1 /* 2 * Copyright (c) 1997, 2013, 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_KLASS_HPP 26 #define SHARE_VM_OOPS_KLASS_HPP 27 28 #include "memory/genOopClosures.hpp" 29 #include "memory/iterator.hpp" 30 #include "memory/memRegion.hpp" 31 #include "memory/specialized_oop_closures.hpp" 32 #include "oops/klassPS.hpp" 33 #include "oops/metadata.hpp" 34 #include "oops/oop.hpp" 35 #include "runtime/orderAccess.hpp" 36 #include "trace/traceMacros.hpp" 37 #include "utilities/accessFlags.hpp" 38 #include "utilities/macros.hpp" 39 #if INCLUDE_ALL_GCS 40 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp" 41 #include "gc_implementation/g1/g1OopClosures.hpp" 42 #include "gc_implementation/parNew/parOopClosures.hpp" 43 #endif // INCLUDE_ALL_GCS 44 45 // 46 // A Klass provides: 47 // 1: language level class object (method dictionary etc.) 48 // 2: provide vm dispatch behavior for the object 49 // Both functions are combined into one C++ class. 50 51 // One reason for the oop/klass dichotomy in the implementation is 52 // that we don't want a C++ vtbl pointer in every object. Thus, 53 // normal oops don't have any virtual functions. Instead, they 54 // forward all "virtual" functions to their klass, which does have 55 // a vtbl and does the C++ dispatch depending on the object's 56 // actual type. (See oop.inline.hpp for some of the forwarding code.) 57 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"! 58 59 // Klass layout: 60 // [C++ vtbl ptr ] (contained in Metadata) 61 // [layout_helper ] 62 // [super_check_offset ] for fast subtype checks 63 // [name ] 64 // [secondary_super_cache] for fast subtype checks 65 // [secondary_supers ] array of 2ndary supertypes 66 // [primary_supers 0] 67 // [primary_supers 1] 68 // [primary_supers 2] 69 // ... 70 // [primary_supers 7] 71 // [java_mirror ] 72 // [super ] 73 // [subklass ] first subclass 74 // [next_sibling ] link to chain additional subklasses 75 // [next_link ] 76 // [class_loader_data] 77 // [modifier_flags] 78 // [access_flags ] 79 // [last_biased_lock_bulk_revocation_time] (64 bits) 80 // [prototype_header] 81 // [biased_lock_revocation_count] 82 // [_modified_oops] 83 // [_accumulated_modified_oops] 84 // [trace_id] 85 86 87 // Forward declarations. 88 template <class T> class Array; 89 template <class T> class GrowableArray; 90 class ClassLoaderData; 91 class klassVtable; 92 class ParCompactionManager; 93 class KlassSizeStats; 94 95 class Klass : public Metadata { 96 friend class VMStructs; 97 protected: 98 // note: put frequently-used fields together at start of klass structure 99 // for better cache behavior (may not make much of a difference but sure won't hurt) 100 enum { _primary_super_limit = 8 }; 101 102 // The "layout helper" is a combined descriptor of object layout. 103 // For klasses which are neither instance nor array, the value is zero. 104 // 105 // For instances, layout helper is a positive number, the instance size. 106 // This size is already passed through align_object_size and scaled to bytes. 107 // The low order bit is set if instances of this class cannot be 108 // allocated using the fastpath. 109 // 110 // For arrays, layout helper is a negative number, containing four 111 // distinct bytes, as follows: 112 // MSB:[tag, hsz, ebt, log2(esz)]:LSB 113 // where: 114 // tag is 0x80 if the elements are oops, 0xC0 if non-oops 115 // hsz is array header size in bytes (i.e., offset of first element) 116 // ebt is the BasicType of the elements 117 // esz is the element size in bytes 118 // This packed word is arranged so as to be quickly unpacked by the 119 // various fast paths that use the various subfields. 120 // 121 // The esz bits can be used directly by a SLL instruction, without masking. 122 // 123 // Note that the array-kind tag looks like 0x00 for instance klasses, 124 // since their length in bytes is always less than 24Mb. 125 // 126 // Final note: This comes first, immediately after C++ vtable, 127 // because it is frequently queried. 128 jint _layout_helper; 129 130 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers 131 // and _primary_supers all help make fast subtype checks. See big discussion 132 // in doc/server_compiler/checktype.txt 133 // 134 // Where to look to observe a supertype (it is &_secondary_super_cache for 135 // secondary supers, else is &_primary_supers[depth()]. 136 juint _super_check_offset; 137 138 // Class name. Instance classes: java/lang/String, etc. Array classes: [I, 139 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes. 140 Symbol* _name; 141 142 // Cache of last observed secondary supertype 143 Klass* _secondary_super_cache; 144 // Array of all secondary supertypes 145 Array<Klass*>* _secondary_supers; 146 // Ordered list of all primary supertypes 147 Klass* _primary_supers[_primary_super_limit]; 148 // java/lang/Class instance mirroring this class 149 oop _java_mirror; 150 // Superclass 151 Klass* _super; 152 // First subclass (NULL if none); _subklass->next_sibling() is next one 153 Klass* _subklass; 154 // Sibling link (or NULL); links all subklasses of a klass 155 Klass* _next_sibling; 156 157 // All klasses loaded by a class loader are chained through these links 158 Klass* _next_link; 159 160 // The VM's representation of the ClassLoader used to load this class. 161 // Provide access the corresponding instance java.lang.ClassLoader. 162 ClassLoaderData* _class_loader_data; 163 164 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers. 165 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here. 166 167 // Biased locking implementation and statistics 168 // (the 64-bit chunk goes first, to avoid some fragmentation) 169 jlong _last_biased_lock_bulk_revocation_time; 170 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type 171 jint _biased_lock_revocation_count; 172 173 TRACE_DEFINE_KLASS_TRACE_ID; 174 175 // Remembered sets support for the oops in the klasses. 176 jbyte _modified_oops; // Card Table Equivalent (YC/CMS support) 177 jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support) 178 179 // Constructor 180 Klass(); 181 182 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS); 183 184 public: 185 bool is_klass() const volatile { return true; } 186 187 // super 188 Klass* super() const { return _super; } 189 void set_super(Klass* k) { _super = k; } 190 191 // initializes _super link, _primary_supers & _secondary_supers arrays 192 void initialize_supers(Klass* k, TRAPS); 193 void initialize_supers_impl1(Klass* k); 194 void initialize_supers_impl2(Klass* k); 195 196 // klass-specific helper for initializing _secondary_supers 197 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots); 198 199 // java_super is the Java-level super type as specified by Class.getSuperClass. 200 virtual Klass* java_super() const { return NULL; } 201 202 juint super_check_offset() const { return _super_check_offset; } 203 void set_super_check_offset(juint o) { _super_check_offset = o; } 204 205 Klass* secondary_super_cache() const { return _secondary_super_cache; } 206 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; } 207 208 Array<Klass*>* secondary_supers() const { return _secondary_supers; } 209 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; } 210 211 // Return the element of the _super chain of the given depth. 212 // If there is no such element, return either NULL or this. 213 Klass* primary_super_of_depth(juint i) const { 214 assert(i < primary_super_limit(), "oob"); 215 Klass* super = _primary_supers[i]; 216 assert(super == NULL || super->super_depth() == i, "correct display"); 217 return super; 218 } 219 220 // Can this klass be a primary super? False for interfaces and arrays of 221 // interfaces. False also for arrays or classes with long super chains. 222 bool can_be_primary_super() const { 223 const juint secondary_offset = in_bytes(secondary_super_cache_offset()); 224 return super_check_offset() != secondary_offset; 225 } 226 virtual bool can_be_primary_super_slow() const; 227 228 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit]. 229 juint super_depth() const { 230 if (!can_be_primary_super()) { 231 return primary_super_limit(); 232 } else { 233 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*); 234 assert(d < primary_super_limit(), "oob"); 235 assert(_primary_supers[d] == this, "proper init"); 236 return d; 237 } 238 } 239 240 // store an oop into a field of a Klass 241 void klass_oop_store(oop* p, oop v); 242 void klass_oop_store(volatile oop* p, oop v); 243 244 // java mirror 245 oop java_mirror() const { return _java_mirror; } 246 void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); } 247 248 // modifier flags 249 jint modifier_flags() const { return _modifier_flags; } 250 void set_modifier_flags(jint flags) { _modifier_flags = flags; } 251 252 // size helper 253 int layout_helper() const { return _layout_helper; } 254 void set_layout_helper(int lh) { _layout_helper = lh; } 255 256 // Note: for instances layout_helper() may include padding. 257 // Use InstanceKlass::contains_field_offset to classify field offsets. 258 259 // sub/superklass links 260 InstanceKlass* superklass() const; 261 Klass* subklass() const; 262 Klass* next_sibling() const; 263 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list 264 265 void set_next_link(Klass* k) { _next_link = k; } 266 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader. 267 268 // class loader data 269 ClassLoaderData* class_loader_data() const { return _class_loader_data; } 270 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; } 271 272 // The Klasses are not placed in the Heap, so the Card Table or 273 // the Mod Union Table can't be used to mark when klasses have modified oops. 274 // The CT and MUT bits saves this information for the individual Klasses. 275 void record_modified_oops() { _modified_oops = 1; } 276 void clear_modified_oops() { _modified_oops = 0; } 277 bool has_modified_oops() { return _modified_oops == 1; } 278 279 void accumulate_modified_oops() { if (has_modified_oops()) _accumulated_modified_oops = 1; } 280 void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; } 281 bool has_accumulated_modified_oops() { return _accumulated_modified_oops == 1; } 282 283 protected: // internal accessors 284 Klass* subklass_oop() const { return _subklass; } 285 Klass* next_sibling_oop() const { return _next_sibling; } 286 void set_subklass(Klass* s); 287 void set_next_sibling(Klass* s); 288 289 public: 290 291 // Compiler support 292 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); } 293 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); } 294 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); } 295 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); } 296 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); } 297 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); } 298 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); } 299 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); } 300 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); } 301 302 // Unpacking layout_helper: 303 enum { 304 _lh_neutral_value = 0, // neutral non-array non-instance value 305 _lh_instance_slow_path_bit = 0x01, 306 _lh_log2_element_size_shift = BitsPerByte*0, 307 _lh_log2_element_size_mask = BitsPerLong-1, 308 _lh_element_type_shift = BitsPerByte*1, 309 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask 310 _lh_header_size_shift = BitsPerByte*2, 311 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask 312 _lh_array_tag_bits = 2, 313 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits, 314 _lh_array_tag_type_value = ~0x00, // 0xC0000000 >> 30 315 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30 316 }; 317 318 static int layout_helper_size_in_bytes(jint lh) { 319 assert(lh > (jint)_lh_neutral_value, "must be instance"); 320 return (int) lh & ~_lh_instance_slow_path_bit; 321 } 322 static bool layout_helper_needs_slow_path(jint lh) { 323 assert(lh > (jint)_lh_neutral_value, "must be instance"); 324 return (lh & _lh_instance_slow_path_bit) != 0; 325 } 326 static bool layout_helper_is_instance(jint lh) { 327 return (jint)lh > (jint)_lh_neutral_value; 328 } 329 static bool layout_helper_is_array(jint lh) { 330 return (jint)lh < (jint)_lh_neutral_value; 331 } 332 static bool layout_helper_is_typeArray(jint lh) { 333 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift); 334 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift); 335 } 336 static bool layout_helper_is_objArray(jint lh) { 337 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift); 338 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift); 339 } 340 static int layout_helper_header_size(jint lh) { 341 assert(lh < (jint)_lh_neutral_value, "must be array"); 342 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask; 343 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity"); 344 return hsize; 345 } 346 static BasicType layout_helper_element_type(jint lh) { 347 assert(lh < (jint)_lh_neutral_value, "must be array"); 348 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask; 349 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity"); 350 return (BasicType) btvalue; 351 } 352 static int layout_helper_log2_element_size(jint lh) { 353 assert(lh < (jint)_lh_neutral_value, "must be array"); 354 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask; 355 assert(l2esz <= LogBitsPerLong, 356 err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh)); 357 return l2esz; 358 } 359 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) { 360 return (tag << _lh_array_tag_shift) 361 | (hsize << _lh_header_size_shift) 362 | ((int)etype << _lh_element_type_shift) 363 | (log2_esize << _lh_log2_element_size_shift); 364 } 365 static jint instance_layout_helper(jint size, bool slow_path_flag) { 366 return (size << LogHeapWordSize) 367 | (slow_path_flag ? _lh_instance_slow_path_bit : 0); 368 } 369 static int layout_helper_to_size_helper(jint lh) { 370 assert(lh > (jint)_lh_neutral_value, "must be instance"); 371 // Note that the following expression discards _lh_instance_slow_path_bit. 372 return lh >> LogHeapWordSize; 373 } 374 // Out-of-line version computes everything based on the etype: 375 static jint array_layout_helper(BasicType etype); 376 377 // What is the maximum number of primary superclasses any klass can have? 378 #ifdef PRODUCT 379 static juint primary_super_limit() { return _primary_super_limit; } 380 #else 381 static juint primary_super_limit() { 382 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob"); 383 return FastSuperclassLimit; 384 } 385 #endif 386 387 // vtables 388 virtual klassVtable* vtable() const { return NULL; } 389 virtual int vtable_length() const { return 0; } 390 391 // subclass check 392 bool is_subclass_of(const Klass* k) const; 393 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it 394 bool is_subtype_of(Klass* k) const { 395 juint off = k->super_check_offset(); 396 Klass* sup = *(Klass**)( (address)this + off ); 397 const juint secondary_offset = in_bytes(secondary_super_cache_offset()); 398 if (sup == k) { 399 return true; 400 } else if (off != secondary_offset) { 401 return false; 402 } else { 403 return search_secondary_supers(k); 404 } 405 } 406 bool search_secondary_supers(Klass* k) const; 407 408 // Find LCA in class hierarchy 409 Klass *LCA( Klass *k ); 410 411 // Check whether reflection/jni/jvm code is allowed to instantiate this class; 412 // if not, throw either an Error or an Exception. 413 virtual void check_valid_for_instantiation(bool throwError, TRAPS); 414 415 // array copying 416 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS); 417 418 // tells if the class should be initialized 419 virtual bool should_be_initialized() const { return false; } 420 // initializes the klass 421 virtual void initialize(TRAPS); 422 // lookup operation for MethodLookupCache 423 friend class MethodLookupCache; 424 virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature) const; 425 public: 426 Method* lookup_method(Symbol* name, Symbol* signature) const { 427 return uncached_lookup_method(name, signature); 428 } 429 430 // array class with specific rank 431 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); } 432 433 // array class with this klass as element type 434 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); } 435 436 // These will return NULL instead of allocating on the heap: 437 // NB: these can block for a mutex, like other functions with TRAPS arg. 438 Klass* array_klass_or_null(int rank); 439 Klass* array_klass_or_null(); 440 441 virtual oop protection_domain() const = 0; 442 443 oop class_loader() const; 444 445 virtual oop klass_holder() const { return class_loader(); } 446 447 protected: 448 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS); 449 virtual Klass* array_klass_impl(bool or_null, TRAPS); 450 451 public: 452 // CDS support - remove and restore oops from metadata. Oops are not shared. 453 virtual void remove_unshareable_info(); 454 virtual void restore_unshareable_info(TRAPS); 455 456 protected: 457 // computes the subtype relationship 458 virtual bool compute_is_subtype_of(Klass* k); 459 public: 460 // subclass accessor (here for convenience; undefined for non-klass objects) 461 virtual bool is_leaf_class() const { fatal("not a class"); return false; } 462 public: 463 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP 464 // These functions describe behavior for the oop not the KLASS. 465 466 // actual oop size of obj in memory 467 virtual int oop_size(oop obj) const = 0; 468 469 // Size of klass in word size. 470 virtual int size() const = 0; 471 #if INCLUDE_SERVICES 472 virtual void collect_statistics(KlassSizeStats *sz) const; 473 #endif 474 475 // Returns the Java name for a class (Resource allocated) 476 // For arrays, this returns the name of the element with a leading '['. 477 // For classes, this returns the name with the package separators 478 // turned into '.'s. 479 const char* external_name() const; 480 // Returns the name for a class (Resource allocated) as the class 481 // would appear in a signature. 482 // For arrays, this returns the name of the element with a leading '['. 483 // For classes, this returns the name with a leading 'L' and a trailing ';' 484 // and the package separators as '/'. 485 virtual const char* signature_name() const; 486 487 // garbage collection support 488 virtual void oop_follow_contents(oop obj) = 0; 489 virtual int oop_adjust_pointers(oop obj) = 0; 490 491 // Parallel Scavenge and Parallel Old 492 PARALLEL_GC_DECLS_PV 493 494 // type testing operations 495 protected: 496 virtual bool oop_is_instance_slow() const { return false; } 497 virtual bool oop_is_array_slow() const { return false; } 498 virtual bool oop_is_objArray_slow() const { return false; } 499 virtual bool oop_is_typeArray_slow() const { return false; } 500 public: 501 virtual bool oop_is_instanceMirror() const { return false; } 502 virtual bool oop_is_instanceRef() const { return false; } 503 504 // Fast non-virtual versions 505 #ifndef ASSERT 506 #define assert_same_query(xval, xcheck) xval 507 #else 508 private: 509 static bool assert_same_query(bool xval, bool xslow) { 510 assert(xval == xslow, "slow and fast queries agree"); 511 return xval; 512 } 513 public: 514 #endif 515 inline bool oop_is_instance() const { return assert_same_query( 516 layout_helper_is_instance(layout_helper()), 517 oop_is_instance_slow()); } 518 inline bool oop_is_array() const { return assert_same_query( 519 layout_helper_is_array(layout_helper()), 520 oop_is_array_slow()); } 521 inline bool oop_is_objArray() const { return assert_same_query( 522 layout_helper_is_objArray(layout_helper()), 523 oop_is_objArray_slow()); } 524 inline bool oop_is_typeArray() const { return assert_same_query( 525 layout_helper_is_typeArray(layout_helper()), 526 oop_is_typeArray_slow()); } 527 #undef assert_same_query 528 529 // Access flags 530 AccessFlags access_flags() const { return _access_flags; } 531 void set_access_flags(AccessFlags flags) { _access_flags = flags; } 532 533 bool is_public() const { return _access_flags.is_public(); } 534 bool is_final() const { return _access_flags.is_final(); } 535 bool is_interface() const { return _access_flags.is_interface(); } 536 bool is_abstract() const { return _access_flags.is_abstract(); } 537 bool is_super() const { return _access_flags.is_super(); } 538 bool is_synthetic() const { return _access_flags.is_synthetic(); } 539 void set_is_synthetic() { _access_flags.set_is_synthetic(); } 540 bool has_finalizer() const { return _access_flags.has_finalizer(); } 541 bool has_final_method() const { return _access_flags.has_final_method(); } 542 void set_has_finalizer() { _access_flags.set_has_finalizer(); } 543 void set_has_final_method() { _access_flags.set_has_final_method(); } 544 bool is_cloneable() const { return _access_flags.is_cloneable(); } 545 void set_is_cloneable() { _access_flags.set_is_cloneable(); } 546 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); } 547 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); } 548 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); } 549 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); } 550 551 // Biased locking support 552 // Note: the prototype header is always set up to be at least the 553 // prototype markOop. If biased locking is enabled it may further be 554 // biasable and have an epoch. 555 markOop prototype_header() const { return _prototype_header; } 556 // NOTE: once instances of this klass are floating around in the 557 // system, this header must only be updated at a safepoint. 558 // NOTE 2: currently we only ever set the prototype header to the 559 // biasable prototype for instanceKlasses. There is no technical 560 // reason why it could not be done for arrayKlasses aside from 561 // wanting to reduce the initial scope of this optimization. There 562 // are potential problems in setting the bias pattern for 563 // JVM-internal oops. 564 inline void set_prototype_header(markOop header); 565 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); } 566 567 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; } 568 // Atomically increments biased_lock_revocation_count and returns updated value 569 int atomic_incr_biased_lock_revocation_count(); 570 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; } 571 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; } 572 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; } 573 574 TRACE_DEFINE_KLASS_METHODS; 575 576 // garbage collection support 577 virtual void oops_do(OopClosure* cl); 578 579 // Iff the class loader (or mirror for anonymous classes) is alive the 580 // Klass is considered alive. 581 // The is_alive closure passed in depends on the Garbage Collector used. 582 bool is_loader_alive(BoolObjectClosure* is_alive); 583 584 static void clean_weak_klass_links(BoolObjectClosure* is_alive); 585 586 // Prefetch within oop iterators. This is a macro because we 587 // can't guarantee that the compiler will inline it. In 64-bit 588 // it generally doesn't. Signature is 589 // 590 // static void prefetch_beyond(oop* const start, 591 // oop* const end, 592 // const intx foffset, 593 // const Prefetch::style pstyle); 594 #define prefetch_beyond(start, end, foffset, pstyle) { \ 595 const intx foffset_ = (foffset); \ 596 const Prefetch::style pstyle_ = (pstyle); \ 597 assert(foffset_ > 0, "prefetch beyond, not behind"); \ 598 if (pstyle_ != Prefetch::do_none) { \ 599 oop* ref = (start); \ 600 if (ref < (end)) { \ 601 switch (pstyle_) { \ 602 case Prefetch::do_read: \ 603 Prefetch::read(*ref, foffset_); \ 604 break; \ 605 case Prefetch::do_write: \ 606 Prefetch::write(*ref, foffset_); \ 607 break; \ 608 default: \ 609 ShouldNotReachHere(); \ 610 break; \ 611 } \ 612 } \ 613 } \ 614 } 615 616 // iterators 617 virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0; 618 virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) { 619 return oop_oop_iterate(obj, blk); 620 } 621 622 #if INCLUDE_ALL_GCS 623 // In case we don't have a specialized backward scanner use forward 624 // iteration. 625 virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) { 626 return oop_oop_iterate_v(obj, blk); 627 } 628 #endif // INCLUDE_ALL_GCS 629 630 // Iterates "blk" over all the oops in "obj" (of type "this") within "mr". 631 // (I don't see why the _m should be required, but without it the Solaris 632 // C++ gives warning messages about overridings of the "oop_oop_iterate" 633 // defined above "hiding" this virtual function. (DLD, 6/20/00)) */ 634 virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0; 635 virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) { 636 return oop_oop_iterate_m(obj, blk, mr); 637 } 638 639 // Versions of the above iterators specialized to particular subtypes 640 // of OopClosure, to avoid closure virtual calls. 641 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \ 642 virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) { \ 643 /* Default implementation reverts to general version. */ \ 644 return oop_oop_iterate(obj, blk); \ 645 } \ 646 \ 647 /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \ 648 (I don't see why the _m should be required, but without it the Solaris \ 649 C++ gives warning messages about overridings of the "oop_oop_iterate" \ 650 defined above "hiding" this virtual function. (DLD, 6/20/00)) */ \ 651 virtual int oop_oop_iterate##nv_suffix##_m(oop obj, \ 652 OopClosureType* blk, \ 653 MemRegion mr) { \ 654 return oop_oop_iterate_m(obj, blk, mr); \ 655 } 656 657 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL) 658 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL) 659 660 #if INCLUDE_ALL_GCS 661 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \ 662 virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, \ 663 OopClosureType* blk) { \ 664 /* Default implementation reverts to general version. */ \ 665 return oop_oop_iterate_backwards_v(obj, blk); \ 666 } 667 668 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL) 669 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL) 670 #endif // INCLUDE_ALL_GCS 671 672 virtual void array_klasses_do(void f(Klass* k)) {} 673 674 // Return self, except for abstract classes with exactly 1 675 // implementor. Then return the 1 concrete implementation. 676 Klass *up_cast_abstract(); 677 678 // klass name 679 Symbol* name() const { return _name; } 680 void set_name(Symbol* n); 681 682 public: 683 // jvm support 684 virtual jint compute_modifier_flags(TRAPS) const; 685 686 // JVMTI support 687 virtual jint jvmti_class_status() const; 688 689 // Printing 690 virtual void print_on(outputStream* st) const; 691 692 virtual void oop_print_value_on(oop obj, outputStream* st); 693 virtual void oop_print_on (oop obj, outputStream* st); 694 695 virtual const char* internal_name() const = 0; 696 697 // Verification 698 virtual void verify_on(outputStream* st, bool check_dictionary); 699 void verify(bool check_dictionary = true) { verify_on(tty, check_dictionary); } 700 701 #ifndef PRODUCT 702 void verify_vtable_index(int index); 703 #endif 704 705 virtual void oop_verify_on(oop obj, outputStream* st); 706 707 private: 708 // barriers used by klass_oop_store 709 void klass_update_barrier_set(oop v); 710 void klass_update_barrier_set_pre(void* p, oop v); 711 }; 712 713 #endif // SHARE_VM_OOPS_KLASS_HPP