1 /*
2 * Copyright (c) 2011, 2025, 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
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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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25 #ifndef SHARE_OOPS_FIELDINFO_HPP
26 #define SHARE_OOPS_FIELDINFO_HPP
27
28 #include "memory/allocation.hpp"
29 #include "oops/typeArrayOop.hpp"
30 #include "utilities/unsigned5.hpp"
31 #include "utilities/vmEnums.hpp"
32
33 static constexpr u4 flag_mask(int pos) {
34 return (u4)1 << pos;
35 }
36
37
38 // Helper class for access to the underlying Array<u1> used to
39 // store the compressed stream of FieldInfo
40 template<typename ARR, typename OFF>
41 struct ArrayHelper {
42 uint8_t operator()(ARR a, OFF i) const { return a->at(i); };
43 void operator()(ARR a, OFF i, uint8_t b) const { a->at_put(i,b); };
44 // So, an expression ArrayWriterHelper() acts like these lambdas:
45 // auto get = [&](ARR a, OFF i){ return a[i]; };
46 // auto set = [&](ARR a, OFF i, uint8_t x){ a[i] = x; };
47 };
48
49 // This class represents the field information contained in the fields
50 // array of an InstanceKlass. Currently it's laid on top an array of
51 // Java shorts but in the future it could simply be used as a real
52 // array type. FieldInfo generally shouldn't be used directly.
53 // Fields should be queried either through InstanceKlass or through
54 // the various FieldStreams.
55 class FieldInfo {
56 friend class fieldDescriptor;
57 friend class JavaFieldStream;
58 friend class ClassFileParser;
59 friend class FieldInfoStream;
60 friend class FieldStreamBase;
61 friend class FieldInfoReader;
62 friend class VMStructs;
63
64 public:
65
66 class FieldFlags {
67 friend class VMStructs;
68 friend class JVMCIVMStructs;
69
70 // The ordering of this enum is totally internal. More frequent
71 // flags should come earlier than less frequent ones, because
72 // earlier ones compress better.
73 enum FieldFlagBitPosition {
74 _ff_initialized, // has ConstantValue initializer attribute
75 _ff_injected, // internal field injected by the JVM
76 _ff_generic, // has a generic signature
77 _ff_stable, // trust as stable b/c declared as @Stable
78 _ff_contended, // is contended, may have contention-group
79 };
80
81 // Some but not all of the flag bits signal the presence of an
82 // additional 32-bit item in the field record.
83 static const u4 _optional_item_bit_mask =
84 flag_mask((int)_ff_initialized) |
85 flag_mask((int)_ff_generic) |
86 flag_mask((int)_ff_contended);
87
88 // boilerplate:
89 u4 _flags;
90
91 bool test_flag(FieldFlagBitPosition pos) const {
92 return (_flags & flag_mask(pos)) != 0;
93 }
94 void update_flag(FieldFlagBitPosition pos, bool z) {
95 if (z) _flags |= flag_mask(pos);
96 else _flags &= ~flag_mask(pos);
97 }
98
99 public:
100 FieldFlags(u4 flags) {
101 _flags = flags;
102 }
103 u4 as_uint() const { return _flags; }
104 bool has_any_optionals() const {
105 return (_flags & _optional_item_bit_mask) != 0;
106 }
107
108 bool is_initialized() const { return test_flag(_ff_initialized); }
109 bool is_injected() const { return test_flag(_ff_injected); }
110 bool is_generic() const { return test_flag(_ff_generic); }
111 bool is_stable() const { return test_flag(_ff_stable); }
112 bool is_contended() const { return test_flag(_ff_contended); }
113
114 void update_initialized(bool z) { update_flag(_ff_initialized, z); }
115 void update_injected(bool z) { update_flag(_ff_injected, z); }
116 void update_generic(bool z) { update_flag(_ff_generic, z); }
117 void update_stable(bool z) { update_flag(_ff_stable, z); }
118 void update_contended(bool z) { update_flag(_ff_contended, z); }
119 };
120
121 private:
122 // The following items are the unpacked bitwise information content
123 // of a field record. Per-field metadata extracted from the class
124 // file are stored logically as a group of these items. The
125 // classfile parser produces these records in a temporary array, and
126 // then compresses them into a FieldInfoStream.
127 //
128 u4 _index; // which field it is
129 u2 _name_index; // index in CP of name
130 u2 _signature_index; // index in CP of descriptor
131 u4 _offset; // offset in object layout
132 AccessFlags _access_flags; // access flags (JVM spec)
133 FieldFlags _field_flags; // VM defined flags (not JVM spec)
134 u2 _initializer_index; // index from ConstantValue attr (or 0)
135 u2 _generic_signature_index; // index from GenericSignature attr (or 0)
136 u2 _contention_group; // index from @Contended group item (or 0)
137
138 public:
139
140 FieldInfo() : _index(0),
141 _name_index(0),
142 _signature_index(0),
143 _offset(0),
144 _access_flags(AccessFlags(0)),
145 _field_flags(FieldFlags(0)),
146 _initializer_index(0),
147 _generic_signature_index(0),
148 _contention_group(0) { }
149
150 FieldInfo(AccessFlags access_flags, u2 name_index, u2 signature_index, u2 initval_index, FieldInfo::FieldFlags fflags) :
151 _index(0),
152 _name_index(name_index),
153 _signature_index(signature_index),
154 _offset(0),
155 _access_flags(access_flags),
156 _field_flags(fflags),
157 _initializer_index(initval_index),
158 _generic_signature_index(0),
159 _contention_group(0) {
160 if (initval_index != 0) {
161 _field_flags.update_initialized(true);
162 }
163 }
164
165 u4 index() const { return _index; }
166 void set_index(u4 index) { _index = index; }
167 u2 name_index() const { return _name_index; }
168 void set_name_index(u2 index) { _name_index = index; }
169 u2 signature_index() const { return _signature_index; }
170 void set_signature_index(u2 index) { _signature_index = index; }
171 u4 offset() const { return _offset; }
172 void set_offset(u4 offset) { _offset = offset; }
173 AccessFlags access_flags() const { return _access_flags; }
174 FieldFlags field_flags() const { return _field_flags; }
175 FieldFlags* field_flags_addr() { return &_field_flags; }
176 u2 initializer_index() const { return _initializer_index; }
177 void set_initializer_index(u2 index) { _initializer_index = index; }
178 u2 generic_signature_index() const { return _generic_signature_index; }
179 void set_generic_signature_index(u2 index) { _generic_signature_index = index; }
180 u2 contention_group() const { return _contention_group; }
181
182 bool is_contended() const {
183 return _field_flags.is_contended();
184 }
185
186 u2 contended_group() const {
187 assert(is_contended(), "");
188 return _contention_group;
189 }
190
191 void set_contended_group(u2 group) {
192 _field_flags.update_contended(true);
193 _contention_group = group;
194 }
195
196 bool is_offset_set() const {
197 return _offset != 0;
198 }
199
200 inline Symbol* name(ConstantPool* cp) const;
201
202 inline Symbol* signature(ConstantPool* cp) const;
203
204 inline Symbol* lookup_symbol(int symbol_index) const;
205
206 void print(outputStream* os, ConstantPool* cp);
207 void static print_from_growable_array(outputStream* os, GrowableArray<FieldInfo>* array, ConstantPool* cp);
208 };
209
210 class FieldInfoStream;
211
212 // Gadget for sizing and/or writing a stream of field records.
213 template<typename CON>
214 class Mapper {
215 CON* _consumer; // can be UNSIGNED5::Writer or UNSIGNED5::Sizer
216 int _next_index;
217 public:
218 Mapper(CON* consumer) : _consumer(consumer) { _next_index = 0; }
219 int next_index() const { return _next_index; }
220 void set_next_index(int next_index) { _next_index = next_index; }
221 CON* consumer() const { return _consumer; }
222 void map_field_info(const FieldInfo& fi);
223 };
224
225 // Gadget for decoding and reading the stream of field records.
226 class FieldInfoReader {
227 UNSIGNED5::Reader<const u1*, int> _r;
228 int _next_index;
229
230 public:
231 FieldInfoReader(const Array<u1>* fi);
232
233 private:
234 inline uint32_t next_uint() { return _r.next_uint(); }
235 void skip(int n) { int s = _r.try_skip(n); assert(s == n,""); }
236
237 public:
238 void read_field_counts(int* java_fields, int* injected_fields);
239 int has_next() const { return _r.position() < _r.limit(); }
240 int position() const { return _r.position(); }
241 int next_index() const { return _next_index; }
242 void read_name_and_signature(u2* name_index, u2* signature_index);
243 void read_field_info(FieldInfo& fi);
244
245 int search_table_lookup(const Array<u1>* search_table, const Symbol* name, const Symbol* signature, ConstantPool* cp, int java_fields);
246
247 // skip a whole field record, both required and optional bits
248 FieldInfoReader& skip_field_info();
249
250 // Skip to the nth field. If the reader is freshly initialized to
251 // the zero index, this will call skip_field_info() n times.
252 FieldInfoReader& skip_to_field_info(int n);
253
254 // for random access, if you know where to go up front:
255 FieldInfoReader& set_position_and_next_index(int position, int next_index);
256 };
257
258 // The format of the stream, after decompression, is a series of
259 // integers organized like this:
260 //
261 // FieldInfoStream := j=num_java_fields k=num_injected_fields Field[j+k] End
262 // Field := name sig offset access flags Optionals(flags)
263 // Optionals(i) := initval?[i&is_init] // ConstantValue attr
264 // gsig?[i&is_generic] // signature attr
265 // group?[i&is_contended] // Contended anno (group)
266 // End = 0
267 //
268 class FieldInfoStream : AllStatic {
269 friend class fieldDescriptor;
270 friend class JavaFieldStream;
271 friend class FieldStreamBase;
272 friend class ClassFileParser;
273 friend class FieldInfoReader;
274 friend class FieldInfoComparator;
275
276 private:
277 static int compare_name_and_sig(const Symbol* n1, const Symbol* s1, const Symbol* n2, const Symbol* s2);
278
279 public:
280 static int num_java_fields(const Array<u1>* fis);
281 static int num_injected_java_fields(const Array<u1>* fis);
282 static int num_total_fields(const Array<u1>* fis);
283
284 static Array<u1>* create_FieldInfoStream(GrowableArray<FieldInfo>* fields, int java_fields, int injected_fields,
285 ClassLoaderData* loader_data, TRAPS);
286 static Array<u1>* create_search_table(ConstantPool* cp, const Array<u1>* fis, ClassLoaderData* loader_data, TRAPS);
287 static GrowableArray<FieldInfo>* create_FieldInfoArray(const Array<u1>* fis, int* java_fields_count, int* injected_fields_count);
288 static void print_from_fieldinfo_stream(Array<u1>* fis, outputStream* os, ConstantPool* cp);
289
290 DEBUG_ONLY(static void validate_search_table(ConstantPool* cp, const Array<u1>* fis, const Array<u1>* search_table);)
291
292 static void print_search_table(outputStream* st, ConstantPool* cp, const Array<u1>* fis, const Array<u1>* search_table);
293 };
294
295 class FieldStatus {
296 enum FieldStatusBitPosition {
297 _fs_access_watched, // field access is watched by JVMTI
298 _fs_modification_watched, // field modification is watched by JVMTI
299 _initialized_final_update // (static) final field updated outside (class) initializer
300 };
301
302 // boilerplate:
303 u1 _flags;
304 static constexpr u1 flag_mask(FieldStatusBitPosition pos) { return (u1)1 << (int)pos; }
305 bool test_flag(FieldStatusBitPosition pos) { return (_flags & flag_mask(pos)) != 0; }
306 // this performs an atomic update on a live status byte!
307 void update_flag(FieldStatusBitPosition pos, bool z);
308 // out-of-line functions do a CAS-loop
309 static void atomic_set_bits(u1& flags, u1 mask);
310 static void atomic_clear_bits(u1& flags, u1 mask);
311
312 public:
313 FieldStatus() { _flags = 0; }
314 FieldStatus(u1 flags) { _flags = flags; }
315 u1 as_uint() { return _flags; }
316
317 bool is_access_watched() { return test_flag(_fs_access_watched); }
318 bool is_modification_watched() { return test_flag(_fs_modification_watched); }
319 bool is_initialized_final_update() { return test_flag(_initialized_final_update); }
320
321 void update_access_watched(bool z);
322 void update_modification_watched(bool z);
323 void update_initialized_final_update(bool z);
324 };
325
326 #endif // SHARE_OOPS_FIELDINFO_HPP