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.
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23 */
24
25 #ifndef SHARE_VM_OOPS_KLASS_HPP
26 #define SHARE_VM_OOPS_KLASS_HPP
27
28 #include "memory/genOopClosures.hpp"
29 #include "memory/iterator.hpp"
30 #include "memory/memRegion.hpp"
31 #include "memory/specialized_oop_closures.hpp"
32 #include "oops/klassPS.hpp"
33 #include "oops/metadata.hpp"
34 #include "oops/oop.hpp"
35 #include "utilities/accessFlags.hpp"
36 #include "utilities/macros.hpp"
37 #if INCLUDE_ALL_GCS
38 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp"
39 #include "gc_implementation/g1/g1OopClosures.hpp"
40 #include "gc_implementation/shenandoah/shenandoahOopClosures.hpp"
41 #include "gc_implementation/parNew/parOopClosures.hpp"
42 #endif // INCLUDE_ALL_GCS
43 #if INCLUDE_JFR
44 #include "jfr/support/jfrTraceIdExtension.hpp"
45 #endif
46
47 //
48 // A Klass provides:
49 // 1: language level class object (method dictionary etc.)
50 // 2: provide vm dispatch behavior for the object
51 // Both functions are combined into one C++ class.
52
53 // One reason for the oop/klass dichotomy in the implementation is
54 // that we don't want a C++ vtbl pointer in every object. Thus,
55 // normal oops don't have any virtual functions. Instead, they
56 // forward all "virtual" functions to their klass, which does have
57 // a vtbl and does the C++ dispatch depending on the object's
58 // actual type. (See oop.inline.hpp for some of the forwarding code.)
59 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
60
61 // Klass layout:
62 // [C++ vtbl ptr ] (contained in Metadata)
63 // [layout_helper ]
64 // [super_check_offset ] for fast subtype checks
65 // [name ]
66 // [secondary_super_cache] for fast subtype checks
67 // [secondary_supers ] array of 2ndary supertypes
68 // [primary_supers 0]
69 // [primary_supers 1]
70 // [primary_supers 2]
71 // ...
72 // [primary_supers 7]
73 // [java_mirror ]
74 // [super ]
75 // [subklass ] first subclass
76 // [next_sibling ] link to chain additional subklasses
77 // [next_link ]
78 // [class_loader_data]
79 // [modifier_flags]
80 // [access_flags ]
81 // [last_biased_lock_bulk_revocation_time] (64 bits)
82 // [prototype_header]
83 // [biased_lock_revocation_count]
84 // [_modified_oops]
85 // [_accumulated_modified_oops]
86 // [trace_id]
87
88
89 // Forward declarations.
90 template <class T> class Array;
91 template <class T> class GrowableArray;
92 class ClassLoaderData;
93 class klassVtable;
94 class ParCompactionManager;
95 class KlassSizeStats;
96 class fieldDescriptor;
97
98 class Klass : public Metadata {
99 friend class VMStructs;
100 protected:
101 // note: put frequently-used fields together at start of klass structure
102 // for better cache behavior (may not make much of a difference but sure won't hurt)
103 enum { _primary_super_limit = 8 };
104
105 // The "layout helper" is a combined descriptor of object layout.
106 // For klasses which are neither instance nor array, the value is zero.
107 //
108 // For instances, layout helper is a positive number, the instance size.
109 // This size is already passed through align_object_size and scaled to bytes.
110 // The low order bit is set if instances of this class cannot be
111 // allocated using the fastpath.
112 //
113 // For arrays, layout helper is a negative number, containing four
114 // distinct bytes, as follows:
115 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
116 // where:
117 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
118 // hsz is array header size in bytes (i.e., offset of first element)
119 // ebt is the BasicType of the elements
120 // esz is the element size in bytes
121 // This packed word is arranged so as to be quickly unpacked by the
122 // various fast paths that use the various subfields.
123 //
124 // The esz bits can be used directly by a SLL instruction, without masking.
125 //
126 // Note that the array-kind tag looks like 0x00 for instance klasses,
127 // since their length in bytes is always less than 24Mb.
128 //
129 // Final note: This comes first, immediately after C++ vtable,
130 // because it is frequently queried.
131 jint _layout_helper;
132
133 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
134 // and _primary_supers all help make fast subtype checks. See big discussion
135 // in doc/server_compiler/checktype.txt
136 //
137 // Where to look to observe a supertype (it is &_secondary_super_cache for
138 // secondary supers, else is &_primary_supers[depth()].
139 juint _super_check_offset;
140
141 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
142 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
143 Symbol* _name;
144
145 // Cache of last observed secondary supertype
146 Klass* _secondary_super_cache;
147 // Array of all secondary supertypes
148 Array<Klass*>* _secondary_supers;
149 // Ordered list of all primary supertypes
150 Klass* _primary_supers[_primary_super_limit];
151 // java/lang/Class instance mirroring this class
152 oop _java_mirror;
153 // Superclass
154 Klass* _super;
155 // First subclass (NULL if none); _subklass->next_sibling() is next one
156 Klass* _subklass;
157 // Sibling link (or NULL); links all subklasses of a klass
158 Klass* _next_sibling;
159
160 // All klasses loaded by a class loader are chained through these links
161 Klass* _next_link;
162
163 // The VM's representation of the ClassLoader used to load this class.
164 // Provide access the corresponding instance java.lang.ClassLoader.
165 ClassLoaderData* _class_loader_data;
166
167 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
168 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
169
170 // Biased locking implementation and statistics
171 // (the 64-bit chunk goes first, to avoid some fragmentation)
172 jlong _last_biased_lock_bulk_revocation_time;
173 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type
174 jint _biased_lock_revocation_count;
175
176 JFR_ONLY(DEFINE_TRACE_ID_FIELD;)
177
178 // Remembered sets support for the oops in the klasses.
179 jbyte _modified_oops; // Card Table Equivalent (YC/CMS support)
180 jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
181
182 private:
183 // This is an index into FileMapHeader::_classpath_entry_table[], to
184 // associate this class with the JAR file where it's loaded from during
185 // dump time. If a class is not loaded from the shared archive, this field is
186 // -1.
187 jshort _shared_class_path_index;
188
189 friend class SharedClassUtil;
190 protected:
191
192 // Constructor
193 Klass();
194
195 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
196
197 public:
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
206 Klass* super() const { return _super; }
207 void set_super(Klass* k) { _super = k; }
208
209 // initializes _super link, _primary_supers & _secondary_supers arrays
210 void initialize_supers(Klass* k, TRAPS);
211 void initialize_supers_impl1(Klass* k);
212 void initialize_supers_impl2(Klass* k);
213
214 // klass-specific helper for initializing _secondary_supers
215 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
216
217 // java_super is the Java-level super type as specified by Class.getSuperClass.
218 virtual Klass* java_super() const { return NULL; }
219
220 juint super_check_offset() const { return _super_check_offset; }
221 void set_super_check_offset(juint o) { _super_check_offset = o; }
222
223 Klass* secondary_super_cache() const { return _secondary_super_cache; }
224 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
225
226 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
227 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
228
229 // Return the element of the _super chain of the given depth.
230 // If there is no such element, return either NULL or this.
231 Klass* primary_super_of_depth(juint i) const {
232 assert(i < primary_super_limit(), "oob");
233 Klass* super = _primary_supers[i];
234 assert(super == NULL || super->super_depth() == i, "correct display");
235 return super;
236 }
237
238 // Can this klass be a primary super? False for interfaces and arrays of
239 // interfaces. False also for arrays or classes with long super chains.
240 bool can_be_primary_super() const {
241 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
242 return super_check_offset() != secondary_offset;
243 }
244 virtual bool can_be_primary_super_slow() const;
245
246 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
247 juint super_depth() const {
248 if (!can_be_primary_super()) {
249 return primary_super_limit();
250 } else {
251 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
252 assert(d < primary_super_limit(), "oob");
253 assert(_primary_supers[d] == this, "proper init");
254 return d;
255 }
256 }
257
258 // store an oop into a field of a Klass
259 void klass_oop_store(oop* p, oop v);
260 void klass_oop_store(volatile oop* p, oop v);
261
262 // java mirror
263 oop java_mirror() const { return _java_mirror; }
264 void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
265
266 // modifier flags
267 jint modifier_flags() const { return _modifier_flags; }
268 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
269
270 // size helper
271 int layout_helper() const { return _layout_helper; }
272 void set_layout_helper(int lh) { _layout_helper = lh; }
273
274 // Note: for instances layout_helper() may include padding.
275 // Use InstanceKlass::contains_field_offset to classify field offsets.
276
277 // sub/superklass links
278 InstanceKlass* superklass() const;
279 Klass* subklass() const;
280 Klass* next_sibling() const;
281 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
282
283 void set_next_link(Klass* k) { _next_link = k; }
284 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
285
286 // class loader data
287 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
288 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
289
290 // The Klasses are not placed in the Heap, so the Card Table or
291 // the Mod Union Table can't be used to mark when klasses have modified oops.
292 // The CT and MUT bits saves this information for the individual Klasses.
293 void record_modified_oops() { _modified_oops = 1; }
294 void clear_modified_oops() { _modified_oops = 0; }
295 bool has_modified_oops() { return _modified_oops == 1; }
296
297 void accumulate_modified_oops() { if (has_modified_oops()) _accumulated_modified_oops = 1; }
298 void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
299 bool has_accumulated_modified_oops() { return _accumulated_modified_oops == 1; }
300
301 int shared_classpath_index() const {
302 return _shared_class_path_index;
303 };
304
305 void set_shared_classpath_index(int index) {
306 _shared_class_path_index = index;
307 };
308
309
310 protected: // internal accessors
311 Klass* subklass_oop() const { return _subklass; }
312 Klass* next_sibling_oop() const { return _next_sibling; }
313 void set_subklass(Klass* s);
314 void set_next_sibling(Klass* s);
315
316 public:
317
318 // Compiler support
319 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
320 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
321 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
322 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
323 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
324 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
325 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
326 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
327 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
328
329 // Unpacking layout_helper:
330 enum {
331 _lh_neutral_value = 0, // neutral non-array non-instance value
332 _lh_instance_slow_path_bit = 0x01,
333 _lh_log2_element_size_shift = BitsPerByte*0,
334 _lh_log2_element_size_mask = BitsPerLong-1,
335 _lh_element_type_shift = BitsPerByte*1,
336 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
337 _lh_header_size_shift = BitsPerByte*2,
338 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
339 _lh_array_tag_bits = 2,
340 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
341 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30
342 };
343
344 static const unsigned int _lh_array_tag_type_value = 0Xffffffff; // ~0x00, // 0xC0000000 >> 30
345
346 static int layout_helper_size_in_bytes(jint lh) {
347 assert(lh > (jint)_lh_neutral_value, "must be instance");
348 return (int) lh & ~_lh_instance_slow_path_bit;
349 }
350 static bool layout_helper_needs_slow_path(jint lh) {
351 assert(lh > (jint)_lh_neutral_value, "must be instance");
352 return (lh & _lh_instance_slow_path_bit) != 0;
353 }
354 static bool layout_helper_is_instance(jint lh) {
355 return (jint)lh > (jint)_lh_neutral_value;
356 }
357 static bool layout_helper_is_array(jint lh) {
358 return (jint)lh < (jint)_lh_neutral_value;
359 }
360 static bool layout_helper_is_typeArray(jint lh) {
361 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
362 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
363 }
364 static bool layout_helper_is_objArray(jint lh) {
365 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
366 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
367 }
368 static int layout_helper_header_size(jint lh) {
369 assert(lh < (jint)_lh_neutral_value, "must be array");
370 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
371 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
372 return hsize;
373 }
374 static BasicType layout_helper_element_type(jint lh) {
375 assert(lh < (jint)_lh_neutral_value, "must be array");
376 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
377 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
378 return (BasicType) btvalue;
379 }
380
381 // Want a pattern to quickly diff against layout header in register
382 // find something less clever!
383 static int layout_helper_boolean_diffbit() {
384 jint zlh = array_layout_helper(T_BOOLEAN);
385 jint blh = array_layout_helper(T_BYTE);
386 assert(zlh != blh, "array layout helpers must differ");
387 int diffbit = 1;
388 while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
389 diffbit <<= 1;
390 assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
391 }
392 return diffbit;
393 }
394
395 static int layout_helper_log2_element_size(jint lh) {
396 assert(lh < (jint)_lh_neutral_value, "must be array");
397 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
398 assert(l2esz <= LogBitsPerLong,
399 err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh));
400 return l2esz;
401 }
402 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
403 return (tag << _lh_array_tag_shift)
404 | (hsize << _lh_header_size_shift)
405 | ((int)etype << _lh_element_type_shift)
406 | (log2_esize << _lh_log2_element_size_shift);
407 }
408 static jint instance_layout_helper(jint size, bool slow_path_flag) {
409 return (size << LogHeapWordSize)
410 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
411 }
412 static int layout_helper_to_size_helper(jint lh) {
413 assert(lh > (jint)_lh_neutral_value, "must be instance");
414 // Note that the following expression discards _lh_instance_slow_path_bit.
415 return lh >> LogHeapWordSize;
416 }
417 // Out-of-line version computes everything based on the etype:
418 static jint array_layout_helper(BasicType etype);
419
420 // What is the maximum number of primary superclasses any klass can have?
421 #ifdef PRODUCT
422 static juint primary_super_limit() { return _primary_super_limit; }
423 #else
424 static juint primary_super_limit() {
425 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
426 return FastSuperclassLimit;
427 }
428 #endif
429
430 // vtables
431 virtual klassVtable* vtable() const { return NULL; }
432 virtual int vtable_length() const { return 0; }
433
434 // subclass check
435 bool is_subclass_of(const Klass* k) const;
436 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
437 bool is_subtype_of(Klass* k) const {
438 juint off = k->super_check_offset();
439 Klass* sup = *(Klass**)( (address)this + off );
440 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
441 if (sup == k) {
442 return true;
443 } else if (off != secondary_offset) {
444 return false;
445 } else {
446 return search_secondary_supers(k);
447 }
448 }
449 bool search_secondary_supers(Klass* k) const;
450
451 // Find LCA in class hierarchy
452 Klass *LCA( Klass *k );
453
454 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
455 // if not, throw either an Error or an Exception.
456 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
457
458 // array copying
459 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
460
461 // tells if the class should be initialized
462 virtual bool should_be_initialized() const { return false; }
463 // initializes the klass
464 virtual void initialize(TRAPS);
465 // lookup operation for MethodLookupCache
466 friend class MethodLookupCache;
467 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
468 virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature, OverpassLookupMode overpass_mode) const;
469 public:
470 Method* lookup_method(Symbol* name, Symbol* signature) const {
471 return uncached_lookup_method(name, signature, find_overpass);
472 }
473
474 // array class with specific rank
475 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
476
477 // array class with this klass as element type
478 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
479
480 // These will return NULL instead of allocating on the heap:
481 // NB: these can block for a mutex, like other functions with TRAPS arg.
482 Klass* array_klass_or_null(int rank);
483 Klass* array_klass_or_null();
484
485 virtual oop protection_domain() const = 0;
486
487 oop class_loader() const;
488
489 virtual oop klass_holder() const { return class_loader(); }
490
491 protected:
492 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
493 virtual Klass* array_klass_impl(bool or_null, TRAPS);
494
495 public:
496 // CDS support - remove and restore oops from metadata. Oops are not shared.
497 virtual void remove_unshareable_info();
498 virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
499
500 protected:
501 // computes the subtype relationship
502 virtual bool compute_is_subtype_of(Klass* k);
503 public:
504 // subclass accessor (here for convenience; undefined for non-klass objects)
505 virtual bool is_leaf_class() const { fatal("not a class"); return false; }
506 public:
507 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
508 // These functions describe behavior for the oop not the KLASS.
509
510 // actual oop size of obj in memory
511 virtual int oop_size(oop obj) const = 0;
512
513 // Size of klass in word size.
514 virtual int size() const = 0;
515 #if INCLUDE_SERVICES
516 virtual void collect_statistics(KlassSizeStats *sz) const;
517 #endif
518
519 // Returns the Java name for a class (Resource allocated)
520 // For arrays, this returns the name of the element with a leading '['.
521 // For classes, this returns the name with the package separators
522 // turned into '.'s.
523 const char* external_name() const;
524 // Returns the name for a class (Resource allocated) as the class
525 // would appear in a signature.
526 // For arrays, this returns the name of the element with a leading '['.
527 // For classes, this returns the name with a leading 'L' and a trailing ';'
528 // and the package separators as '/'.
529 virtual const char* signature_name() const;
530
531 // garbage collection support
532 virtual void oop_follow_contents(oop obj) = 0;
533 virtual int oop_adjust_pointers(oop obj) = 0;
534
535 // Parallel Scavenge and Parallel Old
536 PARALLEL_GC_DECLS_PV
537
538 // type testing operations
539 protected:
540 virtual bool oop_is_instance_slow() const { return false; }
541 virtual bool oop_is_array_slow() const { return false; }
542 virtual bool oop_is_objArray_slow() const { return false; }
543 virtual bool oop_is_typeArray_slow() const { return false; }
544 public:
545 virtual bool oop_is_instanceClassLoader() const { return false; }
546 virtual bool oop_is_instanceMirror() const { return false; }
547 virtual bool oop_is_instanceRef() const { return false; }
548
549 // Fast non-virtual versions
550 #ifndef ASSERT
551 #define assert_same_query(xval, xcheck) xval
552 #else
553 private:
554 static bool assert_same_query(bool xval, bool xslow) {
555 assert(xval == xslow, "slow and fast queries agree");
556 return xval;
557 }
558 public:
559 #endif
560 inline bool oop_is_instance() const { return assert_same_query(
561 layout_helper_is_instance(layout_helper()),
562 oop_is_instance_slow()); }
563 inline bool oop_is_array() const { return assert_same_query(
564 layout_helper_is_array(layout_helper()),
565 oop_is_array_slow()); }
566 inline bool oop_is_objArray() const { return assert_same_query(
567 layout_helper_is_objArray(layout_helper()),
568 oop_is_objArray_slow()); }
569 inline bool oop_is_typeArray() const { return assert_same_query(
570 layout_helper_is_typeArray(layout_helper()),
571 oop_is_typeArray_slow()); }
572 #undef assert_same_query
573
574 // Access flags
575 AccessFlags access_flags() const { return _access_flags; }
576 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
577
578 bool is_public() const { return _access_flags.is_public(); }
579 bool is_final() const { return _access_flags.is_final(); }
580 bool is_interface() const { return _access_flags.is_interface(); }
581 bool is_abstract() const { return _access_flags.is_abstract(); }
582 bool is_super() const { return _access_flags.is_super(); }
583 bool is_synthetic() const { return _access_flags.is_synthetic(); }
584 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
585 bool has_finalizer() const { return _access_flags.has_finalizer(); }
586 bool has_final_method() const { return _access_flags.has_final_method(); }
587 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
588 void set_has_final_method() { _access_flags.set_has_final_method(); }
589 bool is_cloneable() const;
590 void set_is_cloneable();
591 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
592 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
593 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
594 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
595
596 // Biased locking support
597 // Note: the prototype header is always set up to be at least the
598 // prototype markOop. If biased locking is enabled it may further be
599 // biasable and have an epoch.
600 markOop prototype_header() const { return _prototype_header; }
601 // NOTE: once instances of this klass are floating around in the
602 // system, this header must only be updated at a safepoint.
603 // NOTE 2: currently we only ever set the prototype header to the
604 // biasable prototype for instanceKlasses. There is no technical
605 // reason why it could not be done for arrayKlasses aside from
606 // wanting to reduce the initial scope of this optimization. There
607 // are potential problems in setting the bias pattern for
608 // JVM-internal oops.
609 inline void set_prototype_header(markOop header);
610 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
611
612 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
613 // Atomically increments biased_lock_revocation_count and returns updated value
614 int atomic_incr_biased_lock_revocation_count();
615 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
616 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
617 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
618
619 JFR_ONLY(DEFINE_TRACE_ID_METHODS;)
620
621 // garbage collection support
622 virtual void oops_do(OopClosure* cl);
623
624 // Iff the class loader (or mirror for anonymous classes) is alive the
625 // Klass is considered alive.
626 // The is_alive closure passed in depends on the Garbage Collector used.
627 bool is_loader_alive(BoolObjectClosure* is_alive);
628
629 static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
630 static void clean_subklass_tree(BoolObjectClosure* is_alive) {
631 clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
632 }
633
634 // iterators
635 virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0;
636 virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) {
637 return oop_oop_iterate(obj, blk);
638 }
639
640 #if INCLUDE_ALL_GCS
641 // In case we don't have a specialized backward scanner use forward
642 // iteration.
643 virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) {
644 return oop_oop_iterate_v(obj, blk);
645 }
646 #endif // INCLUDE_ALL_GCS
647
648 // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
649 // (I don't see why the _m should be required, but without it the Solaris
650 // C++ gives warning messages about overridings of the "oop_oop_iterate"
651 // defined above "hiding" this virtual function. (DLD, 6/20/00)) */
652 virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0;
653 virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
654 return oop_oop_iterate_m(obj, blk, mr);
655 }
656
657 // Versions of the above iterators specialized to particular subtypes
658 // of OopClosure, to avoid closure virtual calls.
659 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
660 virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) { \
661 /* Default implementation reverts to general version. */ \
662 return oop_oop_iterate(obj, blk); \
663 } \
664 \
665 /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
666 (I don't see why the _m should be required, but without it the Solaris \
667 C++ gives warning messages about overridings of the "oop_oop_iterate" \
668 defined above "hiding" this virtual function. (DLD, 6/20/00)) */ \
669 virtual int oop_oop_iterate##nv_suffix##_m(oop obj, \
670 OopClosureType* blk, \
671 MemRegion mr) { \
672 return oop_oop_iterate_m(obj, blk, mr); \
673 }
674
675 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
676 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
677
678 #if INCLUDE_ALL_GCS
679 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
680 virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, \
681 OopClosureType* blk) { \
682 /* Default implementation reverts to general version. */ \
683 return oop_oop_iterate_backwards_v(obj, blk); \
684 }
685
686 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
687 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
688 #endif // INCLUDE_ALL_GCS
689
690 virtual void array_klasses_do(void f(Klass* k)) {}
691
692 // Return self, except for abstract classes with exactly 1
693 // implementor. Then return the 1 concrete implementation.
694 Klass *up_cast_abstract();
695
696 // klass name
697 Symbol* name() const { return _name; }
698 void set_name(Symbol* n);
699
700 public:
701 // jvm support
702 virtual jint compute_modifier_flags(TRAPS) const;
703
704 // JVMTI support
705 virtual jint jvmti_class_status() const;
706
707 // Printing
708 virtual void print_on(outputStream* st) const;
709
710 virtual void oop_print_value_on(oop obj, outputStream* st);
711 virtual void oop_print_on (oop obj, outputStream* st);
712
713 virtual const char* internal_name() const = 0;
714
715 // Verification
716 virtual void verify_on(outputStream* st);
717 void verify() { verify_on(tty); }
718
719 #ifndef PRODUCT
720 bool verify_vtable_index(int index);
721 bool verify_itable_index(int index);
722 #endif
723
724 virtual void oop_verify_on(oop obj, outputStream* st);
725
726 static bool is_null(narrowKlass obj);
727 static bool is_null(Klass* obj);
728
729 // klass encoding for klass pointer in objects.
730 static narrowKlass encode_klass_not_null(Klass* v);
731 static narrowKlass encode_klass(Klass* v);
732
733 static Klass* decode_klass_not_null(narrowKlass v);
734 static Klass* decode_klass(narrowKlass v);
735
736 private:
737 // barriers used by klass_oop_store
738 void klass_update_barrier_set(oop v);
739 void klass_update_barrier_set_pre(oop* p, oop v);
740 };
741
742 #endif // SHARE_VM_OOPS_KLASS_HPP