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 markWord _prototype_header; // Used to initialize objects' header
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 jshort _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 _archived_lambda_proxy_is_available = 1 << 1,
182 _has_value_based_class_annotation = 1 << 2,
183 _verified_at_dump_time = 1 << 3,
184 _has_archived_enum_objs = 1 << 4,
185 // This class was not loaded from a classfile in the module image
186 // or classpath.
187 _is_generated_shared_class = 1 << 5
188 };
189 #endif
190
191 CDS_JAVA_HEAP_ONLY(int _archived_mirror_index;)
192
193 protected:
194
195 // Constructor
196 Klass(KlassKind kind);
197 Klass() : _kind(KlassKind(-1)) { assert(DumpSharedSpaces || UseSharedSpaces, "only for cds"); }
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 int shared_classpath_index() const {
308 return _shared_class_path_index;
309 };
310
311 void set_shared_classpath_index(int 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 &= ~_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 &= ~_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 // Obtain the module or package for this class
369 virtual ModuleEntry* module() const = 0;
370 virtual PackageEntry* package() const = 0;
371
372 protected: // internal accessors
373 void set_subklass(Klass* s);
374 void set_next_sibling(Klass* s);
375
376 public:
377
378 // Compiler support
379 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
380 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
381 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
382 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
383 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
384 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
385 static ByteSize class_loader_data_offset() { return in_ByteSize(offset_of(Klass, _class_loader_data)); }
386 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
387 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
388 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
389
390 // Unpacking layout_helper:
391 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
392 static const int _lh_instance_slow_path_bit = 0x01;
393 static const int _lh_log2_element_size_shift = BitsPerByte*0;
394 static const int _lh_log2_element_size_mask = BitsPerLong-1;
395 static const int _lh_element_type_shift = BitsPerByte*1;
396 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
397 static const int _lh_header_size_shift = BitsPerByte*2;
398 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
399 static const int _lh_array_tag_bits = 2;
400 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
401 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
402
403 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
404
405 static int layout_helper_size_in_bytes(jint lh) {
406 assert(lh > (jint)_lh_neutral_value, "must be instance");
407 return (int) lh & ~_lh_instance_slow_path_bit;
408 }
409 static bool layout_helper_needs_slow_path(jint lh) {
410 assert(lh > (jint)_lh_neutral_value, "must be instance");
411 return (lh & _lh_instance_slow_path_bit) != 0;
412 }
413 static bool layout_helper_is_instance(jint lh) {
414 return (jint)lh > (jint)_lh_neutral_value;
415 }
416 static bool layout_helper_is_array(jint lh) {
417 return (jint)lh < (jint)_lh_neutral_value;
418 }
419 static bool layout_helper_is_typeArray(jint lh) {
420 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
421 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
422 }
423 static bool layout_helper_is_objArray(jint lh) {
424 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
425 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
426 }
427 static int layout_helper_header_size(jint lh) {
428 assert(lh < (jint)_lh_neutral_value, "must be array");
429 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
430 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
431 return hsize;
432 }
433 static BasicType layout_helper_element_type(jint lh) {
434 assert(lh < (jint)_lh_neutral_value, "must be array");
435 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
436 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
437 return (BasicType) btvalue;
438 }
439
440 // Want a pattern to quickly diff against layout header in register
441 // find something less clever!
442 static int layout_helper_boolean_diffbit() {
443 jint zlh = array_layout_helper(T_BOOLEAN);
444 jint blh = array_layout_helper(T_BYTE);
445 assert(zlh != blh, "array layout helpers must differ");
446 int diffbit = 1;
447 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
448 diffbit <<= 1;
449 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
450 }
451 return diffbit;
452 }
453
454 static int layout_helper_log2_element_size(jint lh) {
455 assert(lh < (jint)_lh_neutral_value, "must be array");
456 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
457 assert(l2esz <= LogBytesPerLong,
458 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
459 return l2esz;
460 }
461 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
462 return (tag << _lh_array_tag_shift)
463 | (hsize << _lh_header_size_shift)
464 | ((int)etype << _lh_element_type_shift)
465 | (log2_esize << _lh_log2_element_size_shift);
466 }
467 static jint instance_layout_helper(jint size, bool slow_path_flag) {
468 return (size << LogBytesPerWord)
469 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
470 }
471 static int layout_helper_to_size_helper(jint lh) {
472 assert(lh > (jint)_lh_neutral_value, "must be instance");
473 // Note that the following expression discards _lh_instance_slow_path_bit.
474 return lh >> LogBytesPerWord;
475 }
476 // Out-of-line version computes everything based on the etype:
477 static jint array_layout_helper(BasicType etype);
478
479 // What is the maximum number of primary superclasses any klass can have?
480 static juint primary_super_limit() { return _primary_super_limit; }
481
482 // vtables
483 klassVtable vtable() const;
484 int vtable_length() const { return _vtable_len; }
485
486 // subclass check
487 bool is_subclass_of(const Klass* k) const;
488 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
489 bool is_subtype_of(Klass* k) const {
490 juint off = k->super_check_offset();
491 Klass* sup = *(Klass**)( (address)this + off );
492 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
493 if (sup == k) {
494 return true;
495 } else if (off != secondary_offset) {
496 return false;
497 } else {
498 return search_secondary_supers(k);
499 }
500 }
501
502 bool search_secondary_supers(Klass* k) const;
503
504 // Find LCA in class hierarchy
505 Klass *LCA( Klass *k );
506
507 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
508 // if not, throw either an Error or an Exception.
509 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
510
511 // array copying
512 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
513
514 // tells if the class should be initialized
515 virtual bool should_be_initialized() const { return false; }
516 // initializes the klass
517 virtual void initialize(TRAPS);
518 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
519 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
520 OverpassLookupMode overpass_mode,
521 PrivateLookupMode = PrivateLookupMode::find) const;
522 public:
523 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
524 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
525 }
526
527 // array class with specific rank
528 virtual Klass* array_klass(int rank, TRAPS) = 0;
529
530 // array class with this klass as element type
531 virtual Klass* array_klass(TRAPS) = 0;
532
533 // These will return null instead of allocating on the heap:
534 virtual Klass* array_klass_or_null(int rank) = 0;
535 virtual Klass* array_klass_or_null() = 0;
536
537 virtual oop protection_domain() const = 0;
538
539 oop class_loader() const;
540
541 inline oop klass_holder() const;
542
543 protected:
544
545 // Error handling when length > max_length or length < 0
546 static void check_array_allocation_length(int length, int max_length, TRAPS);
547
548 void set_vtable_length(int len) { _vtable_len= len; }
549
550 vtableEntry* start_of_vtable() const;
551 #if INCLUDE_CDS
552 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
553 #endif
554 public:
555 Method* method_at_vtable(int index);
556
557 static ByteSize vtable_start_offset();
558 static ByteSize vtable_length_offset() {
559 return byte_offset_of(Klass, _vtable_len);
560 }
561
562 #if INCLUDE_CDS
563 // CDS support - remove and restore oops from metadata. Oops are not shared.
564 virtual void remove_unshareable_info();
565 virtual void remove_java_mirror();
566
567 bool is_unshareable_info_restored() const {
568 assert(is_shared(), "use this for shared classes only");
569 if (has_archived_mirror_index()) {
570 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
571 return false;
572 } else if (_java_mirror.ptr_raw() == nullptr) {
573 return false;
574 } else {
575 return true;
576 }
577 }
578 #endif // INCLUDE_CDS
579
580 public:
581 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
582 // These functions describe behavior for the oop not the KLASS.
583
584 // actual oop size of obj in memory in word size.
585 virtual size_t oop_size(oop obj) const = 0;
586
587 // Size of klass in word size.
588 virtual int size() const = 0;
589
590 // Returns the Java name for a class (Resource allocated)
591 // For arrays, this returns the name of the element with a leading '['.
592 // For classes, this returns the name with the package separators
593 // turned into '.'s.
594 const char* external_name() const;
595 // Returns the name for a class (Resource allocated) as the class
596 // would appear in a signature.
597 // For arrays, this returns the name of the element with a leading '['.
598 // For classes, this returns the name with a leading 'L' and a trailing ';'
599 // and the package separators as '/'.
600 virtual const char* signature_name() const;
601
602 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
603 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
604
605 // Returns "interface", "abstract class" or "class".
606 const char* external_kind() const;
607
608 // type testing operations
609 #ifdef ASSERT
610 protected:
611 virtual bool is_instance_klass_slow() const { return false; }
612 virtual bool is_array_klass_slow() const { return false; }
613 virtual bool is_objArray_klass_slow() const { return false; }
614 virtual bool is_typeArray_klass_slow() const { return false; }
615 #endif // ASSERT
616 public:
617
618 // Fast non-virtual versions
619 #ifndef ASSERT
620 #define assert_same_query(xval, xcheck) xval
621 #else
622 private:
623 static bool assert_same_query(bool xval, bool xslow) {
624 assert(xval == xslow, "slow and fast queries agree");
625 return xval;
626 }
627 public:
628 #endif
629
630 bool is_instance_klass() const { return assert_same_query(_kind <= InstanceStackChunkKlassKind, is_instance_klass_slow()); }
631 // Other is anything that is not one of the more specialized kinds of InstanceKlass.
632 bool is_other_instance_klass() const { return _kind == InstanceKlassKind; }
633 bool is_reference_instance_klass() const { return _kind == InstanceRefKlassKind; }
634 bool is_mirror_instance_klass() const { return _kind == InstanceMirrorKlassKind; }
635 bool is_class_loader_instance_klass() const { return _kind == InstanceClassLoaderKlassKind; }
636 bool is_array_klass() const { return assert_same_query( _kind >= TypeArrayKlassKind, is_array_klass_slow()); }
637 bool is_stack_chunk_instance_klass() const { return _kind == InstanceStackChunkKlassKind; }
638 bool is_objArray_klass() const { return assert_same_query( _kind == ObjArrayKlassKind, is_objArray_klass_slow()); }
639 bool is_typeArray_klass() const { return assert_same_query( _kind == TypeArrayKlassKind, is_typeArray_klass_slow()); }
640 #undef assert_same_query
641
642 // Access flags
643 AccessFlags access_flags() const { return _access_flags; }
644 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
645
646 bool is_public() const { return _access_flags.is_public(); }
647 bool is_final() const { return _access_flags.is_final(); }
648 bool is_interface() const { return _access_flags.is_interface(); }
649 bool is_abstract() const { return _access_flags.is_abstract(); }
650 bool is_super() const { return _access_flags.is_super(); }
651 bool is_synthetic() const { return _access_flags.is_synthetic(); }
652 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
653 bool has_finalizer() const { return _access_flags.has_finalizer(); }
654 bool has_final_method() const { return _access_flags.has_final_method(); }
655 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
656 void set_has_final_method() { _access_flags.set_has_final_method(); }
657 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
658 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
659 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
660 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
661 bool is_shared() const { return access_flags().is_shared_class(); } // shadows MetaspaceObj::is_shared)()
662 void set_is_shared() { _access_flags.set_is_shared_class(); }
663 bool is_hidden() const { return access_flags().is_hidden_class(); }
664 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
665 bool is_value_based() { return _access_flags.is_value_based_class(); }
666 void set_is_value_based() { _access_flags.set_is_value_based_class(); }
667
668 inline bool is_non_strong_hidden() const;
669
670 bool is_cloneable() const;
671 void set_is_cloneable();
672
673 markWord prototype_header() const {
674 assert(UseCompactObjectHeaders, "only use with compact object headers");
675 return _prototype_header;
676 }
677 inline void set_prototype_header(markWord header);
678 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
679
680 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
681
682 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
683 virtual MetaspaceObj::Type type() const { return ClassType; }
684
685 inline bool is_loader_alive() const;
686
687 void clean_subklass();
688
689 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
690 static void clean_subklass_tree() {
691 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
692 }
693
694 // Return self, except for abstract classes with exactly 1
695 // implementor. Then return the 1 concrete implementation.
696 Klass *up_cast_abstract();
697
698 // klass name
699 Symbol* name() const { return _name; }
700 void set_name(Symbol* n);
701
702 virtual void release_C_heap_structures(bool release_constant_pool = true);
703
704 public:
705 virtual jint compute_modifier_flags() const = 0;
706
707 // JVMTI support
708 virtual jint jvmti_class_status() const;
709
710 // Printing
711 virtual void print_on(outputStream* st) const;
712
713 virtual void oop_print_value_on(oop obj, outputStream* st);
714 virtual void oop_print_on (oop obj, outputStream* st);
715
716 virtual const char* internal_name() const = 0;
717
718 // Verification
719 virtual void verify_on(outputStream* st);
720 void verify() { verify_on(tty); }
721
722 #ifndef PRODUCT
723 bool verify_vtable_index(int index);
724 #endif
725
726 virtual void oop_verify_on(oop obj, outputStream* st);
727
728 // for error reporting
729 static bool is_valid(Klass* k);
730 };
731
732 #endif // SHARE_OOPS_KLASS_HPP