1 /* 2 * Copyright (c) 1997, 2025, 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_KLASS_HPP 26 #define SHARE_OOPS_KLASS_HPP 27 28 #include "oops/klassFlags.hpp" 29 #include "oops/markWord.hpp" 30 #include "oops/metadata.hpp" 31 #include "oops/oop.hpp" 32 #include "oops/oopHandle.hpp" 33 #include "utilities/accessFlags.hpp" 34 #include "utilities/macros.hpp" 35 #if INCLUDE_JFR 36 #include "jfr/support/jfrTraceIdExtension.hpp" 37 #endif 38 39 // 40 // A Klass provides: 41 // 1: language level class object (method dictionary etc.) 42 // 2: provide vm dispatch behavior for the object 43 // Both functions are combined into one C++ class. 44 45 // One reason for the oop/klass dichotomy in the implementation is 46 // that we don't want a C++ vtbl pointer in every object. Thus, 47 // normal oops don't have any virtual functions. Instead, they 48 // forward all "virtual" functions to their klass, which does have 49 // a vtbl and does the C++ dispatch depending on the object's 50 // actual type. (See oop.inline.hpp for some of the forwarding code.) 51 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"! 52 53 // Forward declarations. 54 template <class T> class Array; 55 template <class T> class GrowableArray; 56 class ClassLoaderData; 57 class fieldDescriptor; 58 class klassVtable; 59 class ModuleEntry; 60 class PackageEntry; 61 class vtableEntry; 62 63 class Klass : public Metadata { 64 65 friend class VMStructs; 66 friend class JVMCIVMStructs; 67 public: 68 // Klass Kinds for all subclasses of Klass 69 enum KlassKind : u2 { 70 InstanceKlassKind, 71 InstanceRefKlassKind, 72 InstanceMirrorKlassKind, 73 InstanceClassLoaderKlassKind, 74 InstanceStackChunkKlassKind, 75 TypeArrayKlassKind, 76 ObjArrayKlassKind, 77 UnknownKlassKind 78 }; 79 80 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1; 81 protected: 82 83 // If you add a new field that points to any metaspace object, you 84 // must add this field to Klass::metaspace_pointers_do(). 85 86 // note: put frequently-used fields together at start of klass structure 87 // for better cache behavior (may not make much of a difference but sure won't hurt) 88 enum { _primary_super_limit = 8 }; 89 90 // The "layout helper" is a combined descriptor of object layout. 91 // For klasses which are neither instance nor array, the value is zero. 92 // 93 // For instances, layout helper is a positive number, the instance size. 94 // This size is already passed through align_object_size and scaled to bytes. 95 // The low order bit is set if instances of this class cannot be 96 // allocated using the fastpath. 97 // 98 // For arrays, layout helper is a negative number, containing four 99 // distinct bytes, as follows: 100 // MSB:[tag, hsz, ebt, log2(esz)]:LSB 101 // where: 102 // tag is 0x80 if the elements are oops, 0xC0 if non-oops 103 // hsz is array header size in bytes (i.e., offset of first element) 104 // ebt is the BasicType of the elements 105 // esz is the element size in bytes 106 // This packed word is arranged so as to be quickly unpacked by the 107 // various fast paths that use the various subfields. 108 // 109 // The esz bits can be used directly by a SLL instruction, without masking. 110 // 111 // Note that the array-kind tag looks like 0x00 for instance klasses, 112 // since their length in bytes is always less than 24Mb. 113 // 114 // Final note: This comes first, immediately after C++ vtable, 115 // because it is frequently queried. 116 jint _layout_helper; 117 118 // Klass kind used to resolve the runtime type of the instance. 119 // - Used to implement devirtualized oop closure dispatching. 120 // - Various type checking in the JVM 121 const KlassKind _kind; 122 123 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here. 124 // Some flags created by the JVM, not in the class file itself, 125 // are in _misc_flags below. 126 // Processed access flags, for use by Class.getModifiers. 127 u2 _modifier_flags; 128 129 KlassFlags _misc_flags; 130 131 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers 132 // and _primary_supers all help make fast subtype checks. See big discussion 133 // in doc/server_compiler/checktype.txt 134 // 135 // Where to look to observe a supertype (it is &_secondary_super_cache for 136 // secondary supers, else is &_primary_supers[depth()]. 137 juint _super_check_offset; 138 139 // Class name. Instance classes: java/lang/String, etc. Array classes: [I, 140 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes. 141 Symbol* _name; 142 143 // Cache of last observed secondary supertype 144 Klass* _secondary_super_cache; 145 // Array of all secondary supertypes 146 Array<Klass*>* _secondary_supers; 147 // Ordered list of all primary supertypes 148 Klass* _primary_supers[_primary_super_limit]; 149 // java/lang/Class instance mirroring this class 150 OopHandle _java_mirror; 151 // Superclass 152 Klass* _super; 153 // First subclass (null if none); _subklass->next_sibling() is next one 154 Klass* volatile _subklass; 155 // Sibling link (or null); links all subklasses of a klass 156 Klass* volatile _next_sibling; 157 158 // All klasses loaded by a class loader are chained through these links 159 Klass* _next_link; 160 161 // The VM's representation of the ClassLoader used to load this class. 162 // Provide access the corresponding instance java.lang.ClassLoader. 163 ClassLoaderData* _class_loader_data; 164 165 markWord _prototype_header; // Used to initialize objects' header 166 167 // Bitmap and hash code used by hashed secondary supers. 168 uintx _secondary_supers_bitmap; 169 uint8_t _hash_slot; 170 171 private: 172 // This is an index into FileMapHeader::_shared_path_table[], to 173 // associate this class with the JAR file where it's loaded from during 174 // dump time. If a class is not loaded from the shared archive, this field is 175 // -1. 176 s2 _shared_class_path_index; 177 178 #if INCLUDE_CDS 179 // Various attributes for shared classes. Should be zero for a non-shared class. 180 u2 _shared_class_flags; 181 enum CDSSharedClassFlags { 182 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared 183 _archived_lambda_proxy_is_available = 1 << 1, 184 _has_value_based_class_annotation = 1 << 2, 185 _verified_at_dump_time = 1 << 3, 186 _has_archived_enum_objs = 1 << 4, 187 // This class was not loaded from a classfile in the module image 188 // or classpath. 189 _is_generated_shared_class = 1 << 5, 190 // archived mirror already initialized by AOT-cache assembly: no further need to call <clinit> 191 _has_aot_initialized_mirror = 1 << 6, 192 // If this class has been aot-inititalized, do we need to call its runtimeSetup() 193 // method during the production run? 194 _is_runtime_setup_required = 1 << 7, 195 }; 196 #endif 197 198 int _vtable_len; // vtable length. This field may be read very often when we 199 // have lots of itable dispatches (e.g., lambdas and streams). 200 // Keep it away from the beginning of a Klass to avoid cacheline 201 // contention that may happen when a nearby object is modified. 202 203 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;) 204 205 public: 206 207 JFR_ONLY(DEFINE_TRACE_ID_FIELD;) 208 209 protected: 210 211 Klass(KlassKind kind); 212 Klass(); 213 214 public: 215 int kind() { return _kind; } 216 217 enum class DefaultsLookupMode { find, skip }; 218 enum class OverpassLookupMode { find, skip }; 219 enum class StaticLookupMode { find, skip }; 220 enum class PrivateLookupMode { find, skip }; 221 222 virtual bool is_klass() const { return true; } 223 224 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used 225 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;" 226 // If this is not what your code expects, you're probably looking for Klass::java_super(). 227 Klass* super() const { return _super; } 228 void set_super(Klass* k) { _super = k; } 229 230 // initializes _super link, _primary_supers & _secondary_supers arrays 231 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS); 232 233 // klass-specific helper for initializing _secondary_supers 234 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots, 235 Array<InstanceKlass*>* transitive_interfaces); 236 237 // java_super is the Java-level super type as specified by Class.getSuperClass. 238 virtual InstanceKlass* java_super() const { return nullptr; } 239 240 juint super_check_offset() const { return _super_check_offset; } 241 void set_super_check_offset(juint o) { _super_check_offset = o; } 242 243 Klass* secondary_super_cache() const { return _secondary_super_cache; } 244 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; } 245 246 Array<Klass*>* secondary_supers() const { return _secondary_supers; } 247 void set_secondary_supers(Array<Klass*>* k, uintx bitmap); 248 249 uint8_t hash_slot() const { return _hash_slot; } 250 251 // Return the element of the _super chain of the given depth. 252 // If there is no such element, return either null or this. 253 Klass* primary_super_of_depth(juint i) const { 254 assert(i < primary_super_limit(), "oob"); 255 Klass* super = _primary_supers[i]; 256 assert(super == nullptr || super->super_depth() == i, "correct display"); 257 return super; 258 } 259 260 // Can this klass be a primary super? False for interfaces and arrays of 261 // interfaces. False also for arrays or classes with long super chains. 262 bool can_be_primary_super() const { 263 const juint secondary_offset = in_bytes(secondary_super_cache_offset()); 264 return super_check_offset() != secondary_offset; 265 } 266 virtual bool can_be_primary_super_slow() const; 267 268 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit]. 269 juint super_depth() const { 270 if (!can_be_primary_super()) { 271 return primary_super_limit(); 272 } else { 273 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*); 274 assert(d < primary_super_limit(), "oob"); 275 assert(_primary_supers[d] == this, "proper init"); 276 return d; 277 } 278 } 279 280 // java mirror 281 oop java_mirror() const; 282 oop java_mirror_no_keepalive() const; 283 void set_java_mirror(Handle m); 284 285 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr); 286 287 // Temporary mirror switch used by RedefineClasses 288 OopHandle java_mirror_handle() const { return _java_mirror; } 289 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); } 290 291 // Set java mirror OopHandle to null for CDS 292 // This leaves the OopHandle in the CLD, but that's ok, you can't release them. 293 void clear_java_mirror_handle() { _java_mirror = OopHandle(); } 294 295 // modifier flags 296 u2 modifier_flags() const { return _modifier_flags; } 297 void set_modifier_flags(u2 flags) { _modifier_flags = flags; } 298 299 // size helper 300 int layout_helper() const { return _layout_helper; } 301 void set_layout_helper(int lh) { _layout_helper = lh; } 302 303 // Note: for instances layout_helper() may include padding. 304 // Use InstanceKlass::contains_field_offset to classify field offsets. 305 306 // sub/superklass links 307 Klass* subklass(bool log = false) const; 308 Klass* next_sibling(bool log = false) const; 309 310 InstanceKlass* superklass() const; 311 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list 312 313 void set_next_link(Klass* k) { _next_link = k; } 314 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader. 315 Klass** next_link_addr() { return &_next_link; } 316 317 // class loader data 318 ClassLoaderData* class_loader_data() const { return _class_loader_data; } 319 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; } 320 321 s2 shared_classpath_index() const { 322 return _shared_class_path_index; 323 }; 324 325 void set_shared_classpath_index(s2 index) { 326 _shared_class_path_index = index; 327 }; 328 329 bool has_archived_mirror_index() const { 330 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;) 331 NOT_CDS_JAVA_HEAP(return false); 332 } 333 334 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN; 335 336 void set_lambda_proxy_is_available() { 337 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;) 338 } 339 void clear_lambda_proxy_is_available() { 340 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);) 341 } 342 bool lambda_proxy_is_available() const { 343 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;) 344 NOT_CDS(return false;) 345 } 346 347 void set_has_value_based_class_annotation() { 348 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;) 349 } 350 void clear_has_value_based_class_annotation() { 351 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);) 352 } 353 bool has_value_based_class_annotation() const { 354 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;) 355 NOT_CDS(return false;) 356 } 357 358 void set_verified_at_dump_time() { 359 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;) 360 } 361 bool verified_at_dump_time() const { 362 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;) 363 NOT_CDS(return false;) 364 } 365 366 void set_has_archived_enum_objs() { 367 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;) 368 } 369 bool has_archived_enum_objs() const { 370 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;) 371 NOT_CDS(return false;) 372 } 373 374 void set_is_generated_shared_class() { 375 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;) 376 } 377 bool is_generated_shared_class() const { 378 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;) 379 NOT_CDS(return false;) 380 } 381 382 void set_has_aot_initialized_mirror() { 383 CDS_ONLY(_shared_class_flags |= _has_aot_initialized_mirror;) 384 } 385 bool has_aot_initialized_mirror() const { 386 CDS_ONLY(return (_shared_class_flags & _has_aot_initialized_mirror) != 0;) 387 NOT_CDS(return false;) 388 } 389 390 void set_is_runtime_setup_required() { 391 assert(has_aot_initialized_mirror(), "sanity"); 392 CDS_ONLY(_shared_class_flags |= _is_runtime_setup_required;) 393 } 394 bool is_runtime_setup_required() const { 395 CDS_ONLY(return (_shared_class_flags & _is_runtime_setup_required) != 0;) 396 NOT_CDS(return false;) 397 } 398 399 bool is_shared() const { // shadows MetaspaceObj::is_shared)() 400 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;) 401 NOT_CDS(return false;) 402 } 403 404 void set_is_shared() { 405 CDS_ONLY(_shared_class_flags |= _is_shared_class;) 406 } 407 408 // Obtain the module or package for this class 409 virtual ModuleEntry* module() const = 0; 410 virtual PackageEntry* package() const = 0; 411 412 protected: // internal accessors 413 void set_subklass(Klass* s); 414 void set_next_sibling(Klass* s); 415 416 private: 417 static uint8_t compute_hash_slot(Symbol* s); 418 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap); 419 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite); 420 421 bool search_secondary_supers(Klass* k) const; 422 bool lookup_secondary_supers_table(Klass *k) const; 423 bool linear_search_secondary_supers(const Klass* k) const; 424 bool fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const; 425 426 public: 427 // Secondary supers table support 428 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data, 429 GrowableArray<Klass*>* primaries, 430 GrowableArray<Klass*>* secondaries, 431 uintx& bitmap, 432 TRAPS); 433 434 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers); 435 static uint8_t compute_home_slot(Klass* k, uintx bitmap); 436 437 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_secondary_supers_bitmap) * 8; 438 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1; 439 440 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0; 441 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0; 442 443 // Compiler support 444 static ByteSize super_offset() { return byte_offset_of(Klass, _super); } 445 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); } 446 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); } 447 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); } 448 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); } 449 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); } 450 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); } 451 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); } 452 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); } 453 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); } 454 #if INCLUDE_JVMCI 455 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); } 456 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); } 457 #endif 458 static ByteSize secondary_supers_bitmap_offset() 459 { return byte_offset_of(Klass, _secondary_supers_bitmap); } 460 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); } 461 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); } 462 463 // Unpacking layout_helper: 464 static const int _lh_neutral_value = 0; // neutral non-array non-instance value 465 static const int _lh_instance_slow_path_bit = 0x01; 466 static const int _lh_log2_element_size_shift = BitsPerByte*0; 467 static const int _lh_log2_element_size_mask = BitsPerLong-1; 468 static const int _lh_element_type_shift = BitsPerByte*1; 469 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask 470 static const int _lh_header_size_shift = BitsPerByte*2; 471 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask 472 static const int _lh_array_tag_bits = 2; 473 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits; 474 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30 475 476 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30 477 478 static int layout_helper_size_in_bytes(jint lh) { 479 assert(lh > (jint)_lh_neutral_value, "must be instance"); 480 return (int) lh & ~_lh_instance_slow_path_bit; 481 } 482 static bool layout_helper_needs_slow_path(jint lh) { 483 assert(lh > (jint)_lh_neutral_value, "must be instance"); 484 return (lh & _lh_instance_slow_path_bit) != 0; 485 } 486 static bool layout_helper_is_instance(jint lh) { 487 return (jint)lh > (jint)_lh_neutral_value; 488 } 489 static bool layout_helper_is_array(jint lh) { 490 return (jint)lh < (jint)_lh_neutral_value; 491 } 492 static bool layout_helper_is_typeArray(jint lh) { 493 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift); 494 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift); 495 } 496 static bool layout_helper_is_objArray(jint lh) { 497 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift); 498 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift); 499 } 500 static int layout_helper_header_size(jint lh) { 501 assert(lh < (jint)_lh_neutral_value, "must be array"); 502 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask; 503 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity"); 504 return hsize; 505 } 506 static BasicType layout_helper_element_type(jint lh) { 507 assert(lh < (jint)_lh_neutral_value, "must be array"); 508 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask; 509 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity"); 510 return (BasicType) btvalue; 511 } 512 513 // Want a pattern to quickly diff against layout header in register 514 // find something less clever! 515 static int layout_helper_boolean_diffbit() { 516 jint zlh = array_layout_helper(T_BOOLEAN); 517 jint blh = array_layout_helper(T_BYTE); 518 assert(zlh != blh, "array layout helpers must differ"); 519 int diffbit = 1; 520 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) { 521 diffbit <<= 1; 522 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE"); 523 } 524 return diffbit; 525 } 526 527 static int layout_helper_log2_element_size(jint lh) { 528 assert(lh < (jint)_lh_neutral_value, "must be array"); 529 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask; 530 assert(l2esz <= LogBytesPerLong, 531 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh); 532 return l2esz; 533 } 534 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) { 535 return (tag << _lh_array_tag_shift) 536 | (hsize << _lh_header_size_shift) 537 | ((int)etype << _lh_element_type_shift) 538 | (log2_esize << _lh_log2_element_size_shift); 539 } 540 static jint instance_layout_helper(jint size, bool slow_path_flag) { 541 return (size << LogBytesPerWord) 542 | (slow_path_flag ? _lh_instance_slow_path_bit : 0); 543 } 544 static int layout_helper_to_size_helper(jint lh) { 545 assert(lh > (jint)_lh_neutral_value, "must be instance"); 546 // Note that the following expression discards _lh_instance_slow_path_bit. 547 return lh >> LogBytesPerWord; 548 } 549 // Out-of-line version computes everything based on the etype: 550 static jint array_layout_helper(BasicType etype); 551 552 // What is the maximum number of primary superclasses any klass can have? 553 static juint primary_super_limit() { return _primary_super_limit; } 554 555 // vtables 556 klassVtable vtable() const; 557 int vtable_length() const { return _vtable_len; } 558 559 // subclass check 560 bool is_subclass_of(const Klass* k) const; 561 562 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it 563 bool is_subtype_of(Klass* k) const; 564 565 public: 566 // Find LCA in class hierarchy 567 Klass *LCA( Klass *k ); 568 569 // Check whether reflection/jni/jvm code is allowed to instantiate this class; 570 // if not, throw either an Error or an Exception. 571 virtual void check_valid_for_instantiation(bool throwError, TRAPS); 572 573 // array copying 574 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS); 575 576 // tells if the class should be initialized 577 virtual bool should_be_initialized() const { return false; } 578 // initializes the klass 579 virtual void initialize(TRAPS); 580 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const; 581 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature, 582 OverpassLookupMode overpass_mode, 583 PrivateLookupMode = PrivateLookupMode::find) const; 584 public: 585 Method* lookup_method(const Symbol* name, const Symbol* signature) const { 586 return uncached_lookup_method(name, signature, OverpassLookupMode::find); 587 } 588 589 // array class with specific rank 590 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0; 591 592 // array class with this klass as element type 593 virtual ArrayKlass* array_klass(TRAPS) = 0; 594 595 // These will return null instead of allocating on the heap: 596 virtual ArrayKlass* array_klass_or_null(int rank) = 0; 597 virtual ArrayKlass* array_klass_or_null() = 0; 598 599 virtual oop protection_domain() const = 0; 600 601 oop class_loader() const; 602 603 inline oop klass_holder() const; 604 605 inline void keep_alive() const; 606 607 protected: 608 609 // Error handling when length > max_length or length < 0 610 static void check_array_allocation_length(int length, int max_length, TRAPS); 611 612 void set_vtable_length(int len) { _vtable_len= len; } 613 614 vtableEntry* start_of_vtable() const; 615 #if INCLUDE_CDS 616 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS); 617 #endif 618 public: 619 Method* method_at_vtable(int index); 620 621 static ByteSize vtable_start_offset(); 622 static ByteSize vtable_length_offset() { 623 return byte_offset_of(Klass, _vtable_len); 624 } 625 626 #if INCLUDE_CDS 627 // CDS support - remove and restore oops from metadata. Oops are not shared. 628 virtual void remove_unshareable_info(); 629 virtual void remove_java_mirror(); 630 631 bool is_unshareable_info_restored() const { 632 assert(is_shared(), "use this for shared classes only"); 633 if (has_archived_mirror_index()) { 634 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap 635 return false; 636 } else if (_java_mirror.is_empty()) { 637 return false; 638 } else { 639 return true; 640 } 641 } 642 #endif // INCLUDE_CDS 643 644 public: 645 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP 646 // These functions describe behavior for the oop not the KLASS. 647 648 // actual oop size of obj in memory in word size. 649 virtual size_t oop_size(oop obj) const = 0; 650 651 // Size of klass in word size. 652 virtual int size() const = 0; 653 654 // Returns the Java name for a class (Resource allocated) 655 // For arrays, this returns the name of the element with a leading '['. 656 // For classes, this returns the name with the package separators 657 // turned into '.'s. 658 const char* external_name() const; 659 // Returns the name for a class (Resource allocated) as the class 660 // would appear in a signature. 661 // For arrays, this returns the name of the element with a leading '['. 662 // For classes, this returns the name with a leading 'L' and a trailing ';' 663 // and the package separators as '/'. 664 virtual const char* signature_name() const; 665 666 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const; 667 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const; 668 669 // Returns "interface", "abstract class" or "class". 670 const char* external_kind() const; 671 672 // type testing operations 673 #ifdef ASSERT 674 protected: 675 virtual bool is_instance_klass_slow() const { return false; } 676 virtual bool is_array_klass_slow() const { return false; } 677 virtual bool is_objArray_klass_slow() const { return false; } 678 virtual bool is_typeArray_klass_slow() const { return false; } 679 #endif // ASSERT 680 public: 681 682 // Fast non-virtual versions 683 #ifndef ASSERT 684 #define assert_same_query(xval, xcheck) xval 685 #else 686 private: 687 static bool assert_same_query(bool xval, bool xslow) { 688 assert(xval == xslow, "slow and fast queries agree"); 689 return xval; 690 } 691 public: 692 #endif 693 694 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); } 695 // Other is anything that is not one of the more specialized kinds of InstanceKlass. 696 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; } 697 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; } 698 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; } 699 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; } 700 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); } 701 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; } 702 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); } 703 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); } 704 #undef assert_same_query 705 706 // Access flags 707 AccessFlags access_flags() const { return _access_flags; } 708 void set_access_flags(AccessFlags flags) { _access_flags = flags; } 709 710 bool is_public() const { return _access_flags.is_public(); } 711 bool is_final() const { return _access_flags.is_final(); } 712 bool is_interface() const { return _access_flags.is_interface(); } 713 bool is_abstract() const { return _access_flags.is_abstract(); } 714 bool is_super() const { return _access_flags.is_super(); } 715 bool is_synthetic() const { return _access_flags.is_synthetic(); } 716 void set_is_synthetic() { _access_flags.set_is_synthetic(); } 717 bool has_finalizer() const { return _misc_flags.has_finalizer(); } 718 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); } 719 bool is_hidden() const { return _misc_flags.is_hidden_class(); } 720 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); } 721 bool is_value_based() const { return _misc_flags.is_value_based_class(); } 722 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); } 723 724 klass_flags_t misc_flags() const { return _misc_flags.value(); } 725 726 inline bool is_non_strong_hidden() const; 727 728 bool is_cloneable() const; 729 void set_is_cloneable(); 730 731 inline markWord prototype_header() const; 732 inline void set_prototype_header(markWord header); 733 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); } 734 735 JFR_ONLY(DEFINE_TRACE_ID_METHODS;) 736 737 virtual void metaspace_pointers_do(MetaspaceClosure* iter); 738 virtual MetaspaceObj::Type type() const { return ClassType; } 739 740 inline bool is_loader_alive() const; 741 742 void clean_subklass(); 743 744 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true); 745 static void clean_subklass_tree() { 746 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false); 747 } 748 749 // Return self, except for abstract classes with exactly 1 750 // implementor. Then return the 1 concrete implementation. 751 Klass *up_cast_abstract(); 752 753 // klass name 754 Symbol* name() const { return _name; } 755 void set_name(Symbol* n); 756 757 virtual void release_C_heap_structures(bool release_constant_pool = true); 758 759 public: 760 virtual u2 compute_modifier_flags() const = 0; 761 762 // JVMTI support 763 virtual jint jvmti_class_status() const; 764 765 // Printing 766 virtual void print_on(outputStream* st) const; 767 768 virtual void oop_print_value_on(oop obj, outputStream* st); 769 virtual void oop_print_on (oop obj, outputStream* st); 770 771 void print_secondary_supers_on(outputStream* st) const; 772 773 virtual const char* internal_name() const = 0; 774 775 // Verification 776 virtual void verify_on(outputStream* st); 777 void verify() { verify_on(tty); } 778 779 #ifndef PRODUCT 780 bool verify_vtable_index(int index); 781 #endif 782 783 virtual void oop_verify_on(oop obj, outputStream* st); 784 785 // for error reporting 786 static bool is_valid(Klass* k); 787 788 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg); 789 790 // Returns true if this Klass needs to be addressable via narrow Klass ID. 791 inline bool needs_narrow_id() const; 792 793 }; 794 795 #endif // SHARE_OOPS_KLASS_HPP