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