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