1 /*
2 * Copyright (c) 1997, 2016, 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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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 "trace/traceMacros.hpp"
34 #include "utilities/accessFlags.hpp"
35 #include "utilities/macros.hpp"
36
37 //
38 // A Klass provides:
39 // 1: language level class object (method dictionary etc.)
40 // 2: provide vm dispatch behavior for the object
41 // Both functions are combined into one C++ class.
42
43 // One reason for the oop/klass dichotomy in the implementation is
44 // that we don't want a C++ vtbl pointer in every object. Thus,
45 // normal oops don't have any virtual functions. Instead, they
46 // forward all "virtual" functions to their klass, which does have
47 // a vtbl and does the C++ dispatch depending on the object's
48 // actual type. (See oop.inline.hpp for some of the forwarding code.)
49 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
50
51 // Forward declarations.
52 template <class T> class Array;
53 template <class T> class GrowableArray;
54 class ClassLoaderData;
55 class klassVtable;
56 class ParCompactionManager;
57 class PSPromotionManager;
58 class KlassSizeStats;
59 class fieldDescriptor;
60 class vtableEntry;
61
62 class Klass : public Metadata {
63 friend class VMStructs;
64 friend class JVMCIVMStructs;
65 protected:
66 // note: put frequently-used fields together at start of klass structure
67 // for better cache behavior (may not make much of a difference but sure won't hurt)
68 enum { _primary_super_limit = 8 };
69
70 // The "layout helper" is a combined descriptor of object layout.
71 // For klasses which are neither instance nor array, the value is zero.
72 //
73 // For instances, layout helper is a positive number, the instance size.
74 // This size is already passed through align_object_size and scaled to bytes.
75 // The low order bit is set if instances of this class cannot be
76 // allocated using the fastpath.
77 //
78 // For arrays, layout helper is a negative number, containing four
79 // distinct bytes, as follows:
80 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
81 // where:
82 // tag is 0x80 if the elements are oops, 0xC0 if non-oops, 0xA0 if value types
83 // hsz is array header size in bytes (i.e., offset of first element)
84 // ebt is the BasicType of the elements
85 // esz is the element size in bytes
86 // This packed word is arranged so as to be quickly unpacked by the
87 // various fast paths that use the various subfields.
88 //
89 // The esz bits can be used directly by a SLL instruction, without masking.
90 //
91 // Note that the array-kind tag looks like 0x00 for instance klasses,
92 // since their length in bytes is always less than 24Mb.
93 //
94 // Final note: This comes first, immediately after C++ vtable,
95 // because it is frequently queried.
96 jint _layout_helper;
97
98 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
99 // and _primary_supers all help make fast subtype checks. See big discussion
100 // in doc/server_compiler/checktype.txt
101 //
102 // Where to look to observe a supertype (it is &_secondary_super_cache for
103 // secondary supers, else is &_primary_supers[depth()].
104 juint _super_check_offset;
105
106 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
107 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
108 Symbol* _name;
109
110 // Cache of last observed secondary supertype
111 Klass* _secondary_super_cache;
112 // Array of all secondary supertypes
113 Array<Klass*>* _secondary_supers;
114 // Ordered list of all primary supertypes
115 Klass* _primary_supers[_primary_super_limit];
116 // Extra injectable types
117 InstanceKlass* _extra_super;
118 // java/lang/Class instance mirroring this class
119 oop _java_mirror;
120 // Superclass
121 Klass* _super;
122 // First subclass (NULL if none); _subklass->next_sibling() is next one
123 Klass* _subklass;
124 // Sibling link (or NULL); links all subklasses of a klass
125 Klass* _next_sibling;
126
127 // All klasses loaded by a class loader are chained through these links
128 Klass* _next_link;
129
130 // The VM's representation of the ClassLoader used to load this class.
131 // Provide access the corresponding instance java.lang.ClassLoader.
132 ClassLoaderData* _class_loader_data;
133
134 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
135 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
136
137 TRACE_DEFINE_TRACE_ID_FIELD;
138
139 // Biased locking implementation and statistics
140 // (the 64-bit chunk goes first, to avoid some fragmentation)
141 jlong _last_biased_lock_bulk_revocation_time;
142 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type
143 jint _biased_lock_revocation_count;
144
145 // vtable length
146 int _vtable_len;
147
148 // Remembered sets support for the oops in the klasses.
149 jbyte _modified_oops; // Card Table Equivalent (YC/CMS support)
150 jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
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 // store an oop into a field of a Klass
229 void klass_oop_store(oop* p, oop v);
230 void klass_oop_store(volatile oop* p, oop v);
231
232 // java mirror
233 oop java_mirror() const { return _java_mirror; }
234 void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
235
236 // modifier flags
237 jint modifier_flags() const { return _modifier_flags; }
238 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
239
240 // size helper
241 int layout_helper() const { return _layout_helper; }
242 void set_layout_helper(int lh) { _layout_helper = lh; }
243
244 // Note: for instances layout_helper() may include padding.
245 // Use InstanceKlass::contains_field_offset to classify field offsets.
246
247 // sub/superklass links
248 Klass* subklass() const { return _subklass; }
249 Klass* next_sibling() const { return _next_sibling; }
250 InstanceKlass* superklass() const;
251 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
252
253 void set_next_link(Klass* k) { _next_link = k; }
254 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
255
256 // patchable link to additional behaviors and interfaces
257 // Being used for prototying arrays with interfaces, can be move to ArrayKlass
258 // Lives here for now, just to keep macro asm simple
259 InstanceKlass* extra_super() const { return _extra_super; }
260 void set_extra_super(InstanceKlass* extra_super) {
261 assert(EnableExtraSuper || extra_super == NULL, "ExtraSuper not enabled");
262 assert(extra_super == NULL || _extra_super == NULL, "One-shot");
263 _extra_super = extra_super;
264 }
265
266 // class loader data
267 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
268 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
269
270 // The Klasses are not placed in the Heap, so the Card Table or
271 // the Mod Union Table can't be used to mark when klasses have modified oops.
272 // The CT and MUT bits saves this information for the individual Klasses.
273 void record_modified_oops() { _modified_oops = 1; }
274 void clear_modified_oops() { _modified_oops = 0; }
275 bool has_modified_oops() { return _modified_oops == 1; }
276
277 void accumulate_modified_oops() { if (has_modified_oops()) _accumulated_modified_oops = 1; }
278 void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
279 bool has_accumulated_modified_oops() { return _accumulated_modified_oops == 1; }
280
281 int shared_classpath_index() const {
282 return _shared_class_path_index;
283 };
284
285 void set_shared_classpath_index(int index) {
286 _shared_class_path_index = index;
287 };
288
289
290 protected: // internal accessors
291 void set_subklass(Klass* s);
292 void set_next_sibling(Klass* s);
293
294 public:
295
296 // Compiler support
297 static ByteSize extra_super_offset() { return in_ByteSize(offset_of(Klass, _extra_super)); }
298 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
299 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
300 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
301 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
302 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
303 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
304 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
305 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
306 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
307
308 // Unpacking layout_helper:
309 enum {
310 _lh_neutral_value = 0, // neutral non-array non-instance value
311 _lh_instance_slow_path_bit = 0x01,
312 _lh_log2_element_size_shift = BitsPerByte*0,
313 _lh_log2_element_size_mask = BitsPerLong-1,
314 _lh_element_type_shift = BitsPerByte*1,
315 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
316 _lh_header_size_shift = BitsPerByte*2,
317 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
318
319 _lh_array_tag_bits = 3,
320 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
321 _lh_array_tag_type_value = ~0x3, // bits ~100 compare as int, ie. sign extended
322 _lh_array_tag_vt_value = ~0x2, // bits ~101
323 _lh_array_tag_obj_value = ~0x1, // bits ~110
324 };
325
326 static int layout_helper_size_in_bytes(jint lh) {
327 assert(lh > (jint)_lh_neutral_value, "must be instance");
328 return (int) lh & ~_lh_instance_slow_path_bit;
329 }
330 static bool layout_helper_needs_slow_path(jint lh) {
331 assert(lh > (jint)_lh_neutral_value, "must be instance");
332 return (lh & _lh_instance_slow_path_bit) != 0;
333 }
334 static bool layout_helper_is_instance(jint lh) {
335 return (jint)lh > (jint)_lh_neutral_value;
336 }
337 static bool layout_helper_is_array(jint lh) {
338 return (jint)lh < (jint)_lh_neutral_value;
339 }
340 static bool layout_helper_is_typeArray(jint lh) {
341 return _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
342 }
343 static bool layout_helper_is_objArray(jint lh) {
344 return _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
345 }
346 static bool layout_helper_is_valueArray(jint lh) {
347 return _lh_array_tag_vt_value == (lh >> _lh_array_tag_shift);
348 }
349 static int layout_helper_header_size(jint lh) {
350 assert(lh < (jint)_lh_neutral_value, "must be array");
351 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
352 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
353 return hsize;
354 }
355 static BasicType layout_helper_element_type(jint lh) {
356 assert(lh < (jint)_lh_neutral_value, "must be array");
357 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
358 assert((btvalue >= T_BOOLEAN && btvalue <= T_OBJECT) || btvalue == T_VALUETYPE, "sanity");
359 return (BasicType) btvalue;
360 }
361 static int layout_helper_log2_element_size(jint lh) {
362 assert(lh < (jint)_lh_neutral_value, "must be array");
363 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
364 assert(l2esz <= LogBitsPerLong,
365 "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
366 return l2esz;
367 }
368 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
369 return (tag << _lh_array_tag_shift)
370 | (hsize << _lh_header_size_shift)
371 | ((int)etype << _lh_element_type_shift)
372 | (log2_esize << _lh_log2_element_size_shift);
373 }
374 static jint instance_layout_helper(jint size, bool slow_path_flag) {
375 return (size << LogBytesPerWord)
376 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
377 }
378 static int layout_helper_to_size_helper(jint lh) {
379 assert(lh > (jint)_lh_neutral_value, "must be instance");
380 // Note that the following expression discards _lh_instance_slow_path_bit.
381 return lh >> LogBytesPerWord;
382 }
383 // Out-of-line version computes everything based on the etype:
384 static jint array_layout_helper(BasicType etype);
385
386 // What is the maximum number of primary superclasses any klass can have?
387 #ifdef PRODUCT
388 static juint primary_super_limit() { return _primary_super_limit; }
389 #else
390 static juint primary_super_limit() {
391 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
392 return FastSuperclassLimit;
393 }
394 #endif
395
396 // vtables
397 klassVtable* vtable() const;
398 int vtable_length() const { return _vtable_len; }
399
400 // subclass check
401 bool is_subclass_of(const Klass* k) const;
402 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
403 bool is_subtype_of(Klass* k) const {
404 juint off = k->super_check_offset();
405 Klass* sup = *(Klass**)( (address)this + off );
406 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
407 if (sup == k) {
408 return true;
409 } else if (off != secondary_offset) {
410 return false;
411 } else {
412 return search_secondary_supers(k);
413 }
414 }
415 bool search_secondary_supers(Klass* k) const;
416
417 // Find LCA in class hierarchy
418 Klass *LCA( Klass *k );
419
420 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
421 // if not, throw either an Error or an Exception.
422 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
423
424 // array copying
425 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
426
427 // tells if the class should be initialized
428 virtual bool should_be_initialized() const { return false; }
429 // initializes the klass
430 virtual void initialize(TRAPS);
431 // lookup operation for MethodLookupCache
432 friend class MethodLookupCache;
433 virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
434 virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature, OverpassLookupMode overpass_mode) const;
435 public:
436 Method* lookup_method(const Symbol* name, const Symbol* signature) const {
437 return uncached_lookup_method(name, signature, find_overpass);
438 }
439
440 // array class with specific rank
441 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
442
443 // array class with this klass as element type
444 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
445
446 // These will return NULL instead of allocating on the heap:
447 // NB: these can block for a mutex, like other functions with TRAPS arg.
448 Klass* array_klass_or_null(int rank);
449 Klass* array_klass_or_null();
450
451 virtual oop protection_domain() const = 0;
452
453 oop class_loader() const;
454
455 virtual oop klass_holder() const { return class_loader(); }
456
457 protected:
458 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
459 virtual Klass* array_klass_impl(bool or_null, TRAPS);
460
461 void set_vtable_length(int len) { _vtable_len= len; }
462
463 vtableEntry* start_of_vtable() const;
464 public:
465 Method* method_at_vtable(int index);
466
467 static ByteSize vtable_start_offset();
468 static ByteSize vtable_length_offset() {
469 return byte_offset_of(Klass, _vtable_len);
470 }
471
472 // CDS support - remove and restore oops from metadata. Oops are not shared.
473 virtual void remove_unshareable_info();
474 virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
475
476 protected:
477 // computes the subtype relationship
478 virtual bool compute_is_subtype_of(Klass* k);
479 public:
480 // subclass accessor (here for convenience; undefined for non-klass objects)
481 virtual bool is_leaf_class() const { fatal("not a class"); return false; }
482 public:
483 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
484 // These functions describe behavior for the oop not the KLASS.
485
486 // actual oop size of obj in memory
487 virtual int oop_size(oop obj) const = 0;
488
489 // Size of klass in word size.
490 virtual int size() const = 0;
491 #if INCLUDE_SERVICES
492 virtual void collect_statistics(KlassSizeStats *sz) const;
493 #endif
494
495 // Returns the Java name for a class (Resource allocated)
496 // For arrays, this returns the name of the element with a leading '['.
497 // For classes, this returns the name with the package separators
498 // turned into '.'s.
499 const char* external_name() const;
500 // Returns the name for a class (Resource allocated) as the class
501 // would appear in a signature.
502 // For arrays, this returns the name of the element with a leading '['.
503 // For classes, this returns the name with a leading 'L' and a trailing ';'
504 // and the package separators as '/'.
505 virtual const char* signature_name() const;
506
507 // type testing operations
508 #ifdef ASSERT
509 protected:
510 virtual bool is_instance_klass_slow() const { return false; }
511 virtual bool is_array_klass_slow() const { return false; }
512 virtual bool is_objArray_klass_slow() const { return false; }
513 virtual bool is_typeArray_klass_slow() const { return false; }
514 virtual bool is_valueArray_klass_slow() const { return false; }
515 #endif // ASSERT
516 // current implementation uses this method even in non debug builds
517 virtual bool is_value_slow() const { return false; }
518 public:
519
520 // Fast non-virtual versions
521 #ifndef ASSERT
522 #define assert_same_query(xval, xcheck) xval
523 #else
524 private:
525 static bool assert_same_query(bool xval, bool xslow) {
526 assert(xval == xslow, "slow and fast queries agree");
527 return xval;
528 }
529 public:
530 #endif
531 inline bool is_instance_klass() const { return assert_same_query(
532 layout_helper_is_instance(layout_helper()),
533 is_instance_klass_slow()); }
534 inline bool is_array_klass() const { return assert_same_query(
535 layout_helper_is_array(layout_helper()),
536 is_array_klass_slow()); }
537 inline bool is_objArray_klass() const { return assert_same_query(
538 layout_helper_is_objArray(layout_helper()),
539 is_objArray_klass_slow()); }
540 inline bool is_typeArray_klass() const { return assert_same_query(
541 layout_helper_is_typeArray(layout_helper()),
542 is_typeArray_klass_slow()); }
543 inline bool is_value() const { return is_value_slow(); } //temporary hack
544 inline bool is_valueArray_klass() const { return assert_same_query(
545 layout_helper_is_valueArray(layout_helper()),
546 is_valueArray_klass_slow()); }
547 #undef assert_same_query
548
549 // Access flags
550 AccessFlags access_flags() const { return _access_flags; }
551 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
552
553 bool is_public() const { return _access_flags.is_public(); }
554 bool is_final() const { return _access_flags.is_final(); }
555 bool is_interface() const { return _access_flags.is_interface(); }
556 bool is_abstract() const { return _access_flags.is_abstract(); }
557 bool is_super() const { return _access_flags.is_super(); }
558 bool is_synthetic() const { return _access_flags.is_synthetic(); }
559 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
560 bool has_finalizer() const { return _access_flags.has_finalizer(); }
561 bool has_final_method() const { return _access_flags.has_final_method(); }
562 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
563 void set_has_final_method() { _access_flags.set_has_final_method(); }
564 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
565 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
566 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
567 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
568
569 bool is_cloneable() const;
570 void set_is_cloneable();
571
572 // Biased locking support
573 // Note: the prototype header is always set up to be at least the
574 // prototype markOop. If biased locking is enabled it may further be
575 // biasable and have an epoch.
576 markOop prototype_header() const { return _prototype_header; }
577 // NOTE: once instances of this klass are floating around in the
578 // system, this header must only be updated at a safepoint.
579 // NOTE 2: currently we only ever set the prototype header to the
580 // biasable prototype for instanceKlasses. There is no technical
581 // reason why it could not be done for arrayKlasses aside from
582 // wanting to reduce the initial scope of this optimization. There
583 // are potential problems in setting the bias pattern for
584 // JVM-internal oops.
585 inline void set_prototype_header(markOop header);
586 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
587
588 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
589 // Atomically increments biased_lock_revocation_count and returns updated value
590 int atomic_incr_biased_lock_revocation_count();
591 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
592 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
593 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
594
595 TRACE_DEFINE_TRACE_ID_METHODS;
596
597 // garbage collection support
598 void oops_do(OopClosure* cl);
599
600 // Iff the class loader (or mirror for anonymous classes) is alive the
601 // Klass is considered alive.
602 // The is_alive closure passed in depends on the Garbage Collector used.
603 bool is_loader_alive(BoolObjectClosure* is_alive);
604
605 static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
606 static void clean_subklass_tree(BoolObjectClosure* is_alive) {
607 clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
608 }
609
610 // GC specific object visitors
611 //
612 // Mark Sweep
613 virtual int oop_ms_adjust_pointers(oop obj) = 0;
614 #if INCLUDE_ALL_GCS
615 // Parallel Scavenge
616 virtual void oop_ps_push_contents( oop obj, PSPromotionManager* pm) = 0;
617 // Parallel Compact
618 virtual void oop_pc_follow_contents(oop obj, ParCompactionManager* cm) = 0;
619 virtual void oop_pc_update_pointers(oop obj, ParCompactionManager* cm) = 0;
620 #endif
621
622 // Iterators specialized to particular subtypes
623 // of ExtendedOopClosure, to avoid closure virtual calls.
624 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
625 virtual void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) = 0; \
626 /* Iterates "closure" over all the oops in "obj" (of type "this") within "mr". */ \
627 virtual void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) = 0;
628
629 ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
630 ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
631
632 #if INCLUDE_ALL_GCS
633 #define Klass_OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix) \
634 virtual void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) = 0;
635
636 ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
637 ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
638 #endif // INCLUDE_ALL_GCS
639
640 virtual void array_klasses_do(void f(Klass* k)) {}
641
642 // Return self, except for abstract classes with exactly 1
643 // implementor. Then return the 1 concrete implementation.
644 Klass *up_cast_abstract();
645
646 // klass name
647 Symbol* name() const { return _name; }
648 void set_name(Symbol* n);
649
650 public:
651 // jvm support
652 virtual jint compute_modifier_flags(TRAPS) const;
653
654 // JVMTI support
655 virtual jint jvmti_class_status() const;
656
657 // Printing
658 virtual void print_on(outputStream* st) const;
659
660 virtual void oop_print_value_on(oop obj, outputStream* st);
661 virtual void oop_print_on (oop obj, outputStream* st);
662
663 virtual const char* internal_name() const = 0;
664
665 // Verification
666 virtual void verify_on(outputStream* st);
667 void verify() { verify_on(tty); }
668
669 #ifndef PRODUCT
670 bool verify_vtable_index(int index);
671 bool verify_itable_index(int index);
672 #endif
673
674 virtual void oop_verify_on(oop obj, outputStream* st);
675
676 static bool is_null(narrowKlass obj);
677 static bool is_null(Klass* obj);
678
679 // klass encoding for klass pointer in objects.
680 static narrowKlass encode_klass_not_null(Klass* v);
681 static narrowKlass encode_klass(Klass* v);
682
683 static Klass* decode_klass_not_null(narrowKlass v);
684 static Klass* decode_klass(narrowKlass v);
685
686 private:
687 // barriers used by klass_oop_store
688 void klass_update_barrier_set(oop v);
689 void klass_update_barrier_set_pre(oop* p, oop 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