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 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_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