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.
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23 */
24
25 #ifndef SHARE_OOPS_FIELDSTREAMS_HPP
26 #define SHARE_OOPS_FIELDSTREAMS_HPP
27
28 #include "oops/instanceKlass.hpp"
29 #include "oops/fieldInfo.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
43 protected:
44 const Array<u1>* _fieldinfo_stream;
45 FieldInfoReader _reader;
46 constantPoolHandle _constants;
47 int _index;
48 int _limit;
49
50 FieldInfo _fi_buf;
51 fieldDescriptor _fd_buf;
52
53 FieldInfo const * field() const {
54 assert(!done(), "no more fields");
55 return &_fi_buf;
56 }
57
58 inline FieldStreamBase(const Array<u1>* fieldinfo_stream, ConstantPool* constants, int start, int limit);
59
60 inline FieldStreamBase(Array<u1>* fieldinfo_stream, ConstantPool* constants);
61
62 private:
63 void initialize() {
64 int java_fields_count = _reader.next_uint();
65 int injected_fields_count = _reader.next_uint();
66 assert( _limit <= java_fields_count + injected_fields_count, "Safety check");
67 if (_limit != 0) {
68 _reader.read_field_info(_fi_buf);
69 }
70 }
71 public:
72 inline FieldStreamBase(InstanceKlass* klass);
73
74 // accessors
75 int index() const { return _index; }
76 InstanceKlass* field_holder() const { return _constants->pool_holder(); }
77
78 void next() {
79 _index += 1;
80 if (done()) return;
81 _reader.read_field_info(_fi_buf);
82 }
83 bool done() const { return _index >= _limit; }
84
85 // Accessors for current field
86 AccessFlags access_flags() const {
87 return field()->access_flags();
88 }
89
90 FieldInfo::FieldFlags field_flags() const {
91 return field()->field_flags();
92 }
93
94 Symbol* name() const {
95 return field()->name(_constants());
96 }
97
98 Symbol* signature() const {
99 return field()->signature(_constants());
100 }
101
102 Symbol* generic_signature() const {
103 if (field()->field_flags().is_generic()) {
104 return _constants->symbol_at(field()->generic_signature_index());
105 } else {
106 return nullptr;
107 }
108 }
109
110 int offset() const {
111 return field()->offset();
112 }
113
114 bool is_null_free_inline_type() {
115 return field()->field_flags().is_null_free_inline_type();
116 }
117
118 bool is_flat() const {
119 return field()->field_flags().is_flat();
120 }
121
122 bool is_contended() const {
123 return field()->is_contended();
124 }
125
126 int contended_group() const {
127 return field()->contended_group();
128 }
129
130 int null_marker_offset() const {
131 return field()->null_marker_offset();
132 }
133
134 // Convenient methods
135
136 const FieldInfo& to_FieldInfo() const {
137 return _fi_buf;
138 }
139
140 int num_total_fields() const {
141 return FieldInfoStream::num_total_fields(_fieldinfo_stream);
142 }
143
144 // bridge to a heavier API:
145 fieldDescriptor& field_descriptor() const {
146 fieldDescriptor& field = const_cast<fieldDescriptor&>(_fd_buf);
147 field.reinitialize(field_holder(), to_FieldInfo());
148 return field;
149 }
150 };
151
152 // Iterate over only the Java fields
153 class JavaFieldStream : public FieldStreamBase {
154 public:
155 JavaFieldStream(const InstanceKlass* k): FieldStreamBase(k->fieldinfo_stream(), k->constants(), 0, k->java_fields_count()) {}
156
157 u2 name_index() const {
158 assert(!field()->field_flags().is_injected(), "regular only");
159 return field()->name_index();
160 }
161
162 u2 signature_index() const {
163 assert(!field()->field_flags().is_injected(), "regular only");
164 return field()->signature_index();
165 return -1;
166 }
167
168 u2 generic_signature_index() const {
169 assert(!field()->field_flags().is_injected(), "regular only");
170 if (field()->field_flags().is_generic()) {
171 return field()->generic_signature_index();
172 }
173 return 0;
174 }
175
176 u2 initval_index() const {
177 assert(!field()->field_flags().is_injected(), "regular only");
178 return field()->initializer_index();
179 }
180 };
181
182
183 // Iterate over only the internal fields
184 class InternalFieldStream : public FieldStreamBase {
185 public:
186 InternalFieldStream(InstanceKlass* k): FieldStreamBase(k->fieldinfo_stream(), k->constants(), k->java_fields_count(), 0) {}
187 };
188
189
190 class AllFieldStream : public FieldStreamBase {
191 public:
192 AllFieldStream(Array<u1>* fieldinfo, ConstantPool* constants): FieldStreamBase(fieldinfo, constants) {}
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->java_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 int index() const {
254 return _current_stream.index();
255 }
256
257 AccessFlags access_flags() const {
258 return _current_stream.access_flags();
259 }
260
261 FieldInfo::FieldFlags field_flags() const {
262 return _current_stream.field_flags();
263 }
264
265 Symbol* name() const {
266 return _current_stream.name();
267 }
268
269 Symbol* signature() const {
270 return _current_stream.signature();
271 }
272
273 Symbol* generic_signature() const {
274 return _current_stream.generic_signature();
275 }
276
277 int offset() const {
278 return _current_stream.offset();
279 }
280
281 bool is_contended() const {
282 return _current_stream.is_contended();
283 }
284
285 int contended_group() const {
286 return _current_stream.contended_group();
287 }
288
289 FieldInfo to_FieldInfo() {
290 return _current_stream.to_FieldInfo();
291 }
292
293 fieldDescriptor& field_descriptor() const {
294 return _current_stream.field_descriptor();
295 }
296
297 bool is_flat() const {
298 return _current_stream.is_flat();
299 }
300
301 bool is_null_free_inline_type() {
302 return _current_stream.is_null_free_inline_type();
303 }
304
305 int null_marker_offset() {
306 return _current_stream.null_marker_offset();
307 }
308 };
309
310 #endif // SHARE_OOPS_FIELDSTREAMS_HPP