1 #ifdef USE_PRAGMA_IDENT_HDR 2 #pragma ident "@(#)constantPoolOop.hpp 1.105 07/08/29 13:42:26 JVM" 3 #endif 4 /* 5 * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved. 6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 7 * 8 * This code is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 only, as 10 * published by the Free Software Foundation. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 23 * CA 95054 USA or visit www.sun.com if you need additional information or 24 * have any questions. 25 * 26 */ 27 28 // A constantPool is an array containing class constants as described in the 29 // class file. 30 // 31 // Most of the constant pool entries are written during class parsing, which 32 // is safe. For klass and string types, the constant pool entry is 33 // modified when the entry is resolved. If a klass or string constant pool 34 // entry is read without a lock, only the resolved state guarantees that 35 // the entry in the constant pool is a klass or String object and 36 // not a symbolOop. 37 38 class SymbolHashMap; 39 40 class constantPoolOopDesc : public arrayOopDesc { 41 friend class VMStructs; 42 friend class BytecodeInterpreter; // Directly extracts an oop in the pool for fast instanceof/checkcast 43 private: 44 typeArrayOop _tags; // the tag array describing the constant pool's contents 45 constantPoolCacheOop _cache; // the cache holding interpreter runtime information 46 klassOop _pool_holder; // the corresponding class 47 // only set to non-zero if constant pool is merged by RedefineClasses 48 int _orig_length; 49 50 void set_tags(typeArrayOop tags) { oop_store_without_check((oop*)&_tags, tags); } 51 void tag_at_put(int which, jbyte t) { tags()->byte_at_put(which, t); } 52 void release_tag_at_put(int which, jbyte t) { tags()->release_byte_at_put(which, t); } 53 54 private: 55 intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(constantPoolOopDesc)); } 56 oop* tags_addr() { return (oop*)&_tags; } 57 oop* cache_addr() { return (oop*)&_cache; } 58 59 oop* obj_at_addr(int which) const { 60 assert(is_within_bounds(which), "index out of bounds"); 61 return (oop*) &base()[which]; 62 } 63 64 jint* int_at_addr(int which) const { 65 assert(is_within_bounds(which), "index out of bounds"); 66 return (jint*) &base()[which]; 67 } 68 69 jlong* long_at_addr(int which) const { 70 assert(is_within_bounds(which), "index out of bounds"); 71 return (jlong*) &base()[which]; 72 } 73 74 jfloat* float_at_addr(int which) const { 75 assert(is_within_bounds(which), "index out of bounds"); 76 return (jfloat*) &base()[which]; 77 } 78 79 jdouble* double_at_addr(int which) const { 80 assert(is_within_bounds(which), "index out of bounds"); 81 return (jdouble*) &base()[which]; 82 } 83 84 public: 85 typeArrayOop tags() const { return _tags; } 86 87 // Klass holding pool 88 klassOop pool_holder() const { return _pool_holder; } 89 void set_pool_holder(klassOop k) { oop_store_without_check((oop*)&_pool_holder, (oop) k); } 90 oop* pool_holder_addr() { return (oop*)&_pool_holder; } 91 92 // Interpreter runtime support 93 constantPoolCacheOop cache() const { return _cache; } 94 void set_cache(constantPoolCacheOop cache){ oop_store((oop*)&_cache, cache); } 95 96 // Assembly code support 97 static int tags_offset_in_bytes() { return offset_of(constantPoolOopDesc, _tags); } 98 static int cache_offset_in_bytes() { return offset_of(constantPoolOopDesc, _cache); } 99 static int pool_holder_offset_in_bytes() { return offset_of(constantPoolOopDesc, _pool_holder); } 100 101 // Storing constants 102 103 void klass_at_put(int which, klassOop k) { 104 oop_store_without_check((volatile oop *)obj_at_addr(which), oop(k)); 105 // The interpreter assumes when the tag is stored, the klass is resolved 106 // and the klassOop is a klass rather than a symbolOop, so we need 107 // hardware store ordering here. 108 release_tag_at_put(which, JVM_CONSTANT_Class); 109 if (UseConcMarkSweepGC) { 110 // In case the earlier card-mark was consumed by a concurrent 111 // marking thread before the tag was updated, redirty the card. 112 oop_store_without_check((volatile oop *)obj_at_addr(which), oop(k)); 113 } 114 } 115 116 // For temporary use while constructing constant pool 117 void klass_index_at_put(int which, int name_index) { 118 tag_at_put(which, JVM_CONSTANT_ClassIndex); 119 *int_at_addr(which) = name_index; 120 } 121 122 // Temporary until actual use 123 void unresolved_klass_at_put(int which, symbolOop s) { 124 // Overwrite the old index with a GC friendly value so 125 // that if GC looks during the transition it won't try 126 // to treat a small integer as oop. 127 *obj_at_addr(which) = NULL; 128 release_tag_at_put(which, JVM_CONSTANT_UnresolvedClass); 129 oop_store_without_check(obj_at_addr(which), oop(s)); 130 } 131 132 // Temporary until actual use 133 void unresolved_string_at_put(int which, symbolOop s) { 134 *obj_at_addr(which) = NULL; 135 release_tag_at_put(which, JVM_CONSTANT_UnresolvedString); 136 oop_store_without_check(obj_at_addr(which), oop(s)); 137 } 138 139 void int_at_put(int which, jint i) { 140 tag_at_put(which, JVM_CONSTANT_Integer); 141 *int_at_addr(which) = i; 142 } 143 144 void long_at_put(int which, jlong l) { 145 tag_at_put(which, JVM_CONSTANT_Long); 146 // *long_at_addr(which) = l; 147 Bytes::put_native_u8((address)long_at_addr(which), *((u8*) &l)); 148 } 149 150 void float_at_put(int which, jfloat f) { 151 tag_at_put(which, JVM_CONSTANT_Float); 152 *float_at_addr(which) = f; 153 } 154 155 void double_at_put(int which, jdouble d) { 156 tag_at_put(which, JVM_CONSTANT_Double); 157 // *double_at_addr(which) = d; 158 // u8 temp = *(u8*) &d; 159 Bytes::put_native_u8((address) double_at_addr(which), *((u8*) &d)); 160 } 161 162 void symbol_at_put(int which, symbolOop s) { 163 tag_at_put(which, JVM_CONSTANT_Utf8); 164 oop_store_without_check(obj_at_addr(which), oop(s)); 165 } 166 167 void string_at_put(int which, oop str) { 168 oop_store((volatile oop*)obj_at_addr(which), str); 169 release_tag_at_put(which, JVM_CONSTANT_String); 170 if (UseConcMarkSweepGC) { 171 // In case the earlier card-mark was consumed by a concurrent 172 // marking thread before the tag was updated, redirty the card. 173 oop_store_without_check((volatile oop *)obj_at_addr(which), str); 174 } 175 } 176 177 // For temporary use while constructing constant pool 178 void string_index_at_put(int which, int string_index) { 179 tag_at_put(which, JVM_CONSTANT_StringIndex); 180 *int_at_addr(which) = string_index; 181 } 182 183 void field_at_put(int which, int class_index, int name_and_type_index) { 184 tag_at_put(which, JVM_CONSTANT_Fieldref); 185 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index; 186 } 187 188 void method_at_put(int which, int class_index, int name_and_type_index) { 189 tag_at_put(which, JVM_CONSTANT_Methodref); 190 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index; 191 } 192 193 void interface_method_at_put(int which, int class_index, int name_and_type_index) { 194 tag_at_put(which, JVM_CONSTANT_InterfaceMethodref); 195 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index; // Not so nice 196 } 197 198 void name_and_type_at_put(int which, int name_index, int signature_index) { 199 tag_at_put(which, JVM_CONSTANT_NameAndType); 200 *int_at_addr(which) = ((jint) signature_index<<16) | name_index; // Not so nice 201 } 202 203 // Tag query 204 205 constantTag tag_at(int which) const { return (constantTag)tags()->byte_at_acquire(which); } 206 207 // Whether the entry is a pointer that must be GC'd. 208 bool is_pointer_entry(int which) { 209 constantTag tag = tag_at(which); 210 return tag.is_klass() || 211 tag.is_unresolved_klass() || 212 tag.is_symbol() || 213 tag.is_unresolved_string() || 214 tag.is_string(); 215 } 216 217 // Fetching constants 218 219 klassOop klass_at(int which, TRAPS) { 220 constantPoolHandle h_this(THREAD, this); 221 return klass_at_impl(h_this, which, CHECK_NULL); 222 } 223 224 symbolOop klass_name_at(int which); // Returns the name, w/o resolving. 225 226 klassOop resolved_klass_at(int which) { // Used by Compiler 227 guarantee(tag_at(which).is_klass(), "Corrupted constant pool"); 228 // Must do an acquire here in case another thread resolved the klass 229 // behind our back, lest we later load stale values thru the oop. 230 return klassOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which))); 231 } 232 233 // This method should only be used with a cpool lock or during parsing or gc 234 symbolOop unresolved_klass_at(int which) { // Temporary until actual use 235 symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which))); 236 // check that the klass is still unresolved. 237 assert(tag_at(which).is_unresolved_klass(), "Corrupted constant pool"); 238 return s; 239 } 240 241 // RedefineClasses() API support: 242 symbolOop klass_at_noresolve(int which) { return klass_name_at(which); } 243 244 jint int_at(int which) { 245 assert(tag_at(which).is_int(), "Corrupted constant pool"); 246 return *int_at_addr(which); 247 } 248 249 jlong long_at(int which) { 250 assert(tag_at(which).is_long(), "Corrupted constant pool"); 251 // return *long_at_addr(which); 252 u8 tmp = Bytes::get_native_u8((address)&base()[which]); 253 return *((jlong*)&tmp); 254 } 255 256 jfloat float_at(int which) { 257 assert(tag_at(which).is_float(), "Corrupted constant pool"); 258 return *float_at_addr(which); 259 } 260 261 jdouble double_at(int which) { 262 assert(tag_at(which).is_double(), "Corrupted constant pool"); 263 u8 tmp = Bytes::get_native_u8((address)&base()[which]); 264 return *((jdouble*)&tmp); 265 } 266 267 symbolOop symbol_at(int which) { 268 assert(tag_at(which).is_utf8(), "Corrupted constant pool"); 269 return symbolOop(*obj_at_addr(which)); 270 } 271 272 oop string_at(int which, TRAPS) { 273 constantPoolHandle h_this(THREAD, this); 274 return string_at_impl(h_this, which, CHECK_NULL); 275 } 276 277 // only called when we are sure a string entry is already resolved (via an 278 // earlier string_at call. 279 oop resolved_string_at(int which) { 280 assert(tag_at(which).is_string(), "Corrupted constant pool"); 281 // Must do an acquire here in case another thread resolved the klass 282 // behind our back, lest we later load stale values thru the oop. 283 return (oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)); 284 } 285 286 // This method should only be used with a cpool lock or during parsing or gc 287 symbolOop unresolved_string_at(int which) { // Temporary until actual use 288 symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which))); 289 // check that the string is still unresolved. 290 assert(tag_at(which).is_unresolved_string(), "Corrupted constant pool"); 291 return s; 292 } 293 294 // Returns an UTF8 for a CONSTANT_String entry at a given index. 295 // UTF8 char* representation was chosen to avoid conversion of 296 // java_lang_Strings at resolved entries into symbolOops 297 // or vice versa. 298 char* string_at_noresolve(int which); 299 300 jint name_and_type_at(int which) { 301 assert(tag_at(which).is_name_and_type(), "Corrupted constant pool"); 302 return *int_at_addr(which); 303 } 304 305 // The following methods (klass_ref_at, klass_ref_at_noresolve, name_ref_at, 306 // signature_ref_at, klass_ref_index_at, name_and_type_ref_index_at, 307 // name_ref_index_at, signature_ref_index_at) all expect constant pool indices 308 // from the bytecodes to be passed in, which are actually potentially byte-swapped 309 // contstant pool cache indices. See field_or_method_at. 310 311 // Lookup for entries consisting of (klass_index, name_and_type index) 312 klassOop klass_ref_at(int which, TRAPS); 313 symbolOop klass_ref_at_noresolve(int which); 314 symbolOop name_ref_at(int which); 315 symbolOop signature_ref_at(int which); // the type descriptor 316 317 int klass_ref_index_at(int which); 318 int name_and_type_ref_index_at(int which); 319 320 // Lookup for entries consisting of (name_index, signature_index) 321 int name_ref_index_at(int which); 322 int signature_ref_index_at(int which); 323 324 BasicType basic_type_for_signature_at(int which); 325 326 // Resolve string constants (to prevent allocation during compilation) 327 void resolve_string_constants(TRAPS) { 328 constantPoolHandle h_this(THREAD, this); 329 resolve_string_constants_impl(h_this, CHECK); 330 } 331 332 // Klass name matches name at offset 333 bool klass_name_at_matches(instanceKlassHandle k, int which); 334 335 // Sizing 336 static int header_size() { return sizeof(constantPoolOopDesc)/HeapWordSize; } 337 static int object_size(int length) { return align_object_size(header_size() + length); } 338 int object_size() { return object_size(length()); } 339 340 friend class constantPoolKlass; 341 friend class ClassFileParser; 342 friend class SystemDictionary; 343 344 // Used by compiler to prevent classloading. 345 static klassOop klass_at_if_loaded (constantPoolHandle this_oop, int which); 346 static klassOop klass_ref_at_if_loaded (constantPoolHandle this_oop, int which); 347 // Same as above - but does LinkResolving. 348 static klassOop klass_ref_at_if_loaded_check(constantPoolHandle this_oop, int which, TRAPS); 349 350 // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the 351 // future by other Java code. These take constant pool indices rather than possibly-byte-swapped 352 // constant pool cache indices as do the peer methods above. 353 symbolOop uncached_name_ref_at(int which); 354 symbolOop uncached_signature_ref_at(int which); 355 int uncached_klass_ref_index_at(int which); 356 int uncached_name_and_type_ref_index_at(int which); 357 358 // Sharing 359 int pre_resolve_shared_klasses(TRAPS); 360 void shared_symbols_iterate(OopClosure* closure0); 361 void shared_tags_iterate(OopClosure* closure0); 362 void shared_strings_iterate(OopClosure* closure0); 363 364 // Debugging 365 const char* printable_name_at(int which) PRODUCT_RETURN0; 366 367 private: 368 369 // Takes either a constant pool cache index in possibly byte-swapped 370 // byte order (which comes from the bytecodes after rewriting) or, 371 // if "uncached" is true, a vanilla constant pool index 372 jint field_or_method_at(int which, bool uncached) { 373 int i = -1; 374 if (uncached || cache() == NULL) { 375 i = which; 376 } else { 377 // change byte-ordering and go via cache 378 i = cache()->entry_at(Bytes::swap_u2(which))->constant_pool_index(); 379 } 380 assert(tag_at(i).is_field_or_method(), "Corrupted constant pool"); 381 return *int_at_addr(i); 382 } 383 384 // Used while constructing constant pool (only by ClassFileParser) 385 jint klass_index_at(int which) { 386 assert(tag_at(which).is_klass_index(), "Corrupted constant pool"); 387 return *int_at_addr(which); 388 } 389 390 jint string_index_at(int which) { 391 assert(tag_at(which).is_string_index(), "Corrupted constant pool"); 392 return *int_at_addr(which); 393 } 394 395 // Performs the LinkResolver checks 396 static void verify_constant_pool_resolve(constantPoolHandle this_oop, KlassHandle klass, TRAPS); 397 398 // Implementation of methods that needs an exposed 'this' pointer, in order to 399 // handle GC while executing the method 400 static klassOop klass_at_impl(constantPoolHandle this_oop, int which, TRAPS); 401 static oop string_at_impl(constantPoolHandle this_oop, int which, TRAPS); 402 403 // Resolve string constants (to prevent allocation during compilation) 404 static void resolve_string_constants_impl(constantPoolHandle this_oop, TRAPS); 405 406 public: 407 // Merging constantPoolOop support: 408 bool compare_entry_to(int index1, constantPoolHandle cp2, int index2, TRAPS); 409 void copy_cp_to(int start_i, int end_i, constantPoolHandle to_cp, int to_i, 410 TRAPS); 411 void copy_entry_to(int from_i, constantPoolHandle to_cp, int to_i, TRAPS); 412 int find_matching_entry(int pattern_i, constantPoolHandle search_cp, TRAPS); 413 int orig_length() const { return _orig_length; } 414 void set_orig_length(int orig_length) { _orig_length = orig_length; } 415 416 417 // JVMTI accesss - GetConstantPool, RetransformClasses, ... 418 friend class JvmtiConstantPoolReconstituter; 419 420 private: 421 jint cpool_entry_size(jint idx); 422 jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap); 423 424 // Copy cpool bytes into byte array. 425 // Returns: 426 // int > 0, count of the raw cpool bytes that have been copied 427 // 0, OutOfMemory error 428 // -1, Internal error 429 int copy_cpool_bytes(int cpool_size, 430 SymbolHashMap* tbl, 431 unsigned char *bytes); 432 }; 433 434 class SymbolHashMapEntry : public CHeapObj { 435 private: 436 unsigned int _hash; // 32-bit hash for item 437 SymbolHashMapEntry* _next; // Next element in the linked list for this bucket 438 symbolOop _symbol; // 1-st part of the mapping: symbol => value 439 u2 _value; // 2-nd part of the mapping: symbol => value 440 441 public: 442 unsigned int hash() const { return _hash; } 443 void set_hash(unsigned int hash) { _hash = hash; } 444 445 SymbolHashMapEntry* next() const { return _next; } 446 void set_next(SymbolHashMapEntry* next) { _next = next; } 447 448 symbolOop symbol() const { return _symbol; } 449 void set_symbol(symbolOop sym) { _symbol = sym; } 450 451 u2 value() const { return _value; } 452 void set_value(u2 value) { _value = value; } 453 454 SymbolHashMapEntry(unsigned int hash, symbolOop symbol, u2 value) 455 : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {} 456 457 }; // End SymbolHashMapEntry class 458 459 460 class SymbolHashMapBucket : public CHeapObj { 461 462 private: 463 SymbolHashMapEntry* _entry; 464 465 public: 466 SymbolHashMapEntry* entry() const { return _entry; } 467 void set_entry(SymbolHashMapEntry* entry) { _entry = entry; } 468 void clear() { _entry = NULL; } 469 470 }; // End SymbolHashMapBucket class 471 472 473 class SymbolHashMap: public CHeapObj { 474 475 private: 476 // Default number of entries in the table 477 enum SymbolHashMap_Constants { 478 _Def_HashMap_Size = 256 479 }; 480 481 int _table_size; 482 SymbolHashMapBucket* _buckets; 483 484 void initialize_table(int table_size) { 485 _table_size = table_size; 486 _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size); 487 for (int index = 0; index < table_size; index++) { 488 _buckets[index].clear(); 489 } 490 } 491 492 public: 493 494 int table_size() const { return _table_size; } 495 496 SymbolHashMap() { initialize_table(_Def_HashMap_Size); } 497 SymbolHashMap(int table_size) { initialize_table(table_size); } 498 499 // hash P(31) from Kernighan & Ritchie 500 static unsigned int compute_hash(const char* str, int len) { 501 unsigned int hash = 0; 502 while (len-- > 0) { 503 hash = 31*hash + (unsigned) *str; 504 str++; 505 } 506 return hash; 507 } 508 509 SymbolHashMapEntry* bucket(int i) { 510 return _buckets[i].entry(); 511 } 512 513 void add_entry(symbolOop sym, u2 value); 514 SymbolHashMapEntry* find_entry(symbolOop sym); 515 516 u2 symbol_to_value(symbolOop sym) { 517 SymbolHashMapEntry *entry = find_entry(sym); 518 return (entry == NULL) ? 0 : entry->value(); 519 } 520 521 ~SymbolHashMap() { 522 SymbolHashMapEntry* next; 523 for (int i = 0; i < _table_size; i++) { 524 for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) { 525 next = cur->next(); 526 delete(cur); 527 } 528 } 529 delete _buckets; 530 } 531 }; // End SymbolHashMap class