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 // Klass Kinds for all subclasses of Klass
41 enum KlassKind {
42 InstanceKlassKind,
43 InstanceRefKlassKind,
44 InstanceMirrorKlassKind,
45 InstanceClassLoaderKlassKind,
46 InstanceStackChunkKlassKind,
47 TypeArrayKlassKind,
48 ObjArrayKlassKind
49 };
50
51 const uint KLASS_KIND_COUNT = ObjArrayKlassKind + 1;
52
53 //
54 // A Klass provides:
55 // 1: language level class object (method dictionary etc.)
56 // 2: provide vm dispatch behavior for the object
57 // Both functions are combined into one C++ class.
58
59 // One reason for the oop/klass dichotomy in the implementation is
60 // that we don't want a C++ vtbl pointer in every object. Thus,
61 // normal oops don't have any virtual functions. Instead, they
62 // forward all "virtual" functions to their klass, which does have
63 // a vtbl and does the C++ dispatch depending on the object's
64 // actual type. (See oop.inline.hpp for some of the forwarding code.)
65 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
66
67 // Forward declarations.
68 template <class T> class Array;
69 template <class T> class GrowableArray;
70 class ClassLoaderData;
71 class fieldDescriptor;
72 class klassVtable;
73 class ModuleEntry;
74 class PackageEntry;
75 class ParCompactionManager;
76 class PSPromotionManager;
77 class vtableEntry;
78
79 class Klass : public Metadata {
80 friend class VMStructs;
81 friend class JVMCIVMStructs;
82 protected:
83 // If you add a new field that points to any metaspace object, you
84 // must add this field to Klass::metaspace_pointers_do().
85
86 // note: put frequently-used fields together at start of klass structure
87 // for better cache behavior (may not make much of a difference but sure won't hurt)
88 enum { _primary_super_limit = 8 };
89
90 // The "layout helper" is a combined descriptor of object layout.
91 // For klasses which are neither instance nor array, the value is zero.
92 //
93 // For instances, layout helper is a positive number, the instance size.
94 // This size is already passed through align_object_size and scaled to bytes.
95 // The low order bit is set if instances of this class cannot be
96 // allocated using the fastpath.
97 //
98 // For arrays, layout helper is a negative number, containing four
99 // distinct bytes, as follows:
100 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
101 // where:
102 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
103 // hsz is array header size in bytes (i.e., offset of first element)
104 // ebt is the BasicType of the elements
105 // esz is the element size in bytes
106 // This packed word is arranged so as to be quickly unpacked by the
107 // various fast paths that use the various subfields.
108 //
109 // The esz bits can be used directly by a SLL instruction, without masking.
110 //
111 // Note that the array-kind tag looks like 0x00 for instance klasses,
112 // since their length in bytes is always less than 24Mb.
113 //
114 // Final note: This comes first, immediately after C++ vtable,
115 // because it is frequently queried.
116 jint _layout_helper;
117
118 // Klass kind used to resolve the runtime type of the instance.
119 // - Used to implement devirtualized oop closure dispatching.
120 // - Various type checking in the JVM
121 const KlassKind _kind;
122
123 // Processed access flags, for use by Class.getModifiers.
124 jint _modifier_flags;
125
126 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
127 // and _primary_supers all help make fast subtype checks. See big discussion
128 // in doc/server_compiler/checktype.txt
129 //
130 // Where to look to observe a supertype (it is &_secondary_super_cache for
131 // secondary supers, else is &_primary_supers[depth()].
132 juint _super_check_offset;
133
134 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
135 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
136 Symbol* _name;
137
138 // Cache of last observed secondary supertype
139 Klass* _secondary_super_cache;
140 // Array of all secondary supertypes
141 Array<Klass*>* _secondary_supers;
142 // Ordered list of all primary supertypes
143 Klass* _primary_supers[_primary_super_limit];
144 // java/lang/Class instance mirroring this class
145 OopHandle _java_mirror;
146 // Superclass
147 Klass* _super;
148 // First subclass (null if none); _subklass->next_sibling() is next one
149 Klass* volatile _subklass;
150 // Sibling link (or null); links all subklasses of a klass
151 Klass* volatile _next_sibling;
152
153 // All klasses loaded by a class loader are chained through these links
154 Klass* _next_link;
155
156 // The VM's representation of the ClassLoader used to load this class.
157 // Provide access the corresponding instance java.lang.ClassLoader.
158 ClassLoaderData* _class_loader_data;
159
160 int _vtable_len; // vtable length. This field may be read very often when we
161 // have lots of itable dispatches (e.g., lambdas and streams).
162 // Keep it away from the beginning of a Klass to avoid cacheline
163 // contention that may happen when a nearby object is modified.
164 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
165
166 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
167
168 private:
169 // This is an index into FileMapHeader::_shared_path_table[], to
170 // associate this class with the JAR file where it's loaded from during
171 // dump time. If a class is not loaded from the shared archive, this field is
172 // -1.
173 jshort _shared_class_path_index;
174
175 #if INCLUDE_CDS
176 // Various attributes for shared classes. Should be zero for a non-shared class.
177 u2 _shared_class_flags;
178 enum CDSSharedClassFlags {
179 _archived_lambda_proxy_is_available = 1 << 1,
180 _has_value_based_class_annotation = 1 << 2,
181 _verified_at_dump_time = 1 << 3,
182 _has_archived_enum_objs = 1 << 4,
183 // This class was not loaded from a classfile in the module image
184 // or classpath.
185 _is_generated_shared_class = 1 << 5
186 };
187 #endif
188
189 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
190
191 protected:
192
193 // Constructor
194 Klass(KlassKind kind);
195 Klass() : _kind(KlassKind(-1)) { assert(DumpSharedSpaces || UseSharedSpaces, "only for cds"); }
196
197 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
198
199 public:
200 int kind() { return _kind; }
201
202 enum class DefaultsLookupMode { find, skip };
203 enum class OverpassLookupMode { find, skip };
204 enum class StaticLookupMode { find, skip };
205 enum class PrivateLookupMode { find, skip };
206
207 virtual bool is_klass() const { return true; }
208
209 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
210 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
211 // If this is not what your code expects, you're probably looking for Klass::java_super().
212 Klass* super() const { return _super; }
213 void set_super(Klass* k) { _super = k; }
214
215 // initializes _super link, _primary_supers & _secondary_supers arrays
216 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
217
218 // klass-specific helper for initializing _secondary_supers
219 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
220 Array<InstanceKlass*>* transitive_interfaces);
221
222 // java_super is the Java-level super type as specified by Class.getSuperClass.
223 virtual InstanceKlass* java_super() const { return nullptr; }
224
225 juint super_check_offset() const { return _super_check_offset; }
226 void set_super_check_offset(juint o) { _super_check_offset = o; }
227
228 Klass* secondary_super_cache() const { return _secondary_super_cache; }
229 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
230
231 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
232 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
233
234 // Return the element of the _super chain of the given depth.
235 // If there is no such element, return either null or this.
236 Klass* primary_super_of_depth(juint i) const {
237 assert(i < primary_super_limit(), "oob");
238 Klass* super = _primary_supers[i];
239 assert(super == nullptr || super->super_depth() == i, "correct display");
240 return super;
241 }
242
243 // Can this klass be a primary super? False for interfaces and arrays of
244 // interfaces. False also for arrays or classes with long super chains.
245 bool can_be_primary_super() const {
246 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
247 return super_check_offset() != secondary_offset;
248 }
249 virtual bool can_be_primary_super_slow() const;
250
251 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
252 juint super_depth() const {
253 if (!can_be_primary_super()) {
254 return primary_super_limit();
255 } else {
256 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
257 assert(d < primary_super_limit(), "oob");
258 assert(_primary_supers[d] == this, "proper init");
259 return d;
260 }
261 }
262
263 // java mirror
264 oop java_mirror() const;
265 oop java_mirror_no_keepalive() const;
266 void set_java_mirror(Handle m);
267
268 oop archived_java_mirror() NOT_CDS_JAVA_HEAP_RETURN_(nullptr);
269 void set_archived_java_mirror(int mirror_index) NOT_CDS_JAVA_HEAP_RETURN;
270
271 // Temporary mirror switch used by RedefineClasses
272 OopHandle java_mirror_handle() const { return _java_mirror; }
273 void swap_java_mirror_handle(OopHandle& mirror) { _java_mirror.swap(mirror); }
274
275 // Set java mirror OopHandle to null for CDS
276 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
277 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
278
279 // modifier flags
280 jint modifier_flags() const { return _modifier_flags; }
281 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
282
283 // size helper
284 int layout_helper() const { return _layout_helper; }
285 void set_layout_helper(int lh) { _layout_helper = lh; }
286
287 // Note: for instances layout_helper() may include padding.
288 // Use InstanceKlass::contains_field_offset to classify field offsets.
289
290 // sub/superklass links
291 Klass* subklass(bool log = false) const;
292 Klass* next_sibling(bool log = false) const;
293
294 InstanceKlass* superklass() const;
295 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
296
297 void set_next_link(Klass* k) { _next_link = k; }
298 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
299 Klass** next_link_addr() { return &_next_link; }
300
301 // class loader data
302 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
303 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
304
305 int shared_classpath_index() const {
306 return _shared_class_path_index;
307 };
308
309 void set_shared_classpath_index(int index) {
310 _shared_class_path_index = index;
311 };
312
313 bool has_archived_mirror_index() const {
314 CDS_JAVA_HEAP_ONLY(return _archived_mirror_index >= 0;)
315 NOT_CDS_JAVA_HEAP(return false);
316 }
317
318 void clear_archived_mirror_index() NOT_CDS_JAVA_HEAP_RETURN;
319
320 void set_lambda_proxy_is_available() {
321 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
322 }
323 void clear_lambda_proxy_is_available() {
324 CDS_ONLY(_shared_class_flags &= ~_archived_lambda_proxy_is_available;)
325 }
326 bool lambda_proxy_is_available() const {
327 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
328 NOT_CDS(return false;)
329 }
330
331 void set_has_value_based_class_annotation() {
332 CDS_ONLY(_shared_class_flags |= _has_value_based_class_annotation;)
333 }
334 void clear_has_value_based_class_annotation() {
335 CDS_ONLY(_shared_class_flags &= ~_has_value_based_class_annotation;)
336 }
337 bool has_value_based_class_annotation() const {
338 CDS_ONLY(return (_shared_class_flags & _has_value_based_class_annotation) != 0;)
339 NOT_CDS(return false;)
340 }
341
342 void set_verified_at_dump_time() {
343 CDS_ONLY(_shared_class_flags |= _verified_at_dump_time;)
344 }
345 bool verified_at_dump_time() const {
346 CDS_ONLY(return (_shared_class_flags & _verified_at_dump_time) != 0;)
347 NOT_CDS(return false;)
348 }
349
350 void set_has_archived_enum_objs() {
351 CDS_ONLY(_shared_class_flags |= _has_archived_enum_objs;)
352 }
353 bool has_archived_enum_objs() const {
354 CDS_ONLY(return (_shared_class_flags & _has_archived_enum_objs) != 0;)
355 NOT_CDS(return false;)
356 }
357
358 void set_is_generated_shared_class() {
359 CDS_ONLY(_shared_class_flags |= _is_generated_shared_class;)
360 }
361 bool is_generated_shared_class() const {
362 CDS_ONLY(return (_shared_class_flags & _is_generated_shared_class) != 0;)
363 NOT_CDS(return false;)
364 }
365
366 // Obtain the module or package for this class
367 virtual ModuleEntry* module() const = 0;
368 virtual PackageEntry* package() const = 0;
369
370 protected: // internal accessors
371 void set_subklass(Klass* s);
372 void set_next_sibling(Klass* s);
373
374 public:
375
376 // Compiler support
377 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
378 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
379 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
380 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
381 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
382 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
383 static ByteSize class_loader_data_offset() { return in_ByteSize(offset_of(Klass, _class_loader_data)); }
384 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
385 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
386 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
387
388 // Unpacking layout_helper:
389 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
390 static const int _lh_instance_slow_path_bit = 0x01;
391 static const int _lh_log2_element_size_shift = BitsPerByte*0;
392 static const int _lh_log2_element_size_mask = BitsPerLong-1;
393 static const int _lh_element_type_shift = BitsPerByte*1;
394 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
395 static const int _lh_header_size_shift = BitsPerByte*2;
396 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
397 static const int _lh_array_tag_bits = 2;
398 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
399 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
400
401 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
402
403 static int layout_helper_size_in_bytes(jint lh) {
404 assert(lh > (jint)_lh_neutral_value, "must be instance");
405 return (int) lh & ~_lh_instance_slow_path_bit;
406 }
407 static bool layout_helper_needs_slow_path(jint lh) {
408 assert(lh > (jint)_lh_neutral_value, "must be instance");
409 return (lh & _lh_instance_slow_path_bit) != 0;
410 }
411 static bool layout_helper_is_instance(jint lh) {
412 return (jint)lh > (jint)_lh_neutral_value;
413 }
414 static bool layout_helper_is_array(jint lh) {
415 return (jint)lh < (jint)_lh_neutral_value;
416 }
417 static bool layout_helper_is_typeArray(jint lh) {
418 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
419 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
420 }
421 static bool layout_helper_is_objArray(jint lh) {
422 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
423 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
424 }
425 static int layout_helper_header_size(jint lh) {
426 assert(lh < (jint)_lh_neutral_value, "must be array");
427 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
428 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
429 return hsize;
430 }
431 static BasicType layout_helper_element_type(jint lh) {
432 assert(lh < (jint)_lh_neutral_value, "must be array");
433 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
434 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
435 return (BasicType) btvalue;
436 }
437
438 // Want a pattern to quickly diff against layout header in register
439 // find something less clever!
440 static int layout_helper_boolean_diffbit() {
441 jint zlh = array_layout_helper(T_BOOLEAN);
442 jint blh = array_layout_helper(T_BYTE);
443 assert(zlh != blh, "array layout helpers must differ");
444 int diffbit = 1;
445 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
446 diffbit <<= 1;
447 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
448 }
449 return diffbit;
450 }
451
452 static int layout_helper_log2_element_size(jint lh) {
453 assert(lh < (jint)_lh_neutral_value, "must be array");
454 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
455 assert(l2esz <= LogBytesPerLong,
456 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
457 return l2esz;
458 }
459 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
460 return (tag << _lh_array_tag_shift)
461 | (hsize << _lh_header_size_shift)
462 | ((int)etype << _lh_element_type_shift)
463 | (log2_esize << _lh_log2_element_size_shift);
464 }
465 static jint instance_layout_helper(jint size, bool slow_path_flag) {
466 return (size << LogBytesPerWord)
467 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
468 }
469 static int layout_helper_to_size_helper(jint lh) {
470 assert(lh > (jint)_lh_neutral_value, "must be instance");
471 // Note that the following expression discards _lh_instance_slow_path_bit.
472 return lh >> LogBytesPerWord;
473 }
474 // Out-of-line version computes everything based on the etype:
475 static jint array_layout_helper(BasicType etype);
476
477 // What is the maximum number of primary superclasses any klass can have?
478 static juint primary_super_limit() { return _primary_super_limit; }
479
480 // vtables
481 klassVtable vtable() const;
482 int vtable_length() const { return _vtable_len; }
483
484 // subclass check
485 bool is_subclass_of(const Klass* k) const;
486 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
487 bool is_subtype_of(Klass* k) const {
488 juint off = k->super_check_offset();
489 Klass* sup = *(Klass**)( (address)this + off );
490 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
491 if (sup == k) {
492 return true;
493 } else if (off != secondary_offset) {
494 return false;
495 } else {
496 return search_secondary_supers(k);
497 }
498 }
499
500 bool search_secondary_supers(Klass* k) const;
501
502 // Find LCA in class hierarchy
503 Klass *LCA( Klass *k );
504
505 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
506 // if not, throw either an Error or an Exception.
507 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
508
509 // array copying
510 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
511
512 // tells if the class should be initialized
513 virtual bool should_be_initialized() const { return false; }
514 // initializes the klass
515 virtual void initialize(TRAPS);
516 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
517 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
518 OverpassLookupMode overpass_mode,
519 PrivateLookupMode = PrivateLookupMode::find) const;
520 public:
521 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
522 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
523 }
524
525 // array class with specific rank
526 virtual Klass* array_klass(int rank, TRAPS) = 0;
527
528 // array class with this klass as element type
529 virtual Klass* array_klass(TRAPS) = 0;
530
531 // These will return null instead of allocating on the heap:
532 virtual Klass* array_klass_or_null(int rank) = 0;
533 virtual Klass* array_klass_or_null() = 0;
534
535 virtual oop protection_domain() const = 0;
536
537 oop class_loader() const;
538
539 inline oop klass_holder() const;
540
541 protected:
542
543 // Error handling when length > max_length or length < 0
544 static void check_array_allocation_length(int length, int max_length, TRAPS);
545
546 void set_vtable_length(int len) { _vtable_len= len; }
547
548 vtableEntry* start_of_vtable() const;
549 #if INCLUDE_CDS
550 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
551 #endif
552 public:
553 Method* method_at_vtable(int index);
554
555 static ByteSize vtable_start_offset();
556 static ByteSize vtable_length_offset() {
557 return byte_offset_of(Klass, _vtable_len);
558 }
559
560 #if INCLUDE_CDS
561 // CDS support - remove and restore oops from metadata. Oops are not shared.
562 virtual void remove_unshareable_info();
563 virtual void remove_java_mirror();
564
565 bool is_unshareable_info_restored() const {
566 assert(is_shared(), "use this for shared classes only");
567 if (has_archived_mirror_index()) {
568 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
569 return false;
570 } else if (_java_mirror.ptr_raw() == nullptr) {
571 return false;
572 } else {
573 return true;
574 }
575 }
576 #endif // INCLUDE_CDS
577
578 public:
579 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
580 // These functions describe behavior for the oop not the KLASS.
581
582 // actual oop size of obj in memory in word size.
583 virtual size_t oop_size(oop obj) const = 0;
584
585 // Size of klass in word size.
586 virtual int size() const = 0;
587
588 // Returns the Java name for a class (Resource allocated)
589 // For arrays, this returns the name of the element with a leading '['.
590 // For classes, this returns the name with the package separators
591 // turned into '.'s.
592 const char* external_name() const;
593 // Returns the name for a class (Resource allocated) as the class
594 // would appear in a signature.
595 // For arrays, this returns the name of the element with a leading '['.
596 // For classes, this returns the name with a leading 'L' and a trailing ';'
597 // and the package separators as '/'.
598 virtual const char* signature_name() const;
599
600 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
601 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
602
603 // Returns "interface", "abstract class" or "class".
604 const char* external_kind() const;
605
606 // type testing operations
607 #ifdef ASSERT
608 protected:
609 virtual bool is_instance_klass_slow() const { return false; }
610 virtual bool is_array_klass_slow() const { return false; }
611 virtual bool is_objArray_klass_slow() const { return false; }
612 virtual bool is_typeArray_klass_slow() const { return false; }
613 #endif // ASSERT
614 public:
615
616 // Fast non-virtual versions
617 #ifndef ASSERT
618 #define assert_same_query(xval, xcheck) xval
619 #else
620 private:
621 static bool assert_same_query(bool xval, bool xslow) {
622 assert(xval == xslow, "slow and fast queries agree");
623 return xval;
624 }
625 public:
626 #endif
627
628 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
629 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
630 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
631 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
632 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
633 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
634 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
635 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
636 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
637 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
638 #undef assert_same_query
639
640 // Access flags
641 AccessFlags access_flags() const { return _access_flags; }
642 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
643
644 bool is_public() const { return _access_flags.is_public(); }
645 bool is_final() const { return _access_flags.is_final(); }
646 bool is_interface() const { return _access_flags.is_interface(); }
647 bool is_abstract() const { return _access_flags.is_abstract(); }
648 bool is_super() const { return _access_flags.is_super(); }
649 bool is_synthetic() const { return _access_flags.is_synthetic(); }
650 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
651 bool has_finalizer() const { return _access_flags.has_finalizer(); }
652 bool has_final_method() const { return _access_flags.has_final_method(); }
653 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
654 void set_has_final_method() { _access_flags.set_has_final_method(); }
655 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
656 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
657 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
658 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
659 bool is_shared() const { return access_flags().is_shared_class(); } // shadows MetaspaceObj::is_shared)()
660 void set_is_shared() { _access_flags.set_is_shared_class(); }
661 bool is_hidden() const { return access_flags().is_hidden_class(); }
662 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
663 bool is_value_based() { return _access_flags.is_value_based_class(); }
664 void set_is_value_based() { _access_flags.set_is_value_based_class(); }
665
666 inline bool is_non_strong_hidden() const;
667
668 bool is_cloneable() const;
669 void set_is_cloneable();
670
671 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
672
673 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
674 virtual MetaspaceObj::Type type() const { return ClassType; }
675
676 inline bool is_loader_alive() const;
677
678 void clean_subklass();
679
680 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
681 static void clean_subklass_tree() {
682 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
683 }
684
685 // Return self, except for abstract classes with exactly 1
686 // implementor. Then return the 1 concrete implementation.
687 Klass *up_cast_abstract();
688
689 // klass name
690 Symbol* name() const { return _name; }
691 void set_name(Symbol* n);
692
693 virtual void release_C_heap_structures(bool release_constant_pool = true);
694
695 public:
696 virtual jint compute_modifier_flags() const = 0;
697
698 // JVMTI support
699 virtual jint jvmti_class_status() const;
700
701 // Printing
702 virtual void print_on(outputStream* st) const;
703
704 virtual void oop_print_value_on(oop obj, outputStream* st);
705 virtual void oop_print_on (oop obj, outputStream* st);
706
707 virtual const char* internal_name() const = 0;
708
709 // Verification
710 virtual void verify_on(outputStream* st);
711 void verify() { verify_on(tty); }
712
713 #ifndef PRODUCT
714 bool verify_vtable_index(int index);
715 #endif
716
717 virtual void oop_verify_on(oop obj, outputStream* st);
718
719 // for error reporting
720 static bool is_valid(Klass* k);
721 };
722
723 #endif // SHARE_OOPS_KLASS_HPP