1 /* 2 * Copyright (c) 2011, 2026, 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/layoutKind.hpp" 30 #include "oops/typeArrayOop.hpp" 31 #include "utilities/accessFlags.hpp" 32 #include "utilities/unsigned5.hpp" 33 #include "utilities/vmEnums.hpp" 34 35 static constexpr u4 flag_mask(int pos) { 36 return (u4)1 << pos; 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 friend class FieldDesc; 71 72 // The ordering of this enum is totally internal. More frequent 73 // flags should come earlier than less frequent ones, because 74 // earlier ones compress better. 75 enum FieldFlagBitPosition { 76 _ff_null_free_inline_type, // field's type is an inline type and the field is null free 77 _ff_flat, // field is a flat field, optional section includes a layout kind 78 _ff_null_marker, // field has a null marker, optional section includes the null marker offset 79 _ff_initialized, // has ConstantValue initializer attribute 80 _ff_injected, // internal field injected by the JVM 81 _ff_generic, // has a generic signature 82 _ff_stable, // trust as stable b/c declared as @Stable 83 _ff_contended // is contended, may have contention-group 84 }; 85 86 // Some but not all of the flag bits signal the presence of an 87 // additional 32-bit item in the field record. 88 static const u4 _optional_item_bit_mask = 89 flag_mask((int)_ff_initialized) | 90 flag_mask((int)_ff_generic) | 91 flag_mask((int)_ff_contended) | 92 flag_mask((int)_ff_flat) | 93 flag_mask((int)_ff_null_marker); 94 95 // boilerplate: 96 u4 _flags; 97 98 bool test_flag(FieldFlagBitPosition pos) const { 99 return (_flags & flag_mask(pos)) != 0; 100 } 101 void update_flag(FieldFlagBitPosition pos, bool z) { 102 if (z) _flags |= flag_mask(pos); 103 else _flags &= ~flag_mask(pos); 104 } 105 106 public: 107 FieldFlags(u4 flags) { 108 _flags = flags; 109 } 110 u4 as_uint() const { return _flags; } 111 bool has_any_optionals() const { 112 return (_flags & _optional_item_bit_mask) != 0; 113 } 114 115 bool is_initialized() const { return test_flag(_ff_initialized); } 116 bool is_null_free_inline_type() const { return test_flag(_ff_null_free_inline_type); } 117 bool is_flat() const { return test_flag(_ff_flat); } 118 bool is_injected() const { return test_flag(_ff_injected); } 119 bool is_generic() const { return test_flag(_ff_generic); } 120 bool is_stable() const { return test_flag(_ff_stable); } 121 bool is_contended() const { return test_flag(_ff_contended); } 122 bool has_null_marker() const { return test_flag(_ff_null_marker); } 123 124 void update_initialized(bool z) { update_flag(_ff_initialized, z); } 125 void update_null_free_inline_type(bool z) { update_flag(_ff_null_free_inline_type, z); } 126 void update_flat(bool z) { update_flag(_ff_flat, z); } 127 void update_injected(bool z) { update_flag(_ff_injected, z); } 128 void update_generic(bool z) { update_flag(_ff_generic, z); } 129 void update_stable(bool z) { update_flag(_ff_stable, z); } 130 void update_contended(bool z) { update_flag(_ff_contended, z); } 131 void update_null_marker(bool z) { update_flag(_ff_null_marker, z); } 132 }; 133 134 private: 135 // The following items are the unpacked bitwise information content 136 // of a field record. Per-field metadata extracted from the class 137 // file are stored logically as a group of these items. The 138 // classfile parser produces these records in a temporary array, and 139 // then compresses them into a FieldInfoStream. 140 // 141 u4 _index; // which field it is 142 u2 _name_index; // index in CP of name 143 u2 _signature_index; // index in CP of descriptor 144 u4 _offset; // offset in object layout 145 AccessFlags _access_flags; // access flags (JVM spec) 146 FieldFlags _field_flags; // VM defined flags (not JVM spec) 147 LayoutKind _layout_kind; // LayoutKind if the field is flat 148 u4 _null_marker_offset; // null marker offset for this field in the object layout 149 u2 _initializer_index; // index from ConstantValue attr (or 0) 150 u2 _generic_signature_index; // index from GenericSignature attr (or 0) 151 u2 _contention_group; // index from @Contended group item (or 0) 152 153 public: 154 155 FieldInfo() : _index(0), 156 _name_index(0), 157 _signature_index(0), 158 _offset(0), 159 _access_flags(AccessFlags(0)), 160 _field_flags(FieldFlags(0)), 161 _layout_kind(LayoutKind::UNKNOWN), 162 _null_marker_offset(0), 163 _initializer_index(0), 164 _generic_signature_index(0), 165 _contention_group(0) { } 166 167 FieldInfo(AccessFlags access_flags, u2 name_index, u2 signature_index, u2 initval_index, FieldInfo::FieldFlags fflags) : 168 _index(0), 169 _name_index(name_index), 170 _signature_index(signature_index), 171 _offset(0), 172 _access_flags(access_flags), 173 _field_flags(fflags), 174 _layout_kind(LayoutKind::UNKNOWN), 175 _null_marker_offset(0), 176 _initializer_index(initval_index), 177 _generic_signature_index(0), 178 _contention_group(0) { 179 if (initval_index != 0) { 180 _field_flags.update_initialized(true); 181 } 182 } 183 184 u4 index() const { return _index; } 185 void set_index(u4 index) { _index = index; } 186 u2 name_index() const { return _name_index; } 187 void set_name_index(u2 index) { _name_index = index; } 188 u2 signature_index() const { return _signature_index; } 189 void set_signature_index(u2 index) { _signature_index = index; } 190 u4 offset() const { return _offset; } 191 void set_offset(u4 offset) { _offset = offset; } 192 AccessFlags access_flags() const { return _access_flags; } 193 FieldFlags field_flags() const { return _field_flags; } 194 FieldFlags* field_flags_addr() { return &_field_flags; } 195 LayoutKind layout_kind() const { return _layout_kind; } 196 void set_layout_kind(LayoutKind lk) { 197 assert(_field_flags.is_flat(), "Must be"); 198 _layout_kind = lk; 199 } 200 u4 null_marker_offset() const { return _null_marker_offset; } 201 void set_null_marker_offset(u4 offset) { 202 _field_flags.update_null_marker(true); 203 _null_marker_offset = offset; 204 } 205 u2 initializer_index() const { return _initializer_index; } 206 void set_initializer_index(u2 index) { _initializer_index = index; } 207 u2 generic_signature_index() const { return _generic_signature_index; } 208 void set_generic_signature_index(u2 index) { _generic_signature_index = index; } 209 u2 contention_group() const { return _contention_group; } 210 211 bool is_contended() const { 212 return _field_flags.is_contended(); 213 } 214 215 u2 contended_group() const { 216 assert(is_contended(), ""); 217 return _contention_group; 218 } 219 220 void set_contended_group(u2 group) { 221 _field_flags.update_contended(true); 222 _contention_group = group; 223 } 224 225 bool is_offset_set() const { 226 return _offset != 0; 227 } 228 229 inline Symbol* name(ConstantPool* cp) const; 230 231 inline Symbol* signature(ConstantPool* cp) const; 232 233 inline Symbol* lookup_symbol(int symbol_index) const; 234 235 void print(outputStream* os, ConstantPool* cp); 236 void static print_from_growable_array(outputStream* os, GrowableArray<FieldInfo>* array, ConstantPool* cp); 237 }; 238 239 class FieldInfoStream; 240 241 // Gadget for sizing and/or writing a stream of field records. 242 template<typename CON> 243 class Mapper { 244 CON* _consumer; // can be UNSIGNED5::Writer or UNSIGNED5::Sizer 245 int _next_index; 246 public: 247 Mapper(CON* consumer) : _consumer(consumer) { _next_index = 0; } 248 int next_index() const { return _next_index; } 249 void set_next_index(int next_index) { _next_index = next_index; } 250 CON* consumer() const { return _consumer; } 251 void map_field_info(const FieldInfo& fi); 252 }; 253 254 // Gadget for decoding and reading the stream of field records. 255 class FieldInfoReader { 256 UNSIGNED5::Reader<const u1*, int> _r; 257 int _next_index; 258 259 public: 260 FieldInfoReader(const Array<u1>* fi); 261 262 private: 263 inline uint32_t next_uint() { return _r.next_uint(); } 264 void skip(int n) { int s = _r.try_skip(n); assert(s == n,""); } 265 266 public: 267 void read_field_counts(int* java_fields, int* injected_fields); 268 int has_next() const { return _r.position() < _r.limit(); } 269 int position() const { return _r.position(); } 270 int next_index() const { return _next_index; } 271 void read_name_and_signature(u2* name_index, u2* signature_index); 272 void read_field_info(FieldInfo& fi); 273 274 int search_table_lookup(const Array<u1>* search_table, const Symbol* name, const Symbol* signature, ConstantPool* cp, int java_fields); 275 276 // skip a whole field record, both required and optional bits 277 FieldInfoReader& skip_field_info(); 278 279 // Skip to the nth field. If the reader is freshly initialized to 280 // the zero index, this will call skip_field_info() n times. 281 FieldInfoReader& skip_to_field_info(int n); 282 283 // for random access, if you know where to go up front: 284 FieldInfoReader& set_position_and_next_index(int position, int next_index); 285 }; 286 287 // The format of the stream, after decompression, is a series of 288 // integers organized like this: 289 // 290 // FieldInfoStream := j=num_java_fields k=num_injected_fields Field[j+k] End 291 // Field := name sig offset access flags Optionals(flags) 292 // Optionals(i) := initval?[i&is_init] // ConstantValue attr 293 // gsig?[i&is_generic] // signature attr 294 // group?[i&is_contended] // Contended anno (group) 295 // End = 0 296 // 297 class FieldInfoStream : AllStatic { 298 friend class fieldDescriptor; 299 friend class JavaFieldStream; 300 friend class FieldStreamBase; 301 friend class ClassFileParser; 302 friend class FieldInfoReader; 303 friend class FieldInfoComparator; 304 305 private: 306 static int compare_name_and_sig(const Symbol* n1, const Symbol* s1, const Symbol* n2, const Symbol* s2); 307 308 public: 309 static int num_java_fields(const Array<u1>* fis); 310 static int num_injected_java_fields(const Array<u1>* fis); 311 static int num_total_fields(const Array<u1>* fis); 312 313 static Array<u1>* create_FieldInfoStream(GrowableArray<FieldInfo>* fields, int java_fields, int injected_fields, 314 ClassLoaderData* loader_data, TRAPS); 315 static Array<u1>* create_search_table(ConstantPool* cp, const Array<u1>* fis, ClassLoaderData* loader_data, TRAPS); 316 static GrowableArray<FieldInfo>* create_FieldInfoArray(const Array<u1>* fis, int* java_fields_count, int* injected_fields_count); 317 static void print_from_fieldinfo_stream(Array<u1>* fis, outputStream* os, ConstantPool* cp); 318 319 DEBUG_ONLY(static void validate_search_table(ConstantPool* cp, const Array<u1>* fis, const Array<u1>* search_table);) 320 321 static void print_search_table(outputStream* st, ConstantPool* cp, const Array<u1>* fis, const Array<u1>* search_table); 322 }; 323 324 class FieldStatus { 325 enum FieldStatusBitPosition { 326 _fs_access_watched, // field access is watched by JVMTI 327 _fs_modification_watched, // field modification is watched by JVMTI 328 _fs_strict_static_unset, // JVM_ACC_STRICT_INIT static field has not yet been set 329 _fs_strict_static_unread, // SS field has not yet been read 330 _initialized_final_update // (static) final field updated outside (class) initializer 331 }; 332 333 // boilerplate: 334 u1 _flags; 335 static constexpr u1 flag_mask(FieldStatusBitPosition pos) { return (u1)1 << (int)pos; } 336 bool test_flag(FieldStatusBitPosition pos) { return (_flags & flag_mask(pos)) != 0; } 337 // this performs an atomic update on a live status byte! 338 void update_flag(FieldStatusBitPosition pos, bool z); 339 // out-of-line functions do a CAS-loop 340 static void atomic_set_bits(u1& flags, u1 mask); 341 static void atomic_clear_bits(u1& flags, u1 mask); 342 343 public: 344 FieldStatus() { _flags = 0; } 345 FieldStatus(u1 flags) { _flags = flags; } 346 u1 as_uint() { return _flags; } 347 348 bool is_access_watched() { return test_flag(_fs_access_watched); } 349 bool is_modification_watched() { return test_flag(_fs_modification_watched); } 350 bool is_strict_static_unset() { return test_flag(_fs_strict_static_unset); } 351 bool is_strict_static_unread() { return test_flag(_fs_strict_static_unread); } 352 bool is_initialized_final_update() { return test_flag(_initialized_final_update); } 353 354 void update_access_watched(bool z); 355 void update_modification_watched(bool z); 356 void update_strict_static_unset(bool z); 357 void update_strict_static_unread(bool z); 358 void update_initialized_final_update(bool z); 359 }; 360 361 #endif // SHARE_OOPS_FIELDINFO_HPP --- EOF ---