1 /*
2 * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_OOPS_KLASS_HPP
26 #define SHARE_OOPS_KLASS_HPP
27
28 #include "memory/iterator.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/markWord.hpp"
31 #include "oops/metadata.hpp"
32 #include "oops/oop.hpp"
33 #include "oops/oopHandle.hpp"
34 #include "utilities/accessFlags.hpp"
35 #include "utilities/macros.hpp"
36 #if INCLUDE_JFR
37 #include "jfr/support/jfrTraceIdExtension.hpp"
38 #endif
39
40 //
41 // A Klass provides:
42 // 1: language level class object (method dictionary etc.)
43 // 2: provide vm dispatch behavior for the object
44 // Both functions are combined into one C++ class.
45
46 // One reason for the oop/klass dichotomy in the implementation is
47 // that we don't want a C++ vtbl pointer in every object. Thus,
48 // normal oops don't have any virtual functions. Instead, they
49 // forward all "virtual" functions to their klass, which does have
50 // a vtbl and does the C++ dispatch depending on the object's
51 // actual type. (See oop.inline.hpp for some of the forwarding code.)
52 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
53
54 // Forward declarations.
55 template <class T> class Array;
56 template <class T> class GrowableArray;
57 class ClassLoaderData;
58 class fieldDescriptor;
59 class klassVtable;
60 class ModuleEntry;
61 class PackageEntry;
62 class ParCompactionManager;
63 class PSPromotionManager;
64 class vtableEntry;
65
66 class Klass : public Metadata {
67 friend class VMStructs;
68 friend class JVMCIVMStructs;
69 public:
70 // Klass Kinds for all subclasses of Klass
71 enum KlassKind {
72 InstanceKlassKind,
73 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 int _vtable_len; // vtable length. This field may be read very often when we
163 // have lots of itable dispatches (e.g., lambdas and streams).
164 // Keep it away from the beginning of a Klass to avoid cacheline
165 // contention that may happen when a nearby object is modified.
166 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
167
168 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
169
170 private:
171 // This is an index into FileMapHeader::_shared_path_table[], to
172 // associate this class with the JAR file where it's loaded from during
173 // dump time. If a class is not loaded from the shared archive, this field is
174 // -1.
175 s2 _shared_class_path_index;
176
177 #if INCLUDE_CDS
178 // Various attributes for shared classes. Should be zero for a non-shared class.
179 u2 _shared_class_flags;
180 enum CDSSharedClassFlags {
181 _is_shared_class = 1 << 0, // shadows MetaspaceObj::is_shared
182 _archived_lambda_proxy_is_available = 1 << 1,
183 _has_value_based_class_annotation = 1 << 2,
184 _verified_at_dump_time = 1 << 3,
185 _has_archived_enum_objs = 1 << 4,
186 // This class was not loaded from a classfile in the module image
187 // or classpath.
188 _is_generated_shared_class = 1 << 5
189 };
190 #endif
191
192 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
193
194 protected:
195
196 Klass(KlassKind kind);
197 Klass();
198
199 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
200
201 public:
202 int kind() { return _kind; }
203
204 enum class DefaultsLookupMode { find, skip };
205 enum class OverpassLookupMode { find, skip };
206 enum class StaticLookupMode { find, skip };
207 enum class PrivateLookupMode { find, skip };
208
209 virtual bool is_klass() const { return true; }
210
211 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
212 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
213 // If this is not what your code expects, you're probably looking for Klass::java_super().
214 Klass* super() const { return _super; }
215 void set_super(Klass* k) { _super = k; }
216
217 // initializes _super link, _primary_supers & _secondary_supers arrays
218 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
219
220 // klass-specific helper for initializing _secondary_supers
221 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
222 Array<InstanceKlass*>* transitive_interfaces);
223
224 // java_super is the Java-level super type as specified by Class.getSuperClass.
225 virtual InstanceKlass* java_super() const { return nullptr; }
226
227 juint super_check_offset() const { return _super_check_offset; }
228 void set_super_check_offset(juint o) { _super_check_offset = o; }
229
230 Klass* secondary_super_cache() const { return _secondary_super_cache; }
231 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
232
233 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
234 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
235
236 // Return the element of the _super chain of the given depth.
237 // If there is no such element, return either null or this.
238 Klass* primary_super_of_depth(juint i) const {
239 assert(i < primary_super_limit(), "oob");
240 Klass* super = _primary_supers[i];
241 assert(super == nullptr || super->super_depth() == i, "correct display");
242 return super;
243 }
244
245 // Can this klass be a primary super? False for interfaces and arrays of
246 // interfaces. False also for arrays or classes with long super chains.
247 bool can_be_primary_super() const {
248 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
249 return super_check_offset() != secondary_offset;
250 }
251 virtual bool can_be_primary_super_slow() const;
252
253 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
254 juint super_depth() const {
255 if (!can_be_primary_super()) {
256 return primary_super_limit();
257 } else {
258 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
259 assert(d < primary_super_limit(), "oob");
260 assert(_primary_supers[d] == this, "proper init");
261 return d;
262 }
263 }
264
265 // java mirror
266 oop java_mirror() const;
267 oop java_mirror_no_keepalive() const;
268 void set_java_mirror(Handle m);
269
270 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
271 void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN;
272
273 // Temporary mirror switch used by RedefineClasses
274 OopHandle java_mirror_handle() const { return _java_mirror; }
275 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
276
277 // Set java mirror OopHandle to null for CDS
278 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
279 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
280
281 // modifier flags
282 jint modifier_flags() const { return _modifier_flags; }
283 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
284
285 // size helper
286 int layout_helper() const { return _layout_helper; }
287 void set_layout_helper(int lh) { _layout_helper = lh; }
288
289 // Note: for instances layout_helper() may include padding.
290 // Use InstanceKlass::contains_field_offset to classify field offsets.
291
292 // sub/superklass links
293 Klass* subklass(bool log = false) const;
294 Klass* next_sibling(bool log = false) const;
295
296 InstanceKlass* superklass() const;
297 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
298
299 void set_next_link(Klass* k) { _next_link = k; }
300 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
301 Klass** next_link_addr() { return &_next_link; }
302
303 // class loader data
304 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
305 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
306
307 s2 shared_classpath_index() const {
308 return _shared_class_path_index;
309 };
310
311 void set_shared_classpath_index(s2 index) {
312 _shared_class_path_index = index;
313 };
314
315 bool has_archived_mirror_index() const {
316 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
317 NOT_CDS_JAVA_HEAP(return false);
318 }
319
320 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
321
322 void set_lambda_proxy_is_available() {
323 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
324 }
325 void clear_lambda_proxy_is_available() {
326 CDS_ONLY(_shared_class_flags &= (u2)(~_archived_lambda_proxy_is_available);)
327 }
328 bool lambda_proxy_is_available() const {
329 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
330 NOT_CDS(return false;)
331 }
332
333 void set_has_value_based_class_annotation() {
334 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
335 }
336 void clear_has_value_based_class_annotation() {
337 CDS_ONLY(_shared_class_flags &= (u2)(~_has_value_based_class_annotation);)
338 }
339 bool has_value_based_class_annotation() const {
340 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
341 NOT_CDS(return false;)
342 }
343
344 void set_verified_at_dump_time() {
345 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
346 }
347 bool verified_at_dump_time() const {
348 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
349 NOT_CDS(return false;)
350 }
351
352 void set_has_archived_enum_objs() {
353 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
354 }
355 bool has_archived_enum_objs() const {
356 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
357 NOT_CDS(return false;)
358 }
359
360 void set_is_generated_shared_class() {
361 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
362 }
363 bool is_generated_shared_class() const {
364 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
365 NOT_CDS(return false;)
366 }
367
368 bool is_shared() const { // shadows MetaspaceObj::is_shared)()
369 CDS_ONLY(return (_shared_class_flags & _is_shared_class) != 0;)
370 NOT_CDS(return false;)
371 }
372
373 void set_is_shared() {
374 CDS_ONLY(_shared_class_flags |= _is_shared_class;)
375 }
376
377 // Obtain the module or package for this class
378 virtual ModuleEntry* module() const = 0;
379 virtual PackageEntry* package() const = 0;
380
381 protected: // internal accessors
382 void set_subklass(Klass* s);
383 void set_next_sibling(Klass* s);
384
385 public:
386
387 // Compiler support
388 static ByteSize super_offset() { return byte_offset_of(Klass, _super); }
389 static ByteSize super_check_offset_offset() { return byte_offset_of(Klass, _super_check_offset); }
390 static ByteSize primary_supers_offset() { return byte_offset_of(Klass, _primary_supers); }
391 static ByteSize secondary_super_cache_offset() { return byte_offset_of(Klass, _secondary_super_cache); }
392 static ByteSize secondary_supers_offset() { return byte_offset_of(Klass, _secondary_supers); }
393 static ByteSize java_mirror_offset() { return byte_offset_of(Klass, _java_mirror); }
394 static ByteSize class_loader_data_offset() { return byte_offset_of(Klass, _class_loader_data); }
395 static ByteSize modifier_flags_offset() { return byte_offset_of(Klass, _modifier_flags); }
396 static ByteSize layout_helper_offset() { return byte_offset_of(Klass, _layout_helper); }
397 static ByteSize access_flags_offset() { return byte_offset_of(Klass, _access_flags); }
398 #if INCLUDE_JVMCI
399 static ByteSize subklass_offset() { return byte_offset_of(Klass, _subklass); }
400 static ByteSize next_sibling_offset() { return byte_offset_of(Klass, _next_sibling); }
401 #endif
402
403 // Unpacking layout_helper:
404 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
405 static const int _lh_instance_slow_path_bit = 0x01;
406 static const int _lh_log2_element_size_shift = BitsPerByte*0;
407 static const int _lh_log2_element_size_mask = BitsPerLong-1;
408 static const int _lh_element_type_shift = BitsPerByte*1;
409 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
410 static const int _lh_header_size_shift = BitsPerByte*2;
411 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
412 static const int _lh_array_tag_bits = 2;
413 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
414 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
415
416 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
417
418 static int layout_helper_size_in_bytes(jint lh) {
419 assert(lh > (jint)_lh_neutral_value, "must be instance");
420 return (int) lh & ~_lh_instance_slow_path_bit;
421 }
422 static bool layout_helper_needs_slow_path(jint lh) {
423 assert(lh > (jint)_lh_neutral_value, "must be instance");
424 return (lh & _lh_instance_slow_path_bit) != 0;
425 }
426 static bool layout_helper_is_instance(jint lh) {
427 return (jint)lh > (jint)_lh_neutral_value;
428 }
429 static bool layout_helper_is_array(jint lh) {
430 return (jint)lh < (jint)_lh_neutral_value;
431 }
432 static bool layout_helper_is_typeArray(jint lh) {
433 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
434 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
435 }
436 static bool layout_helper_is_objArray(jint lh) {
437 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
438 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
439 }
440 static int layout_helper_header_size(jint lh) {
441 assert(lh < (jint)_lh_neutral_value, "must be array");
442 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
443 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
444 return hsize;
445 }
446 static BasicType layout_helper_element_type(jint lh) {
447 assert(lh < (jint)_lh_neutral_value, "must be array");
448 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
449 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
450 return (BasicType) btvalue;
451 }
452
453 // Want a pattern to quickly diff against layout header in register
454 // find something less clever!
455 static int layout_helper_boolean_diffbit() {
456 jint zlh = array_layout_helper(T_BOOLEAN);
457 jint blh = array_layout_helper(T_BYTE);
458 assert(zlh != blh, "array layout helpers must differ");
459 int diffbit = 1;
460 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
461 diffbit <<= 1;
462 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
463 }
464 return diffbit;
465 }
466
467 static int layout_helper_log2_element_size(jint lh) {
468 assert(lh < (jint)_lh_neutral_value, "must be array");
469 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
470 assert(l2esz <= LogBytesPerLong,
471 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
472 return l2esz;
473 }
474 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
475 return (tag << _lh_array_tag_shift)
476 | (hsize << _lh_header_size_shift)
477 | ((int)etype << _lh_element_type_shift)
478 | (log2_esize << _lh_log2_element_size_shift);
479 }
480 static jint instance_layout_helper(jint size, bool slow_path_flag) {
481 return (size << LogBytesPerWord)
482 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
483 }
484 static int layout_helper_to_size_helper(jint lh) {
485 assert(lh > (jint)_lh_neutral_value, "must be instance");
486 // Note that the following expression discards _lh_instance_slow_path_bit.
487 return lh >> LogBytesPerWord;
488 }
489 // Out-of-line version computes everything based on the etype:
490 static jint array_layout_helper(BasicType etype);
491
492 // What is the maximum number of primary superclasses any klass can have?
493 static juint primary_super_limit() { return _primary_super_limit; }
494
495 // vtables
496 klassVtable vtable() const;
497 int vtable_length() const { return _vtable_len; }
498
499 // subclass check
500 bool is_subclass_of(const Klass* k) const;
501 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
502 bool is_subtype_of(Klass* k) const {
503 juint off = k->super_check_offset();
504 Klass* sup = *(Klass**)( (address)this + off );
505 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
506 if (sup == k) {
507 return true;
508 } else if (off != secondary_offset) {
509 return false;
510 } else {
511 return search_secondary_supers(k);
512 }
513 }
514
515 bool search_secondary_supers(Klass* k) const;
516
517 // Find LCA in class hierarchy
518 Klass *LCA( Klass *k );
519
520 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
521 // if not, throw either an Error or an Exception.
522 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
523
524 // array copying
525 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
526
527 // tells if the class should be initialized
528 virtual bool should_be_initialized() const { return false; }
529 // initializes the klass
530 virtual void initialize(TRAPS);
531 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
532 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
533 OverpassLookupMode overpass_mode,
534 PrivateLookupMode = PrivateLookupMode::find) const;
535 public:
536 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
537 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
538 }
539
540 // array class with specific rank
541 virtual ArrayKlass* array_klass(int rank, TRAPS) = 0;
542
543 // array class with this klass as element type
544 virtual ArrayKlass* array_klass(TRAPS) = 0;
545
546 // These will return null instead of allocating on the heap:
547 virtual ArrayKlass* array_klass_or_null(int rank) = 0;
548 virtual ArrayKlass* array_klass_or_null() = 0;
549
550 virtual oop protection_domain() const = 0;
551
552 oop class_loader() const;
553
554 inline oop klass_holder() const;
555
556 protected:
557
558 // Error handling when length > max_length or length < 0
559 static void check_array_allocation_length(int length, int max_length, TRAPS);
560
561 void set_vtable_length(int len) { _vtable_len= len; }
562
563 vtableEntry* start_of_vtable() const;
564 #if INCLUDE_CDS
565 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
566 #endif
567 public:
568 Method* method_at_vtable(int index);
569
570 static ByteSize vtable_start_offset();
571 static ByteSize vtable_length_offset() {
572 return byte_offset_of(Klass, _vtable_len);
573 }
574
575 #if INCLUDE_CDS
576 // CDS support - remove and restore oops from metadata. Oops are not shared.
577 virtual void remove_unshareable_info();
578 virtual void remove_java_mirror();
579
580 bool is_unshareable_info_restored() const {
581 assert(is_shared(), "use this for shared classes only");
582 if (has_archived_mirror_index()) {
583 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
584 return false;
585 } else if (_java_mirror.ptr_raw() == nullptr) {
586 return false;
587 } else {
588 return true;
589 }
590 }
591 #endif // INCLUDE_CDS
592
593 public:
594 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
595 // These functions describe behavior for the oop not the KLASS.
596
597 // actual oop size of obj in memory in word size.
598 virtual size_t oop_size(oop obj) const = 0;
599
600 // Size of klass in word size.
601 virtual int size() const = 0;
602
603 // Returns the Java name for a class (Resource allocated)
604 // For arrays, this returns the name of the element with a leading '['.
605 // For classes, this returns the name with the package separators
606 // turned into '.'s.
607 const char* external_name() const;
608 // Returns the name for a class (Resource allocated) as the class
609 // would appear in a signature.
610 // For arrays, this returns the name of the element with a leading '['.
611 // For classes, this returns the name with a leading 'L' and a trailing ';'
612 // and the package separators as '/'.
613 virtual const char* signature_name() const;
614
615 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
616 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
617
618 // Returns "interface", "abstract class" or "class".
619 const char* external_kind() const;
620
621 // type testing operations
622 #ifdef ASSERT
623 protected:
624 virtual bool is_instance_klass_slow() const { return false; }
625 virtual bool is_array_klass_slow() const { return false; }
626 virtual bool is_objArray_klass_slow() const { return false; }
627 virtual bool is_typeArray_klass_slow() const { return false; }
628 #endif // ASSERT
629 public:
630
631 // Fast non-virtual versions
632 #ifndef ASSERT
633 #define assert_same_query(xval, xcheck) xval
634 #else
635 private:
636 static bool assert_same_query(bool xval, bool xslow) {
637 assert(xval == xslow, "slow and fast queries agree");
638 return xval;
639 }
640 public:
641 #endif
642
643 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
644 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
645 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
646 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
647 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
648 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
649 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
650 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
651 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
652 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
653 #undef assert_same_query
654
655 // Access flags
656 AccessFlags access_flags() const { return _access_flags; }
657 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
658
659 bool is_public() const { return _access_flags.is_public(); }
660 bool is_final() const { return _access_flags.is_final(); }
661 bool is_interface() const { return _access_flags.is_interface(); }
662 bool is_abstract() const { return _access_flags.is_abstract(); }
663 bool is_super() const { return _access_flags.is_super(); }
664 bool is_synthetic() const { return _access_flags.is_synthetic(); }
665 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
666 bool has_finalizer() const { return _access_flags.has_finalizer(); }
667 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
668 bool is_hidden() const { return access_flags().is_hidden_class(); }
669 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
670 bool is_value_based() { return _access_flags.is_value_based_class(); }
671 void set_is_value_based() { _access_flags.set_is_value_based_class(); }
672
673 inline bool is_non_strong_hidden() const;
674
675 bool is_cloneable() const;
676 void set_is_cloneable();
677
678 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
679
680 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
681 virtual MetaspaceObj::Type type() const { return ClassType; }
682
683 inline bool is_loader_alive() const;
684
685 void clean_subklass();
686
687 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
688 static void clean_subklass_tree() {
689 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
690 }
691
692 // Return self, except for abstract classes with exactly 1
693 // implementor. Then return the 1 concrete implementation.
694 Klass *up_cast_abstract();
695
696 // klass name
697 Symbol* name() const { return _name; }
698 void set_name(Symbol* n);
699
700 virtual void release_C_heap_structures(bool release_constant_pool = true);
701
702 public:
703 virtual jint compute_modifier_flags() const = 0;
704
705 // JVMTI support
706 virtual jint jvmti_class_status() const;
707
708 // Printing
709 virtual void print_on(outputStream* st) const;
710
711 virtual void oop_print_value_on(oop obj, outputStream* st);
712 virtual void oop_print_on (oop obj, outputStream* st);
713
714 virtual const char* internal_name() const = 0;
715
716 // Verification
717 virtual void verify_on(outputStream* st);
718 void verify() { verify_on(tty); }
719
720 #ifndef PRODUCT
721 bool verify_vtable_index(int index);
722 #endif
723
724 virtual void oop_verify_on(oop obj, outputStream* st);
725
726 // for error reporting
727 static bool is_valid(Klass* k);
728 };
729
730 #endif // SHARE_OOPS_KLASS_HPP