1 /*
2 * Copyright (c) 1997, 2017, 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).
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23 */
24
25 #ifndef SHARE_VM_OOPS_KLASS_HPP
26 #define SHARE_VM_OOPS_KLASS_HPP
27
28 #include "gc/shared/specialized_oop_closures.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 "trace/traceMacros.hpp"
35 #include "utilities/accessFlags.hpp"
36 #include "utilities/macros.hpp"
37
38 //
39 // A Klass provides:
40 // 1: language level class object (method dictionary etc.)
41 // 2: provide vm dispatch behavior for the object
42 // Both functions are combined into one C++ class.
43
44 // One reason for the oop/klass dichotomy in the implementation is
45 // that we don't want a C++ vtbl pointer in every object. Thus,
46 // normal oops don't have any virtual functions. Instead, they
47 // forward all "virtual" functions to their klass, which does have
48 // a vtbl and does the C++ dispatch depending on the object's
49 // actual type. (See oop.inline.hpp for some of the forwarding code.)
50 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
51
52 // Forward declarations.
53 template <class T> class Array;
54 template <class T> class GrowableArray;
55 class ClassLoaderData;
56 class fieldDescriptor;
57 class KlassSizeStats;
58 class klassVtable;
59 class ModuleEntry;
60 class PackageEntry;
61 class ParCompactionManager;
62 class PSPromotionManager;
63 class vtableEntry;
64
65 class Klass : public Metadata {
66 friend class VMStructs;
67 friend class JVMCIVMStructs;
68 protected:
69 // If you add a new field that points to any metaspace object, you
70 // must add this field to Klass::metaspace_pointers_do().
71
72 // note: put frequently-used fields together at start of klass structure
73 // for better cache behavior (may not make much of a difference but sure won't hurt)
74 enum { _primary_super_limit = 8 };
75
76 // The "layout helper" is a combined descriptor of object layout.
77 // For klasses which are neither instance nor array, the value is zero.
78 //
79 // For instances, layout helper is a positive number, the instance size.
80 // This size is already passed through align_object_size and scaled to bytes.
81 // The low order bit is set if instances of this class cannot be
82 // allocated using the fastpath.
83 //
84 // For arrays, layout helper is a negative number, containing four
85 // distinct bytes, as follows:
86 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
87 // where:
88 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
89 // hsz is array header size in bytes (i.e., offset of first element)
90 // ebt is the BasicType of the elements
91 // esz is the element size in bytes
92 // This packed word is arranged so as to be quickly unpacked by the
93 // various fast paths that use the various subfields.
94 //
95 // The esz bits can be used directly by a SLL instruction, without masking.
96 //
97 // Note that the array-kind tag looks like 0x00 for instance klasses,
98 // since their length in bytes is always less than 24Mb.
99 //
100 // Final note: This comes first, immediately after C++ vtable,
101 // because it is frequently queried.
102 jint _layout_helper;
103
104 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
105 // and _primary_supers all help make fast subtype checks. See big discussion
106 // in doc/server_compiler/checktype.txt
107 //
108 // Where to look to observe a supertype (it is &_secondary_super_cache for
109 // secondary supers, else is &_primary_supers[depth()].
110 juint _super_check_offset;
111
112 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
113 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
114 Symbol* _name;
115
116 // Cache of last observed secondary supertype
117 Klass* _secondary_super_cache;
118 // Array of all secondary supertypes
119 Array<Klass*>* _secondary_supers;
120 // Ordered list of all primary supertypes
121 Klass* _primary_supers[_primary_super_limit];
122 // java/lang/Class instance mirroring this class
123 OopHandle _java_mirror;
124 // Superclass
125 Klass* _super;
126 // First subclass (NULL if none); _subklass->next_sibling() is next one
127 Klass* _subklass;
128 // Sibling link (or NULL); links all subklasses of a klass
129 Klass* _next_sibling;
130
131 // All klasses loaded by a class loader are chained through these links
132 Klass* _next_link;
133
134 // The VM's representation of the ClassLoader used to load this class.
135 // Provide access the corresponding instance java.lang.ClassLoader.
136 ClassLoaderData* _class_loader_data;
137
138 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
139 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
140
141 TRACE_DEFINE_TRACE_ID_FIELD;
142
143 // Biased locking implementation and statistics
144 // (the 64-bit chunk goes first, to avoid some fragmentation)
145 jlong _last_biased_lock_bulk_revocation_time;
146 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type
147 jint _biased_lock_revocation_count;
148
149 // vtable length
150 int _vtable_len;
151
152 private:
153 // This is an index into FileMapHeader::_classpath_entry_table[], to
154 // associate this class with the JAR file where it's loaded from during
155 // dump time. If a class is not loaded from the shared archive, this field is
156 // -1.
157 jshort _shared_class_path_index;
158
159 friend class SharedClassUtil;
160 protected:
161
162 // Constructor
163 Klass();
164
165 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
166
167 public:
168 enum DefaultsLookupMode { find_defaults, skip_defaults };
169 enum OverpassLookupMode { find_overpass, skip_overpass };
170 enum StaticLookupMode { find_static, skip_static };
171 enum PrivateLookupMode { find_private, skip_private };
172
173 bool is_klass() const volatile { return true; }
174
175 // super
176 Klass* super() const { return _super; }
177 void set_super(Klass* k) { _super = k; }
178
179 // initializes _super link, _primary_supers & _secondary_supers arrays
180 void initialize_supers(Klass* k, TRAPS);
181 void initialize_supers_impl1(Klass* k);
182 void initialize_supers_impl2(Klass* k);
183
184 // klass-specific helper for initializing _secondary_supers
185 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
186
187 // java_super is the Java-level super type as specified by Class.getSuperClass.
188 virtual Klass* java_super() const { return NULL; }
189
190 juint super_check_offset() const { return _super_check_offset; }
191 void set_super_check_offset(juint o) { _super_check_offset = o; }
192
193 Klass* secondary_super_cache() const { return _secondary_super_cache; }
194 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
195
196 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
197 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
198
199 // Return the element of the _super chain of the given depth.
200 // If there is no such element, return either NULL or this.
201 Klass* primary_super_of_depth(juint i) const {
202 assert(i < primary_super_limit(), "oob");
203 Klass* super = _primary_supers[i];
204 assert(super == NULL || super->super_depth() == i, "correct display");
205 return super;
206 }
207
208 // Can this klass be a primary super? False for interfaces and arrays of
209 // interfaces. False also for arrays or classes with long super chains.
210 bool can_be_primary_super() const {
211 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
212 return super_check_offset() != secondary_offset;
213 }
214 virtual bool can_be_primary_super_slow() const;
215
216 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
217 juint super_depth() const {
218 if (!can_be_primary_super()) {
219 return primary_super_limit();
220 } else {
221 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
222 assert(d < primary_super_limit(), "oob");
223 assert(_primary_supers[d] == this, "proper init");
224 return d;
225 }
226 }
227
228 // java mirror
229 oop java_mirror() const;
230 // Load the java_mirror as a phantom. This is useful when a weak Klass
231 // pointer has been "peeked" and then must be kept alive before it may
232 // be used safely. The Klass will be kept alive and not be unloaded due
233 // to concurrent marking.
234 virtual oop java_mirror_phantom();
235 void set_java_mirror(Handle m);
236
237 // Temporary mirror switch used by RedefineClasses
238 // Both mirrors are on the ClassLoaderData::_handles list already so no
239 // barriers are needed.
240 void set_java_mirror_handle(OopHandle mirror) { _java_mirror = mirror; }
241 OopHandle java_mirror_handle() const { return _java_mirror; }
242
243 // modifier flags
244 jint modifier_flags() const { return _modifier_flags; }
245 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
246
247 // size helper
248 int layout_helper() const { return _layout_helper; }
249 void set_layout_helper(int lh) { _layout_helper = lh; }
250
251 // Note: for instances layout_helper() may include padding.
252 // Use InstanceKlass::contains_field_offset to classify field offsets.
253
254 // sub/superklass links
255 Klass* subklass() const { return _subklass; }
256 Klass* next_sibling() const { return _next_sibling; }
257 InstanceKlass* superklass() const;
258 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
259
260 void set_next_link(Klass* k) { _next_link = k; }
261 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
262
263 // class loader data
264 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
265 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
266
267 int shared_classpath_index() const {
268 return _shared_class_path_index;
269 };
270
271 void set_shared_classpath_index(int index) {
272 _shared_class_path_index = index;
273 };
274
275 // Obtain the module or package for this class
276 virtual ModuleEntry* module() const = 0;
277 virtual PackageEntry* package() const = 0;
278
279 protected: // internal accessors
280 void set_subklass(Klass* s);
281 void set_next_sibling(Klass* s);
282
283 public:
284
285 // Compiler support
286 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
287 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
288 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
289 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
290 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
291 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
292 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
293 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
294 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
295
296 // Unpacking layout_helper:
297 enum {
298 _lh_neutral_value = 0, // neutral non-array non-instance value
299 _lh_instance_slow_path_bit = 0x01,
300 _lh_log2_element_size_shift = BitsPerByte*0,
301 _lh_log2_element_size_mask = BitsPerLong-1,
302 _lh_element_type_shift = BitsPerByte*1,
303 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
304 _lh_header_size_shift = BitsPerByte*2,
305 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
306 _lh_array_tag_bits = 2,
307 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
308 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30
309 };
310
311 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
312
313 static int layout_helper_size_in_bytes(jint lh) {
314 assert(lh > (jint)_lh_neutral_value, "must be instance");
315 return (int) lh & ~_lh_instance_slow_path_bit;
316 }
317 static bool layout_helper_needs_slow_path(jint lh) {
318 assert(lh > (jint)_lh_neutral_value, "must be instance");
319 return (lh & _lh_instance_slow_path_bit) != 0;
320 }
321 static bool layout_helper_is_instance(jint lh) {
322 return (jint)lh > (jint)_lh_neutral_value;
323 }
324 static bool layout_helper_is_array(jint lh) {
325 return (jint)lh < (jint)_lh_neutral_value;
326 }
327 static bool layout_helper_is_typeArray(jint lh) {
328 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
329 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
330 }
331 static bool layout_helper_is_objArray(jint lh) {
332 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
333 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
334 }
335 static int layout_helper_header_size(jint lh) {
336 assert(lh < (jint)_lh_neutral_value, "must be array");
337 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
338 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
339 return hsize;
340 }
341 static BasicType layout_helper_element_type(jint lh) {
342 assert(lh < (jint)_lh_neutral_value, "must be array");
343 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
344 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
345 return (BasicType) btvalue;
346 }
347
348 // Want a pattern to quickly diff against layout header in register
349 // find something less clever!
350 static int layout_helper_boolean_diffbit() {
351 jint zlh = array_layout_helper(T_BOOLEAN);
352 jint blh = array_layout_helper(T_BYTE);
353 assert(zlh != blh, "array layout helpers must differ");
354 int diffbit = 1;
355 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
356 diffbit <<= 1;
357 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
358 }
359 return diffbit;
360 }
361
362 static int layout_helper_log2_element_size(jint lh) {
363 assert(lh < (jint)_lh_neutral_value, "must be array");
364 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
365 assert(l2esz <= LogBytesPerLong,
366 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
367 return l2esz;
368 }
369 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
370 return (tag << _lh_array_tag_shift)
371 | (hsize << _lh_header_size_shift)
372 | ((int)etype << _lh_element_type_shift)
373 | (log2_esize << _lh_log2_element_size_shift);
374 }
375 static jint instance_layout_helper(jint size, bool slow_path_flag) {
376 return (size << LogBytesPerWord)
377 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
378 }
379 static int layout_helper_to_size_helper(jint lh) {
380 assert(lh > (jint)_lh_neutral_value, "must be instance");
381 // Note that the following expression discards _lh_instance_slow_path_bit.
382 return lh >> LogBytesPerWord;
383 }
384 // Out-of-line version computes everything based on the etype:
385 static jint array_layout_helper(BasicType etype);
386
387 // What is the maximum number of primary superclasses any klass can have?
388 #ifdef PRODUCT
389 static juint primary_super_limit() { return _primary_super_limit; }
390 #else
391 static juint primary_super_limit() {
392 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
393 return FastSuperclassLimit;
394 }
395 #endif
396
397 // vtables
398 klassVtable vtable() const;
399 int vtable_length() const { return _vtable_len; }
400
401 // subclass check
402 bool is_subclass_of(const Klass* k) const;
403 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
404 bool is_subtype_of(Klass* k) const {
405 juint off = k->super_check_offset();
406 Klass* sup = *(Klass**)( (address)this + off );
407 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
408 if (sup == k) {
409 return true;
410 } else if (off != secondary_offset) {
411 return false;
412 } else {
413 return search_secondary_supers(k);
414 }
415 }
416
417 // Is an oop/narrowOop null or subtype of this Klass?
418 template <typename T>
419 bool is_instanceof_or_null(T element);
420
421 bool search_secondary_supers(Klass* k) const;
422
423 // Find LCA in class hierarchy
424 Klass *LCA( Klass *k );
425
426 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
427 // if not, throw either an Error or an Exception.
428 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
429
430 // array copying
431 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
432
433 // tells if the class should be initialized
434 virtual bool should_be_initialized() const { return false; }
435 // initializes the klass
436 virtual void initialize(TRAPS);
437 // lookup operation for MethodLookupCache
438 friend class MethodLookupCache;
439 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
440 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature, OverpassLookupMode overpass_mode) const;
441 public:
442 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
443 return uncached_lookup_method(name, signature, find_overpass);
444 }
445
446 // array class with specific rank
447 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
448
449 // array class with this klass as element type
450 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
451
452 // These will return NULL instead of allocating on the heap:
453 // NB: these can block for a mutex, like other functions with TRAPS arg.
454 Klass* array_klass_or_null(int rank);
455 Klass* array_klass_or_null();
456
457 virtual oop protection_domain() const = 0;
458
459 oop class_loader() const;
460
461 virtual oop klass_holder() const { return class_loader(); }
462 // Load the klass_holder as a phantom. This is useful when a weak Klass
463 // pointer has been "peeked" and then must be kept alive before it may
464 // be used safely. The Klass will be kept alive and not be unloaded due
465 // to concurrent marking.
466 virtual oop klass_holder_phantom();
467
468 protected:
469 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
470 virtual Klass* array_klass_impl(bool or_null, TRAPS);
471
472 void set_vtable_length(int len) { _vtable_len= len; }
473
474 vtableEntry* start_of_vtable() const;
475 public:
476 Method* method_at_vtable(int index);
477
478 static ByteSize vtable_start_offset();
479 static ByteSize vtable_length_offset() {
480 return byte_offset_of(Klass, _vtable_len);
481 }
482
483 // CDS support - remove and restore oops from metadata. Oops are not shared.
484 virtual void remove_unshareable_info();
485 virtual void remove_java_mirror();
486 virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
487
488 protected:
489 // computes the subtype relationship
490 virtual bool compute_is_subtype_of(Klass* k);
491 public:
492 // subclass accessor (here for convenience; undefined for non-klass objects)
493 virtual bool is_leaf_class() const { fatal("not a class"); return false; }
494 public:
495 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
496 // These functions describe behavior for the oop not the KLASS.
497
498 // actual oop size of obj in memory
499 virtual int oop_size(oop obj) const = 0;
500
501 // Size of klass in word size.
502 virtual int size() const = 0;
503 #if INCLUDE_SERVICES
504 virtual void collect_statistics(KlassSizeStats *sz) const;
505 #endif
506
507 // Returns the Java name for a class (Resource allocated)
508 // For arrays, this returns the name of the element with a leading '['.
509 // For classes, this returns the name with the package separators
510 // turned into '.'s.
511 const char* external_name() const;
512 // Returns the name for a class (Resource allocated) as the class
513 // would appear in a signature.
514 // For arrays, this returns the name of the element with a leading '['.
515 // For classes, this returns the name with a leading 'L' and a trailing ';'
516 // and the package separators as '/'.
517 virtual const char* signature_name() const;
518
519 // type testing operations
520 #ifdef ASSERT
521 protected:
522 virtual bool is_instance_klass_slow() const { return false; }
523 virtual bool is_array_klass_slow() const { return false; }
524 virtual bool is_objArray_klass_slow() const { return false; }
525 virtual bool is_typeArray_klass_slow() const { return false; }
526 #endif // ASSERT
527 public:
528
529 // Fast non-virtual versions
530 #ifndef ASSERT
531 #define assert_same_query(xval, xcheck) xval
532 #else
533 private:
534 static bool assert_same_query(bool xval, bool xslow) {
535 assert(xval == xslow, "slow and fast queries agree");
536 return xval;
537 }
538 public:
539 #endif
540 inline bool is_instance_klass() const { return assert_same_query(
541 layout_helper_is_instance(layout_helper()),
542 is_instance_klass_slow()); }
543 inline bool is_array_klass() const { return assert_same_query(
544 layout_helper_is_array(layout_helper()),
545 is_array_klass_slow()); }
546 inline bool is_objArray_klass() const { return assert_same_query(
547 layout_helper_is_objArray(layout_helper()),
548 is_objArray_klass_slow()); }
549 inline bool is_typeArray_klass() const { return assert_same_query(
550 layout_helper_is_typeArray(layout_helper()),
551 is_typeArray_klass_slow()); }
552 #undef assert_same_query
553
554 // Access flags
555 AccessFlags access_flags() const { return _access_flags; }
556 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
557
558 bool is_public() const { return _access_flags.is_public(); }
559 bool is_final() const { return _access_flags.is_final(); }
560 bool is_interface() const { return _access_flags.is_interface(); }
561 bool is_abstract() const { return _access_flags.is_abstract(); }
562 bool is_super() const { return _access_flags.is_super(); }
563 bool is_synthetic() const { return _access_flags.is_synthetic(); }
564 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
565 bool has_finalizer() const { return _access_flags.has_finalizer(); }
566 bool has_final_method() const { return _access_flags.has_final_method(); }
567 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
568 void set_has_final_method() { _access_flags.set_has_final_method(); }
569 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
570 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
571 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
572 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
573 bool is_shared() const { return access_flags().is_shared_class(); } // shadows MetaspaceObj::is_shared)()
574 void set_is_shared() { _access_flags.set_is_shared_class(); }
575
576 bool is_cloneable() const;
577 void set_is_cloneable();
578
579 // Biased locking support
580 // Note: the prototype header is always set up to be at least the
581 // prototype markOop. If biased locking is enabled it may further be
582 // biasable and have an epoch.
583 markOop prototype_header() const { return _prototype_header; }
584 // NOTE: once instances of this klass are floating around in the
585 // system, this header must only be updated at a safepoint.
586 // NOTE 2: currently we only ever set the prototype header to the
587 // biasable prototype for instanceKlasses. There is no technical
588 // reason why it could not be done for arrayKlasses aside from
589 // wanting to reduce the initial scope of this optimization. There
590 // are potential problems in setting the bias pattern for
591 // JVM-internal oops.
592 inline void set_prototype_header(markOop header);
593 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
594
595 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
596 // Atomically increments biased_lock_revocation_count and returns updated value
597 int atomic_incr_biased_lock_revocation_count();
598 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
599 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
600 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
601
602 TRACE_DEFINE_TRACE_ID_METHODS;
603
604 virtual void metaspace_pointers_do(MetaspaceClosure* iter);
605 virtual MetaspaceObj::Type type() const { return ClassType; }
606
607 // Iff the class loader (or mirror for anonymous classes) is alive the
608 // Klass is considered alive.
609 // The is_alive closure passed in depends on the Garbage Collector used.
610 bool is_loader_alive(BoolObjectClosure* is_alive);
611
612 static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
613 static void clean_subklass_tree(BoolObjectClosure* is_alive) {
614 clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
615 }
616
617 // GC specific object visitors
618 //
619 #if INCLUDE_ALL_GCS
620 // Parallel Scavenge
621 virtual void oop_ps_push_contents( oop obj, PSPromotionManager* pm) = 0;
622 // Parallel Compact
623 virtual void oop_pc_follow_contents(oop obj, ParCompactionManager* cm) = 0;
624 virtual void oop_pc_update_pointers(oop obj, ParCompactionManager* cm) = 0;
625 #endif
626
627 // Iterators specialized to particular subtypes
628 // of ExtendedOopClosure, to avoid closure virtual calls.
629 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
630 virtual void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) = 0; \
631 /* Iterates "closure" over all the oops in "obj" (of type "this") within "mr". */ \
632 virtual void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) = 0;
633
634 ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
635 ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
636
637 #if INCLUDE_ALL_GCS
638 #define Klass_OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix) \
639 virtual void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) = 0;
640
641 ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
642 ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
643 #endif // INCLUDE_ALL_GCS
644
645 virtual void array_klasses_do(void f(Klass* k)) {}
646
647 // Return self, except for abstract classes with exactly 1
648 // implementor. Then return the 1 concrete implementation.
649 Klass *up_cast_abstract();
650
651 // klass name
652 Symbol* name() const { return _name; }
653 void set_name(Symbol* n);
654
655 public:
656 // jvm support
657 virtual jint compute_modifier_flags(TRAPS) const;
658
659 // JVMTI support
660 virtual jint jvmti_class_status() const;
661
662 // Printing
663 virtual void print_on(outputStream* st) const;
664
665 virtual void oop_print_value_on(oop obj, outputStream* st);
666 virtual void oop_print_on (oop obj, outputStream* st);
667
668 virtual const char* internal_name() const = 0;
669
670 // Verification
671 virtual void verify_on(outputStream* st);
672 void verify() { verify_on(tty); }
673
674 #ifndef PRODUCT
675 bool verify_vtable_index(int index);
676 bool verify_itable_index(int index);
677 #endif
678
679 virtual void oop_verify_on(oop obj, outputStream* st);
680
681 static bool is_null(narrowKlass obj);
682 static bool is_null(Klass* obj);
683
684 // klass encoding for klass pointer in objects.
685 static narrowKlass encode_klass_not_null(Klass* v);
686 static narrowKlass encode_klass(Klass* v);
687
688 static Klass* decode_klass_not_null(narrowKlass v);
689 static Klass* decode_klass(narrowKlass v);
690 };
691
692 // Helper to convert the oop iterate macro suffixes into bool values that can be used by template functions.
693 #define nvs_nv_to_bool true
694 #define nvs_v_to_bool false
695 #define nvs_to_bool(nv_suffix) nvs##nv_suffix##_to_bool
696
697 // Oop iteration macros for declarations.
698 // Used to generate declarations in the *Klass header files.
699
700 #define OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
701 void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure); \
702 void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr);
703
704 #if INCLUDE_ALL_GCS
705 #define OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix) \
706 void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure);
707 #endif // INCLUDE_ALL_GCS
708
709
710 // Oop iteration macros for definitions.
711 // Used to generate definitions in the *Klass.inline.hpp files.
712
713 #define OOP_OOP_ITERATE_DEFN(KlassType, OopClosureType, nv_suffix) \
714 void KlassType::oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) { \
715 oop_oop_iterate<nvs_to_bool(nv_suffix)>(obj, closure); \
716 }
717
718 #if INCLUDE_ALL_GCS
719 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix) \
720 void KlassType::oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) { \
721 oop_oop_iterate_reverse<nvs_to_bool(nv_suffix)>(obj, closure); \
722 }
723 #else
724 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)
725 #endif
726
727 #define OOP_OOP_ITERATE_DEFN_BOUNDED(KlassType, OopClosureType, nv_suffix) \
728 void KlassType::oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) { \
729 oop_oop_iterate_bounded<nvs_to_bool(nv_suffix)>(obj, closure, mr); \
730 }
731
732 #endif // SHARE_VM_OOPS_KLASS_HPP