1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #ifndef SHARE_VM_OOPS_KLASS_HPP
26 #define SHARE_VM_OOPS_KLASS_HPP
27
28 #include "classfile/classLoaderData.hpp"
29 #include "memory/iterator.hpp"
30 #include "memory/memRegion.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 IDs for all subclasses of Klass
41 enum KlassID {
42 InstanceKlassID,
43 InstanceRefKlassID,
44 InstanceMirrorKlassID,
45 InstanceClassLoaderKlassID,
46 TypeArrayKlassID,
47 ObjArrayKlassID
48 };
49
50 const uint KLASS_ID_COUNT = 6;
51
52 //
53 // A Klass provides:
54 // 1: language level class object (method dictionary etc.)
55 // 2: provide vm dispatch behavior for the object
56 // Both functions are combined into one C++ class.
57
58 // One reason for the oop/klass dichotomy in the implementation is
59 // that we don't want a C++ vtbl pointer in every object. Thus,
60 // normal oops don't have any virtual functions. Instead, they
61 // forward all "virtual" functions to their klass, which does have
62 // a vtbl and does the C++ dispatch depending on the object's
63 // actual type. (See oop.inline.hpp for some of the forwarding code.)
64 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
65
66 // Forward declarations.
67 template <class T> class Array;
68 template <class T> class GrowableArray;
69 class fieldDescriptor;
70 class KlassSizeStats;
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 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
121 // and _primary_supers all help make fast subtype checks. See big discussion
122 // in doc/server_compiler/checktype.txt
123 //
124 // Where to look to observe a supertype (it is &_secondary_super_cache for
125 // secondary supers, else is &_primary_supers[depth()].
126 juint _super_check_offset;
127
128 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
129 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
130 Symbol* _name;
131
132 // Cache of last observed secondary supertype
133 Klass* _secondary_super_cache;
134 // Array of all secondary supertypes
135 Array<Klass*>* _secondary_supers;
136 // Ordered list of all primary supertypes
137 Klass* _primary_supers[_primary_super_limit];
138 // java/lang/Class instance mirroring this class
139 OopHandle _java_mirror;
140 // Superclass
141 Klass* _super;
142 // First subclass (NULL if none); _subklass->next_sibling() is next one
143 Klass* _subklass;
144 // Sibling link (or NULL); links all subklasses of a klass
145 Klass* _next_sibling;
146
147 // All klasses loaded by a class loader are chained through these links
148 Klass* _next_link;
149
150 // The VM's representation of the ClassLoader used to load this class.
151 // Provide access the corresponding instance java.lang.ClassLoader.
152 ClassLoaderData* _class_loader_data;
153
154 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
155 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
156
157 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
158
159 // Biased locking implementation and statistics
160 // (the 64-bit chunk goes first, to avoid some fragmentation)
161 jlong _last_biased_lock_bulk_revocation_time;
162 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type
163 jint _biased_lock_revocation_count;
164
165 // vtable length
166 int _vtable_len;
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 _has_signer_and_not_archived = 1 << 2
181 };
182 #endif
183 // The _archived_mirror is set at CDS dump time pointing to the cached mirror
184 // in the open archive heap region when archiving java object is supported.
185 CDS_JAVA_HEAP_ONLY(narrowOop _archived_mirror;)
186
187 protected:
188
189 // Constructor
190 Klass(KlassID id);
191 Klass() : _id(KlassID(-1)) { assert(DumpSharedSpaces || UseSharedSpaces, "only for cds"); }
192
193 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
194
195 public:
196 int id() { return _id; }
197
198 enum DefaultsLookupMode { find_defaults, skip_defaults };
199 enum OverpassLookupMode { find_overpass, skip_overpass };
200 enum StaticLookupMode { find_static, skip_static };
201 enum PrivateLookupMode { find_private, skip_private };
202
203 bool is_klass() const volatile { return true; }
204
205 // super() cannot be InstanceKlass* -- Java arrays are covariant, and _super is used
206 // to implement that. NB: the _super of "[Ljava/lang/Integer;" is "[Ljava/lang/Number;"
207 // If this is not what your code expects, you're probably looking for Klass::java_super().
208 Klass* super() const { return _super; }
209 void set_super(Klass* k) { _super = k; }
210
211 // initializes _super link, _primary_supers & _secondary_supers arrays
212 void initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS);
213
214 // klass-specific helper for initializing _secondary_supers
215 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots,
216 Array<InstanceKlass*>* transitive_interfaces);
217
218 // java_super is the Java-level super type as specified by Class.getSuperClass.
219 virtual InstanceKlass* java_super() const { return NULL; }
220
221 juint super_check_offset() const { return _super_check_offset; }
222 void set_super_check_offset(juint o) { _super_check_offset = o; }
223
224 Klass* secondary_super_cache() const { return _secondary_super_cache; }
225 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
226
227 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
228 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
229
230 // Return the element of the _super chain of the given depth.
231 // If there is no such element, return either NULL or this.
232 Klass* primary_super_of_depth(juint i) const {
233 assert(i < primary_super_limit(), "oob");
234 Klass* super = _primary_supers[i];
235 assert(super == NULL || super->super_depth() == i, "correct display");
236 return super;
237 }
238
239 // Can this klass be a primary super? False for interfaces and arrays of
240 // interfaces. False also for arrays or classes with long super chains.
241 bool can_be_primary_super() const {
242 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
243 return super_check_offset() != secondary_offset;
244 }
245 virtual bool can_be_primary_super_slow() const;
246
247 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
248 juint super_depth() const {
249 if (!can_be_primary_super()) {
250 return primary_super_limit();
251 } else {
252 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
253 assert(d < primary_super_limit(), "oob");
254 assert(_primary_supers[d] == this, "proper init");
255 return d;
256 }
257 }
258
259 // java mirror
260 oop java_mirror() const;
261 oop java_mirror_no_keepalive() const;
262 void set_java_mirror(Handle m);
263
264 oop archived_java_mirror_raw() NOT_CDS_JAVA_HEAP_RETURN_(NULL); // no GC barrier
265 narrowOop archived_java_mirror_raw_narrow() NOT_CDS_JAVA_HEAP_RETURN_(0); // no GC barrier
266 void set_archived_java_mirror_raw(oop m) NOT_CDS_JAVA_HEAP_RETURN; // no GC barrier
267
268 // Temporary mirror switch used by RedefineClasses
269 // Both mirrors are on the ClassLoaderData::_handles list already so no
270 // barriers are needed.
271 void set_java_mirror_handle(OopHandle mirror) { _java_mirror = mirror; }
272 OopHandle java_mirror_handle() const {
273 return _java_mirror;
274 }
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() const { return _subklass; }
289 Klass* next_sibling() const { return _next_sibling; }
290 InstanceKlass* superklass() const;
291 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
292
293 void set_next_link(Klass* k) { _next_link = k; }
294 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
295
296 // class loader data
297 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
298 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
299
300 int shared_classpath_index() const {
301 return _shared_class_path_index;
302 };
303
304 void set_shared_classpath_index(int index) {
305 _shared_class_path_index = index;
306 };
307
308 void set_has_raw_archived_mirror() {
309 CDS_ONLY(_shared_class_flags |= _has_raw_archived_mirror;)
310 }
311 void clear_has_raw_archived_mirror() {
312 CDS_ONLY(_shared_class_flags &= ~_has_raw_archived_mirror;)
313 }
314 bool has_raw_archived_mirror() const {
315 CDS_ONLY(return (_shared_class_flags & _has_raw_archived_mirror) != 0;)
316 NOT_CDS(return false;)
317 }
318 #if INCLUDE_CDS
319 void set_has_signer_and_not_archived() {
320 _shared_class_flags |= _has_signer_and_not_archived;
321 }
322 bool has_signer_and_not_archived() const {
323 assert(DumpSharedSpaces, "dump time only");
324 return (_shared_class_flags & _has_signer_and_not_archived) != 0;
325 }
326 #endif // INCLUDE_CDS
327
328 // Obtain the module or package for this class
329 virtual ModuleEntry* module() const = 0;
330 virtual PackageEntry* package() const = 0;
331
332 protected: // internal accessors
333 void set_subklass(Klass* s);
334 void set_next_sibling(Klass* s);
335
336 public:
337
338 // Compiler support
339 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
340 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
341 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
342 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
343 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
344 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
345 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
346 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
347 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
348
349 // Unpacking layout_helper:
350 enum {
351 _lh_neutral_value = 0, // neutral non-array non-instance value
352 _lh_instance_slow_path_bit = 0x01,
353 _lh_log2_element_size_shift = BitsPerByte*0,
354 _lh_log2_element_size_mask = BitsPerLong-1,
355 _lh_element_type_shift = BitsPerByte*1,
356 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
357 _lh_header_size_shift = BitsPerByte*2,
358 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
359 _lh_array_tag_bits = 2,
360 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
361 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30
362 };
363
364 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
365
366 static int layout_helper_size_in_bytes(jint lh) {
367 assert(lh > (jint)_lh_neutral_value, "must be instance");
368 return (int) lh & ~_lh_instance_slow_path_bit;
369 }
370 static bool layout_helper_needs_slow_path(jint lh) {
371 assert(lh > (jint)_lh_neutral_value, "must be instance");
372 return (lh & _lh_instance_slow_path_bit) != 0;
373 }
374 static bool layout_helper_is_instance(jint lh) {
375 return (jint)lh > (jint)_lh_neutral_value;
376 }
377 static bool layout_helper_is_array(jint lh) {
378 return (jint)lh < (jint)_lh_neutral_value;
379 }
380 static bool layout_helper_is_typeArray(jint lh) {
381 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
382 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
383 }
384 static bool layout_helper_is_objArray(jint lh) {
385 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
386 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
387 }
388 static int layout_helper_header_size(jint lh) {
389 assert(lh < (jint)_lh_neutral_value, "must be array");
390 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
391 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
392 return hsize;
393 }
394 static BasicType layout_helper_element_type(jint lh) {
395 assert(lh < (jint)_lh_neutral_value, "must be array");
396 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
397 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
398 return (BasicType) btvalue;
399 }
400
401 // Want a pattern to quickly diff against layout header in register
402 // find something less clever!
403 static int layout_helper_boolean_diffbit() {
404 jint zlh = array_layout_helper(T_BOOLEAN);
405 jint blh = array_layout_helper(T_BYTE);
406 assert(zlh != blh, "array layout helpers must differ");
407 int diffbit = 1;
408 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
409 diffbit <<= 1;
410 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
411 }
412 return diffbit;
413 }
414
415 static int layout_helper_log2_element_size(jint lh) {
416 assert(lh < (jint)_lh_neutral_value, "must be array");
417 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
418 assert(l2esz <= LogBytesPerLong,
419 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
420 return l2esz;
421 }
422 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
423 return (tag << _lh_array_tag_shift)
424 | (hsize << _lh_header_size_shift)
425 | ((int)etype << _lh_element_type_shift)
426 | (log2_esize << _lh_log2_element_size_shift);
427 }
428 static jint instance_layout_helper(jint size, bool slow_path_flag) {
429 return (size << LogBytesPerWord)
430 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
431 }
432 static int layout_helper_to_size_helper(jint lh) {
433 assert(lh > (jint)_lh_neutral_value, "must be instance");
434 // Note that the following expression discards _lh_instance_slow_path_bit.
435 return lh >> LogBytesPerWord;
436 }
437 // Out-of-line version computes everything based on the etype:
438 static jint array_layout_helper(BasicType etype);
439
440 // What is the maximum number of primary superclasses any klass can have?
441 #ifdef PRODUCT
442 static juint primary_super_limit() { return _primary_super_limit; }
443 #else
444 static juint primary_super_limit() {
445 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
446 return FastSuperclassLimit;
447 }
448 #endif
449
450 // vtables
451 klassVtable vtable() const;
452 int vtable_length() const { return _vtable_len; }
453
454 // subclass check
455 bool is_subclass_of(const Klass* k) const;
456 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
457 bool is_subtype_of(Klass* k) const {
458 juint off = k->super_check_offset();
459 Klass* sup = *(Klass**)( (address)this + off );
460 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
461 if (sup == k) {
462 return true;
463 } else if (off != secondary_offset) {
464 return false;
465 } else {
466 return search_secondary_supers(k);
467 }
468 }
469
470 bool search_secondary_supers(Klass* k) const;
471
472 // Find LCA in class hierarchy
473 Klass *LCA( Klass *k );
474
475 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
476 // if not, throw either an Error or an Exception.
477 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
478
479 // array copying
480 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
481
482 // tells if the class should be initialized
483 virtual bool should_be_initialized() const { return false; }
484 // initializes the klass
485 virtual void initialize(TRAPS);
486 // lookup operation for MethodLookupCache
487 friend class MethodLookupCache;
488 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
489 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature,
490 OverpassLookupMode overpass_mode,
491 PrivateLookupMode = find_private) const;
492 public:
493 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
494 return uncached_lookup_method(name, signature, find_overpass);
495 }
496
497 // array class with specific rank
498 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
499
500 // array class with this klass as element type
501 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
502
503 // These will return NULL instead of allocating on the heap:
504 // NB: these can block for a mutex, like other functions with TRAPS arg.
505 Klass* array_klass_or_null(int rank);
506 Klass* array_klass_or_null();
507
508 virtual oop protection_domain() const = 0;
509
510 oop class_loader() const;
511
512 virtual oop klass_holder() const { return class_loader(); }
513
514 protected:
515 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
516 virtual Klass* array_klass_impl(bool or_null, TRAPS);
517
518 // Error handling when length > max_length or length < 0
519 static void check_array_allocation_length(int length, int max_length, TRAPS);
520
521 void set_vtable_length(int len) { _vtable_len= len; }
522
523 vtableEntry* start_of_vtable() const;
524 public:
525 Method* method_at_vtable(int index);
526
527 static ByteSize vtable_start_offset();
528 static ByteSize vtable_length_offset() {
529 return byte_offset_of(Klass, _vtable_len);
530 }
531
532 // CDS support - remove and restore oops from metadata. Oops are not shared.
533 virtual void remove_unshareable_info();
534 virtual void remove_java_mirror();
535 virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
536
537 protected:
538 // computes the subtype relationship
539 virtual bool compute_is_subtype_of(Klass* k);
540 public:
541 // subclass accessor (here for convenience; undefined for non-klass objects)
542 virtual bool is_leaf_class() const { fatal("not a class"); return false; }
543 public:
544 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
545 // These functions describe behavior for the oop not the KLASS.
546
547 // actual oop size of obj in memory
548 virtual int oop_size(oop obj) const = 0;
549
550 // Size of klass in word size.
551 virtual int size() const = 0;
552 #if INCLUDE_SERVICES
553 virtual void collect_statistics(KlassSizeStats *sz) const;
554 #endif
555
556 // Returns the Java name for a class (Resource allocated)
557 // For arrays, this returns the name of the element with a leading '['.
558 // For classes, this returns the name with the package separators
559 // turned into '.'s.
560 const char* external_name() const;
561 // Returns the name for a class (Resource allocated) as the class
562 // would appear in a signature.
563 // For arrays, this returns the name of the element with a leading '['.
564 // For classes, this returns the name with a leading 'L' and a trailing ';'
565 // and the package separators as '/'.
566 virtual const char* signature_name() const;
567
568 const char* joint_in_module_of_loader(const Klass* class2, bool include_parent_loader = false) const;
569 const char* class_in_module_of_loader(bool use_are = false, bool include_parent_loader = false) const;
570
571 // Returns "interface", "abstract class" or "class".
572 const char* external_kind() const;
573
574 // type testing operations
575 #ifdef ASSERT
576 protected:
577 virtual bool is_instance_klass_slow() const { return false; }
578 virtual bool is_array_klass_slow() const { return false; }
579 virtual bool is_objArray_klass_slow() const { return false; }
580 virtual bool is_typeArray_klass_slow() const { return false; }
581 #endif // ASSERT
582 public:
583
584 // Fast non-virtual versions
585 #ifndef ASSERT
586 #define assert_same_query(xval, xcheck) xval
587 #else
588 private:
589 static bool assert_same_query(bool xval, bool xslow) {
590 assert(xval == xslow, "slow and fast queries agree");
591 return xval;
592 }
593 public:
594 #endif
595 inline bool is_instance_klass() const { return assert_same_query(
596 layout_helper_is_instance(layout_helper()),
597 is_instance_klass_slow()); }
598 inline bool is_array_klass() const { return assert_same_query(
599 layout_helper_is_array(layout_helper()),
600 is_array_klass_slow()); }
601 inline bool is_objArray_klass() const { return assert_same_query(
602 layout_helper_is_objArray(layout_helper()),
603 is_objArray_klass_slow()); }
604 inline bool is_typeArray_klass() const { return assert_same_query(
605 layout_helper_is_typeArray(layout_helper()),
606 is_typeArray_klass_slow()); }
607 #undef assert_same_query
608
609 // Access flags
610 AccessFlags access_flags() const { return _access_flags; }
611 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
612
613 bool is_public() const { return _access_flags.is_public(); }
614 bool is_final() const { return _access_flags.is_final(); }
615 bool is_interface() const { return _access_flags.is_interface(); }
616 bool is_abstract() const { return _access_flags.is_abstract(); }
617 bool is_super() const { return _access_flags.is_super(); }
618 bool is_synthetic() const { return _access_flags.is_synthetic(); }
619 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
620 bool has_finalizer() const { return _access_flags.has_finalizer(); }
621 bool has_final_method() const { return _access_flags.has_final_method(); }
622 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
623 void set_has_final_method() { _access_flags.set_has_final_method(); }
624 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
625 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
626 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
627 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
628 bool is_shared() const { return access_flags().is_shared_class(); } // shadows MetaspaceObj::is_shared)()
629 void set_is_shared() { _access_flags.set_is_shared_class(); }
630
631 bool is_cloneable() const;
632 void set_is_cloneable();
633
634 // Biased locking support
635 // Note: the prototype header is always set up to be at least the
636 // prototype markOop. If biased locking is enabled it may further be
637 // biasable and have an epoch.
638 markOop prototype_header() const { return _prototype_header; }
639 // NOTE: once instances of this klass are floating around in the
640 // system, this header must only be updated at a safepoint.
641 // NOTE 2: currently we only ever set the prototype header to the
642 // biasable prototype for instanceKlasses. There is no technical
643 // reason why it could not be done for arrayKlasses aside from
644 // wanting to reduce the initial scope of this optimization. There
645 // are potential problems in setting the bias pattern for
646 // JVM-internal oops.
647 inline void set_prototype_header(markOop header);
648 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
649
650 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
651 // Atomically increments biased_lock_revocation_count and returns updated value
652 int atomic_incr_biased_lock_revocation_count();
653 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
654 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
655 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
656
657 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
658
659 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
660 virtual MetaspaceObj::Type type() const { return ClassType; }
661
662 // Iff the class loader (or mirror for unsafe anonymous classes) is alive the
663 // Klass is considered alive. This is safe to call before the CLD is marked as
664 // unloading, and hence during concurrent class unloading.
665 bool is_loader_alive() const { return class_loader_data()->is_alive(); }
666
667 // Load the klass's holder as a phantom. This is useful when a weak Klass
668 // pointer has been "peeked" and then must be kept alive before it may
669 // be used safely.
670 oop holder_phantom() const;
671
672 static void clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses = true);
673 static void clean_subklass_tree() {
674 clean_weak_klass_links(/*unloading_occurred*/ true , /* clean_alive_klasses */ false);
675 }
676
677 virtual void array_klasses_do(void f(Klass* k)) {}
678
679 // Return self, except for abstract classes with exactly 1
680 // implementor. Then return the 1 concrete implementation.
681 Klass *up_cast_abstract();
682
683 // klass name
684 Symbol* name() const { return _name; }
685 void set_name(Symbol* n);
686
687 public:
688 // jvm support
689 virtual jint compute_modifier_flags(TRAPS) const;
690
691 // JVMTI support
692 virtual jint jvmti_class_status() const;
693
694 // Printing
695 virtual void print_on(outputStream* st) const;
696
697 virtual void oop_print_value_on(oop obj, outputStream* st);
698 virtual void oop_print_on (oop obj, outputStream* st);
699
700 virtual const char* internal_name() const = 0;
701
702 // Verification
703 virtual void verify_on(outputStream* st);
704 void verify() { verify_on(tty); }
705
706 #ifndef PRODUCT
707 bool verify_vtable_index(int index);
708 #endif
709
710 virtual void oop_verify_on(oop obj, outputStream* st);
711
712 // for error reporting
713 static Klass* decode_klass_raw(narrowKlass narrow_klass);
714 static bool is_valid(Klass* k);
715
716 static bool is_null(narrowKlass obj);
717 static bool is_null(Klass* obj);
718
719 // klass encoding for klass pointer in objects.
720 static narrowKlass encode_klass_not_null(Klass* v);
721 static narrowKlass encode_klass(Klass* v);
722
723 static Klass* decode_klass_not_null(narrowKlass v);
724 static Klass* decode_klass(narrowKlass v);
725 };
726
727 #endif // SHARE_VM_OOPS_KLASS_HPP