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.
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
20 * or visit www.oracle.com if you need additional information or have any
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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/layoutKind.hpp"
30 #include "oops/typeArrayOop.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 // 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 friend class FieldDesc;
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_null_free_inline_type, // field's type is an inline type and the field is null free
76 _ff_flat, // field is a flat field, optional section includes a layout kind
77 _ff_null_marker, // field has a null marker, optional section includes the null marker offset
78 _ff_initialized, // has ConstantValue initializer attribute
79 _ff_injected, // internal field injected by the JVM
80 _ff_generic, // has a generic signature
81 _ff_stable, // trust as stable b/c declared as @Stable
82 _ff_contended // is contended, may have contention-group
83 };
84
85 // Some but not all of the flag bits signal the presence of an
86 // additional 32-bit item in the field record.
87 static const u4 _optional_item_bit_mask =
88 flag_mask((int)_ff_initialized) |
89 flag_mask((int)_ff_generic) |
90 flag_mask((int)_ff_contended) |
91 flag_mask((int)_ff_flat) |
92 flag_mask((int)_ff_null_marker);
93
94 // boilerplate:
95 u4 _flags;
96
97 bool test_flag(FieldFlagBitPosition pos) const {
98 return (_flags & flag_mask(pos)) != 0;
99 }
100 void update_flag(FieldFlagBitPosition pos, bool z) {
101 if (z) _flags |= flag_mask(pos);
102 else _flags &= ~flag_mask(pos);
103 }
104
105 public:
106 FieldFlags(u4 flags) {
107 _flags = flags;
108 }
109 u4 as_uint() const { return _flags; }
110 bool has_any_optionals() const {
111 return (_flags & _optional_item_bit_mask) != 0;
112 }
113
114 bool is_initialized() const { return test_flag(_ff_initialized); }
115 bool is_null_free_inline_type() const { return test_flag(_ff_null_free_inline_type); }
116 bool is_flat() const { return test_flag(_ff_flat); }
117 bool is_injected() const { return test_flag(_ff_injected); }
118 bool is_generic() const { return test_flag(_ff_generic); }
119 bool is_stable() const { return test_flag(_ff_stable); }
120 bool is_contended() const { return test_flag(_ff_contended); }
121 bool has_null_marker() const { return test_flag(_ff_null_marker); }
122
123 void update_initialized(bool z) { update_flag(_ff_initialized, z); }
124 void update_null_free_inline_type(bool z) { update_flag(_ff_null_free_inline_type, z); }
125 void update_flat(bool z) { update_flag(_ff_flat, z); }
126 void update_injected(bool z) { update_flag(_ff_injected, z); }
127 void update_generic(bool z) { update_flag(_ff_generic, z); }
128 void update_stable(bool z) { update_flag(_ff_stable, z); }
129 void update_contended(bool z) { update_flag(_ff_contended, z); }
130 void update_null_marker(bool z) { update_flag(_ff_null_marker, z); }
131 };
132
133 private:
134 // The following items are the unpacked bitwise information content
135 // of a field record. Per-field metadata extracted from the class
136 // file are stored logically as a group of these items. The
137 // classfile parser produces these records in a temporary array, and
138 // then compresses them into a FieldInfoStream.
139 //
140 u4 _index; // which field it is
141 u2 _name_index; // index in CP of name
142 u2 _signature_index; // index in CP of descriptor
143 u4 _offset; // offset in object layout
144 AccessFlags _access_flags; // access flags (JVM spec)
145 FieldFlags _field_flags; // VM defined flags (not JVM spec)
146 LayoutKind _layout_kind; // LayoutKind if the field is flat
147 u4 _null_marker_offset; // null marker offset for this field in the object layout
148 u2 _initializer_index; // index from ConstantValue attr (or 0)
149 u2 _generic_signature_index; // index from GenericSignature attr (or 0)
150 u2 _contention_group; // index from @Contended group item (or 0)
151
152 public:
153
154 FieldInfo() : _name_index(0),
155 _signature_index(0),
156 _offset(0),
157 _access_flags(AccessFlags(0)),
158 _field_flags(FieldFlags(0)),
159 _layout_kind(LayoutKind::UNKNOWN),
160 _null_marker_offset(0),
161 _initializer_index(0),
162 _generic_signature_index(0),
163 _contention_group(0) { }
164
165 FieldInfo(AccessFlags access_flags, u2 name_index, u2 signature_index, u2 initval_index, FieldInfo::FieldFlags fflags) :
166 _name_index(name_index),
167 _signature_index(signature_index),
168 _offset(0),
169 _access_flags(access_flags),
170 _field_flags(fflags),
171 _layout_kind(LayoutKind::UNKNOWN),
172 _null_marker_offset(0),
173 _initializer_index(initval_index),
174 _generic_signature_index(0),
175 _contention_group(0) {
176 if (initval_index != 0) {
177 _field_flags.update_initialized(true);
178 }
179 }
180
181 u4 index() const { return _index; }
182 void set_index(u4 index) { _index = index; }
183 u2 name_index() const { return _name_index; }
184 void set_name_index(u2 index) { _name_index = index; }
185 u2 signature_index() const { return _signature_index; }
186 void set_signature_index(u2 index) { _signature_index = index; }
187 u4 offset() const { return _offset; }
188 void set_offset(u4 offset) { _offset = offset; }
189 AccessFlags access_flags() const { return _access_flags; }
190 FieldFlags field_flags() const { return _field_flags; }
191 FieldFlags* field_flags_addr() { return &_field_flags; }
192 LayoutKind layout_kind() const { return _layout_kind; }
193 void set_layout_kind(LayoutKind lk) {
194 assert(_field_flags.is_flat(), "Must be");
195 _layout_kind = lk;
196 }
197 u4 null_marker_offset() const { return _null_marker_offset; }
198 void set_null_marker_offset(u4 offset) {
199 _field_flags.update_null_marker(true);
200 _null_marker_offset = offset;
201 }
202 u2 initializer_index() const { return _initializer_index; }
203 void set_initializer_index(u2 index) { _initializer_index = index; }
204 u2 generic_signature_index() const { return _generic_signature_index; }
205 void set_generic_signature_index(u2 index) { _generic_signature_index = index; }
206 u2 contention_group() const { return _contention_group; }
207
208 bool is_contended() const {
209 return _field_flags.is_contended();
210 }
211
212 u2 contended_group() const {
213 assert(is_contended(), "");
214 return _contention_group;
215 }
216
217 void set_contended_group(u2 group) {
218 _field_flags.update_contended(true);
219 _contention_group = group;
220 }
221
222 bool is_offset_set() const {
223 return _offset != 0;
224 }
225
226 inline Symbol* name(ConstantPool* cp) const;
227
228 inline Symbol* signature(ConstantPool* cp) const;
229
230 inline Symbol* lookup_symbol(int symbol_index) const;
231
232 void print(outputStream* os, ConstantPool* cp);
233 void static print_from_growable_array(outputStream* os, GrowableArray<FieldInfo>* array, ConstantPool* cp);
234 };
235
236 class FieldInfoStream;
237
238 // Gadget for sizing and/or writing a stream of field records.
239 template<typename CON>
240 class Mapper {
241 CON* _consumer; // can be UNSIGNED5::Writer or UNSIGNED5::Sizer
242 int _next_index;
243 public:
244 Mapper(CON* consumer) : _consumer(consumer) { _next_index = 0; }
245 int next_index() const { return _next_index; }
246 void set_next_index(int next_index) { _next_index = next_index; }
247 CON* consumer() const { return _consumer; }
248 void map_field_info(const FieldInfo& fi);
249 };
250
251
252 // Gadget for decoding and reading the stream of field records.
253 class FieldInfoReader {
254 friend class FieldInfoStream;
255 friend class ClassFileParser;
256 friend class FieldStreamBase;
257 friend class FieldInfo;
258
259 UNSIGNED5::Reader<const u1*, int> _r;
260 int _next_index;
261
262 public:
263 FieldInfoReader(const Array<u1>* fi);
264
265 private:
266 uint32_t next_uint() { return _r.next_uint(); }
267 void skip(int n) { int s = _r.try_skip(n); assert(s == n,""); }
268
269 public:
270 int has_next() { return _r.has_next(); }
271 int position() { return _r.position(); }
272 int next_index() { return _next_index; }
273 void read_field_info(FieldInfo& fi);
274 // skip a whole field record, both required and optional bits
275 FieldInfoReader& skip_field_info();
276
277 // Skip to the nth field. If the reader is freshly initialized to
278 // the zero index, this will call skip_field_info() n times.
279 FieldInfoReader& skip_to_field_info(int n);
280
281 // for random access, if you know where to go up front:
282 FieldInfoReader& set_position_and_next_index(int position, int next_index);
283 };
284
285 // The format of the stream, after decompression, is a series of
286 // integers organized like this:
287 //
288 // FieldInfoStream := j=num_java_fields k=num_injected_fields Field[j+k] End
289 // Field := name sig offset access flags Optionals(flags)
290 // Optionals(i) := initval?[i&is_init] // ConstantValue attr
291 // gsig?[i&is_generic] // signature attr
292 // group?[i&is_contended] // Contended anno (group)
293 // End = 0
294 //
295 class FieldInfoStream : AllStatic {
296 friend class fieldDescriptor;
297 friend class JavaFieldStream;
298 friend class FieldStreamBase;
299 friend class ClassFileParser;
300
301 public:
302 static int num_java_fields(const Array<u1>* fis);
303 static int num_injected_java_fields(const Array<u1>* fis);
304 static int num_total_fields(const Array<u1>* fis);
305
306 static Array<u1>* create_FieldInfoStream(GrowableArray<FieldInfo>* fields, int java_fields, int injected_fields,
307 ClassLoaderData* loader_data, TRAPS);
308 static GrowableArray<FieldInfo>* create_FieldInfoArray(const Array<u1>* fis, int* java_fields_count, int* injected_fields_count);
309 static void print_from_fieldinfo_stream(Array<u1>* fis, outputStream* os, ConstantPool* cp);
310 };
311
312 class FieldStatus {
313 enum FieldStatusBitPosition {
314 _fs_access_watched, // field access is watched by JVMTI
315 _fs_modification_watched, // field modification is watched by JVMTI
316 _initialized_final_update // (static) final field updated outside (class) initializer
317 };
318
319 // boilerplate:
320 u1 _flags;
321 static constexpr u1 flag_mask(FieldStatusBitPosition pos) { return (u1)1 << (int)pos; }
322 bool test_flag(FieldStatusBitPosition pos) { return (_flags & flag_mask(pos)) != 0; }
323 // this performs an atomic update on a live status byte!
324 void update_flag(FieldStatusBitPosition pos, bool z);
325 // out-of-line functions do a CAS-loop
326 static void atomic_set_bits(u1& flags, u1 mask);
327 static void atomic_clear_bits(u1& flags, u1 mask);
328
329 public:
330 FieldStatus() { _flags = 0; }
331 FieldStatus(u1 flags) { _flags = flags; }
332 u1 as_uint() { return _flags; }
333
334 bool is_access_watched() { return test_flag(_fs_access_watched); }
335 bool is_modification_watched() { return test_flag(_fs_modification_watched); }
336 bool is_initialized_final_update() { return test_flag(_initialized_final_update); }
337
338 void update_access_watched(bool z);
339 void update_modification_watched(bool z);
340 void update_initialized_final_update(bool z);
341 };
342
343 #endif // SHARE_OOPS_FIELDINFO_HPP