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. 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() : _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 --- EOF ---