1 /* 2 * Copyright (c) 1997, 2024, 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 "memory/iterator.hpp" 29 #include "memory/memRegion.hpp" 30 #include "oops/markWord.hpp" 31 #include "oops/metadata.hpp" 32 #include "oops/oop.hpp" 33 #include "oops/oopHandle.hpp" 34 #include "utilities/accessFlags.hpp" 35 #include "utilities/macros.hpp" 36 #if INCLUDE_JFR 37 #include "jfr/support/jfrTraceIdExtension.hpp" 38 #endif 39 40 // 41 // A Klass provides: 42 // 1: language level class object (method dictionary etc.) 43 // 2: provide vm dispatch behavior for the object 44 // Both functions are combined into one C++ class. 45 46 // One reason for the oop/klass dichotomy in the implementation is 47 // that we don't want a C++ vtbl pointer in every object. Thus, 48 // normal oops don't have any virtual functions. Instead, they 49 // forward all "virtual" functions to their klass, which does have 50 // a vtbl and does the C++ dispatch depending on the object's 51 // actual type. (See oop.inline.hpp for some of the forwarding code.) 52 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"! 53 54 // Forward declarations. 55 template <class T> class Array; 56 template <class T> class GrowableArray; 57 class ClassLoaderData; 58 class fieldDescriptor; 59 class klassVtable; 60 class ModuleEntry; 61 class PackageEntry; 62 class ParCompactionManager; 63 class PSPromotionManager; 64 class vtableEntry; 65 66 class Klass : public Metadata { 67 friend class VMStructs; 68 friend class JVMCIVMStructs; 69 public: 70 // Klass Kinds for all subclasses of Klass 71 enum KlassKind { 72 InstanceKlassKind, 73 InlineKlassKind, 74 InstanceRefKlassKind, 75 InstanceMirrorKlassKind, 76 InstanceClassLoaderKlassKind, 77 InstanceStackChunkKlassKind, 78 TypeArrayKlassKind, 79 FlatArrayKlassKind, 80 ObjArrayKlassKind, 81 UnknownKlassKind 82 }; 83 84 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1; 85 protected: 86 87 // If you add a new field that points to any metaspace object, you 88 // must add this field to Klass::metaspace_pointers_do(). 89 90 // note: put frequently-used fields together at start of klass structure 91 // for better cache behavior (may not make much of a difference but sure won't hurt) 92 enum { _primary_super_limit = 8 }; 93 94 // The "layout helper" is a combined descriptor of object layout. 95 // For klasses which are neither instance nor array, the value is zero. 96 // 97 // For instances, layout helper is a positive number, the instance size. 98 // This size is already passed through align_object_size and scaled to bytes. 99 // The low order bit is set if instances of this class cannot be 100 // allocated using the fastpath. 101 // 102 // For arrays, layout helper is a negative number, containing four 103 // distinct bytes, as follows: 104 // MSB:[tag, hsz, ebt, log2(esz)]:LSB 105 // where: 106 // tag is 0x80 if the elements are oops, 0xC0 if non-oops, 0xA0 if value types 107 // hsz is array header size in bytes (i.e., offset of first element) 108 // ebt is the BasicType of the elements 109 // esz is the element size in bytes 110 // This packed word is arranged so as to be quickly unpacked by the 111 // various fast paths that use the various subfields. 112 // 113 // The esz bits can be used directly by a SLL instruction, without masking. 114 // 115 // Note that the array-kind tag looks like 0x00 for instance klasses, 116 // since their length in bytes is always less than 24Mb. 117 // 118 // Final note: This comes first, immediately after C++ vtable, 119 // because it is frequently queried. 120 jint _layout_helper; 121 122 // Klass kind used to resolve the runtime type of the instance. 123 // - Used to implement devirtualized oop closure dispatching. 124 // - Various type checking in the JVM 125 const KlassKind _kind; 126 127 // Processed access flags, for use by Class.getModifiers. 128 jint _modifier_flags; 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 OopHandle _java_mirror; 150 // Superclass 151 Klass* _super; 152 // First subclass (null if none); _subklass->next_sibling() is next one 153 Klass* volatile _subklass; 154 // Sibling link (or null); links all subklasses of a klass 155 Klass* volatile _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 // Bitmap and hash code used by hashed secondary supers. 165 uintx _bitmap; 166 uint8_t _hash_slot; 167 168 static uint8_t compute_hash_slot(Symbol* s); 169 170 int _vtable_len; // vtable length. This field may be read very often when we 171 // have lots of itable dispatches (e.g., lambdas and streams). 172 // Keep it away from the beginning of a Klass to avoid cacheline 173 // contention that may happen when a nearby object is modified. 174 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here. 175 176 JFR_ONLY(DEFINE_TRACE_ID_FIELD;) 177 178 markWord _prototype_header; // inline type and inline array mark patterns 179 private: 180 // This is an index into FileMapHeader::_shared_path_table[], to 181 // associate this class with the JAR file where it's loaded from during 182 // dump time. If a class is not loaded from the shared archive, this field is 183 // -1. 184 s2 _shared_class_path_index; 185 186 #if INCLUDE_CDS 187 // Various attributes for shared classes. Should be zero for a non-shared class. 188 u2 _shared_class_flags; 189 enum CDSSharedClassFlags { 190 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared 191 _archived_lambda_proxy_is_available = 1 << 1, 192 _has_value_based_class_annotation = 1 << 2, 193 _verified_at_dump_time = 1 << 3, 194 _has_archived_enum_objs = 1 << 4, 195 // This class was not loaded from a classfile in the module image 196 // or classpath. 197 _is_generated_shared_class = 1 << 5 198 }; 199 #endif 200 201 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;) 202 203 protected: 204 205 Klass(KlassKind kind); 206 Klass(); 207 208 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw(); 209 210 public: 211 int kind() { return _kind; } 212 213 enum class DefaultsLookupMode { find, skip }; 214 enum class OverpassLookupMode { find, skip }; 215 enum class StaticLookupMode { find, skip }; 216 enum class PrivateLookupMode { find, skip }; 217 218 virtual bool is_klass() const { return true; } 219 220 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used 221 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;" 222 // If this is not what your code expects, you're probably looking for Klass::java_super(). 223 Klass* super() const { return _super; } 224 void set_super(Klass* k) { _super = k; } 225 226 // initializes _super link, _primary_supers & _secondary_supers arrays 227 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS); 228 229 // klass-specific helper for initializing _secondary_supers 230 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots, 231 Array<InstanceKlass*>* transitive_interfaces); 232 233 // java_super is the Java-level super type as specified by Class.getSuperClass. 234 virtual InstanceKlass* java_super() const { return nullptr; } 235 236 juint super_check_offset() const { return _super_check_offset; } 237 void set_super_check_offset(juint o) { _super_check_offset = o; } 238 239 Klass* secondary_super_cache() const { return _secondary_super_cache; } 240 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; } 241 242 Array<Klass*>* secondary_supers() const { return _secondary_supers; } 243 void set_secondary_supers(Array<Klass*>* k); 244 void set_secondary_supers(Array<Klass*>* k, uintx bitmap); 245 246 uint8_t hash_slot() const { return _hash_slot; } 247 248 // Return the element of the _super chain of the given depth. 249 // If there is no such element, return either null or this. 250 Klass* primary_super_of_depth(juint i) const { 251 assert(i < primary_super_limit(), "oob"); 252 Klass* super = _primary_supers[i]; 253 assert(super == nullptr || super->super_depth() == i, "correct display"); 254 return super; 255 } 256 257 // Can this klass be a primary super? False for interfaces and arrays of 258 // interfaces. False also for arrays or classes with long super chains. 259 bool can_be_primary_super() const { 260 const juint secondary_offset = in_bytes(secondary_super_cache_offset()); 261 return super_check_offset() != secondary_offset; 262 } 263 virtual bool can_be_primary_super_slow() const; 264 265 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit]. 266 juint super_depth() const { 267 if (!can_be_primary_super()) { 268 return primary_super_limit(); 269 } else { 270 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*); 271 assert(d < primary_super_limit(), "oob"); 272 assert(_primary_supers[d] == this, "proper init"); 273 return d; 274 } 275 } 276 277 // java mirror 278 oop java_mirror() const; 279 oop java_mirror_no_keepalive() const; 280 void set_java_mirror(Handle m); 281 282 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr); 283 void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN; 284 285 // Temporary mirror switch used by RedefineClasses 286 OopHandle java_mirror_handle() const { return _java_mirror; } 287 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); } 288 289 // Set java mirror OopHandle to null for CDS 290 // This leaves the OopHandle in the CLD, but that's ok, you can't release them. 291 void clear_java_mirror_handle() { _java_mirror = OopHandle(); } 292 293 // modifier flags 294 jint modifier_flags() const { return _modifier_flags; } 295 void set_modifier_flags(jint flags) { _modifier_flags = flags; } 296 297 // size helper 298 int layout_helper() const { return _layout_helper; } 299 void set_layout_helper(int lh) { _layout_helper = lh; } 300 301 // Note: for instances layout_helper() may include padding. 302 // Use InstanceKlass::contains_field_offset to classify field offsets. 303 304 // sub/superklass links 305 Klass* subklass(bool log = false) const; 306 Klass* next_sibling(bool log = false) const; 307 308 InstanceKlass* superklass() const; 309 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list 310 311 void set_next_link(Klass* k) { _next_link = k; } 312 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader. 313 Klass** next_link_addr() { return &_next_link; } 314 315 // class loader data 316 ClassLoaderData* class_loader_data() const { return _class_loader_data; } 317 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; } 318 319 s2 shared_classpath_index() const { 320 return _shared_class_path_index; 321 }; 322 323 void set_shared_classpath_index(s2 index) { 324 _shared_class_path_index = index; 325 }; 326 327 bool has_archived_mirror_index() const { 328 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;) 329 NOT_CDS_JAVA_HEAP(return false); 330 } 331 332 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN; 333 334 void set_lambda_proxy_is_available() { 335 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;) 336 } 337 void clear_lambda_proxy_is_available() { 338 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);) 339 } 340 bool lambda_proxy_is_available() const { 341 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;) 342 NOT_CDS(return false;) 343 } 344 345 void set_has_value_based_class_annotation() { 346 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;) 347 } 348 void clear_has_value_based_class_annotation() { 349 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);) 350 } 351 bool has_value_based_class_annotation() const { 352 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;) 353 NOT_CDS(return false;) 354 } 355 356 void set_verified_at_dump_time() { 357 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;) 358 } 359 bool verified_at_dump_time() const { 360 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;) 361 NOT_CDS(return false;) 362 } 363 364 void set_has_archived_enum_objs() { 365 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;) 366 } 367 bool has_archived_enum_objs() const { 368 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;) 369 NOT_CDS(return false;) 370 } 371 372 void set_is_generated_shared_class() { 373 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;) 374 } 375 bool is_generated_shared_class() const { 376 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;) 377 NOT_CDS(return false;) 378 } 379 380 bool is_shared() const { // shadows MetaspaceObj::is_shared)() 381 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;) 382 NOT_CDS(return false;) 383 } 384 385 void set_is_shared() { 386 CDS_ONLY(_shared_class_flags |= _is_shared_class;) 387 } 388 389 // Obtain the module or package for this class 390 virtual ModuleEntry* module() const = 0; 391 virtual PackageEntry* package() const = 0; 392 393 protected: // internal accessors 394 void set_subklass(Klass* s); 395 void set_next_sibling(Klass* s); 396 397 private: 398 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap); 399 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite); 400 401 public: 402 // Secondary supers table support 403 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data, 404 GrowableArray<Klass*>* primaries, 405 GrowableArray<Klass*>* secondaries, 406 uintx& bitmap, 407 TRAPS); 408 409 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers); 410 static uint8_t compute_home_slot(Klass* k, uintx bitmap); 411 412 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_bitmap) * 8; 413 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1; 414 415 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0; 416 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0; 417 418 // Compiler support 419 static ByteSize super_offset() { return byte_offset_of(Klass, _super); } 420 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); } 421 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); } 422 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); } 423 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); } 424 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); } 425 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); } 426 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); } 427 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); } 428 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); } 429 #if INCLUDE_JVMCI 430 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); } 431 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); } 432 #endif 433 static ByteSize bitmap_offset() { return byte_offset_of(Klass, _bitmap); } 434 435 // Unpacking layout_helper: 436 static const int _lh_neutral_value = 0; // neutral non-array non-instance value 437 static const int _lh_instance_slow_path_bit = 0x01; 438 static const int _lh_log2_element_size_shift = BitsPerByte*0; 439 static const int _lh_log2_element_size_mask = BitsPerLong-1; 440 static const int _lh_element_type_shift = BitsPerByte*1; 441 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask 442 static const int _lh_header_size_shift = BitsPerByte*2; 443 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask 444 static const int _lh_array_tag_bits = 3; 445 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits; 446 447 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc; 448 static const unsigned int _lh_array_tag_vt_value = 0Xfffffffd; 449 static const unsigned int _lh_array_tag_obj_value = 0Xfffffffe; 450 451 // null-free array flag bit under the array tag bits, shift one more to get array tag value 452 static const int _lh_null_free_shift = _lh_array_tag_shift - 1; 453 static const int _lh_null_free_mask = 1; 454 455 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << _lh_array_tag_shift); 456 457 static int layout_helper_size_in_bytes(jint lh) { 458 assert(lh > (jint)_lh_neutral_value, "must be instance"); 459 return (int) lh & ~_lh_instance_slow_path_bit; 460 } 461 static bool layout_helper_needs_slow_path(jint lh) { 462 assert(lh > (jint)_lh_neutral_value, "must be instance"); 463 return (lh & _lh_instance_slow_path_bit) != 0; 464 } 465 static bool layout_helper_is_instance(jint lh) { 466 return (jint)lh > (jint)_lh_neutral_value; 467 } 468 static bool layout_helper_is_array(jint lh) { 469 return (jint)lh < (jint)_lh_neutral_value; 470 } 471 static bool layout_helper_is_typeArray(jint lh) { 472 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift); 473 } 474 static bool layout_helper_is_objArray(jint lh) { 475 return (juint)_lh_array_tag_obj_value == (juint)(lh >> _lh_array_tag_shift); 476 } 477 static bool layout_helper_is_flatArray(jint lh) { 478 return (juint)_lh_array_tag_vt_value == (juint)(lh >> _lh_array_tag_shift); 479 } 480 static bool layout_helper_is_null_free(jint lh) { 481 assert(layout_helper_is_flatArray(lh) || layout_helper_is_objArray(lh), "must be array of inline types"); 482 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask); 483 } 484 static jint layout_helper_set_null_free(jint lh) { 485 lh |= (_lh_null_free_mask << _lh_null_free_shift); 486 assert(layout_helper_is_null_free(lh), "Bad encoding"); 487 return lh; 488 } 489 static int layout_helper_header_size(jint lh) { 490 assert(lh < (jint)_lh_neutral_value, "must be array"); 491 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask; 492 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity"); 493 return hsize; 494 } 495 static BasicType layout_helper_element_type(jint lh) { 496 assert(lh < (jint)_lh_neutral_value, "must be array"); 497 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask; 498 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_PRIMITIVE_OBJECT, "sanity"); 499 return (BasicType) btvalue; 500 } 501 502 // Want a pattern to quickly diff against layout header in register 503 // find something less clever! 504 static int layout_helper_boolean_diffbit() { 505 jint zlh = array_layout_helper(T_BOOLEAN); 506 jint blh = array_layout_helper(T_BYTE); 507 assert(zlh != blh, "array layout helpers must differ"); 508 int diffbit = 1; 509 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) { 510 diffbit <<= 1; 511 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE"); 512 } 513 return diffbit; 514 } 515 516 static int layout_helper_log2_element_size(jint lh) { 517 assert(lh < (jint)_lh_neutral_value, "must be array"); 518 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask; 519 assert(layout_helper_element_type(lh) == T_PRIMITIVE_OBJECT || l2esz <= LogBytesPerLong, 520 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh); 521 return l2esz; 522 } 523 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) { 524 return (tag << _lh_array_tag_shift) 525 | ((null_free ? 1 : 0) << _lh_null_free_shift) 526 | (hsize << _lh_header_size_shift) 527 | ((int)etype << _lh_element_type_shift) 528 | (log2_esize << _lh_log2_element_size_shift); 529 } 530 static jint instance_layout_helper(jint size, bool slow_path_flag) { 531 return (size << LogBytesPerWord) 532 | (slow_path_flag ? _lh_instance_slow_path_bit : 0); 533 } 534 static int layout_helper_to_size_helper(jint lh) { 535 assert(lh > (jint)_lh_neutral_value, "must be instance"); 536 // Note that the following expression discards _lh_instance_slow_path_bit. 537 return lh >> LogBytesPerWord; 538 } 539 // Out-of-line version computes everything based on the etype: 540 static jint array_layout_helper(BasicType etype); 541 542 // What is the maximum number of primary superclasses any klass can have? 543 static juint primary_super_limit() { return _primary_super_limit; } 544 545 // vtables 546 klassVtable vtable() const; 547 int vtable_length() const { return _vtable_len; } 548 549 // subclass check 550 bool is_subclass_of(const Klass* k) const; 551 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it 552 bool is_subtype_of(Klass* k) const { 553 juint off = k->super_check_offset(); 554 Klass* sup = *(Klass**)( (address)this + off ); 555 const juint secondary_offset = in_bytes(secondary_super_cache_offset()); 556 if (sup == k) { 557 return true; 558 } else if (off != secondary_offset) { 559 return false; 560 } else { 561 return search_secondary_supers(k); 562 } 563 } 564 565 bool search_secondary_supers(Klass* k) const; 566 567 // Find LCA in class hierarchy 568 Klass *LCA( Klass *k ); 569 570 // Check whether reflection/jni/jvm code is allowed to instantiate this class; 571 // if not, throw either an Error or an Exception. 572 virtual void check_valid_for_instantiation(bool throwError, TRAPS); 573 574 // array copying 575 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS); 576 577 // tells if the class should be initialized 578 virtual bool should_be_initialized() const { return false; } 579 // initializes the klass 580 virtual void initialize(TRAPS); 581 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const; 582 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature, 583 OverpassLookupMode overpass_mode, 584 PrivateLookupMode = PrivateLookupMode::find) const; 585 public: 586 Method* lookup_method(const Symbol* name, const Symbol* signature) const { 587 return uncached_lookup_method(name, signature, OverpassLookupMode::find); 588 } 589 590 // array class with specific rank 591 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0; 592 593 // array class with this klass as element type 594 virtual ArrayKlass* array_klass(TRAPS) = 0; 595 596 // These will return null instead of allocating on the heap: 597 virtual ArrayKlass* array_klass_or_null(int rank) = 0; 598 virtual ArrayKlass* array_klass_or_null() = 0; 599 600 virtual oop protection_domain() const = 0; 601 602 oop class_loader() const; 603 604 inline oop klass_holder() const; 605 606 protected: 607 608 // Error handling when length > max_length or length < 0 609 static void check_array_allocation_length(int length, int max_length, TRAPS); 610 611 void set_vtable_length(int len) { _vtable_len= len; } 612 613 vtableEntry* start_of_vtable() const; 614 #if INCLUDE_CDS 615 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS); 616 #endif 617 public: 618 Method* method_at_vtable(int index); 619 620 static ByteSize vtable_start_offset(); 621 static ByteSize vtable_length_offset() { 622 return byte_offset_of(Klass, _vtable_len); 623 } 624 625 #if INCLUDE_CDS 626 // CDS support - remove and restore oops from metadata. Oops are not shared. 627 virtual void remove_unshareable_info(); 628 virtual void remove_java_mirror(); 629 630 bool is_unshareable_info_restored() const { 631 assert(is_shared(), "use this for shared classes only"); 632 if (has_archived_mirror_index()) { 633 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap 634 return false; 635 } else if (_java_mirror.is_empty()) { 636 return false; 637 } else { 638 return true; 639 } 640 } 641 #endif // INCLUDE_CDS 642 643 public: 644 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP 645 // These functions describe behavior for the oop not the KLASS. 646 647 // actual oop size of obj in memory in word size. 648 virtual size_t oop_size(oop obj) const = 0; 649 650 // Size of klass in word size. 651 virtual int size() const = 0; 652 653 // Returns the Java name for a class (Resource allocated) 654 // For arrays, this returns the name of the element with a leading '['. 655 // For classes, this returns the name with the package separators 656 // turned into '.'s. 657 const char* external_name() const; 658 // Returns the name for a class (Resource allocated) as the class 659 // would appear in a signature. 660 // For arrays, this returns the name of the element with a leading '['. 661 // For classes, this returns the name with a leading 'L' and a trailing ';' 662 // and the package separators as '/'. 663 virtual const char* signature_name() const; 664 665 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const; 666 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const; 667 668 // Returns "interface", "abstract class" or "class". 669 const char* external_kind() const; 670 671 // type testing operations 672 #ifdef ASSERT 673 protected: 674 virtual bool is_instance_klass_slow() const { return false; } 675 virtual bool is_array_klass_slow() const { return false; } 676 virtual bool is_objArray_klass_slow() const { return false; } 677 virtual bool is_typeArray_klass_slow() const { return false; } 678 virtual bool is_flatArray_klass_slow() const { return false; } 679 #endif // ASSERT 680 // current implementation uses this method even in non debug builds 681 virtual bool is_inline_klass_slow() const { return false; } 682 public: 683 684 // Fast non-virtual versions 685 #ifndef ASSERT 686 #define assert_same_query(xval, xcheck) xval 687 #else 688 private: 689 static bool assert_same_query(bool xval, bool xslow) { 690 assert(xval == xslow, "slow and fast queries agree"); 691 return xval; 692 } 693 public: 694 #endif 695 696 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); } 697 bool is_inline_klass() const { return assert_same_query(_kind == InlineKlassKind, is_inline_klass_slow()); } 698 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; } 699 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; } 700 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; } 701 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); } 702 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; } 703 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); } 704 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); } 705 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); } 706 #undef assert_same_query 707 708 inline bool is_null_free_array_klass() const { return layout_helper_is_null_free(layout_helper()); } 709 710 // Access flags 711 AccessFlags access_flags() const { return _access_flags; } 712 void set_access_flags(AccessFlags flags) { _access_flags = flags; } 713 714 bool is_public() const { return _access_flags.is_public(); } 715 bool is_final() const { return _access_flags.is_final(); } 716 bool is_interface() const { return _access_flags.is_interface(); } 717 bool is_abstract() const { return _access_flags.is_abstract(); } 718 bool is_synthetic() const { return _access_flags.is_synthetic(); } 719 bool is_identity_class() const { return _access_flags.is_identity_class(); } 720 void set_is_synthetic() { _access_flags.set_is_synthetic(); } 721 bool has_finalizer() const { return _access_flags.has_finalizer(); } 722 void set_has_finalizer() { _access_flags.set_has_finalizer(); } 723 bool is_hidden() const { return access_flags().is_hidden_class(); } 724 void set_is_hidden() { _access_flags.set_is_hidden_class(); } 725 bool is_value_based() { return _access_flags.is_value_based_class(); } 726 void set_is_value_based() { _access_flags.set_is_value_based_class(); } 727 728 inline bool is_non_strong_hidden() const; 729 730 bool is_cloneable() const; 731 void set_is_cloneable(); 732 733 // inline types and inline type array patterns 734 markWord prototype_header() const { 735 return _prototype_header; 736 } 737 static inline markWord default_prototype_header(Klass* k) { 738 return (k == nullptr) ? markWord::prototype() : k->prototype_header(); 739 } 740 741 inline void set_prototype_header(markWord header); 742 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); } 743 744 JFR_ONLY(DEFINE_TRACE_ID_METHODS;) 745 746 virtual void metaspace_pointers_do(MetaspaceClosure* iter); 747 virtual MetaspaceObj::Type type() const { return ClassType; } 748 749 inline bool is_loader_alive() const; 750 751 void clean_subklass(); 752 753 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true); 754 static void clean_subklass_tree() { 755 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false); 756 } 757 758 // Return self, except for abstract classes with exactly 1 759 // implementor. Then return the 1 concrete implementation. 760 Klass *up_cast_abstract(); 761 762 // klass name 763 Symbol* name() const { return _name; } 764 void set_name(Symbol* n); 765 766 virtual void release_C_heap_structures(bool release_constant_pool = true); 767 768 public: 769 virtual jint compute_modifier_flags() const = 0; 770 771 // JVMTI support 772 virtual jint jvmti_class_status() const; 773 774 // Printing 775 virtual void print_on(outputStream* st) const; 776 777 virtual void oop_print_value_on(oop obj, outputStream* st); 778 virtual void oop_print_on (oop obj, outputStream* st); 779 780 void print_secondary_supers_on(outputStream* st) const; 781 782 virtual const char* internal_name() const = 0; 783 784 // Verification 785 virtual void verify_on(outputStream* st); 786 void verify() { verify_on(tty); } 787 788 #ifndef PRODUCT 789 bool verify_vtable_index(int index); 790 #endif 791 792 virtual void oop_verify_on(oop obj, outputStream* st); 793 794 // for error reporting 795 static bool is_valid(Klass* k); 796 797 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg); 798 }; 799 800 #endif // SHARE_OOPS_KLASS_HPP