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/klassFlags.hpp" 31 #include "oops/markWord.hpp" 32 #include "oops/metadata.hpp" 33 #include "oops/oop.hpp" 34 #include "oops/oopHandle.hpp" 35 #include "utilities/accessFlags.hpp" 36 #include "utilities/macros.hpp" 37 #if INCLUDE_JFR 38 #include "jfr/support/jfrTraceIdExtension.hpp" 39 #endif 40 41 // 42 // A Klass provides: 43 // 1: language level class object (method dictionary etc.) 44 // 2: provide vm dispatch behavior for the object 45 // Both functions are combined into one C++ class. 46 47 // One reason for the oop/klass dichotomy in the implementation is 48 // that we don't want a C++ vtbl pointer in every object. Thus, 49 // normal oops don't have any virtual functions. Instead, they 50 // forward all "virtual" functions to their klass, which does have 51 // a vtbl and does the C++ dispatch depending on the object's 52 // actual type. (See oop.inline.hpp for some of the forwarding code.) 53 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"! 54 55 // Forward declarations. 56 template <class T> class Array; 57 template <class T> class GrowableArray; 58 class ClassLoaderData; 59 class fieldDescriptor; 60 class klassVtable; 61 class ModuleEntry; 62 class PackageEntry; 63 class ParCompactionManager; 64 class PSPromotionManager; 65 class vtableEntry; 66 67 class Klass : public Metadata { 68 friend class VMStructs; 69 friend class JVMCIVMStructs; 70 public: 71 // Klass Kinds for all subclasses of Klass 72 enum KlassKind { 73 InstanceKlassKind, 74 InlineKlassKind, 75 InstanceRefKlassKind, 76 InstanceMirrorKlassKind, 77 InstanceClassLoaderKlassKind, 78 InstanceStackChunkKlassKind, 79 TypeArrayKlassKind, 80 FlatArrayKlassKind, 81 ObjArrayKlassKind, 82 UnknownKlassKind 83 }; 84 85 static const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1; 86 protected: 87 88 // If you add a new field that points to any metaspace object, you 89 // must add this field to Klass::metaspace_pointers_do(). 90 91 // note: put frequently-used fields together at start of klass structure 92 // for better cache behavior (may not make much of a difference but sure won't hurt) 93 enum { _primary_super_limit = 8 }; 94 95 // The "layout helper" is a combined descriptor of object layout. 96 // For klasses which are neither instance nor array, the value is zero. 97 // 98 // For instances, layout helper is a positive number, the instance size. 99 // This size is already passed through align_object_size and scaled to bytes. 100 // The low order bit is set if instances of this class cannot be 101 // allocated using the fastpath. 102 // 103 // For arrays, layout helper is a negative number, containing four 104 // distinct bytes, as follows: 105 // MSB:[tag, hsz, ebt, log2(esz)]:LSB 106 // where: 107 // tag is 0x80 if the elements are oops, 0xC0 if non-oops, 0xA0 if value types 108 // hsz is array header size in bytes (i.e., offset of first element) 109 // ebt is the BasicType of the elements 110 // esz is the element size in bytes 111 // This packed word is arranged so as to be quickly unpacked by the 112 // various fast paths that use the various subfields. 113 // 114 // The esz bits can be used directly by a SLL instruction, without masking. 115 // 116 // Note that the array-kind tag looks like 0x00 for instance klasses, 117 // since their length in bytes is always less than 24Mb. 118 // 119 // Final note: This comes first, immediately after C++ vtable, 120 // because it is frequently queried. 121 jint _layout_helper; 122 123 // Klass kind used to resolve the runtime type of the instance. 124 // - Used to implement devirtualized oop closure dispatching. 125 // - Various type checking in the JVM 126 const KlassKind _kind; 127 128 // Processed access flags, for use by Class.getModifiers. 129 jint _modifier_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; 164 165 166 int _vtable_len; // vtable length. This field may be read very often when we 167 // have lots of itable dispatches (e.g., lambdas and streams). 168 // Keep it away from the beginning of a Klass to avoid cacheline 169 // contention that may happen when a nearby object is modified. 170 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here. 171 // Some flags created by the JVM, not in the class file itself, 172 // are in _misc_flags below. 173 174 JFR_ONLY(DEFINE_TRACE_ID_FIELD;) 175 176 markWord _prototype_header; // inline type and inline array mark patterns 177 // Bitmap and hash code used by hashed secondary supers. 178 uintx _bitmap; 179 uint8_t _hash_slot; 180 181 private: 182 // This is an index into FileMapHeader::_shared_path_table[], to 183 // associate this class with the JAR file where it's loaded from during 184 // dump time. If a class is not loaded from the shared archive, this field is 185 // -1. 186 s2 _shared_class_path_index; 187 188 #if INCLUDE_CDS 189 // Various attributes for shared classes. Should be zero for a non-shared class. 190 u2 _shared_class_flags; 191 enum CDSSharedClassFlags { 192 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared 193 _archived_lambda_proxy_is_available = 1 << 1, 194 _has_value_based_class_annotation = 1 << 2, 195 _verified_at_dump_time = 1 << 3, 196 _has_archived_enum_objs = 1 << 4, 197 // This class was not loaded from a classfile in the module image 198 // or classpath. 199 _is_generated_shared_class = 1 << 5 200 }; 201 #endif 202 203 KlassFlags _misc_flags; 204 205 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;) 206 207 protected: 208 209 Klass(KlassKind kind); 210 Klass(); 211 212 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw(); 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); 248 void set_secondary_supers(Array<Klass*>* k, uintx bitmap); 249 250 uint8_t hash_slot() const { return _hash_slot; } 251 252 // Return the element of the _super chain of the given depth. 253 // If there is no such element, return either null or this. 254 Klass* primary_super_of_depth(juint i) const { 255 assert(i < primary_super_limit(), "oob"); 256 Klass* super = _primary_supers[i]; 257 assert(super == nullptr || super->super_depth() == i, "correct display"); 258 return super; 259 } 260 261 // Can this klass be a primary super? False for interfaces and arrays of 262 // interfaces. False also for arrays or classes with long super chains. 263 bool can_be_primary_super() const { 264 const juint secondary_offset = in_bytes(secondary_super_cache_offset()); 265 return super_check_offset() != secondary_offset; 266 } 267 virtual bool can_be_primary_super_slow() const; 268 269 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit]. 270 juint super_depth() const { 271 if (!can_be_primary_super()) { 272 return primary_super_limit(); 273 } else { 274 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*); 275 assert(d < primary_super_limit(), "oob"); 276 assert(_primary_supers[d] == this, "proper init"); 277 return d; 278 } 279 } 280 281 // java mirror 282 oop java_mirror() const; 283 oop java_mirror_no_keepalive() const; 284 void set_java_mirror(Handle m); 285 286 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr); 287 void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN; 288 289 // Temporary mirror switch used by RedefineClasses 290 OopHandle java_mirror_handle() const { return _java_mirror; } 291 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); } 292 293 // Set java mirror OopHandle to null for CDS 294 // This leaves the OopHandle in the CLD, but that's ok, you can't release them. 295 void clear_java_mirror_handle() { _java_mirror = OopHandle(); } 296 297 // modifier flags 298 jint modifier_flags() const { return _modifier_flags; } 299 void set_modifier_flags(jint flags) { _modifier_flags = flags; } 300 301 // size helper 302 int layout_helper() const { return _layout_helper; } 303 void set_layout_helper(int lh) { _layout_helper = lh; } 304 305 // Note: for instances layout_helper() may include padding. 306 // Use InstanceKlass::contains_field_offset to classify field offsets. 307 308 // sub/superklass links 309 Klass* subklass(bool log = false) const; 310 Klass* next_sibling(bool log = false) const; 311 312 InstanceKlass* superklass() const; 313 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list 314 315 void set_next_link(Klass* k) { _next_link = k; } 316 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader. 317 Klass** next_link_addr() { return &_next_link; } 318 319 // class loader data 320 ClassLoaderData* class_loader_data() const { return _class_loader_data; } 321 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; } 322 323 s2 shared_classpath_index() const { 324 return _shared_class_path_index; 325 }; 326 327 void set_shared_classpath_index(s2 index) { 328 _shared_class_path_index = index; 329 }; 330 331 bool has_archived_mirror_index() const { 332 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;) 333 NOT_CDS_JAVA_HEAP(return false); 334 } 335 336 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN; 337 338 void set_lambda_proxy_is_available() { 339 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;) 340 } 341 void clear_lambda_proxy_is_available() { 342 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);) 343 } 344 bool lambda_proxy_is_available() const { 345 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;) 346 NOT_CDS(return false;) 347 } 348 349 void set_has_value_based_class_annotation() { 350 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;) 351 } 352 void clear_has_value_based_class_annotation() { 353 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);) 354 } 355 bool has_value_based_class_annotation() const { 356 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;) 357 NOT_CDS(return false;) 358 } 359 360 void set_verified_at_dump_time() { 361 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;) 362 } 363 bool verified_at_dump_time() const { 364 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;) 365 NOT_CDS(return false;) 366 } 367 368 void set_has_archived_enum_objs() { 369 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;) 370 } 371 bool has_archived_enum_objs() const { 372 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;) 373 NOT_CDS(return false;) 374 } 375 376 void set_is_generated_shared_class() { 377 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;) 378 } 379 bool is_generated_shared_class() const { 380 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;) 381 NOT_CDS(return false;) 382 } 383 384 bool is_shared() const { // shadows MetaspaceObj::is_shared)() 385 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;) 386 NOT_CDS(return false;) 387 } 388 389 void set_is_shared() { 390 CDS_ONLY(_shared_class_flags |= _is_shared_class;) 391 } 392 393 // Obtain the module or package for this class 394 virtual ModuleEntry* module() const = 0; 395 virtual PackageEntry* package() const = 0; 396 397 protected: // internal accessors 398 void set_subklass(Klass* s); 399 void set_next_sibling(Klass* s); 400 401 private: 402 static uint8_t compute_hash_slot(Symbol* s); 403 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap); 404 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite); 405 406 public: 407 // Secondary supers table support 408 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data, 409 GrowableArray<Klass*>* primaries, 410 GrowableArray<Klass*>* secondaries, 411 uintx& bitmap, 412 TRAPS); 413 414 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers); 415 static uint8_t compute_home_slot(Klass* k, uintx bitmap); 416 417 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_bitmap) * 8; 418 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1; 419 420 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0; 421 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0; 422 423 // Compiler support 424 static ByteSize super_offset() { return byte_offset_of(Klass, _super); } 425 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); } 426 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); } 427 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); } 428 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); } 429 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); } 430 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); } 431 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); } 432 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); } 433 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); } 434 #if INCLUDE_JVMCI 435 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); } 436 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); } 437 #endif 438 static ByteSize bitmap_offset() { return byte_offset_of(Klass, _bitmap); } 439 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); } 440 441 // Unpacking layout_helper: 442 static const int _lh_neutral_value = 0; // neutral non-array non-instance value 443 static const int _lh_instance_slow_path_bit = 0x01; 444 static const int _lh_log2_element_size_shift = BitsPerByte*0; 445 static const int _lh_log2_element_size_mask = BitsPerLong-1; 446 static const int _lh_element_type_shift = BitsPerByte*1; 447 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask 448 static const int _lh_header_size_shift = BitsPerByte*2; 449 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask 450 static const int _lh_array_tag_bits = 3; 451 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits; 452 453 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc; 454 static const unsigned int _lh_array_tag_vt_value = 0Xfffffffd; 455 static const unsigned int _lh_array_tag_obj_value = 0Xfffffffe; 456 457 // null-free array flag bit under the array tag bits, shift one more to get array tag value 458 static const int _lh_null_free_shift = _lh_array_tag_shift - 1; 459 static const int _lh_null_free_mask = 1; 460 461 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << _lh_array_tag_shift); 462 463 static int layout_helper_size_in_bytes(jint lh) { 464 assert(lh > (jint)_lh_neutral_value, "must be instance"); 465 return (int) lh & ~_lh_instance_slow_path_bit; 466 } 467 static bool layout_helper_needs_slow_path(jint lh) { 468 assert(lh > (jint)_lh_neutral_value, "must be instance"); 469 return (lh & _lh_instance_slow_path_bit) != 0; 470 } 471 static bool layout_helper_is_instance(jint lh) { 472 return (jint)lh > (jint)_lh_neutral_value; 473 } 474 static bool layout_helper_is_array(jint lh) { 475 return (jint)lh < (jint)_lh_neutral_value; 476 } 477 static bool layout_helper_is_typeArray(jint lh) { 478 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift); 479 } 480 static bool layout_helper_is_objArray(jint lh) { 481 return (juint)_lh_array_tag_obj_value == (juint)(lh >> _lh_array_tag_shift); 482 } 483 static bool layout_helper_is_flatArray(jint lh) { 484 return (juint)_lh_array_tag_vt_value == (juint)(lh >> _lh_array_tag_shift); 485 } 486 static bool layout_helper_is_null_free(jint lh) { 487 assert(layout_helper_is_flatArray(lh) || layout_helper_is_objArray(lh), "must be array of inline types"); 488 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask); 489 } 490 static jint layout_helper_set_null_free(jint lh) { 491 lh |= (_lh_null_free_mask << _lh_null_free_shift); 492 assert(layout_helper_is_null_free(lh), "Bad encoding"); 493 return lh; 494 } 495 static int layout_helper_header_size(jint lh) { 496 assert(lh < (jint)_lh_neutral_value, "must be array"); 497 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask; 498 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity"); 499 return hsize; 500 } 501 static BasicType layout_helper_element_type(jint lh) { 502 assert(lh < (jint)_lh_neutral_value, "must be array"); 503 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask; 504 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_PRIMITIVE_OBJECT, "sanity"); 505 return (BasicType) btvalue; 506 } 507 508 // Want a pattern to quickly diff against layout header in register 509 // find something less clever! 510 static int layout_helper_boolean_diffbit() { 511 jint zlh = array_layout_helper(T_BOOLEAN); 512 jint blh = array_layout_helper(T_BYTE); 513 assert(zlh != blh, "array layout helpers must differ"); 514 int diffbit = 1; 515 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) { 516 diffbit <<= 1; 517 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE"); 518 } 519 return diffbit; 520 } 521 522 static int layout_helper_log2_element_size(jint lh) { 523 assert(lh < (jint)_lh_neutral_value, "must be array"); 524 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask; 525 assert(layout_helper_element_type(lh) == T_PRIMITIVE_OBJECT || l2esz <= LogBytesPerLong, 526 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh); 527 return l2esz; 528 } 529 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) { 530 return (tag << _lh_array_tag_shift) 531 | ((null_free ? 1 : 0) << _lh_null_free_shift) 532 | (hsize << _lh_header_size_shift) 533 | ((int)etype << _lh_element_type_shift) 534 | (log2_esize << _lh_log2_element_size_shift); 535 } 536 static jint instance_layout_helper(jint size, bool slow_path_flag) { 537 return (size << LogBytesPerWord) 538 | (slow_path_flag ? _lh_instance_slow_path_bit : 0); 539 } 540 static int layout_helper_to_size_helper(jint lh) { 541 assert(lh > (jint)_lh_neutral_value, "must be instance"); 542 // Note that the following expression discards _lh_instance_slow_path_bit. 543 return lh >> LogBytesPerWord; 544 } 545 // Out-of-line version computes everything based on the etype: 546 static jint array_layout_helper(BasicType etype); 547 548 // What is the maximum number of primary superclasses any klass can have? 549 static juint primary_super_limit() { return _primary_super_limit; } 550 551 // vtables 552 klassVtable vtable() const; 553 int vtable_length() const { return _vtable_len; } 554 555 // subclass check 556 bool is_subclass_of(const Klass* k) const; 557 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it 558 bool is_subtype_of(Klass* k) const { 559 juint off = k->super_check_offset(); 560 Klass* sup = *(Klass**)( (address)this + off ); 561 const juint secondary_offset = in_bytes(secondary_super_cache_offset()); 562 if (sup == k) { 563 return true; 564 } else if (off != secondary_offset) { 565 return false; 566 } else { 567 return search_secondary_supers(k); 568 } 569 } 570 571 bool search_secondary_supers(Klass* k) const; 572 573 // Find LCA in class hierarchy 574 Klass *LCA( Klass *k ); 575 576 // Check whether reflection/jni/jvm code is allowed to instantiate this class; 577 // if not, throw either an Error or an Exception. 578 virtual void check_valid_for_instantiation(bool throwError, TRAPS); 579 580 // array copying 581 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS); 582 583 // tells if the class should be initialized 584 virtual bool should_be_initialized() const { return false; } 585 // initializes the klass 586 virtual void initialize(TRAPS); 587 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const; 588 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature, 589 OverpassLookupMode overpass_mode, 590 PrivateLookupMode = PrivateLookupMode::find) const; 591 public: 592 Method* lookup_method(const Symbol* name, const Symbol* signature) const { 593 return uncached_lookup_method(name, signature, OverpassLookupMode::find); 594 } 595 596 // array class with specific rank 597 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0; 598 599 // array class with this klass as element type 600 virtual ArrayKlass* array_klass(TRAPS) = 0; 601 602 // These will return null instead of allocating on the heap: 603 virtual ArrayKlass* array_klass_or_null(int rank) = 0; 604 virtual ArrayKlass* array_klass_or_null() = 0; 605 606 virtual oop protection_domain() const = 0; 607 608 oop class_loader() const; 609 610 inline oop klass_holder() const; 611 612 protected: 613 614 // Error handling when length > max_length or length < 0 615 static void check_array_allocation_length(int length, int max_length, TRAPS); 616 617 void set_vtable_length(int len) { _vtable_len= len; } 618 619 vtableEntry* start_of_vtable() const; 620 #if INCLUDE_CDS 621 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS); 622 #endif 623 public: 624 Method* method_at_vtable(int index); 625 626 static ByteSize vtable_start_offset(); 627 static ByteSize vtable_length_offset() { 628 return byte_offset_of(Klass, _vtable_len); 629 } 630 631 #if INCLUDE_CDS 632 // CDS support - remove and restore oops from metadata. Oops are not shared. 633 virtual void remove_unshareable_info(); 634 virtual void remove_java_mirror(); 635 636 bool is_unshareable_info_restored() const { 637 assert(is_shared(), "use this for shared classes only"); 638 if (has_archived_mirror_index()) { 639 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap 640 return false; 641 } else if (_java_mirror.is_empty()) { 642 return false; 643 } else { 644 return true; 645 } 646 } 647 #endif // INCLUDE_CDS 648 649 public: 650 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP 651 // These functions describe behavior for the oop not the KLASS. 652 653 // actual oop size of obj in memory in word size. 654 virtual size_t oop_size(oop obj) const = 0; 655 656 // Size of klass in word size. 657 virtual int size() const = 0; 658 659 // Returns the Java name for a class (Resource allocated) 660 // For arrays, this returns the name of the element with a leading '['. 661 // For classes, this returns the name with the package separators 662 // turned into '.'s. 663 const char* external_name() const; 664 // Returns the name for a class (Resource allocated) as the class 665 // would appear in a signature. 666 // For arrays, this returns the name of the element with a leading '['. 667 // For classes, this returns the name with a leading 'L' and a trailing ';' 668 // and the package separators as '/'. 669 virtual const char* signature_name() const; 670 671 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const; 672 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const; 673 674 // Returns "interface", "abstract class" or "class". 675 const char* external_kind() const; 676 677 // type testing operations 678 #ifdef ASSERT 679 protected: 680 virtual bool is_instance_klass_slow() const { return false; } 681 virtual bool is_array_klass_slow() const { return false; } 682 virtual bool is_objArray_klass_slow() const { return false; } 683 virtual bool is_typeArray_klass_slow() const { return false; } 684 virtual bool is_flatArray_klass_slow() const { return false; } 685 #endif // ASSERT 686 // current implementation uses this method even in non debug builds 687 virtual bool is_inline_klass_slow() const { return false; } 688 public: 689 690 // Fast non-virtual versions 691 #ifndef ASSERT 692 #define assert_same_query(xval, xcheck) xval 693 #else 694 private: 695 static bool assert_same_query(bool xval, bool xslow) { 696 assert(xval == xslow, "slow and fast queries agree"); 697 return xval; 698 } 699 public: 700 #endif 701 702 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); } 703 bool is_inline_klass() const { return assert_same_query(_kind == InlineKlassKind, is_inline_klass_slow()); } 704 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; } 705 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; } 706 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; } 707 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); } 708 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; } 709 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); } 710 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); } 711 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); } 712 #undef assert_same_query 713 714 inline bool is_null_free_array_klass() const { return layout_helper_is_null_free(layout_helper()); } 715 716 // Access flags 717 AccessFlags access_flags() const { return _access_flags; } 718 void set_access_flags(AccessFlags flags) { _access_flags = flags; } 719 720 bool is_public() const { return _access_flags.is_public(); } 721 bool is_final() const { return _access_flags.is_final(); } 722 bool is_interface() const { return _access_flags.is_interface(); } 723 bool is_abstract() const { return _access_flags.is_abstract(); } 724 bool is_synthetic() const { return _access_flags.is_synthetic(); } 725 bool is_identity_class() const { return _access_flags.is_identity_class(); } 726 void set_is_synthetic() { _access_flags.set_is_synthetic(); } 727 bool has_finalizer() const { return _misc_flags.has_finalizer(); } 728 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); } 729 bool is_hidden() const { return _misc_flags.is_hidden_class(); } 730 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); } 731 bool is_value_based() const { return _misc_flags.is_value_based_class(); } 732 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); } 733 734 klass_flags_t misc_flags() const { return _misc_flags.value(); } 735 736 inline bool is_non_strong_hidden() const; 737 738 bool is_cloneable() const; 739 void set_is_cloneable(); 740 741 // inline types and inline type array patterns 742 markWord prototype_header() const { 743 return _prototype_header; 744 } 745 static inline markWord default_prototype_header(Klass* k) { 746 return (k == nullptr) ? markWord::prototype() : k->prototype_header(); 747 } 748 749 inline void set_prototype_header(markWord header); 750 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); } 751 752 JFR_ONLY(DEFINE_TRACE_ID_METHODS;) 753 754 virtual void metaspace_pointers_do(MetaspaceClosure* iter); 755 virtual MetaspaceObj::Type type() const { return ClassType; } 756 757 inline bool is_loader_alive() const; 758 759 void clean_subklass(); 760 761 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true); 762 static void clean_subklass_tree() { 763 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false); 764 } 765 766 // Return self, except for abstract classes with exactly 1 767 // implementor. Then return the 1 concrete implementation. 768 Klass *up_cast_abstract(); 769 770 // klass name 771 Symbol* name() const { return _name; } 772 void set_name(Symbol* n); 773 774 virtual void release_C_heap_structures(bool release_constant_pool = true); 775 776 public: 777 virtual jint compute_modifier_flags() const = 0; 778 779 // JVMTI support 780 virtual jint jvmti_class_status() const; 781 782 // Printing 783 virtual void print_on(outputStream* st) const; 784 785 virtual void oop_print_value_on(oop obj, outputStream* st); 786 virtual void oop_print_on (oop obj, outputStream* st); 787 788 void print_secondary_supers_on(outputStream* st) const; 789 790 virtual const char* internal_name() const = 0; 791 792 // Verification 793 virtual void verify_on(outputStream* st); 794 void verify() { verify_on(tty); } 795 796 #ifndef PRODUCT 797 bool verify_vtable_index(int index); 798 #endif 799 800 virtual void oop_verify_on(oop obj, outputStream* st); 801 802 // for error reporting 803 static bool is_valid(Klass* k); 804 805 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg); 806 }; 807 808 #endif // SHARE_OOPS_KLASS_HPP --- EOF ---