1 /* 2 * Copyright (c) 1997, 2016, 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 "memory/allocation.hpp" 29 #include "oops/oopsHierarchy.hpp" 30 #include "runtime/handles.hpp" 31 #include "utilities/growableArray.hpp" 32 33 // A klassVtable abstracts the variable-length vtable that is embedded in InstanceKlass 34 // and ArrayKlass. klassVtable objects are used just as convenient transient accessors to the vtable, 35 // not to actually hold the vtable data. 36 // Note: the klassVtable should not be accessed before the class has been verified 37 // (until that point, the vtable is uninitialized). 38 39 // Currently a klassVtable contains a direct reference to the vtable data, and is therefore 40 // not preserved across GCs. 41 42 class vtableEntry; 43 44 class klassVtable : public ResourceObj { 45 Klass* _klass; // my klass 46 int _tableOffset; // offset of start of vtable data within klass 47 int _length; // length of vtable (number of entries) 48 #ifndef PRODUCT 49 int _verify_count; // to make verify faster 50 #endif 51 52 // Ordering important, so greater_than (>) can be used as an merge operator. 53 enum AccessType { 54 acc_private = 0, 55 acc_package_private = 1, 56 acc_publicprotected = 2 57 }; 58 59 public: 60 klassVtable(Klass* klass, void* base, int length) : _klass(klass) { 61 _tableOffset = (address)base - (address)klass; _length = length; 62 } 63 64 // accessors 65 vtableEntry* table() const { return (vtableEntry*)(address(_klass) + _tableOffset); } 66 Klass* klass() const { return _klass; } 67 int length() const { return _length; } 68 inline Method* method_at(int i) const; 69 inline Method* unchecked_method_at(int i) const; 70 inline Method** adr_method_at(int i) const; 71 72 // searching; all methods return -1 if not found 73 int index_of(Method* m) const { return index_of(m, _length); } 74 int index_of_miranda(Symbol* name, Symbol* signature); 75 76 void initialize_vtable(bool checkconstraints, TRAPS); // initialize vtable of a new klass 77 78 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 79 // at dump time. Clearing gives us an easy way to tell if the vtable has 80 // already been reinitialized at dump time (see dump.cpp). Vtables can 81 // be initialized at run time by RedefineClasses so dumping the right order 82 // is necessary. 83 void clear_vtable(); 84 bool is_initialized(); 85 86 // computes vtable length (in words) and the number of miranda methods 87 static void compute_vtable_size_and_num_mirandas(int* vtable_length, 88 int* num_new_mirandas, 89 GrowableArray<Method*>* all_mirandas, 90 const Klass* super, 91 Array<Method*>* methods, 92 AccessFlags class_flags, 93 u2 major_version, 94 Handle classloader, 95 Symbol* classname, 96 Array<Klass*>* local_interfaces, 97 TRAPS); 98 99 #if INCLUDE_JVMTI 100 // RedefineClasses() API support: 101 // If any entry of this vtable points to any of old_methods, 102 // replace it with the corresponding new_method. 103 // trace_name_printed is set to true if the current call has 104 // printed the klass name so that other routines in the adjust_* 105 // group don't print the klass name. 106 bool adjust_default_method(int vtable_index, Method* old_method, Method* new_method); 107 void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed); 108 bool check_no_old_or_obsolete_entries(); 109 void dump_vtable(); 110 #endif // INCLUDE_JVMTI 111 112 // Debugging code 113 void print() PRODUCT_RETURN; 114 void verify(outputStream* st, bool force = false); 115 static void print_statistics() PRODUCT_RETURN; 116 117 protected: 118 friend class vtableEntry; 119 120 public: 121 // Transitive overridng rules for class files < JDK1_7 use the older JVMS rules. 122 // Overriding is determined as we create the vtable, so we use the class file version 123 // of the class whose vtable we are calculating. 124 enum { VTABLE_TRANSITIVE_OVERRIDE_VERSION = 51 } ; 125 126 private: 127 void copy_vtable_to(vtableEntry* start); 128 int initialize_from_super(Klass* super); 129 int index_of(Method* m, int len) const; // same as index_of, but search only up to len 130 void put_method_at(Method* m, int index); 131 static bool needs_new_vtable_entry(methodHandle m, 132 const Klass* super, 133 Handle classloader, 134 Symbol* classname, 135 AccessFlags access_flags, 136 u2 major_version, 137 TRAPS); 138 139 bool update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, int super_vtable_len, int default_index, bool checkconstraints, TRAPS); 140 InstanceKlass* find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, int vtable_index, 141 Handle target_loader, Symbol* target_classname, Thread* THREAD); 142 143 // support for miranda methods 144 bool is_miranda_entry_at(int i); 145 int fill_in_mirandas(int initialized); 146 static bool is_miranda(Method* m, Array<Method*>* class_methods, 147 Array<Method*>* default_methods, const Klass* super); 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 static void get_mirandas( 156 GrowableArray<Method*>* new_mirandas, 157 GrowableArray<Method*>* all_mirandas, 158 const Klass* super, 159 Array<Method*>* class_methods, 160 Array<Method*>* default_methods, 161 Array<Klass*>* local_interfaces); 162 void verify_against(outputStream* st, klassVtable* vt, int index); 163 inline InstanceKlass* ik() const; 164 // When loading a class from CDS archive at run time, and no class redefintion 165 // has happened, it is expected that the class's itable/vtables are 166 // laid out exactly the same way as they had been during dump time. 167 // Therefore, in klassVtable::initialize_[iv]table, we do not layout the 168 // tables again. Instead, we only rerun the process to create/check 169 // the class loader constraints. In non-product builds, we add asserts to 170 // guarantee that the table's layout would be the same as at dump time. 171 // 172 // If JVMTI redefines any class, the read-only shared memory are remapped 173 // as read-write. A shared class' vtable/itable are re-initialized and 174 // might have different layout due to class redefinition of the shared class 175 // or its super types. 176 bool is_preinitialized_vtable(); 177 }; 178 179 180 // private helper class for klassVtable 181 // description of entry points: 182 // destination is interpreted: 183 // from_compiled_code_entry_point -> c2iadapter 184 // from_interpreter_entry_point -> interpreter entry point 185 // destination is compiled: 186 // from_compiled_code_entry_point -> nmethod entry point 187 // from_interpreter_entry_point -> i2cadapter 188 class vtableEntry VALUE_OBJ_CLASS_SPEC { 189 friend class VMStructs; 190 friend class JVMCIVMStructs; 191 192 public: 193 // size in words 194 static int size() { return sizeof(vtableEntry) / wordSize; } 195 static int size_in_bytes() { return sizeof(vtableEntry); } 196 197 static int method_offset_in_bytes() { return offset_of(vtableEntry, _method); } 198 Method* method() const { return _method; } 199 200 private: 201 Method* _method; 202 void set(Method* method) { assert(method != NULL, "use clear"); _method = method; } 203 void clear() { _method = NULL; } 204 void print() PRODUCT_RETURN; 205 void verify(klassVtable* vt, outputStream* st); 206 207 friend class klassVtable; 208 }; 209 210 211 inline Method* klassVtable::method_at(int i) const { 212 assert(i >= 0 && i < _length, "index out of bounds"); 213 assert(table()[i].method() != NULL, "should not be null"); 214 assert(((Metadata*)table()[i].method())->is_method(), "should be method"); 215 return table()[i].method(); 216 } 217 218 inline Method* klassVtable::unchecked_method_at(int i) const { 219 assert(i >= 0 && i < _length, "index out of bounds"); 220 return table()[i].method(); 221 } 222 223 inline Method** klassVtable::adr_method_at(int i) const { 224 // Allow one past the last entry to be referenced; useful for loop bounds. 225 assert(i >= 0 && i <= _length, "index out of bounds"); 226 return (Method**)(address(table() + i) + vtableEntry::method_offset_in_bytes()); 227 } 228 229 // -------------------------------------------------------------------------------- 230 class klassItable; 231 class itableMethodEntry; 232 233 class itableOffsetEntry VALUE_OBJ_CLASS_SPEC { 234 private: 235 Klass* _interface; 236 int _offset; 237 public: 238 Klass* interface_klass() const { return _interface; } 239 int offset() const { return _offset; } 240 241 static itableMethodEntry* method_entry(Klass* k, int offset) { return (itableMethodEntry*)(((address)k) + offset); } 242 itableMethodEntry* first_method_entry(Klass* k) { return method_entry(k, _offset); } 243 244 void initialize(Klass* interf, int offset) { _interface = interf; _offset = offset; } 245 246 // Static size and offset accessors 247 static int size() { return sizeof(itableOffsetEntry) / wordSize; } // size in words 248 static int interface_offset_in_bytes() { return offset_of(itableOffsetEntry, _interface); } 249 static int offset_offset_in_bytes() { return offset_of(itableOffsetEntry, _offset); } 250 251 friend class klassItable; 252 }; 253 254 255 class itableMethodEntry VALUE_OBJ_CLASS_SPEC { 256 private: 257 Method* _method; 258 259 public: 260 Method* method() const { return _method; } 261 262 void clear() { _method = NULL; } 263 264 void initialize(Method* method); 265 266 // Static size and offset accessors 267 static int size() { return sizeof(itableMethodEntry) / wordSize; } // size in words 268 static int method_offset_in_bytes() { return offset_of(itableMethodEntry, _method); } 269 270 friend class klassItable; 271 }; 272 273 // 274 // Format of an itable 275 // 276 // ---- offset table --- 277 // Klass* of interface 1 \ 278 // offset to vtable from start of oop / offset table entry 279 // ... 280 // Klass* of interface n \ 281 // offset to vtable from start of oop / offset table entry 282 // --- vtable for interface 1 --- 283 // Method* \ 284 // compiler entry point / method table entry 285 // ... 286 // Method* \ 287 // compiler entry point / method table entry 288 // -- vtable for interface 2 --- 289 // ... 290 // 291 class klassItable : public ResourceObj { 292 private: 293 InstanceKlass* _klass; // my klass 294 int _table_offset; // offset of start of itable data within klass (in words) 295 int _size_offset_table; // size of offset table (in itableOffset entries) 296 int _size_method_table; // size of methodtable (in itableMethodEntry entries) 297 298 void initialize_itable_for_interface(int method_table_offset, Klass* interf_h, bool checkconstraints, TRAPS); 299 public: 300 klassItable(InstanceKlass* klass); 301 302 itableOffsetEntry* offset_entry(int i) { assert(0 <= i && i <= _size_offset_table, "index out of bounds"); 303 return &((itableOffsetEntry*)vtable_start())[i]; } 304 305 itableMethodEntry* method_entry(int i) { assert(0 <= i && i <= _size_method_table, "index out of bounds"); 306 return &((itableMethodEntry*)method_start())[i]; } 307 308 int size_offset_table() { return _size_offset_table; } 309 310 // Initialization 311 void initialize_itable(bool checkconstraints, TRAPS); 312 313 // Updates 314 void initialize_with_method(Method* m); 315 316 #if INCLUDE_JVMTI 317 // RedefineClasses() API support: 318 // if any entry of this itable points to any of old_methods, 319 // replace it with the corresponding new_method. 320 // trace_name_printed is set to true if the current call has 321 // printed the klass name so that other routines in the adjust_* 322 // group don't print the klass name. 323 void adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed); 324 bool check_no_old_or_obsolete_entries(); 325 void dump_itable(); 326 #endif // INCLUDE_JVMTI 327 328 // Setup of itable 329 static int assign_itable_indices_for_interface(Klass* klass); 330 static int method_count_for_interface(Klass* klass); 331 static int compute_itable_size(Array<Klass*>* transitive_interfaces); 332 static void setup_itable_offset_table(InstanceKlass* klass); 333 334 // Resolving of method to index 335 static Method* method_for_itable_index(Klass* klass, int itable_index); 336 337 // Debugging/Statistics 338 static void print_statistics() PRODUCT_RETURN; 339 private: 340 intptr_t* vtable_start() const { return ((intptr_t*)_klass) + _table_offset; } 341 intptr_t* method_start() const { return vtable_start() + _size_offset_table * itableOffsetEntry::size(); } 342 343 // Helper methods 344 static int calc_itable_size(int num_interfaces, int num_methods) { return (num_interfaces * itableOffsetEntry::size()) + (num_methods * itableMethodEntry::size()); } 345 346 // Statistics 347 NOT_PRODUCT(static int _total_classes;) // Total no. of classes with itables 348 NOT_PRODUCT(static long _total_size;) // Total no. of bytes used for itables 349 350 static void update_stats(int size) PRODUCT_RETURN NOT_PRODUCT({ _total_classes++; _total_size += size; }) 351 }; 352 353 #endif // SHARE_VM_OOPS_KLASSVTABLE_HPP --- EOF ---