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_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() : _name_index(0),
141 _signature_index(0),
142 _offset(0),
143 _access_flags(AccessFlags(0)),
144 _field_flags(FieldFlags(0)),
145 _initializer_index(0),
146 _generic_signature_index(0),
147 _contention_group(0) { }
148
149 FieldInfo(AccessFlags access_flags, u2 name_index, u2 signature_index, u2 initval_index, FieldInfo::FieldFlags fflags) :
150 _name_index(name_index),
151 _signature_index(signature_index),
152 _offset(0),
153 _access_flags(access_flags),
154 _field_flags(fflags),
155 _initializer_index(initval_index),
156 _generic_signature_index(0),
157 _contention_group(0) {
158 if (initval_index != 0) {
159 _field_flags.update_initialized(true);
160 }
161 }
162
163 u4 index() const { return _index; }
164 void set_index(u4 index) { _index = index; }
165 u2 name_index() const { return _name_index; }
166 void set_name_index(u2 index) { _name_index = index; }
167 u2 signature_index() const { return _signature_index; }
168 void set_signature_index(u2 index) { _signature_index = index; }
169 u4 offset() const { return _offset; }
170 void set_offset(u4 offset) { _offset = offset; }
171 AccessFlags access_flags() const { return _access_flags; }
172 FieldFlags field_flags() const { return _field_flags; }
173 FieldFlags* field_flags_addr() { return &_field_flags; }
174 u2 initializer_index() const { return _initializer_index; }
175 void set_initializer_index(u2 index) { _initializer_index = index; }
176 u2 generic_signature_index() const { return _generic_signature_index; }
177 void set_generic_signature_index(u2 index) { _generic_signature_index = index; }
178 u2 contention_group() const { return _contention_group; }
179
180 bool is_contended() const {
181 return _field_flags.is_contended();
182 }
183
184 u2 contended_group() const {
185 assert(is_contended(), "");
186 return _contention_group;
187 }
188
189 void set_contended_group(u2 group) {
190 _field_flags.update_contended(true);
191 _contention_group = group;
192 }
193
194 bool is_offset_set() const {
195 return _offset != 0;
196 }
197
198 inline Symbol* name(ConstantPool* cp) const;
199
200 inline Symbol* signature(ConstantPool* cp) const;
201
202 inline Symbol* lookup_symbol(int symbol_index) const;
203
204 void print(outputStream* os, ConstantPool* cp);
205 void static print_from_growable_array(outputStream* os, GrowableArray<FieldInfo>* array, ConstantPool* cp);
206 };
207
208 class FieldInfoStream;
209
210 // Gadget for sizing and/or writing a stream of field records.
211 template<typename CON>
212 class Mapper {
213 CON* _consumer; // can be UNSIGNED5::Writer or UNSIGNED5::Sizer
214 int _next_index;
215 public:
216 Mapper(CON* consumer) : _consumer(consumer) { _next_index = 0; }
217 int next_index() const { return _next_index; }
218 void set_next_index(int next_index) { _next_index = next_index; }
219 CON* consumer() const { return _consumer; }
220 void map_field_info(const FieldInfo& fi);
221 };
222
223
224 // Gadget for decoding and reading the stream of field records.
225 class FieldInfoReader {
226 friend class FieldInfoStream;
227 friend class ClassFileParser;
228 friend class FieldStreamBase;
229 friend class FieldInfo;
230
231 UNSIGNED5::Reader<const u1*, int> _r;
232 int _next_index;
233
234 public:
235 FieldInfoReader(const Array<u1>* fi);
236
237 private:
238 uint32_t next_uint() { return _r.next_uint(); }
239 void skip(int n) { int s = _r.try_skip(n); assert(s == n,""); }
240
241 public:
242 int has_next() { return _r.has_next(); }
243 int position() { return _r.position(); }
244 int next_index() { return _next_index; }
245 void read_field_info(FieldInfo& fi);
246 // skip a whole field record, both required and optional bits
247 FieldInfoReader& skip_field_info();
248
249 // Skip to the nth field. If the reader is freshly initialized to
250 // the zero index, this will call skip_field_info() n times.
251 FieldInfoReader& skip_to_field_info(int n);
252
253 // for random access, if you know where to go up front:
254 FieldInfoReader& set_position_and_next_index(int position, int next_index);
255 };
256
257 // The format of the stream, after decompression, is a series of
258 // integers organized like this:
259 //
260 // FieldInfoStream := j=num_java_fields k=num_injected_fields Field[j+k] End
261 // Field := name sig offset access flags Optionals(flags)
262 // Optionals(i) := initval?[i&is_init] // ConstantValue attr
263 // gsig?[i&is_generic] // signature attr
264 // group?[i&is_contended] // Contended anno (group)
265 // End = 0
266 //
267 class FieldInfoStream : AllStatic {
268 friend class fieldDescriptor;
269 friend class JavaFieldStream;
270 friend class FieldStreamBase;
271 friend class ClassFileParser;
272
273 public:
274 static int num_java_fields(const Array<u1>* fis);
275 static int num_injected_java_fields(const Array<u1>* fis);
276 static int num_total_fields(const Array<u1>* fis);
277
278 static Array<u1>* create_FieldInfoStream(GrowableArray<FieldInfo>* fields, int java_fields, int injected_fields,
279 ClassLoaderData* loader_data, TRAPS);
280 static GrowableArray<FieldInfo>* create_FieldInfoArray(const Array<u1>* fis, int* java_fields_count, int* injected_fields_count);
281 static void print_from_fieldinfo_stream(Array<u1>* fis, outputStream* os, ConstantPool* cp);
282 };
283
284 class FieldStatus {
285 enum FieldStatusBitPosition {
286 _fs_access_watched, // field access is watched by JVMTI
287 _fs_modification_watched, // field modification is watched by JVMTI
288 _initialized_final_update // (static) final field updated outside (class) initializer
289 };
290
291 // boilerplate:
292 u1 _flags;
293 static constexpr u1 flag_mask(FieldStatusBitPosition pos) { return (u1)1 << (int)pos; }
294 bool test_flag(FieldStatusBitPosition pos) { return (_flags & flag_mask(pos)) != 0; }
295 // this performs an atomic update on a live status byte!
296 void update_flag(FieldStatusBitPosition pos, bool z);
297 // out-of-line functions do a CAS-loop
298 static void atomic_set_bits(u1& flags, u1 mask);
299 static void atomic_clear_bits(u1& flags, u1 mask);
300
301 public:
302 FieldStatus() { _flags = 0; }
303 FieldStatus(u1 flags) { _flags = flags; }
304 u1 as_uint() { return _flags; }
305
306 bool is_access_watched() { return test_flag(_fs_access_watched); }
307 bool is_modification_watched() { return test_flag(_fs_modification_watched); }
308 bool is_initialized_final_update() { return test_flag(_initialized_final_update); }
309
310 void update_access_watched(bool z);
311 void update_modification_watched(bool z);
312 void update_initialized_final_update(bool z);
313 };
314
315 #endif // SHARE_OOPS_FIELDINFO_HPP