Mon, 07 Jul 2014 10:12:40 +0200
8049421: G1 Class Unloading after completing a concurrent mark cycle
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
Contributed-by: stefan.karlsson@oracle.com, mikael.gerdin@oracle.com
1 /*
2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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23 */
25 #ifndef SHARE_VM_OOPS_KLASS_HPP
26 #define SHARE_VM_OOPS_KLASS_HPP
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 "trace/traceMacros.hpp"
36 #include "utilities/accessFlags.hpp"
37 #include "utilities/macros.hpp"
38 #if INCLUDE_ALL_GCS
39 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp"
40 #include "gc_implementation/g1/g1OopClosures.hpp"
41 #include "gc_implementation/parNew/parOopClosures.hpp"
42 #endif // INCLUDE_ALL_GCS
44 //
45 // A Klass provides:
46 // 1: language level class object (method dictionary etc.)
47 // 2: provide vm dispatch behavior for the object
48 // Both functions are combined into one C++ class.
50 // One reason for the oop/klass dichotomy in the implementation is
51 // that we don't want a C++ vtbl pointer in every object. Thus,
52 // normal oops don't have any virtual functions. Instead, they
53 // forward all "virtual" functions to their klass, which does have
54 // a vtbl and does the C++ dispatch depending on the object's
55 // actual type. (See oop.inline.hpp for some of the forwarding code.)
56 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
58 // Klass layout:
59 // [C++ vtbl ptr ] (contained in Metadata)
60 // [layout_helper ]
61 // [super_check_offset ] for fast subtype checks
62 // [name ]
63 // [secondary_super_cache] for fast subtype checks
64 // [secondary_supers ] array of 2ndary supertypes
65 // [primary_supers 0]
66 // [primary_supers 1]
67 // [primary_supers 2]
68 // ...
69 // [primary_supers 7]
70 // [java_mirror ]
71 // [super ]
72 // [subklass ] first subclass
73 // [next_sibling ] link to chain additional subklasses
74 // [next_link ]
75 // [class_loader_data]
76 // [modifier_flags]
77 // [access_flags ]
78 // [last_biased_lock_bulk_revocation_time] (64 bits)
79 // [prototype_header]
80 // [biased_lock_revocation_count]
81 // [_modified_oops]
82 // [_accumulated_modified_oops]
83 // [trace_id]
86 // Forward declarations.
87 template <class T> class Array;
88 template <class T> class GrowableArray;
89 class ClassLoaderData;
90 class klassVtable;
91 class ParCompactionManager;
92 class KlassSizeStats;
94 class Klass : public Metadata {
95 friend class VMStructs;
96 protected:
97 // note: put frequently-used fields together at start of klass structure
98 // for better cache behavior (may not make much of a difference but sure won't hurt)
99 enum { _primary_super_limit = 8 };
101 // The "layout helper" is a combined descriptor of object layout.
102 // For klasses which are neither instance nor array, the value is zero.
103 //
104 // For instances, layout helper is a positive number, the instance size.
105 // This size is already passed through align_object_size and scaled to bytes.
106 // The low order bit is set if instances of this class cannot be
107 // allocated using the fastpath.
108 //
109 // For arrays, layout helper is a negative number, containing four
110 // distinct bytes, as follows:
111 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
112 // where:
113 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
114 // hsz is array header size in bytes (i.e., offset of first element)
115 // ebt is the BasicType of the elements
116 // esz is the element size in bytes
117 // This packed word is arranged so as to be quickly unpacked by the
118 // various fast paths that use the various subfields.
119 //
120 // The esz bits can be used directly by a SLL instruction, without masking.
121 //
122 // Note that the array-kind tag looks like 0x00 for instance klasses,
123 // since their length in bytes is always less than 24Mb.
124 //
125 // Final note: This comes first, immediately after C++ vtable,
126 // because it is frequently queried.
127 jint _layout_helper;
129 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
130 // and _primary_supers all help make fast subtype checks. See big discussion
131 // in doc/server_compiler/checktype.txt
132 //
133 // Where to look to observe a supertype (it is &_secondary_super_cache for
134 // secondary supers, else is &_primary_supers[depth()].
135 juint _super_check_offset;
137 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
138 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
139 Symbol* _name;
141 // Cache of last observed secondary supertype
142 Klass* _secondary_super_cache;
143 // Array of all secondary supertypes
144 Array<Klass*>* _secondary_supers;
145 // Ordered list of all primary supertypes
146 Klass* _primary_supers[_primary_super_limit];
147 // java/lang/Class instance mirroring this class
148 oop _java_mirror;
149 // Superclass
150 Klass* _super;
151 // First subclass (NULL if none); _subklass->next_sibling() is next one
152 Klass* _subklass;
153 // Sibling link (or NULL); links all subklasses of a klass
154 Klass* _next_sibling;
156 // All klasses loaded by a class loader are chained through these links
157 Klass* _next_link;
159 // The VM's representation of the ClassLoader used to load this class.
160 // Provide access the corresponding instance java.lang.ClassLoader.
161 ClassLoaderData* _class_loader_data;
163 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
164 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
166 // Biased locking implementation and statistics
167 // (the 64-bit chunk goes first, to avoid some fragmentation)
168 jlong _last_biased_lock_bulk_revocation_time;
169 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type
170 jint _biased_lock_revocation_count;
172 TRACE_DEFINE_KLASS_TRACE_ID;
174 // Remembered sets support for the oops in the klasses.
175 jbyte _modified_oops; // Card Table Equivalent (YC/CMS support)
176 jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
178 // Constructor
179 Klass();
181 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
183 public:
184 enum MethodLookupMode { normal, skip_overpass, skip_defaults };
186 bool is_klass() const volatile { return true; }
188 // super
189 Klass* super() const { return _super; }
190 void set_super(Klass* k) { _super = k; }
192 // initializes _super link, _primary_supers & _secondary_supers arrays
193 void initialize_supers(Klass* k, TRAPS);
194 void initialize_supers_impl1(Klass* k);
195 void initialize_supers_impl2(Klass* k);
197 // klass-specific helper for initializing _secondary_supers
198 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
200 // java_super is the Java-level super type as specified by Class.getSuperClass.
201 virtual Klass* java_super() const { return NULL; }
203 juint super_check_offset() const { return _super_check_offset; }
204 void set_super_check_offset(juint o) { _super_check_offset = o; }
206 Klass* secondary_super_cache() const { return _secondary_super_cache; }
207 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
209 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
210 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
212 // Return the element of the _super chain of the given depth.
213 // If there is no such element, return either NULL or this.
214 Klass* primary_super_of_depth(juint i) const {
215 assert(i < primary_super_limit(), "oob");
216 Klass* super = _primary_supers[i];
217 assert(super == NULL || super->super_depth() == i, "correct display");
218 return super;
219 }
221 // Can this klass be a primary super? False for interfaces and arrays of
222 // interfaces. False also for arrays or classes with long super chains.
223 bool can_be_primary_super() const {
224 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
225 return super_check_offset() != secondary_offset;
226 }
227 virtual bool can_be_primary_super_slow() const;
229 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
230 juint super_depth() const {
231 if (!can_be_primary_super()) {
232 return primary_super_limit();
233 } else {
234 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
235 assert(d < primary_super_limit(), "oob");
236 assert(_primary_supers[d] == this, "proper init");
237 return d;
238 }
239 }
241 // store an oop into a field of a Klass
242 void klass_oop_store(oop* p, oop v);
243 void klass_oop_store(volatile oop* p, oop v);
245 // java mirror
246 oop java_mirror() const { return _java_mirror; }
247 void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
249 // modifier flags
250 jint modifier_flags() const { return _modifier_flags; }
251 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
253 // size helper
254 int layout_helper() const { return _layout_helper; }
255 void set_layout_helper(int lh) { _layout_helper = lh; }
257 // Note: for instances layout_helper() may include padding.
258 // Use InstanceKlass::contains_field_offset to classify field offsets.
260 // sub/superklass links
261 InstanceKlass* superklass() const;
262 Klass* subklass() const;
263 Klass* next_sibling() const;
264 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
266 void set_next_link(Klass* k) { _next_link = k; }
267 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
269 // class loader data
270 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
271 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
273 // The Klasses are not placed in the Heap, so the Card Table or
274 // the Mod Union Table can't be used to mark when klasses have modified oops.
275 // The CT and MUT bits saves this information for the individual Klasses.
276 void record_modified_oops() { _modified_oops = 1; }
277 void clear_modified_oops() { _modified_oops = 0; }
278 bool has_modified_oops() { return _modified_oops == 1; }
280 void accumulate_modified_oops() { if (has_modified_oops()) _accumulated_modified_oops = 1; }
281 void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
282 bool has_accumulated_modified_oops() { return _accumulated_modified_oops == 1; }
284 protected: // internal accessors
285 Klass* subklass_oop() const { return _subklass; }
286 Klass* next_sibling_oop() const { return _next_sibling; }
287 void set_subklass(Klass* s);
288 void set_next_sibling(Klass* s);
290 public:
292 // Compiler support
293 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
294 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
295 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
296 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
297 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
298 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
299 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
300 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
301 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
303 // Unpacking layout_helper:
304 enum {
305 _lh_neutral_value = 0, // neutral non-array non-instance value
306 _lh_instance_slow_path_bit = 0x01,
307 _lh_log2_element_size_shift = BitsPerByte*0,
308 _lh_log2_element_size_mask = BitsPerLong-1,
309 _lh_element_type_shift = BitsPerByte*1,
310 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
311 _lh_header_size_shift = BitsPerByte*2,
312 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
313 _lh_array_tag_bits = 2,
314 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
315 _lh_array_tag_type_value = ~0x00, // 0xC0000000 >> 30
316 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30
317 };
319 static int layout_helper_size_in_bytes(jint lh) {
320 assert(lh > (jint)_lh_neutral_value, "must be instance");
321 return (int) lh & ~_lh_instance_slow_path_bit;
322 }
323 static bool layout_helper_needs_slow_path(jint lh) {
324 assert(lh > (jint)_lh_neutral_value, "must be instance");
325 return (lh & _lh_instance_slow_path_bit) != 0;
326 }
327 static bool layout_helper_is_instance(jint lh) {
328 return (jint)lh > (jint)_lh_neutral_value;
329 }
330 static bool layout_helper_is_array(jint lh) {
331 return (jint)lh < (jint)_lh_neutral_value;
332 }
333 static bool layout_helper_is_typeArray(jint lh) {
334 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
335 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
336 }
337 static bool layout_helper_is_objArray(jint lh) {
338 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
339 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
340 }
341 static int layout_helper_header_size(jint lh) {
342 assert(lh < (jint)_lh_neutral_value, "must be array");
343 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
344 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
345 return hsize;
346 }
347 static BasicType layout_helper_element_type(jint lh) {
348 assert(lh < (jint)_lh_neutral_value, "must be array");
349 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
350 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
351 return (BasicType) btvalue;
352 }
353 static int layout_helper_log2_element_size(jint lh) {
354 assert(lh < (jint)_lh_neutral_value, "must be array");
355 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
356 assert(l2esz <= LogBitsPerLong,
357 err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh));
358 return l2esz;
359 }
360 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
361 return (tag << _lh_array_tag_shift)
362 | (hsize << _lh_header_size_shift)
363 | ((int)etype << _lh_element_type_shift)
364 | (log2_esize << _lh_log2_element_size_shift);
365 }
366 static jint instance_layout_helper(jint size, bool slow_path_flag) {
367 return (size << LogHeapWordSize)
368 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
369 }
370 static int layout_helper_to_size_helper(jint lh) {
371 assert(lh > (jint)_lh_neutral_value, "must be instance");
372 // Note that the following expression discards _lh_instance_slow_path_bit.
373 return lh >> LogHeapWordSize;
374 }
375 // Out-of-line version computes everything based on the etype:
376 static jint array_layout_helper(BasicType etype);
378 // What is the maximum number of primary superclasses any klass can have?
379 #ifdef PRODUCT
380 static juint primary_super_limit() { return _primary_super_limit; }
381 #else
382 static juint primary_super_limit() {
383 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
384 return FastSuperclassLimit;
385 }
386 #endif
388 // vtables
389 virtual klassVtable* vtable() const { return NULL; }
390 virtual int vtable_length() const { return 0; }
392 // subclass check
393 bool is_subclass_of(const Klass* k) const;
394 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
395 bool is_subtype_of(Klass* k) const {
396 juint off = k->super_check_offset();
397 Klass* sup = *(Klass**)( (address)this + off );
398 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
399 if (sup == k) {
400 return true;
401 } else if (off != secondary_offset) {
402 return false;
403 } else {
404 return search_secondary_supers(k);
405 }
406 }
407 bool search_secondary_supers(Klass* k) const;
409 // Find LCA in class hierarchy
410 Klass *LCA( Klass *k );
412 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
413 // if not, throw either an Error or an Exception.
414 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
416 // array copying
417 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
419 // tells if the class should be initialized
420 virtual bool should_be_initialized() const { return false; }
421 // initializes the klass
422 virtual void initialize(TRAPS);
423 // lookup operation for MethodLookupCache
424 friend class MethodLookupCache;
425 virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature, MethodLookupMode mode) const;
426 public:
427 Method* lookup_method(Symbol* name, Symbol* signature) const {
428 return uncached_lookup_method(name, signature, normal);
429 }
431 // array class with specific rank
432 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
434 // array class with this klass as element type
435 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
437 // These will return NULL instead of allocating on the heap:
438 // NB: these can block for a mutex, like other functions with TRAPS arg.
439 Klass* array_klass_or_null(int rank);
440 Klass* array_klass_or_null();
442 virtual oop protection_domain() const = 0;
444 oop class_loader() const;
446 virtual oop klass_holder() const { return class_loader(); }
448 protected:
449 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
450 virtual Klass* array_klass_impl(bool or_null, TRAPS);
452 public:
453 // CDS support - remove and restore oops from metadata. Oops are not shared.
454 virtual void remove_unshareable_info();
455 virtual void restore_unshareable_info(TRAPS);
457 protected:
458 // computes the subtype relationship
459 virtual bool compute_is_subtype_of(Klass* k);
460 public:
461 // subclass accessor (here for convenience; undefined for non-klass objects)
462 virtual bool is_leaf_class() const { fatal("not a class"); return false; }
463 public:
464 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
465 // These functions describe behavior for the oop not the KLASS.
467 // actual oop size of obj in memory
468 virtual int oop_size(oop obj) const = 0;
470 // Size of klass in word size.
471 virtual int size() const = 0;
472 #if INCLUDE_SERVICES
473 virtual void collect_statistics(KlassSizeStats *sz) const;
474 #endif
476 // Returns the Java name for a class (Resource allocated)
477 // For arrays, this returns the name of the element with a leading '['.
478 // For classes, this returns the name with the package separators
479 // turned into '.'s.
480 const char* external_name() const;
481 // Returns the name for a class (Resource allocated) as the class
482 // would appear in a signature.
483 // For arrays, this returns the name of the element with a leading '['.
484 // For classes, this returns the name with a leading 'L' and a trailing ';'
485 // and the package separators as '/'.
486 virtual const char* signature_name() const;
488 // garbage collection support
489 virtual void oop_follow_contents(oop obj) = 0;
490 virtual int oop_adjust_pointers(oop obj) = 0;
492 // Parallel Scavenge and Parallel Old
493 PARALLEL_GC_DECLS_PV
495 // type testing operations
496 protected:
497 virtual bool oop_is_instance_slow() const { return false; }
498 virtual bool oop_is_array_slow() const { return false; }
499 virtual bool oop_is_objArray_slow() const { return false; }
500 virtual bool oop_is_typeArray_slow() const { return false; }
501 public:
502 virtual bool oop_is_instanceClassLoader() const { return false; }
503 virtual bool oop_is_instanceMirror() const { return false; }
504 virtual bool oop_is_instanceRef() const { return false; }
506 // Fast non-virtual versions
507 #ifndef ASSERT
508 #define assert_same_query(xval, xcheck) xval
509 #else
510 private:
511 static bool assert_same_query(bool xval, bool xslow) {
512 assert(xval == xslow, "slow and fast queries agree");
513 return xval;
514 }
515 public:
516 #endif
517 inline bool oop_is_instance() const { return assert_same_query(
518 layout_helper_is_instance(layout_helper()),
519 oop_is_instance_slow()); }
520 inline bool oop_is_array() const { return assert_same_query(
521 layout_helper_is_array(layout_helper()),
522 oop_is_array_slow()); }
523 inline bool oop_is_objArray() const { return assert_same_query(
524 layout_helper_is_objArray(layout_helper()),
525 oop_is_objArray_slow()); }
526 inline bool oop_is_typeArray() const { return assert_same_query(
527 layout_helper_is_typeArray(layout_helper()),
528 oop_is_typeArray_slow()); }
529 #undef assert_same_query
531 // Access flags
532 AccessFlags access_flags() const { return _access_flags; }
533 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
535 bool is_public() const { return _access_flags.is_public(); }
536 bool is_final() const { return _access_flags.is_final(); }
537 bool is_interface() const { return _access_flags.is_interface(); }
538 bool is_abstract() const { return _access_flags.is_abstract(); }
539 bool is_super() const { return _access_flags.is_super(); }
540 bool is_synthetic() const { return _access_flags.is_synthetic(); }
541 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
542 bool has_finalizer() const { return _access_flags.has_finalizer(); }
543 bool has_final_method() const { return _access_flags.has_final_method(); }
544 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
545 void set_has_final_method() { _access_flags.set_has_final_method(); }
546 bool is_cloneable() const { return _access_flags.is_cloneable(); }
547 void set_is_cloneable() { _access_flags.set_is_cloneable(); }
548 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
549 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
550 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
551 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
553 // Biased locking support
554 // Note: the prototype header is always set up to be at least the
555 // prototype markOop. If biased locking is enabled it may further be
556 // biasable and have an epoch.
557 markOop prototype_header() const { return _prototype_header; }
558 // NOTE: once instances of this klass are floating around in the
559 // system, this header must only be updated at a safepoint.
560 // NOTE 2: currently we only ever set the prototype header to the
561 // biasable prototype for instanceKlasses. There is no technical
562 // reason why it could not be done for arrayKlasses aside from
563 // wanting to reduce the initial scope of this optimization. There
564 // are potential problems in setting the bias pattern for
565 // JVM-internal oops.
566 inline void set_prototype_header(markOop header);
567 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
569 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
570 // Atomically increments biased_lock_revocation_count and returns updated value
571 int atomic_incr_biased_lock_revocation_count();
572 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
573 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
574 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
576 TRACE_DEFINE_KLASS_METHODS;
578 // garbage collection support
579 virtual void oops_do(OopClosure* cl);
581 // Iff the class loader (or mirror for anonymous classes) is alive the
582 // Klass is considered alive.
583 // The is_alive closure passed in depends on the Garbage Collector used.
584 bool is_loader_alive(BoolObjectClosure* is_alive);
586 static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
587 static void clean_subklass_tree(BoolObjectClosure* is_alive) {
588 clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
589 }
591 // iterators
592 virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0;
593 virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) {
594 return oop_oop_iterate(obj, blk);
595 }
597 #if INCLUDE_ALL_GCS
598 // In case we don't have a specialized backward scanner use forward
599 // iteration.
600 virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) {
601 return oop_oop_iterate_v(obj, blk);
602 }
603 #endif // INCLUDE_ALL_GCS
605 // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
606 // (I don't see why the _m should be required, but without it the Solaris
607 // C++ gives warning messages about overridings of the "oop_oop_iterate"
608 // defined above "hiding" this virtual function. (DLD, 6/20/00)) */
609 virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0;
610 virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
611 return oop_oop_iterate_m(obj, blk, mr);
612 }
614 // Versions of the above iterators specialized to particular subtypes
615 // of OopClosure, to avoid closure virtual calls.
616 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
617 virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) { \
618 /* Default implementation reverts to general version. */ \
619 return oop_oop_iterate(obj, blk); \
620 } \
621 \
622 /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
623 (I don't see why the _m should be required, but without it the Solaris \
624 C++ gives warning messages about overridings of the "oop_oop_iterate" \
625 defined above "hiding" this virtual function. (DLD, 6/20/00)) */ \
626 virtual int oop_oop_iterate##nv_suffix##_m(oop obj, \
627 OopClosureType* blk, \
628 MemRegion mr) { \
629 return oop_oop_iterate_m(obj, blk, mr); \
630 }
632 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
633 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
635 #if INCLUDE_ALL_GCS
636 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
637 virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, \
638 OopClosureType* blk) { \
639 /* Default implementation reverts to general version. */ \
640 return oop_oop_iterate_backwards_v(obj, blk); \
641 }
643 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
644 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
645 #endif // INCLUDE_ALL_GCS
647 virtual void array_klasses_do(void f(Klass* k)) {}
649 // Return self, except for abstract classes with exactly 1
650 // implementor. Then return the 1 concrete implementation.
651 Klass *up_cast_abstract();
653 // klass name
654 Symbol* name() const { return _name; }
655 void set_name(Symbol* n);
657 public:
658 // jvm support
659 virtual jint compute_modifier_flags(TRAPS) const;
661 // JVMTI support
662 virtual jint jvmti_class_status() const;
664 // Printing
665 virtual void print_on(outputStream* st) const;
667 virtual void oop_print_value_on(oop obj, outputStream* st);
668 virtual void oop_print_on (oop obj, outputStream* st);
670 virtual const char* internal_name() const = 0;
672 // Verification
673 virtual void verify_on(outputStream* st);
674 void verify() { verify_on(tty); }
676 #ifndef PRODUCT
677 bool verify_vtable_index(int index);
678 bool verify_itable_index(int index);
679 #endif
681 virtual void oop_verify_on(oop obj, outputStream* st);
683 static bool is_null(narrowKlass obj);
684 static bool is_null(Klass* obj);
686 // klass encoding for klass pointer in objects.
687 static narrowKlass encode_klass_not_null(Klass* v);
688 static narrowKlass encode_klass(Klass* v);
690 static Klass* decode_klass_not_null(narrowKlass v);
691 static Klass* decode_klass(narrowKlass v);
693 private:
694 // barriers used by klass_oop_store
695 void klass_update_barrier_set(oop v);
696 void klass_update_barrier_set_pre(oop* p, oop v);
697 };
699 #endif // SHARE_VM_OOPS_KLASS_HPP