
174 assert(!field()->field_flags().is_injected(), "regular only");
175 return field()->initializer_index();
176 }
177
178 // Performs either a linear search or binary search through the stream
179 // looking for a matching name/signature combo
180 bool lookup(const Symbol* name, const Symbol* signature);
181 };
182
183
184 // Iterate over only the internal fields
185 class InternalFieldStream : public FieldStreamBase {
186 public:
187 InternalFieldStream(InstanceKlass* k): FieldStreamBase(k->fieldinfo_stream(), k->constants(), k->java_fields_count(), -1) {}
188 };
189
190
191 class AllFieldStream : public FieldStreamBase {
192 public:
193 AllFieldStream(const InstanceKlass* k): FieldStreamBase(k->fieldinfo_stream(), k->constants()) {}
194 };
195
196 // Iterate over fields including the ones declared in supertypes
197 template<typename FieldStreamType>
198 class HierarchicalFieldStream : public StackObj {
199 private:
200 const Array<InstanceKlass*>* _interfaces;
201 InstanceKlass* _next_klass; // null indicates no more type to visit
202 FieldStreamType _current_stream;
203 int _interface_index;
204
205 void prepare() {
206 _next_klass = next_klass_with_fields();
207 // special case: the initial klass has no fields. If any supertype has any fields, use that directly.
208 // if no such supertype exists, done() will return false already.
209 next_stream_if_done();
210 }
211
212 InstanceKlass* next_klass_with_fields() {
213 assert(_next_klass != nullptr, "reached end of types already");
214 InstanceKlass* result = _next_klass;
215 do {
216 if (!result->is_interface() && result->super() != nullptr) {
217 result = result->super();
218 } else if (_interface_index > 0) {
219 result = _interfaces->at(--_interface_index);
220 } else {
221 return nullptr; // we did not find any more supertypes with fields
222 }
223 } while (FieldStreamType(result).done());
224 return result;
225 }
226
227 // sets _current_stream to the next if the current is done and any more is available
228 void next_stream_if_done() {
229 if (_next_klass != nullptr && _current_stream.done()) {
230 _current_stream = FieldStreamType(_next_klass);
231 assert(!_current_stream.done(), "created empty stream");
232 _next_klass = next_klass_with_fields();
233 }
234 }
235
236 public:
237 HierarchicalFieldStream(InstanceKlass* klass) :
238 _interfaces(klass->transitive_interfaces()),
239 _next_klass(klass),
240 _current_stream(FieldStreamType(klass)),
241 _interface_index(_interfaces->length()) {
242 prepare();
243 }
244
245 void next() {
246 _current_stream.next();
247 next_stream_if_done();
248 }
249
250 bool done() const { return _next_klass == nullptr && _current_stream.done(); }
251
252 // bridge functions from FieldStreamBase
253
254 AccessFlags access_flags() const {
255 return _current_stream.access_flags();
256 }
257
258 FieldInfo::FieldFlags field_flags() const {
259 return _current_stream.field_flags();
260 }
261
262 Symbol* name() const {
263 return _current_stream.name();
264 }
265
266 Symbol* signature() const {
267 return _current_stream.signature();
268 }
269
270 Symbol* generic_signature() const {
271 return _current_stream.generic_signature();
272 }
273
274 int offset() const {
275 return _current_stream.offset();
276 }
277
278 bool is_contended() const {
279 return _current_stream.is_contended();
280 }
281
282 int contended_group() const {
283 return _current_stream.contended_group();
284 }
285
286 FieldInfo to_FieldInfo() {
287 return _current_stream.to_FieldInfo();
288 }
289
290 fieldDescriptor& field_descriptor() const {
291 return _current_stream.field_descriptor();
292 }
293
294 };
295
296 #endif // SHARE_OOPS_FIELDSTREAMS_HPP