1 /* 2 * Copyright (c) 1997, 2018, 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_VM_OOPS_KLASSVTABLE_HPP 26 #define SHARE_VM_OOPS_KLASSVTABLE_HPP 27 28 #include "oops/oopsHierarchy.hpp" 29 #include "runtime/handles.hpp" 30 #include "utilities/growableArray.hpp" 31 32 // A klassVtable abstracts the variable-length vtable that is embedded in InstanceKlass 33 // and ArrayKlass. klassVtable objects are used just as convenient transient accessors to the vtable, 34 // not to actually hold the vtable data. 35 // Note: the klassVtable should not be accessed before the class has been verified 36 // (until that point, the vtable is uninitialized). 37 38 // Currently a klassVtable contains a direct reference to the vtable data, and is therefore 39 // not preserved across GCs. 40 41 class vtableEntry; 42 43 class klassVtable { 44 Klass* _klass; // my klass 45 int _tableOffset; // offset of start of vtable data within klass 46 int _length; // length of vtable (number of entries) 47 #ifndef PRODUCT 48 int _verify_count; // to make verify faster 49 #endif 50 51 // Ordering important, so greater_than (>) can be used as an merge operator. 52 enum AccessType { 53 acc_private = 0, 54 acc_package_private = 1, 55 acc_publicprotected = 2 56 }; 57 58 public: 59 klassVtable(Klass* klass, void* base, int length) : _klass(klass) { 60 _tableOffset = (address)base - (address)klass; _length = length; 61 } 62 63 // accessors 64 vtableEntry* table() const { return (vtableEntry*)(address(_klass) + _tableOffset); } 65 Klass* klass() const { return _klass; } 66 int length() const { return _length; } 67 inline Method* method_at(int i) const; 68 inline Method* unchecked_method_at(int i) const; 69 inline Method** adr_method_at(int i) const; 70 71 // searching; all methods return -1 if not found 72 int index_of(Method* m) const { return index_of(m, _length); } 73 int index_of_miranda(Symbol* name, Symbol* signature); 74 75 void initialize_vtable(bool checkconstraints, TRAPS); // initialize vtable of a new klass 76 77 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 78 // at dump time. Clearing gives us an easy way to tell if the vtable has 79 // already been reinitialized at dump time (see dump.cpp). Vtables can 80 // be initialized at run time by RedefineClasses so dumping the right order 81 // is necessary. 82 void clear_vtable(); 83 bool is_initialized(); 84 85 // computes vtable length (in words) and the number of miranda methods 86 static void compute_vtable_size_and_num_mirandas(int* vtable_length, 87 int* num_new_mirandas, 88 GrowableArray<Method*>* all_mirandas, 89 const Klass* super, 90 Array<Method*>* methods, 91 AccessFlags class_flags, 92 u2 major_version, 93 Handle classloader, 94 Symbol* classname, 95 Array<Klass*>* local_interfaces, 96 TRAPS); 97 98 #if INCLUDE_JVMTI 99 // RedefineClasses() API support: 100 // If any entry of this vtable points to any of old_methods, 101 // replace it with the corresponding new_method. 102 // trace_name_printed is set to true if the current call has 103 // printed the klass name so that other routines in the adjust_* 104 // group don't print the klass name. 105 bool adjust_default_method(int vtable_index, Method* old_method, Method* new_method); 106 void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed); 107 bool check_no_old_or_obsolete_entries(); 108 void dump_vtable(); 109 #endif // INCLUDE_JVMTI 110 111 // Debugging code 112 void print() PRODUCT_RETURN; 113 void verify(outputStream* st, bool force = false); 114 static void print_statistics() PRODUCT_RETURN; 115 116 protected: 117 friend class vtableEntry; 118 119 public: 120 // Transitive overridng rules for class files < JDK1_7 use the older JVMS rules. 121 // Overriding is determined as we create the vtable, so we use the class file version 122 // of the class whose vtable we are calculating. 123 enum { VTABLE_TRANSITIVE_OVERRIDE_VERSION = 51 } ; 124 125 private: 126 void copy_vtable_to(vtableEntry* start); 127 int initialize_from_super(Klass* super); 128 int index_of(Method* m, int len) const; // same as index_of, but search only up to len 129 void put_method_at(Method* m, int index); 130 static bool needs_new_vtable_entry(const methodHandle& m, 131 const Klass* super, 132 Handle classloader, 133 Symbol* classname, 134 AccessFlags access_flags, 135 u2 major_version, 136 TRAPS); 137 138 bool update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method, int super_vtable_len, int default_index, bool checkconstraints, TRAPS); 139 InstanceKlass* find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method, int vtable_index, 140 Handle target_loader, Symbol* target_classname, Thread* THREAD); 141 142 // support for miranda methods 143 bool is_miranda_entry_at(int i); 144 int fill_in_mirandas(int initialized); 145 static bool is_miranda(Method* m, Array<Method*>* class_methods, 146 Array<Method*>* default_methods, const Klass* super, 147 bool is_interface); 148 static void add_new_mirandas_to_lists( 149 GrowableArray<Method*>* new_mirandas, 150 GrowableArray<Method*>* all_mirandas, 151 Array<Method*>* current_interface_methods, 152 Array<Method*>* class_methods, 153 Array<Method*>* default_methods, 154 const Klass* super, 155 bool is_interface); 156 static void get_mirandas( 157 GrowableArray<Method*>* new_mirandas, 158 GrowableArray<Method*>* all_mirandas, 159 const Klass* super, 160 Array<Method*>* class_methods, 161 Array<Method*>* default_methods, 162 Array<Klass*>* local_interfaces, 163 bool is_interface); 164 void verify_against(outputStream* st, klassVtable* vt, int index); 165 inline InstanceKlass* ik() const; 166 // When loading a class from CDS archive at run time, and no class redefintion 167 // has happened, it is expected that the class's itable/vtables are 168 // laid out exactly the same way as they had been during dump time. 169 // Therefore, in klassVtable::initialize_[iv]table, we do not layout the 170 // tables again. Instead, we only rerun the process to create/check 171 // the class loader constraints. In non-product builds, we add asserts to 172 // guarantee that the table's layout would be the same as at dump time. 173 // 174 // If JVMTI redefines any class, the read-only shared memory are remapped 175 // as read-write. A shared class' vtable/itable are re-initialized and 176 // might have different layout due to class redefinition of the shared class 177 // or its super types. 178 bool is_preinitialized_vtable(); 179 }; 180 181 182 // private helper class for klassVtable 183 // description of entry points: 184 // destination is interpreted: 185 // from_compiled_code_entry_point -> c2iadapter 186 // from_interpreter_entry_point -> interpreter entry point 187 // destination is compiled: 188 // from_compiled_code_entry_point -> nmethod entry point 189 // from_interpreter_entry_point -> i2cadapter 190 class vtableEntry { 191 friend class VMStructs; 192 friend class JVMCIVMStructs; 193 194 public: 195 // size in words 196 static int size() { return sizeof(vtableEntry) / wordSize; } 197 static int size_in_bytes() { return sizeof(vtableEntry); } 198 199 static int method_offset_in_bytes() { return offset_of(vtableEntry, _method); } 200 Method* method() const { return _method; } 201 Method** method_addr() { return &_method; } 202 203 private: 204 Method* _method; 205 void set(Method* method) { assert(method != NULL, "use clear"); _method = method; } 206 void clear() { _method = NULL; } 207 void print() PRODUCT_RETURN; 208 void verify(klassVtable* vt, outputStream* st); 209 210 friend class klassVtable; 211 }; 212 213 214 inline Method* klassVtable::method_at(int i) const { 215 assert(i >= 0 && i < _length, "index out of bounds"); 216 assert(table()[i].method() != NULL, "should not be null"); 217 assert(((Metadata*)table()[i].method())->is_method(), "should be method"); 218 return table()[i].method(); 219 } 220 221 inline Method* klassVtable::unchecked_method_at(int i) const { 222 assert(i >= 0 && i < _length, "index out of bounds"); 223 return table()[i].method(); 224 } 225 226 inline Method** klassVtable::adr_method_at(int i) const { 227 // Allow one past the last entry to be referenced; useful for loop bounds. 228 assert(i >= 0 && i <= _length, "index out of bounds"); 229 return (Method**)(address(table() + i) + vtableEntry::method_offset_in_bytes()); 230 } 231 232 // -------------------------------------------------------------------------------- 233 class klassItable; 234 class itableMethodEntry; 235 236 class itableOffsetEntry { 237 private: 238 Klass* _interface; 239 int _offset; 240 public: 241 Klass* interface_klass() const { return _interface; } 242 Klass**interface_klass_addr() { return &_interface; } 243 int offset() const { return _offset; } 244 245 static itableMethodEntry* method_entry(Klass* k, int offset) { return (itableMethodEntry*)(((address)k) + offset); } 246 itableMethodEntry* first_method_entry(Klass* k) { return method_entry(k, _offset); } 247 248 void initialize(Klass* interf, int offset) { _interface = interf; _offset = offset; } 249 250 // Static size and offset accessors 251 static int size() { return sizeof(itableOffsetEntry) / wordSize; } // size in words 252 static int interface_offset_in_bytes() { return offset_of(itableOffsetEntry, _interface); } 253 static int offset_offset_in_bytes() { return offset_of(itableOffsetEntry, _offset); } 254 255 friend class klassItable; 256 }; 257 258 259 class itableMethodEntry { 260 private: 261 Method* _method; 262 263 public: 264 Method* method() const { return _method; } 265 Method**method_addr() { return &_method; } 266 267 void clear() { _method = NULL; } 268 269 void initialize(Method* method); 270 271 // Static size and offset accessors 272 static int size() { return sizeof(itableMethodEntry) / wordSize; } // size in words 273 static int method_offset_in_bytes() { return offset_of(itableMethodEntry, _method); } 274 275 friend class klassItable; 276 }; 277 278 // 279 // Format of an itable 280 // 281 // ---- offset table --- 282 // Klass* of interface 1 \ 283 // offset to vtable from start of oop / offset table entry 284 // ... 285 // Klass* of interface n \ 286 // offset to vtable from start of oop / offset table entry 287 // --- vtable for interface 1 --- 288 // Method* \ 289 // compiler entry point / method table entry 290 // ... 291 // Method* \ 292 // compiler entry point / method table entry 293 // -- vtable for interface 2 --- 294 // ... 295 // 296 class klassItable { 297 private: 298 InstanceKlass* _klass; // my klass 299 int _table_offset; // offset of start of itable data within klass (in words) 300 int _size_offset_table; // size of offset table (in itableOffset entries) 301 int _size_method_table; // size of methodtable (in itableMethodEntry entries) 302 303 void initialize_itable_for_interface(int method_table_offset, Klass* interf_h, bool checkconstraints, TRAPS); 304 public: 305 klassItable(InstanceKlass* klass); 306 307 itableOffsetEntry* offset_entry(int i) { assert(0 <= i && i <= _size_offset_table, "index out of bounds"); 308 return &((itableOffsetEntry*)vtable_start())[i]; } 309 310 itableMethodEntry* method_entry(int i) { assert(0 <= i && i <= _size_method_table, "index out of bounds"); 311 return &((itableMethodEntry*)method_start())[i]; } 312 313 int size_offset_table() { return _size_offset_table; } 314 315 // Initialization 316 void initialize_itable(bool checkconstraints, TRAPS); 317 318 #if INCLUDE_JVMTI 319 // RedefineClasses() API support: 320 // if any entry of this itable points to any of old_methods, 321 // replace it with the corresponding new_method. 322 // trace_name_printed is set to true if the current call has 323 // printed the klass name so that other routines in the adjust_* 324 // group don't print the klass name. 325 void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed); 326 bool check_no_old_or_obsolete_entries(); 327 void dump_itable(); 328 #endif // INCLUDE_JVMTI 329 330 // Setup of itable 331 static int assign_itable_indices_for_interface(Klass* klass); 332 static int method_count_for_interface(Klass* klass); 333 static int compute_itable_size(Array<Klass*>* transitive_interfaces); 334 static void setup_itable_offset_table(InstanceKlass* klass); 335 336 // Resolving of method to index 337 static Method* method_for_itable_index(Klass* klass, int itable_index); 338 339 // Debugging/Statistics 340 static void print_statistics() PRODUCT_RETURN; 341 private: 342 intptr_t* vtable_start() const { return ((intptr_t*)_klass) + _table_offset; } 343 intptr_t* method_start() const { return vtable_start() + _size_offset_table * itableOffsetEntry::size(); } 344 345 // Helper methods 346 static int calc_itable_size(int num_interfaces, int num_methods) { return (num_interfaces * itableOffsetEntry::size()) + (num_methods * itableMethodEntry::size()); } 347 348 // Statistics 349 NOT_PRODUCT(static int _total_classes;) // Total no. of classes with itables 350 NOT_PRODUCT(static long _total_size;) // Total no. of bytes used for itables 351 352 static void update_stats(int size) PRODUCT_RETURN NOT_PRODUCT({ _total_classes++; _total_size += size; }) 353 }; 354 355 #endif // SHARE_VM_OOPS_KLASSVTABLE_HPP