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_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 /* Very generally, a base class for a stream adapter, a derived class just implements
197 * current_stream that returns a FieldStreamType, and this adapter takes care of providing
198 * the methods of FieldStreamBase.
199 *
200 * In practice, this is used to provide a stream over the fields of a class and its superclasses
201 * and interfaces. The derived class of HierarchicalFieldStreamBase decides in which order we iterate
202 * on the superclasses (and interfaces), and the template parameter FieldStreamType is the underlying
203 * stream we use to iterate over the fields each class. Methods such as done and next are still up to
204 * the derived classes, allowing them to iterate over the class hierarchy, but also skip elements that
205 * the underlying FieldStreamType would otherwise include.
206 */
207 template<typename FieldStreamType>
208 class HierarchicalFieldStreamBase : public StackObj {
209 virtual FieldStreamType& current_stream() = 0;
210 virtual const FieldStreamType& current_stream() const = 0;
211
212 public:
213 // bridge functions from FieldStreamBase
214 int index() const {
215 return current_stream().index();
216 }
217
218 AccessFlags access_flags() const {
219 return current_stream().access_flags();
220 }
221
222 FieldInfo::FieldFlags field_flags() const {
223 return current_stream().field_flags();
224 }
225
226 Symbol* name() const {
227 return current_stream().name();
228 }
229
230 Symbol* signature() const {
231 return current_stream().signature();
232 }
233
234 Symbol* generic_signature() const {
235 return current_stream().generic_signature();
236 }
237
238 int offset() const {
239 return current_stream().offset();
240 }
241
242 bool is_contended() const {
243 return current_stream().is_contended();
244 }
245
246 int contended_group() const {
247 return current_stream().contended_group();
248 }
249
250 FieldInfo to_FieldInfo() {
251 return current_stream().to_FieldInfo();
252 }
253
254 fieldDescriptor& field_descriptor() const {
255 return current_stream().field_descriptor();
256 }
257
258 bool is_flat() const {
259 return current_stream().is_flat();
260 }
261
262 bool is_null_free_inline_type() {
263 return current_stream().is_null_free_inline_type();
264 }
265
266 int null_marker_offset() {
267 return current_stream().null_marker_offset();
268 }
269 };
270
271 /* Iterate over fields including the ones declared in supertypes.
272 * Derived classes are traversed before base classes, and interfaces
273 * at the end.
274 */
275 template<typename FieldStreamType>
276 class HierarchicalFieldStream final : public HierarchicalFieldStreamBase<FieldStreamType> {
277 private:
278 const Array<InstanceKlass*>* _interfaces;
279 InstanceKlass* _next_klass; // null indicates no more type to visit
280 FieldStreamType _current_stream;
281 int _interface_index;
282
283 void prepare() {
284 _next_klass = next_klass_with_fields();
285 // special case: the initial klass has no fields. If any supertype has any fields, use that directly.
286 // if no such supertype exists, done() will return false already.
287 next_stream_if_done();
288 }
289
290 InstanceKlass* next_klass_with_fields() {
291 assert(_next_klass != nullptr, "reached end of types already");
292 InstanceKlass* result = _next_klass;
293 do {
294 if (!result->is_interface() && result->super() != nullptr) {
295 result = result->java_super();
296 } else if (_interface_index > 0) {
297 result = _interfaces->at(--_interface_index);
298 } else {
299 return nullptr; // we did not find any more supertypes with fields
300 }
301 } while (FieldStreamType(result).done());
302 return result;
303 }
304
305 // sets _current_stream to the next if the current is done and any more is available
306 void next_stream_if_done() {
307 if (_next_klass != nullptr && _current_stream.done()) {
308 _current_stream = FieldStreamType(_next_klass);
309 assert(!_current_stream.done(), "created empty stream");
310 _next_klass = next_klass_with_fields();
311 }
312 }
313
314 FieldStreamType& current_stream() override { return _current_stream; }
315 const FieldStreamType& current_stream() const override { return _current_stream; }
316
317 public:
318 explicit HierarchicalFieldStream(InstanceKlass* klass) :
319 _interfaces(klass->transitive_interfaces()),
320 _next_klass(klass),
321 _current_stream(FieldStreamType(klass)),
322 _interface_index(_interfaces->length()) {
323 prepare();
324 }
325
326 void next() {
327 _current_stream.next();
328 next_stream_if_done();
329 }
330
331 bool done() const { return _next_klass == nullptr && _current_stream.done(); }
332 };
333
334 /* Iterates on the fields of a class and its super-class top-down (java.lang.Object first)
335 * Doesn't traverse interfaces for now, because it's not clear which order would make sense
336 * Let's decide when or if the need arises. Since we are not traversing interfaces, we
337 * wouldn't get all the static fields, and since the current use-case of this stream does not
338 * care about static fields, we restrict it to regular non-static fields.
339 */
340 class TopDownHierarchicalNonStaticFieldStreamBase final : public HierarchicalFieldStreamBase<JavaFieldStream> {
341 GrowableArray<InstanceKlass*>* _super_types; // Self and super type, bottom up
342 int _current_stream_index;
343 JavaFieldStream _current_stream;
344
345 void next_stream_if_needed() {
346 precond(_current_stream_index >= 0);
347 while (_current_stream.done()) {
348 _current_stream_index--;
349 if (_current_stream_index < 0) {
350 return;
351 }
352 _current_stream = JavaFieldStream(_super_types->at(_current_stream_index));
353 }
354 }
355
356 GrowableArray<InstanceKlass*>* get_super_types(InstanceKlass* klass) {
357 auto super_types = new GrowableArray<InstanceKlass*>();
358 do {
359 super_types->push(klass);
360 } while ((klass = klass->java_super()) != nullptr);
361 return super_types;
362 }
363
364 void raw_next() {
365 _current_stream.next();
366 next_stream_if_needed();
367 }
368
369 void closest_non_static() {
370 while (!done() && access_flags().is_static()) {
371 raw_next();
372 }
373 }
374
375 JavaFieldStream& current_stream() override { return _current_stream; }
376 const JavaFieldStream& current_stream() const override { return _current_stream; }
377
378 public:
379 explicit TopDownHierarchicalNonStaticFieldStreamBase(InstanceKlass* klass) :
380 _super_types(get_super_types(klass)),
381 _current_stream_index(_super_types->length() - 1),
382 _current_stream(JavaFieldStream(_super_types->at(_current_stream_index))) {
383 next_stream_if_needed();
384 closest_non_static();
385 }
386
387 void next() {
388 raw_next();
389 closest_non_static();
390 }
391
392 bool done() const { return _current_stream_index < 0; }
393 };
394
395 #endif // SHARE_OOPS_FIELDSTREAMS_HPP