1 /*
2 * Copyright (c) 1997, 2020, 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 *
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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 *
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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.
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23 */
24
25 #ifndef SHARE_OOPS_KLASS_HPP
26 #define SHARE_OOPS_KLASS_HPP
27
28 #include "classfile/classLoaderData.hpp"
29 #include "memory/iterator.hpp"
30 #include "memory/memRegion.hpp"
31 #include "oops/markWord.hpp"
32 #include "oops/metadata.hpp"
33 #include "oops/oop.hpp"
34 #include "oops/oopHandle.hpp"
35 #include "utilities/accessFlags.hpp"
36 #include "utilities/macros.hpp"
37 #if INCLUDE_JFR
38 #include "jfr/support/jfrTraceIdExtension.hpp"
39 #endif
40
41 // Klass IDs for all subclasses of Klass
42 enum KlassID {
43 InstanceKlassID,
44 InstanceRefKlassID,
45 InstanceMirrorKlassID,
46 InstanceClassLoaderKlassID,
47 TypeArrayKlassID,
48 ObjArrayKlassID
49 };
50
51 const uint KLASS_ID_COUNT = 6;
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 fieldDescriptor;
71 class klassVtable;
72 class ModuleEntry;
73 class PackageEntry;
74 class ParCompactionManager;
75 class PSPromotionManager;
76 class vtableEntry;
77
78 class Klass : public Metadata {
79 friend class VMStructs;
80 friend class JVMCIVMStructs;
81 protected:
82 // If you add a new field that points to any metaspace object, you
83 // must add this field to Klass::metaspace_pointers_do().
84
85 // note: put frequently-used fields together at start of klass structure
86 // for better cache behavior (may not make much of a difference but sure won't hurt)
87 enum { _primary_super_limit = 8 };
88
89 // The "layout helper" is a combined descriptor of object layout.
90 // For klasses which are neither instance nor array, the value is zero.
91 //
92 // For instances, layout helper is a positive number, the instance size.
93 // This size is already passed through align_object_size and scaled to bytes.
94 // The low order bit is set if instances of this class cannot be
95 // allocated using the fastpath.
96 //
97 // For arrays, layout helper is a negative number, containing four
98 // distinct bytes, as follows:
99 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
100 // where:
101 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
102 // hsz is array header size in bytes (i.e., offset of first element)
103 // ebt is the BasicType of the elements
104 // esz is the element size in bytes
105 // This packed word is arranged so as to be quickly unpacked by the
106 // various fast paths that use the various subfields.
107 //
108 // The esz bits can be used directly by a SLL instruction, without masking.
109 //
110 // Note that the array-kind tag looks like 0x00 for instance klasses,
111 // since their length in bytes is always less than 24Mb.
112 //
113 // Final note: This comes first, immediately after C++ vtable,
114 // because it is frequently queried.
115 jint _layout_helper;
116
117 // Klass identifier used to implement devirtualized oop closure dispatching.
118 const KlassID _id;
119
120 // vtable length
121 int _vtable_len;
122
123 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
124 // and _primary_supers all help make fast subtype checks. See big discussion
125 // in doc/server_compiler/checktype.txt
126 //
127 // Where to look to observe a supertype (it is &_secondary_super_cache for
128 // secondary supers, else is &_primary_supers[depth()].
129 juint _super_check_offset;
130
131 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
132 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
133 Symbol* _name;
134
135 // Cache of last observed secondary supertype
136 Klass* _secondary_super_cache;
137 // Array of all secondary supertypes
138 Array<Klass*>* _secondary_supers;
139 // Ordered list of all primary supertypes
140 Klass* _primary_supers[_primary_super_limit];
141 // java/lang/Class instance mirroring this class
142 OopHandle _java_mirror;
143 // Superclass
144 Klass* _super;
145 // First subclass (NULL if none); _subklass->next_sibling() is next one
146 Klass* volatile _subklass;
147 // Sibling link (or NULL); links all subklasses of a klass
148 Klass* volatile _next_sibling;
149
150 // All klasses loaded by a class loader are chained through these links
151 Klass* _next_link;
152
153 // The VM's representation of the ClassLoader used to load this class.
154 // Provide access the corresponding instance java.lang.ClassLoader.
155 ClassLoaderData* _class_loader_data;
156
157 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
158 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
159
160 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
161
162 // Biased locking implementation and statistics
163 // (the 64-bit chunk goes first, to avoid some fragmentation)
164 jlong _last_biased_lock_bulk_revocation_time;
165 markWord _prototype_header; // Used when biased locking is both enabled and disabled for this type
166 jint _biased_lock_revocation_count;
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 // Flags of the current shared class.
177 u2 _shared_class_flags;
178 enum {
179 _has_raw_archived_mirror = 1,
180 _archived_lambda_proxy_is_available = 2
181 };
182 #endif
183
184 // The _archived_mirror is set at CDS dump time pointing to the cached mirror
185 // in the open archive heap region when archiving java object is supported.
186 CDS_JAVA_HEAP_ONLY(narrowOop _archived_mirror;)
187
188 protected:
189
190 // Constructor
191 Klass(KlassID id);
192 Klass() : _id(KlassID(-1)) { assert(DumpSharedSpaces || UseSharedSpaces, "only for cds"); }
193
194 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
195
196 public:
197 int id() { return _id; }
198
199 enum class DefaultsLookupMode { find, skip };
200 enum class OverpassLookupMode { find, skip };
201 enum class StaticLookupMode { find, skip };
202 enum class PrivateLookupMode { find, skip };
203
204 virtual bool is_klass() const { return true; }
205
206 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
207 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
208 // If this is not what your code expects, you're probably looking for Klass::java_super().
209 Klass* super() const { return _super; }
210 void set_super(Klass* k) { _super = k; }
211
212 // initializes _super link, _primary_supers & _secondary_supers arrays
213 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
214
215 // klass-specific helper for initializing _secondary_supers
216 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
217 Array<InstanceKlass*>* transitive_interfaces);
218
219 // java_super is the Java-level super type as specified by Class.getSuperClass.
220 virtual InstanceKlass* java_super() const { return NULL; }
221
222 juint super_check_offset() const { return _super_check_offset; }
223 void set_super_check_offset(juint o) { _super_check_offset = o; }
224
225 Klass* secondary_super_cache() const { return _secondary_super_cache; }
226 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
227
228 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
229 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
230
231 // Return the element of the _super chain of the given depth.
232 // If there is no such element, return either NULL or this.
233 Klass* primary_super_of_depth(juint i) const {
234 assert(i < primary_super_limit(), "oob");
235 Klass* super = _primary_supers[i];
236 assert(super == NULL || super->super_depth() == i, "correct display");
237 return super;
238 }
239
240 // Can this klass be a primary super? False for interfaces and arrays of
241 // interfaces. False also for arrays or classes with long super chains.
242 bool can_be_primary_super() const {
243 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
244 return super_check_offset() != secondary_offset;
245 }
246 virtual bool can_be_primary_super_slow() const;
247
248 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
249 juint super_depth() const {
250 if (!can_be_primary_super()) {
251 return primary_super_limit();
252 } else {
253 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
254 assert(d < primary_super_limit(), "oob");
255 assert(_primary_supers[d] == this, "proper init");
256 return d;
257 }
258 }
259
260 // java mirror
261 oop java_mirror() const;
262 oop java_mirror_no_keepalive() const;
263 void set_java_mirror(Handle m);
264
265 oop archived_java_mirror_raw() NOT_CDS_JAVA_HEAP_RETURN_(NULL); // no GC barrier
266 narrowOop archived_java_mirror_raw_narrow() NOT_CDS_JAVA_HEAP_RETURN_(narrowOop::null); // no GC barrier
267 void set_archived_java_mirror_raw(oop m) NOT_CDS_JAVA_HEAP_RETURN; // no GC barrier
268
269 // Temporary mirror switch used by RedefineClasses
270 void replace_java_mirror(oop mirror);
271
272 // Set java mirror OopHandle to NULL for CDS
273 // This leaves the OopHandle in the CLD, but that's ok, you can't release them.
274 void clear_java_mirror_handle() { _java_mirror = OopHandle(); }
275
276 // modifier flags
277 jint modifier_flags() const { return _modifier_flags; }
278 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
279
280 // size helper
281 int layout_helper() const { return _layout_helper; }
282 void set_layout_helper(int lh) { _layout_helper = lh; }
283
284 // Note: for instances layout_helper() may include padding.
285 // Use InstanceKlass::contains_field_offset to classify field offsets.
286
287 // sub/superklass links
288 Klass* subklass(bool log = false) const;
289 Klass* next_sibling(bool log = false) const;
290
291 InstanceKlass* superklass() const;
292 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
293
294 void set_next_link(Klass* k) { _next_link = k; }
295 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
296 Klass** next_link_addr() { return &_next_link; }
297
298 // class loader data
299 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
300 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
301
302 int shared_classpath_index() const {
303 return _shared_class_path_index;
304 };
305
306 void set_shared_classpath_index(int index) {
307 _shared_class_path_index = index;
308 };
309
310 void set_has_raw_archived_mirror() {
311 CDS_ONLY(_shared_class_flags |= _has_raw_archived_mirror;)
312 }
313 void clear_has_raw_archived_mirror() {
314 CDS_ONLY(_shared_class_flags &= ~_has_raw_archived_mirror;)
315 }
316 bool has_raw_archived_mirror() const {
317 CDS_ONLY(return (_shared_class_flags & _has_raw_archived_mirror) != 0;)
318 NOT_CDS(return false;)
319 }
320
321 void set_lambda_proxy_is_available() {
322 CDS_ONLY(_shared_class_flags |= _archived_lambda_proxy_is_available;)
323 }
324 void clear_lambda_proxy_is_available() {
325 CDS_ONLY(_shared_class_flags &= ~_archived_lambda_proxy_is_available;)
326 }
327 bool lambda_proxy_is_available() const {
328 CDS_ONLY(return (_shared_class_flags & _archived_lambda_proxy_is_available) != 0;)
329 NOT_CDS(return false;)
330 }
331
332 // Obtain the module or package for this class
333 virtual ModuleEntry* module() const = 0;
334 virtual PackageEntry* package() const = 0;
335
336 protected: // internal accessors
337 void set_subklass(Klass* s);
338 void set_next_sibling(Klass* s);
339
340 public:
341
342 // Compiler support
343 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
344 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
345 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
346 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
347 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
348 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
349 static ByteSize class_loader_data_offset() { return in_ByteSize(offset_of(Klass, _class_loader_data)); }
350 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
351 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
352 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
353
354 // Unpacking layout_helper:
355 static const int _lh_neutral_value = 0; // neutral non-array non-instance value
356 static const int _lh_instance_slow_path_bit = 0x01;
357 static const int _lh_log2_element_size_shift = BitsPerByte*0;
358 static const int _lh_log2_element_size_mask = BitsPerLong-1;
359 static const int _lh_element_type_shift = BitsPerByte*1;
360 static const int _lh_element_type_mask = right_n_bits(BitsPerByte); // shifted mask
361 static const int _lh_header_size_shift = BitsPerByte*2;
362 static const int _lh_header_size_mask = right_n_bits(BitsPerByte); // shifted mask
363 static const int _lh_array_tag_bits = 2;
364 static const int _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits;
365 static const int _lh_array_tag_obj_value = ~0x01; // 0x80000000 >> 30
366
367 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
368
369 static int layout_helper_size_in_bytes(jint lh) {
370 assert(lh > (jint)_lh_neutral_value, "must be instance");
371 return (int) lh & ~_lh_instance_slow_path_bit;
372 }
373 static bool layout_helper_needs_slow_path(jint lh) {
374 assert(lh > (jint)_lh_neutral_value, "must be instance");
375 return (lh & _lh_instance_slow_path_bit) != 0;
376 }
377 static bool layout_helper_is_instance(jint lh) {
378 return (jint)lh > (jint)_lh_neutral_value;
379 }
380 static bool layout_helper_is_array(jint lh) {
381 return (jint)lh < (jint)_lh_neutral_value;
382 }
383 static bool layout_helper_is_typeArray(jint lh) {
384 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
385 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
386 }
387 static bool layout_helper_is_objArray(jint lh) {
388 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
389 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
390 }
391 static int layout_helper_header_size(jint lh) {
392 assert(lh < (jint)_lh_neutral_value, "must be array");
393 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
394 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
395 return hsize;
396 }
397 static BasicType layout_helper_element_type(jint lh) {
398 assert(lh < (jint)_lh_neutral_value, "must be array");
399 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
400 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
401 return (BasicType) btvalue;
402 }
403
404 // Want a pattern to quickly diff against layout header in register
405 // find something less clever!
406 static int layout_helper_boolean_diffbit() {
407 jint zlh = array_layout_helper(T_BOOLEAN);
408 jint blh = array_layout_helper(T_BYTE);
409 assert(zlh != blh, "array layout helpers must differ");
410 int diffbit = 1;
411 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
412 diffbit <<= 1;
413 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
414 }
415 return diffbit;
416 }
417
418 static int layout_helper_log2_element_size(jint lh) {
419 assert(lh < (jint)_lh_neutral_value, "must be array");
420 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
421 assert(l2esz <= LogBytesPerLong,
422 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
423 return l2esz;
424 }
425 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
426 return (tag << _lh_array_tag_shift)
427 | (hsize << _lh_header_size_shift)
428 | ((int)etype << _lh_element_type_shift)
429 | (log2_esize << _lh_log2_element_size_shift);
430 }
431 static jint instance_layout_helper(jint size, bool slow_path_flag) {
432 return (size << LogBytesPerWord)
433 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
434 }
435 static int layout_helper_to_size_helper(jint lh) {
436 assert(lh > (jint)_lh_neutral_value, "must be instance");
437 // Note that the following expression discards _lh_instance_slow_path_bit.
438 return lh >> LogBytesPerWord;
439 }
440 // Out-of-line version computes everything based on the etype:
441 static jint array_layout_helper(BasicType etype);
442
443 // What is the maximum number of primary superclasses any klass can have?
444 static juint primary_super_limit() { return _primary_super_limit; }
445
446 // vtables
447 klassVtable vtable() const;
448 int vtable_length() const { return _vtable_len; }
449
450 // subclass check
451 bool is_subclass_of(const Klass* k) const;
452 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
453 bool is_subtype_of(Klass* k) const {
454 juint off = k->super_check_offset();
455 Klass* sup = *(Klass**)( (address)this + off );
456 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
457 if (sup == k) {
458 return true;
459 } else if (off != secondary_offset) {
460 return false;
461 } else {
462 return search_secondary_supers(k);
463 }
464 }
465
466 bool search_secondary_supers(Klass* k) const;
467
468 // Find LCA in class hierarchy
469 Klass *LCA( Klass *k );
470
471 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
472 // if not, throw either an Error or an Exception.
473 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
474
475 // array copying
476 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
477
478 // tells if the class should be initialized
479 virtual bool should_be_initialized() const { return false; }
480 // initializes the klass
481 virtual void initialize(TRAPS);
482 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
483 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
484 OverpassLookupMode overpass_mode,
485 PrivateLookupMode = PrivateLookupMode::find) const;
486 public:
487 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
488 return uncached_lookup_method(name, signature, OverpassLookupMode::find);
489 }
490
491 // array class with specific rank
492 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
493
494 // array class with this klass as element type
495 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
496
497 // These will return NULL instead of allocating on the heap:
498 // NB: these can block for a mutex, like other functions with TRAPS arg.
499 Klass* array_klass_or_null(int rank);
500 Klass* array_klass_or_null();
501
502 virtual oop protection_domain() const = 0;
503
504 oop class_loader() const;
505
506 // This loads the klass's holder as a phantom. This is useful when a weak Klass
507 // pointer has been "peeked" and then must be kept alive before it may
508 // be used safely. All uses of klass_holder need to apply the appropriate barriers,
509 // except during GC.
510 oop klass_holder() const { return class_loader_data()->holder_phantom(); }
511
512 protected:
513 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
514 virtual Klass* array_klass_impl(bool or_null, TRAPS);
515
516 // Error handling when length > max_length or length < 0
517 static void check_array_allocation_length(int length, int max_length, TRAPS);
518
519 void set_vtable_length(int len) { _vtable_len= len; }
520
521 vtableEntry* start_of_vtable() const;
522 void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
523 public:
524 Method* method_at_vtable(int index);
525
526 static ByteSize vtable_start_offset();
527 static ByteSize vtable_length_offset() {
528 return byte_offset_of(Klass, _vtable_len);
529 }
530
531 // CDS support - remove and restore oops from metadata. Oops are not shared.
532 virtual void remove_unshareable_info();
533 virtual void remove_java_mirror();
534
535 bool is_unshareable_info_restored() const {
536 assert(is_shared(), "use this for shared classes only");
537 if (has_raw_archived_mirror()) {
538 // _java_mirror is not a valid OopHandle but rather an encoded reference in the shared heap
539 return false;
540 } else if (_java_mirror.ptr_raw() == NULL) {
541 return false;
542 } else {
543 return true;
544 }
545 }
546
547 public:
548 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
549 // These functions describe behavior for the oop not the KLASS.
550
551 // actual oop size of obj in memory
552 virtual int oop_size(oop obj) const = 0;
553
554 // Size of klass in word size.
555 virtual int size() const = 0;
556
557 // Returns the Java name for a class (Resource allocated)
558 // For arrays, this returns the name of the element with a leading '['.
559 // For classes, this returns the name with the package separators
560 // turned into '.'s.
561 const char* external_name() const;
562 // Returns the name for a class (Resource allocated) as the class
563 // would appear in a signature.
564 // For arrays, this returns the name of the element with a leading '['.
565 // For classes, this returns the name with a leading 'L' and a trailing ';'
566 // and the package separators as '/'.
567 virtual const char* signature_name() const;
568
569 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
570 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
571
572 // Returns "interface", "abstract class" or "class".
573 const char* external_kind() const;
574
575 // type testing operations
576 #ifdef ASSERT
577 protected:
578 virtual bool is_instance_klass_slow() const { return false; }
579 virtual bool is_array_klass_slow() const { return false; }
580 virtual bool is_objArray_klass_slow() const { return false; }
581 virtual bool is_typeArray_klass_slow() const { return false; }
582 #endif // ASSERT
583 public:
584
585 // Fast non-virtual versions
586 #ifndef ASSERT
587 #define assert_same_query(xval, xcheck) xval
588 #else
589 private:
590 static bool assert_same_query(bool xval, bool xslow) {
591 assert(xval == xslow, "slow and fast queries agree");
592 return xval;
593 }
594 public:
595 #endif
596 inline bool is_instance_klass() const { return assert_same_query(
597 layout_helper_is_instance(layout_helper()),
598 is_instance_klass_slow()); }
599 inline bool is_array_klass() const { return assert_same_query(
600 layout_helper_is_array(layout_helper()),
601 is_array_klass_slow()); }
602 inline bool is_objArray_klass() const { return assert_same_query(
603 layout_helper_is_objArray(layout_helper()),
604 is_objArray_klass_slow()); }
605 inline bool is_typeArray_klass() const { return assert_same_query(
606 layout_helper_is_typeArray(layout_helper()),
607 is_typeArray_klass_slow()); }
608 #undef assert_same_query
609
610 // Access flags
611 AccessFlags access_flags() const { return _access_flags; }
612 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
613
614 bool is_public() const { return _access_flags.is_public(); }
615 bool is_final() const { return _access_flags.is_final(); }
616 bool is_interface() const { return _access_flags.is_interface(); }
617 bool is_abstract() const { return _access_flags.is_abstract(); }
618 bool is_super() const { return _access_flags.is_super(); }
619 bool is_synthetic() const { return _access_flags.is_synthetic(); }
620 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
621 bool has_finalizer() const { return _access_flags.has_finalizer(); }
622 bool has_final_method() const { return _access_flags.has_final_method(); }
623 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
624 void set_has_final_method() { _access_flags.set_has_final_method(); }
625 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
626 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
627 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
628 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
629 bool is_shared() const { return access_flags().is_shared_class(); } // shadows MetaspaceObj::is_shared)()
630 void set_is_shared() { _access_flags.set_is_shared_class(); }
631 bool is_hidden() const { return access_flags().is_hidden_class(); }
632 void set_is_hidden() { _access_flags.set_is_hidden_class(); }
633 bool is_non_strong_hidden() const { return access_flags().is_hidden_class() &&
634 class_loader_data()->has_class_mirror_holder(); }
635 bool is_box() const { return access_flags().is_box_class(); }
636 void set_is_box() { _access_flags.set_is_box_class(); }
637
638 bool is_cloneable() const;
639 void set_is_cloneable();
640
641 // Biased locking support
642 // Note: the prototype header is always set up to be at least the
643 // prototype markWord. If biased locking is enabled it may further be
644 // biasable and have an epoch.
645 markWord prototype_header() const { return _prototype_header; }
646
647 // NOTE: once instances of this klass are floating around in the
648 // system, this header must only be updated at a safepoint.
649 // NOTE 2: currently we only ever set the prototype header to the
650 // biasable prototype for instanceKlasses. There is no technical
651 // reason why it could not be done for arrayKlasses aside from
652 // wanting to reduce the initial scope of this optimization. There
653 // are potential problems in setting the bias pattern for
654 // JVM-internal oops.
655 inline void set_prototype_header(markWord header);
656 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
657
658 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
659 // Atomically increments biased_lock_revocation_count and returns updated value
660 int atomic_incr_biased_lock_revocation_count();
661 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
662 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
663 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
664
665 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
666
667 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
668 virtual MetaspaceObj::Type type() const { return ClassType; }
669
670 // Iff the class loader (or mirror for unsafe anonymous classes) is alive the
671 // Klass is considered alive. This is safe to call before the CLD is marked as
672 // unloading, and hence during concurrent class unloading.
673 bool is_loader_alive() const { return class_loader_data()->is_alive(); }
674
675 void clean_subklass();
676
677 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
678 static void clean_subklass_tree() {
679 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
680 }
681
682 virtual void array_klasses_do(void f(Klass* k)) {}
683
684 // Return self, except for abstract classes with exactly 1
685 // implementor. Then return the 1 concrete implementation.
686 Klass *up_cast_abstract();
687
688 // klass name
689 Symbol* name() const { return _name; }
690 void set_name(Symbol* n);
691
692 virtual void release_C_heap_structures();
693
694 public:
695 // jvm support
696 virtual jint compute_modifier_flags(TRAPS) const;
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