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 { 71 InstanceKlassKind, 72 InlineKlassKind, 73 InstanceRefKlassKind, 74 InstanceMirrorKlassKind, 75 InstanceClassLoaderKlassKind, 76 InstanceStackChunkKlassKind, 77 TypeArrayKlassKind, 78 ObjArrayKlassKind, 79 RefArrayKlassKind, 80 FlatArrayKlassKind, 81 UnknownKlassKind 82 }; 83 84 static const uint KLASS_KIND_COUNT = FlatArrayKlassKind + 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 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here. 128 // Some flags created by the JVM, not in the class file itself, 129 // are in _misc_flags below. 130 KlassFlags _misc_flags; 131 132 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers 133 // and _primary_supers all help make fast subtype checks. See big discussion 134 // in doc/server_compiler/checktype.txt 135 // 136 // Where to look to observe a supertype (it is &_secondary_super_cache for 137 // secondary supers, else is &_primary_supers[depth()]. 138 juint _super_check_offset; 139 140 // Class name. Instance classes: java/lang/String, etc. Array classes: [I, 141 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes. 142 Symbol* _name; 143 144 // Cache of last observed secondary supertype 145 Klass* _secondary_super_cache; 146 // Array of all secondary supertypes 147 Array<Klass*>* _secondary_supers; 148 // Ordered list of all primary supertypes 149 Klass* _primary_supers[_primary_super_limit]; 150 // java/lang/Class instance mirroring this class 151 OopHandle _java_mirror; 152 // Superclass 153 Klass* _super; 154 // First subclass (null if none); _subklass->next_sibling() is next one 155 Klass* volatile _subklass; 156 // Sibling link (or null); links all subklasses of a klass 157 Klass* volatile _next_sibling; 158 159 // All klasses loaded by a class loader are chained through these links 160 Klass* _next_link; 161 162 // The VM's representation of the ClassLoader used to load this class. 163 // Provide access the corresponding instance java.lang.ClassLoader. 164 ClassLoaderData* _class_loader_data; 165 166 markWord _prototype_header; // Used to initialize objects' header 167 168 // Bitmap and hash code used by hashed secondary supers. 169 uintx _secondary_supers_bitmap; 170 uint8_t _hash_slot; 171 172 private: 173 // This is an index into AOTClassLocationConfig::class_locations(), to 174 // indicate the AOTClassLocation where this class is loaded from during 175 // dump time. If a class is not loaded from the AOT cache, this field is 176 // -1. 177 s2 _shared_class_path_index; 178 179 #if INCLUDE_CDS 180 // Various attributes for shared classes. Should be zero for a non-shared class. 181 u2 _shared_class_flags; 182 enum CDSSharedClassFlags { 183 _in_aot_cache = 1 << 0, 184 _archived_lambda_proxy_is_available = 1 << 1, 185 _has_value_based_class_annotation = 1 << 2, 186 _verified_at_dump_time = 1 << 3, 187 _has_archived_enum_objs = 1 << 4, 188 // This class was not loaded from a classfile in the module image 189 // or classpath. 190 _is_generated_shared_class = 1 << 5, 191 // archived mirror already initialized by AOT-cache assembly: no further need to call <clinit> 192 _has_aot_initialized_mirror = 1 << 6, 193 }; 194 #endif 195 196 int _vtable_len; // vtable length. This field may be read very often when we 197 // have lots of itable dispatches (e.g., lambdas and streams). 198 // Keep it away from the beginning of a Klass to avoid cacheline 199 // contention that may happen when a nearby object is modified. 200 201 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;) 202 203 public: 204 205 JFR_ONLY(DEFINE_TRACE_ID_FIELD;) 206 207 protected: 208 209 Klass(KlassKind kind, markWord prototype_header = markWord::prototype()); 210 Klass(); 211 212 public: 213 int kind() { return _kind; } 214 215 enum class DefaultsLookupMode { find, skip }; 216 enum class OverpassLookupMode { find, skip }; 217 enum class StaticLookupMode { find, skip }; 218 enum class PrivateLookupMode { find, skip }; 219 220 virtual bool is_klass() const { return true; } 221 222 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used 223 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;" 224 // If this is not what your code expects, you're probably looking for: 225 // - Klass::java_super() - if you have a Klass* 226 // - InstanceKlass::super() - if you have an InstanceKlass* ik, ik->super() returns InstanceKlass*. 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 // size helper 296 int layout_helper() const { return _layout_helper; } 297 void set_layout_helper(int lh) { _layout_helper = lh; } 298 299 // Note: for instances layout_helper() may include padding. 300 // Use InstanceKlass::contains_field_offset to classify field offsets. 301 302 // sub/superklass links 303 Klass* subklass(bool log = false) const; 304 Klass* next_sibling(bool log = false) const; 305 306 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list 307 308 void set_next_link(Klass* k) { _next_link = k; } 309 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader. 310 Klass** next_link_addr() { return &_next_link; } 311 312 // class loader data 313 ClassLoaderData* class_loader_data() const { return _class_loader_data; } 314 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; } 315 316 s2 shared_classpath_index() const { 317 return _shared_class_path_index; 318 }; 319 320 void set_shared_classpath_index(s2 index) { 321 _shared_class_path_index = index; 322 }; 323 324 bool has_archived_mirror_index() const { 325 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;) 326 NOT_CDS_JAVA_HEAP(return false); 327 } 328 329 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN; 330 331 void set_lambda_proxy_is_available() { 332 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;) 333 } 334 void clear_lambda_proxy_is_available() { 335 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);) 336 } 337 bool lambda_proxy_is_available() const { 338 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;) 339 NOT_CDS(return false;) 340 } 341 342 void set_has_value_based_class_annotation() { 343 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;) 344 } 345 void clear_has_value_based_class_annotation() { 346 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);) 347 } 348 bool has_value_based_class_annotation() const { 349 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;) 350 NOT_CDS(return false;) 351 } 352 353 void set_verified_at_dump_time() { 354 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;) 355 } 356 bool verified_at_dump_time() const { 357 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;) 358 NOT_CDS(return false;) 359 } 360 361 void set_has_archived_enum_objs() { 362 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;) 363 } 364 bool has_archived_enum_objs() const { 365 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;) 366 NOT_CDS(return false;) 367 } 368 369 void set_is_generated_shared_class() { 370 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;) 371 } 372 bool is_generated_shared_class() const { 373 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;) 374 NOT_CDS(return false;) 375 } 376 377 void set_has_aot_initialized_mirror() { 378 CDS_ONLY(_shared_class_flags |= _has_aot_initialized_mirror;) 379 } 380 bool has_aot_initialized_mirror() const { 381 CDS_ONLY(return (_shared_class_flags & _has_aot_initialized_mirror) != 0;) 382 NOT_CDS(return false;) 383 } 384 385 bool in_aot_cache() const { // shadows MetaspaceObj::in_aot_cache)() 386 CDS_ONLY(return (_shared_class_flags & _in_aot_cache) != 0;) 387 NOT_CDS(return false;) 388 } 389 390 void set_in_aot_cache() { 391 CDS_ONLY(_shared_class_flags |= _in_aot_cache;) 392 } 393 394 // Obtain the module or package for this class 395 virtual ModuleEntry* module() const = 0; 396 virtual PackageEntry* package() const = 0; 397 398 protected: // internal accessors 399 void set_subklass(Klass* s); 400 void set_next_sibling(Klass* s); 401 402 private: 403 static uint8_t compute_hash_slot(Symbol* s); 404 static void hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap); 405 static uintx hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite); 406 407 bool search_secondary_supers(Klass* k) const; 408 bool lookup_secondary_supers_table(Klass *k) const; 409 bool linear_search_secondary_supers(const Klass* k) const; 410 bool fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const; 411 412 public: 413 // Secondary supers table support 414 static Array<Klass*>* pack_secondary_supers(ClassLoaderData* loader_data, 415 GrowableArray<Klass*>* primaries, 416 GrowableArray<Klass*>* secondaries, 417 uintx& bitmap, 418 TRAPS); 419 420 static uintx compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers); 421 static uint8_t compute_home_slot(Klass* k, uintx bitmap); 422 423 static constexpr int SECONDARY_SUPERS_TABLE_SIZE = sizeof(_secondary_supers_bitmap) * 8; 424 static constexpr int SECONDARY_SUPERS_TABLE_MASK = SECONDARY_SUPERS_TABLE_SIZE - 1; 425 426 static constexpr uintx SECONDARY_SUPERS_BITMAP_EMPTY = 0; 427 static constexpr uintx SECONDARY_SUPERS_BITMAP_FULL = ~(uintx)0; 428 429 // Compiler support 430 static ByteSize super_offset() { return byte_offset_of(Klass, _super); } 431 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); } 432 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); } 433 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); } 434 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); } 435 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); } 436 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); } 437 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); } 438 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); } 439 #if INCLUDE_JVMCI 440 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); } 441 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); } 442 #endif 443 static ByteSize secondary_supers_bitmap_offset() 444 { return byte_offset_of(Klass, _secondary_supers_bitmap); } 445 static ByteSize hash_slot_offset() { return byte_offset_of(Klass, _hash_slot); } 446 static ByteSize misc_flags_offset() { return byte_offset_of(Klass, _misc_flags._flags); } 447 448 // Unpacking layout_helper: 449 static const int _lh_neutral_value = 0; // neutral non-array non-instance value 450 static const int _lh_instance_slow_path_bit = 0x01; 451 static const int _lh_log2_element_size_shift = BitsPerByte*0; 452 static const int _lh_log2_element_size_mask = BitsPerLong-1; 453 static const int _lh_element_type_shift = BitsPerByte*1; 454 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask 455 static const int _lh_header_size_shift = BitsPerByte*2; 456 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask 457 static const int _lh_array_tag_bits = 4; 458 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits; 459 460 static const unsigned int _lh_array_tag_type_value = 0Xfffffffc; 461 static const unsigned int _lh_array_tag_flat_value = 0Xfffffffa; 462 static const unsigned int _lh_array_tag_ref_value = 0Xfffffff8; 463 464 // null-free array flag bit under the array tag bits, shift one more to get array tag value 465 static const int _lh_null_free_shift = _lh_array_tag_shift - 1; 466 static const int _lh_null_free_mask = 1; 467 468 static const jint _lh_array_tag_flat_value_bit_inplace = (jint) (1 << (_lh_array_tag_shift + 1)); 469 470 static int layout_helper_size_in_bytes(jint lh) { 471 assert(lh > (jint)_lh_neutral_value, "must be instance"); 472 return (int) lh & ~_lh_instance_slow_path_bit; 473 } 474 static bool layout_helper_needs_slow_path(jint lh) { 475 assert(lh > (jint)_lh_neutral_value, "must be instance"); 476 return (lh & _lh_instance_slow_path_bit) != 0; 477 } 478 static bool layout_helper_is_instance(jint lh) { 479 return (jint)lh > (jint)_lh_neutral_value; 480 } 481 static bool layout_helper_is_array(jint lh) { 482 return (jint)lh < (jint)_lh_neutral_value; 483 } 484 static bool layout_helper_is_typeArray(jint lh) { 485 return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift); 486 } 487 static bool layout_helper_is_refArray(jint lh) { 488 return (juint)_lh_array_tag_ref_value == (juint)(lh >> _lh_array_tag_shift); 489 } 490 static bool layout_helper_is_flatArray(jint lh) { 491 return (juint)_lh_array_tag_flat_value == (juint)(lh >> _lh_array_tag_shift); 492 } 493 static bool layout_helper_is_null_free(jint lh) { 494 assert(layout_helper_is_flatArray(lh) || layout_helper_is_refArray(lh), "must be array of inline types"); 495 return ((lh >> _lh_null_free_shift) & _lh_null_free_mask); 496 } 497 static jint layout_helper_set_null_free(jint lh) { 498 lh |= (_lh_null_free_mask << _lh_null_free_shift); 499 assert(layout_helper_is_null_free(lh), "Bad encoding"); 500 return lh; 501 } 502 static int layout_helper_header_size(jint lh) { 503 assert(lh < (jint)_lh_neutral_value, "must be array"); 504 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask; 505 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity"); 506 return hsize; 507 } 508 static BasicType layout_helper_element_type(jint lh) { 509 assert(lh < (jint)_lh_neutral_value, "must be array"); 510 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask; 511 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_FLAT_ELEMENT, "sanity"); 512 return (BasicType) btvalue; 513 } 514 515 // Want a pattern to quickly diff against layout header in register 516 // find something less clever! 517 static int layout_helper_boolean_diffbit() { 518 jint zlh = array_layout_helper(T_BOOLEAN); 519 jint blh = array_layout_helper(T_BYTE); 520 assert(zlh != blh, "array layout helpers must differ"); 521 int diffbit = 1; 522 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) { 523 diffbit <<= 1; 524 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE"); 525 } 526 return diffbit; 527 } 528 529 static int layout_helper_log2_element_size(jint lh) { 530 assert(lh < (jint)_lh_neutral_value, "must be array"); 531 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask; 532 assert(layout_helper_element_type(lh) == T_FLAT_ELEMENT || l2esz <= LogBytesPerLong, 533 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh); 534 return l2esz; 535 } 536 static jint array_layout_helper(jint tag, bool null_free, int hsize, BasicType etype, int log2_esize) { 537 return (tag << _lh_array_tag_shift) 538 | ((null_free ? 1 : 0) << _lh_null_free_shift) 539 | (hsize << _lh_header_size_shift) 540 | ((int)etype << _lh_element_type_shift) 541 | (log2_esize << _lh_log2_element_size_shift); 542 } 543 static jint instance_layout_helper(jint size, bool slow_path_flag) { 544 return (size << LogBytesPerWord) 545 | (slow_path_flag ? _lh_instance_slow_path_bit : 0); 546 } 547 static int layout_helper_to_size_helper(jint lh) { 548 assert(lh > (jint)_lh_neutral_value, "must be instance"); 549 // Note that the following expression discards _lh_instance_slow_path_bit. 550 return lh >> LogBytesPerWord; 551 } 552 // Out-of-line version computes everything based on the etype: 553 static jint array_layout_helper(BasicType etype); 554 555 // What is the maximum number of primary superclasses any klass can have? 556 static juint primary_super_limit() { return _primary_super_limit; } 557 558 // vtables 559 klassVtable vtable() const; 560 int vtable_length() const { return _vtable_len; } 561 562 // subclass check 563 bool is_subclass_of(const Klass* k) const; 564 565 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it 566 bool is_subtype_of(Klass* k) const; 567 568 public: 569 // Find LCA in class hierarchy 570 Klass *LCA( Klass *k ); 571 572 // Check whether reflection/jni/jvm code is allowed to instantiate this class; 573 // if not, throw either an Error or an Exception. 574 virtual void check_valid_for_instantiation(bool throwError, TRAPS); 575 576 // array copying 577 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS); 578 579 // tells if the class should be initialized 580 virtual bool should_be_initialized() const { return false; } 581 // initializes the klass 582 virtual void initialize(TRAPS); 583 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const; 584 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature, 585 OverpassLookupMode overpass_mode, 586 PrivateLookupMode = PrivateLookupMode::find) const; 587 public: 588 Method* lookup_method(const Symbol* name, const Symbol* signature) const { 589 return uncached_lookup_method(name, signature, OverpassLookupMode::find); 590 } 591 592 // array class with specific rank 593 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0; 594 595 // array class with this klass as element type 596 virtual ArrayKlass* array_klass(TRAPS) = 0; 597 598 // These will return null instead of allocating on the heap: 599 virtual ArrayKlass* array_klass_or_null(int rank) = 0; 600 virtual ArrayKlass* array_klass_or_null() = 0; 601 602 virtual oop protection_domain() const = 0; 603 604 oop class_loader() const; 605 606 inline oop klass_holder() const; 607 608 inline void keep_alive() const; 609 610 protected: 611 612 // Error handling when length > max_length or length < 0 613 static void check_array_allocation_length(int length, int max_length, TRAPS); 614 615 void set_vtable_length(int len) { _vtable_len= len; } 616 617 vtableEntry* start_of_vtable() const; 618 #if INCLUDE_CDS 619 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS); 620 #endif 621 public: 622 Method* method_at_vtable(int index); 623 624 static ByteSize vtable_start_offset(); 625 static ByteSize vtable_length_offset() { 626 return byte_offset_of(Klass, _vtable_len); 627 } 628 629 #if INCLUDE_CDS 630 // CDS support - remove and restore oops from metadata. Oops are not shared. 631 virtual void remove_unshareable_info(); 632 virtual void remove_java_mirror(); 633 634 bool is_unshareable_info_restored() const { 635 assert(in_aot_cache(), "use this for shared classes only"); 636 if (has_archived_mirror_index()) { 637 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap 638 return false; 639 } else if (_java_mirror.is_empty()) { 640 return false; 641 } else { 642 return true; 643 } 644 } 645 #endif // INCLUDE_CDS 646 647 public: 648 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP 649 // These functions describe behavior for the oop not the KLASS. 650 651 // actual oop size of obj in memory in word size. 652 virtual size_t oop_size(oop obj) const = 0; 653 654 // Size of klass in word size. 655 virtual int size() const = 0; 656 657 // Returns the Java name for a class (Resource allocated) 658 // For arrays, this returns the name of the element with a leading '['. 659 // For classes, this returns the name with the package separators 660 // turned into '.'s. 661 const char* external_name() const; 662 // Returns the name for a class (Resource allocated) as the class 663 // would appear in a signature. 664 // For arrays, this returns the name of the element with a leading '['. 665 // For classes, this returns the name with a leading 'L' and a trailing ';' 666 // and the package separators as '/'. 667 virtual const char* signature_name() const; 668 669 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const; 670 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const; 671 672 // Returns "interface", "abstract class" or "class". 673 const char* external_kind() const; 674 675 // type testing operations 676 #ifdef ASSERT 677 protected: 678 virtual bool is_instance_klass_slow() const { return false; } 679 virtual bool is_array_klass_slow() const { return false; } 680 virtual bool is_objArray_klass_slow() const { return false; } 681 virtual bool is_refArray_klass_slow() const { return false; } 682 virtual bool is_typeArray_klass_slow() const { return false; } 683 virtual bool is_flatArray_klass_slow() const { return false; } 684 #endif // ASSERT 685 // current implementation uses this method even in non debug builds 686 virtual bool is_inline_klass_slow() const { return false; } 687 public: 688 689 // Fast non-virtual versions 690 #ifndef ASSERT 691 #define assert_same_query(xval, xcheck) xval 692 #else 693 private: 694 static bool assert_same_query(bool xval, bool xslow) { 695 assert(xval == xslow, "slow and fast queries agree"); 696 return xval; 697 } 698 public: 699 #endif 700 701 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); } 702 bool is_inline_klass() const { return assert_same_query(_kind == InlineKlassKind, is_inline_klass_slow()); } 703 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; } 704 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; } 705 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; } 706 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); } 707 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; } 708 bool is_flatArray_klass() const { return assert_same_query( _kind == FlatArrayKlassKind, is_flatArray_klass_slow()); } 709 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind || _kind == RefArrayKlassKind || _kind == FlatArrayKlassKind, is_objArray_klass_slow()); } 710 bool is_refArray_klass() const { return assert_same_query( _kind == RefArrayKlassKind, is_refArray_klass_slow()); } 711 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); } 712 bool is_refined_objArray_klass() const { return is_refArray_klass() || is_flatArray_klass(); } 713 #undef assert_same_query 714 715 inline bool is_null_free_array_klass() const { return !is_typeArray_klass() && layout_helper_is_null_free(layout_helper()); } 716 717 // Access flags 718 AccessFlags access_flags() const { return _access_flags; } 719 void set_access_flags(AccessFlags flags) { _access_flags = flags; } 720 721 bool is_public() const { return _access_flags.is_public(); } 722 bool is_final() const { return _access_flags.is_final(); } 723 bool is_interface() const { return _access_flags.is_interface(); } 724 bool is_abstract() const { return _access_flags.is_abstract(); } 725 bool is_synthetic() const { return _access_flags.is_synthetic(); } 726 bool is_identity_class() const { assert(is_instance_klass(), "only for instanceKlass"); return _access_flags.is_identity_class(); } 727 void set_is_synthetic() { _access_flags.set_is_synthetic(); } 728 bool has_finalizer() const { return _misc_flags.has_finalizer(); } 729 void set_has_finalizer() { _misc_flags.set_has_finalizer(true); } 730 bool is_hidden() const { return _misc_flags.is_hidden_class(); } 731 void set_is_hidden() { _misc_flags.set_is_hidden_class(true); } 732 bool is_value_based() const { return _misc_flags.is_value_based_class(); } 733 void set_is_value_based() { _misc_flags.set_is_value_based_class(true); } 734 735 klass_flags_t misc_flags() const { return _misc_flags.value(); } 736 737 inline bool is_non_strong_hidden() const; 738 739 bool is_cloneable() const; 740 void set_is_cloneable(); 741 742 static inline markWord make_prototype_header(const Klass* kls, markWord prototype = markWord::prototype()); 743 inline markWord prototype_header() const; 744 inline void set_prototype_header(markWord header); 745 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); } 746 inline void set_prototype_header_klass(narrowKlass klass); 747 748 JFR_ONLY(DEFINE_TRACE_ID_METHODS;) 749 750 virtual void metaspace_pointers_do(MetaspaceClosure* iter); 751 virtual MetaspaceObj::Type type() const { return ClassType; } 752 753 inline bool is_loader_alive() const; 754 inline bool is_loader_present_and_alive() const; 755 756 void clean_subklass(); 757 758 // Clean out unnecessary weak klass links from the whole klass hierarchy. 759 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true); 760 // Clean out unnecessary weak klass links from the given InstanceKlass. 761 static void clean_weak_instanceklass_links(InstanceKlass* ik); 762 763 // Return self, except for abstract classes with exactly 1 764 // implementor. Then return the 1 concrete implementation. 765 Klass *up_cast_abstract(); 766 767 // klass name 768 Symbol* name() const { return _name; } 769 void set_name(Symbol* n); 770 771 virtual void release_C_heap_structures(bool release_constant_pool = true); 772 773 public: 774 // Get modifier flags from Java mirror cache. 775 int modifier_flags() const; 776 777 // Compute modifier flags from the original data. This also allows 778 // accessing flags when Java mirror is already dead, e.g. during class 779 // unloading. 780 virtual u2 compute_modifier_flags() const = 0; 781 782 // JVMTI support 783 virtual jint jvmti_class_status() const; 784 785 // Printing 786 virtual void print_on(outputStream* st) const; 787 788 virtual void oop_print_value_on(oop obj, outputStream* st); 789 virtual void oop_print_on (oop obj, outputStream* st); 790 791 void print_secondary_supers_on(outputStream* st) const; 792 793 virtual const char* internal_name() const = 0; 794 795 // Verification 796 virtual void verify_on(outputStream* st); 797 void verify() { verify_on(tty); } 798 799 #ifndef PRODUCT 800 bool verify_vtable_index(int index); 801 #endif 802 803 virtual void oop_verify_on(oop obj, outputStream* st); 804 805 // for error reporting 806 static bool is_valid(Klass* k); 807 808 static void on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg); 809 810 // Returns true if this Klass needs to be addressable via narrow Klass ID. 811 inline bool needs_narrow_id() const; 812 813 }; 814 815 #endif // SHARE_OOPS_KLASS_HPP