Thu, 21 Aug 2014 13:57:51 -0700
8046070: Class Data Sharing clean up and refactoring
Summary: Cleaned up CDS to be more configurable, maintainable and extensible
Reviewed-by: dholmes, coleenp, acorn, mchung
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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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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 private:
179 // This is an index into FileMapHeader::_classpath_entry_table[], to
180 // associate this class with the JAR file where it's loaded from during
181 // dump time. If a class is not loaded from the shared archive, this field is
182 // -1.
183 jshort _shared_class_path_index;
185 friend class SharedClassUtil;
186 protected:
188 // Constructor
189 Klass();
191 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
193 public:
194 enum MethodLookupMode { normal, skip_overpass, skip_defaults };
196 bool is_klass() const volatile { return true; }
198 // super
199 Klass* super() const { return _super; }
200 void set_super(Klass* k) { _super = k; }
202 // initializes _super link, _primary_supers & _secondary_supers arrays
203 void initialize_supers(Klass* k, TRAPS);
204 void initialize_supers_impl1(Klass* k);
205 void initialize_supers_impl2(Klass* k);
207 // klass-specific helper for initializing _secondary_supers
208 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
210 // java_super is the Java-level super type as specified by Class.getSuperClass.
211 virtual Klass* java_super() const { return NULL; }
213 juint super_check_offset() const { return _super_check_offset; }
214 void set_super_check_offset(juint o) { _super_check_offset = o; }
216 Klass* secondary_super_cache() const { return _secondary_super_cache; }
217 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
219 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
220 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
222 // Return the element of the _super chain of the given depth.
223 // If there is no such element, return either NULL or this.
224 Klass* primary_super_of_depth(juint i) const {
225 assert(i < primary_super_limit(), "oob");
226 Klass* super = _primary_supers[i];
227 assert(super == NULL || super->super_depth() == i, "correct display");
228 return super;
229 }
231 // Can this klass be a primary super? False for interfaces and arrays of
232 // interfaces. False also for arrays or classes with long super chains.
233 bool can_be_primary_super() const {
234 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
235 return super_check_offset() != secondary_offset;
236 }
237 virtual bool can_be_primary_super_slow() const;
239 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
240 juint super_depth() const {
241 if (!can_be_primary_super()) {
242 return primary_super_limit();
243 } else {
244 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
245 assert(d < primary_super_limit(), "oob");
246 assert(_primary_supers[d] == this, "proper init");
247 return d;
248 }
249 }
251 // store an oop into a field of a Klass
252 void klass_oop_store(oop* p, oop v);
253 void klass_oop_store(volatile oop* p, oop v);
255 // java mirror
256 oop java_mirror() const { return _java_mirror; }
257 void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
259 // modifier flags
260 jint modifier_flags() const { return _modifier_flags; }
261 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
263 // size helper
264 int layout_helper() const { return _layout_helper; }
265 void set_layout_helper(int lh) { _layout_helper = lh; }
267 // Note: for instances layout_helper() may include padding.
268 // Use InstanceKlass::contains_field_offset to classify field offsets.
270 // sub/superklass links
271 InstanceKlass* superklass() const;
272 Klass* subklass() const;
273 Klass* next_sibling() const;
274 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
276 void set_next_link(Klass* k) { _next_link = k; }
277 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
279 // class loader data
280 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
281 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
283 // The Klasses are not placed in the Heap, so the Card Table or
284 // the Mod Union Table can't be used to mark when klasses have modified oops.
285 // The CT and MUT bits saves this information for the individual Klasses.
286 void record_modified_oops() { _modified_oops = 1; }
287 void clear_modified_oops() { _modified_oops = 0; }
288 bool has_modified_oops() { return _modified_oops == 1; }
290 void accumulate_modified_oops() { if (has_modified_oops()) _accumulated_modified_oops = 1; }
291 void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
292 bool has_accumulated_modified_oops() { return _accumulated_modified_oops == 1; }
294 int shared_classpath_index() const {
295 return _shared_class_path_index;
296 };
298 void set_shared_classpath_index(int index) {
299 _shared_class_path_index = index;
300 };
303 protected: // internal accessors
304 Klass* subklass_oop() const { return _subklass; }
305 Klass* next_sibling_oop() const { return _next_sibling; }
306 void set_subklass(Klass* s);
307 void set_next_sibling(Klass* s);
309 public:
311 // Compiler support
312 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
313 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
314 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
315 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
316 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
317 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
318 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
319 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
320 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
322 // Unpacking layout_helper:
323 enum {
324 _lh_neutral_value = 0, // neutral non-array non-instance value
325 _lh_instance_slow_path_bit = 0x01,
326 _lh_log2_element_size_shift = BitsPerByte*0,
327 _lh_log2_element_size_mask = BitsPerLong-1,
328 _lh_element_type_shift = BitsPerByte*1,
329 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
330 _lh_header_size_shift = BitsPerByte*2,
331 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
332 _lh_array_tag_bits = 2,
333 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
334 _lh_array_tag_type_value = ~0x00, // 0xC0000000 >> 30
335 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30
336 };
338 static int layout_helper_size_in_bytes(jint lh) {
339 assert(lh > (jint)_lh_neutral_value, "must be instance");
340 return (int) lh & ~_lh_instance_slow_path_bit;
341 }
342 static bool layout_helper_needs_slow_path(jint lh) {
343 assert(lh > (jint)_lh_neutral_value, "must be instance");
344 return (lh & _lh_instance_slow_path_bit) != 0;
345 }
346 static bool layout_helper_is_instance(jint lh) {
347 return (jint)lh > (jint)_lh_neutral_value;
348 }
349 static bool layout_helper_is_array(jint lh) {
350 return (jint)lh < (jint)_lh_neutral_value;
351 }
352 static bool layout_helper_is_typeArray(jint lh) {
353 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
354 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
355 }
356 static bool layout_helper_is_objArray(jint lh) {
357 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
358 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
359 }
360 static int layout_helper_header_size(jint lh) {
361 assert(lh < (jint)_lh_neutral_value, "must be array");
362 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
363 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
364 return hsize;
365 }
366 static BasicType layout_helper_element_type(jint lh) {
367 assert(lh < (jint)_lh_neutral_value, "must be array");
368 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
369 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
370 return (BasicType) btvalue;
371 }
372 static int layout_helper_log2_element_size(jint lh) {
373 assert(lh < (jint)_lh_neutral_value, "must be array");
374 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
375 assert(l2esz <= LogBitsPerLong,
376 err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh));
377 return l2esz;
378 }
379 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
380 return (tag << _lh_array_tag_shift)
381 | (hsize << _lh_header_size_shift)
382 | ((int)etype << _lh_element_type_shift)
383 | (log2_esize << _lh_log2_element_size_shift);
384 }
385 static jint instance_layout_helper(jint size, bool slow_path_flag) {
386 return (size << LogHeapWordSize)
387 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
388 }
389 static int layout_helper_to_size_helper(jint lh) {
390 assert(lh > (jint)_lh_neutral_value, "must be instance");
391 // Note that the following expression discards _lh_instance_slow_path_bit.
392 return lh >> LogHeapWordSize;
393 }
394 // Out-of-line version computes everything based on the etype:
395 static jint array_layout_helper(BasicType etype);
397 // What is the maximum number of primary superclasses any klass can have?
398 #ifdef PRODUCT
399 static juint primary_super_limit() { return _primary_super_limit; }
400 #else
401 static juint primary_super_limit() {
402 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
403 return FastSuperclassLimit;
404 }
405 #endif
407 // vtables
408 virtual klassVtable* vtable() const { return NULL; }
409 virtual int vtable_length() const { return 0; }
411 // subclass check
412 bool is_subclass_of(const Klass* k) const;
413 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
414 bool is_subtype_of(Klass* k) const {
415 juint off = k->super_check_offset();
416 Klass* sup = *(Klass**)( (address)this + off );
417 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
418 if (sup == k) {
419 return true;
420 } else if (off != secondary_offset) {
421 return false;
422 } else {
423 return search_secondary_supers(k);
424 }
425 }
426 bool search_secondary_supers(Klass* k) const;
428 // Find LCA in class hierarchy
429 Klass *LCA( Klass *k );
431 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
432 // if not, throw either an Error or an Exception.
433 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
435 // array copying
436 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
438 // tells if the class should be initialized
439 virtual bool should_be_initialized() const { return false; }
440 // initializes the klass
441 virtual void initialize(TRAPS);
442 // lookup operation for MethodLookupCache
443 friend class MethodLookupCache;
444 virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature, MethodLookupMode mode) const;
445 public:
446 Method* lookup_method(Symbol* name, Symbol* signature) const {
447 return uncached_lookup_method(name, signature, normal);
448 }
450 // array class with specific rank
451 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
453 // array class with this klass as element type
454 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
456 // These will return NULL instead of allocating on the heap:
457 // NB: these can block for a mutex, like other functions with TRAPS arg.
458 Klass* array_klass_or_null(int rank);
459 Klass* array_klass_or_null();
461 virtual oop protection_domain() const = 0;
463 oop class_loader() const;
465 virtual oop klass_holder() const { return class_loader(); }
467 protected:
468 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
469 virtual Klass* array_klass_impl(bool or_null, TRAPS);
471 public:
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);
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.
486 // actual oop size of obj in memory
487 virtual int oop_size(oop obj) const = 0;
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
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;
507 // garbage collection support
508 virtual void oop_follow_contents(oop obj) = 0;
509 virtual int oop_adjust_pointers(oop obj) = 0;
511 // Parallel Scavenge and Parallel Old
512 PARALLEL_GC_DECLS_PV
514 // type testing operations
515 protected:
516 virtual bool oop_is_instance_slow() const { return false; }
517 virtual bool oop_is_array_slow() const { return false; }
518 virtual bool oop_is_objArray_slow() const { return false; }
519 virtual bool oop_is_typeArray_slow() const { return false; }
520 public:
521 virtual bool oop_is_instanceClassLoader() const { return false; }
522 virtual bool oop_is_instanceMirror() const { return false; }
523 virtual bool oop_is_instanceRef() const { return false; }
525 // Fast non-virtual versions
526 #ifndef ASSERT
527 #define assert_same_query(xval, xcheck) xval
528 #else
529 private:
530 static bool assert_same_query(bool xval, bool xslow) {
531 assert(xval == xslow, "slow and fast queries agree");
532 return xval;
533 }
534 public:
535 #endif
536 inline bool oop_is_instance() const { return assert_same_query(
537 layout_helper_is_instance(layout_helper()),
538 oop_is_instance_slow()); }
539 inline bool oop_is_array() const { return assert_same_query(
540 layout_helper_is_array(layout_helper()),
541 oop_is_array_slow()); }
542 inline bool oop_is_objArray() const { return assert_same_query(
543 layout_helper_is_objArray(layout_helper()),
544 oop_is_objArray_slow()); }
545 inline bool oop_is_typeArray() const { return assert_same_query(
546 layout_helper_is_typeArray(layout_helper()),
547 oop_is_typeArray_slow()); }
548 #undef assert_same_query
550 // Access flags
551 AccessFlags access_flags() const { return _access_flags; }
552 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
554 bool is_public() const { return _access_flags.is_public(); }
555 bool is_final() const { return _access_flags.is_final(); }
556 bool is_interface() const { return _access_flags.is_interface(); }
557 bool is_abstract() const { return _access_flags.is_abstract(); }
558 bool is_super() const { return _access_flags.is_super(); }
559 bool is_synthetic() const { return _access_flags.is_synthetic(); }
560 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
561 bool has_finalizer() const { return _access_flags.has_finalizer(); }
562 bool has_final_method() const { return _access_flags.has_final_method(); }
563 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
564 void set_has_final_method() { _access_flags.set_has_final_method(); }
565 bool is_cloneable() const { return _access_flags.is_cloneable(); }
566 void set_is_cloneable() { _access_flags.set_is_cloneable(); }
567 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
568 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
569 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
570 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
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)); }
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; }
595 TRACE_DEFINE_KLASS_METHODS;
597 // garbage collection support
598 virtual void oops_do(OopClosure* cl);
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);
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 }
610 // iterators
611 virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0;
612 virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) {
613 return oop_oop_iterate(obj, blk);
614 }
616 #if INCLUDE_ALL_GCS
617 // In case we don't have a specialized backward scanner use forward
618 // iteration.
619 virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) {
620 return oop_oop_iterate_v(obj, blk);
621 }
622 #endif // INCLUDE_ALL_GCS
624 // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
625 // (I don't see why the _m should be required, but without it the Solaris
626 // C++ gives warning messages about overridings of the "oop_oop_iterate"
627 // defined above "hiding" this virtual function. (DLD, 6/20/00)) */
628 virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0;
629 virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
630 return oop_oop_iterate_m(obj, blk, mr);
631 }
633 // Versions of the above iterators specialized to particular subtypes
634 // of OopClosure, to avoid closure virtual calls.
635 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
636 virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) { \
637 /* Default implementation reverts to general version. */ \
638 return oop_oop_iterate(obj, blk); \
639 } \
640 \
641 /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
642 (I don't see why the _m should be required, but without it the Solaris \
643 C++ gives warning messages about overridings of the "oop_oop_iterate" \
644 defined above "hiding" this virtual function. (DLD, 6/20/00)) */ \
645 virtual int oop_oop_iterate##nv_suffix##_m(oop obj, \
646 OopClosureType* blk, \
647 MemRegion mr) { \
648 return oop_oop_iterate_m(obj, blk, mr); \
649 }
651 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
652 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
654 #if INCLUDE_ALL_GCS
655 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
656 virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, \
657 OopClosureType* blk) { \
658 /* Default implementation reverts to general version. */ \
659 return oop_oop_iterate_backwards_v(obj, blk); \
660 }
662 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
663 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
664 #endif // INCLUDE_ALL_GCS
666 virtual void array_klasses_do(void f(Klass* k)) {}
668 // Return self, except for abstract classes with exactly 1
669 // implementor. Then return the 1 concrete implementation.
670 Klass *up_cast_abstract();
672 // klass name
673 Symbol* name() const { return _name; }
674 void set_name(Symbol* n);
676 public:
677 // jvm support
678 virtual jint compute_modifier_flags(TRAPS) const;
680 // JVMTI support
681 virtual jint jvmti_class_status() const;
683 // Printing
684 virtual void print_on(outputStream* st) const;
686 virtual void oop_print_value_on(oop obj, outputStream* st);
687 virtual void oop_print_on (oop obj, outputStream* st);
689 virtual const char* internal_name() const = 0;
691 // Verification
692 virtual void verify_on(outputStream* st);
693 void verify() { verify_on(tty); }
695 #ifndef PRODUCT
696 bool verify_vtable_index(int index);
697 bool verify_itable_index(int index);
698 #endif
700 virtual void oop_verify_on(oop obj, outputStream* st);
702 static bool is_null(narrowKlass obj);
703 static bool is_null(Klass* obj);
705 // klass encoding for klass pointer in objects.
706 static narrowKlass encode_klass_not_null(Klass* v);
707 static narrowKlass encode_klass(Klass* v);
709 static Klass* decode_klass_not_null(narrowKlass v);
710 static Klass* decode_klass(narrowKlass v);
712 private:
713 // barriers used by klass_oop_store
714 void klass_update_barrier_set(oop v);
715 void klass_update_barrier_set_pre(oop* p, oop v);
716 };
718 #endif // SHARE_VM_OOPS_KLASS_HPP