1 /*
2 * Copyright (c) 1997, 2013, 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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
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 "runtime/orderAccess.hpp"
36 #include "trace/traceMacros.hpp"
37 #include "utilities/accessFlags.hpp"
38 #ifndef SERIALGC
39 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp"
40 #include "gc_implementation/g1/g1OopClosures.hpp"
41 #include "gc_implementation/parNew/parOopClosures.hpp"
42 #endif
43
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.
49
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_"!
57
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 // [verify_count ] - not in product
79 // [alloc_count ]
80 // [last_biased_lock_bulk_revocation_time] (64 bits)
81 // [prototype_header]
82 // [biased_lock_revocation_count]
83 // [_modified_oops]
84 // [_accumulated_modified_oops]
85 // [trace_id]
86
87
88 // Forward declarations.
89 template <class T> class Array;
90 template <class T> class GrowableArray;
91 class ClassLoaderData;
92 class klassVtable;
93 class ParCompactionManager;
94 class KlassSizeStats;
95
96 class Klass : public Metadata {
97 friend class VMStructs;
98 protected:
99 // note: put frequently-used fields together at start of klass structure
100 // for better cache behavior (may not make much of a difference but sure won't hurt)
101 enum { _primary_super_limit = 8 };
102
103 // The "layout helper" is a combined descriptor of object layout.
104 // For klasses which are neither instance nor array, the value is zero.
105 //
106 // For instances, layout helper is a positive number, the instance size.
107 // This size is already passed through align_object_size and scaled to bytes.
108 // The low order bit is set if instances of this class cannot be
109 // allocated using the fastpath.
110 //
111 // For arrays, layout helper is a negative number, containing four
112 // distinct bytes, as follows:
113 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
114 // where:
115 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
116 // hsz is array header size in bytes (i.e., offset of first element)
117 // ebt is the BasicType of the elements
118 // esz is the element size in bytes
119 // This packed word is arranged so as to be quickly unpacked by the
120 // various fast paths that use the various subfields.
121 //
122 // The esz bits can be used directly by a SLL instruction, without masking.
123 //
124 // Note that the array-kind tag looks like 0x00 for instance klasses,
125 // since their length in bytes is always less than 24Mb.
126 //
127 // Final note: This comes first, immediately after C++ vtable,
128 // because it is frequently queried.
129 jint _layout_helper;
130
131 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
132 // and _primary_supers all help make fast subtype checks. See big discussion
133 // in doc/server_compiler/checktype.txt
134 //
135 // Where to look to observe a supertype (it is &_secondary_super_cache for
136 // secondary supers, else is &_primary_supers[depth()].
137 juint _super_check_offset;
138
139 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
140 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
141 Symbol* _name;
142
143 // Cache of last observed secondary supertype
144 Klass* _secondary_super_cache;
145 // Array of all secondary supertypes
146 Array<Klass*>* _secondary_supers;
147 // Ordered list of all primary supertypes
148 Klass* _primary_supers[_primary_super_limit];
149 // java/lang/Class instance mirroring this class
150 oop _java_mirror;
151 // Superclass
152 Klass* _super;
153 // First subclass (NULL if none); _subklass->next_sibling() is next one
154 Klass* _subklass;
155 // Sibling link (or NULL); links all subklasses of a klass
156 Klass* _next_sibling;
157
158 // All klasses loaded by a class loader are chained through these links
159 Klass* _next_link;
160
161 // The VM's representation of the ClassLoader used to load this class.
162 // Provide access the corresponding instance java.lang.ClassLoader.
163 ClassLoaderData* _class_loader_data;
164
165 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
166 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
167
168 #ifndef PRODUCT
169 int _verify_count; // to avoid redundant verifies
170 #endif
171
172 juint _alloc_count; // allocation profiling support
173
174 // Biased locking implementation and statistics
175 // (the 64-bit chunk goes first, to avoid some fragmentation)
176 jlong _last_biased_lock_bulk_revocation_time;
177 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type
178 jint _biased_lock_revocation_count;
179
180 TRACE_DEFINE_KLASS_TRACE_ID;
181
182 // Remembered sets support for the oops in the klasses.
183 jbyte _modified_oops; // Card Table Equivalent (YC/CMS support)
184 jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
185
186 // Constructor
187 Klass();
188
189 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS);
190
191 public:
192 bool is_klass() const volatile { return true; }
193
194 // super
195 Klass* super() const { return _super; }
196 void set_super(Klass* k) { _super = k; }
197
198 // initializes _super link, _primary_supers & _secondary_supers arrays
199 void initialize_supers(Klass* k, TRAPS);
200 void initialize_supers_impl1(Klass* k);
201 void initialize_supers_impl2(Klass* k);
202
203 // klass-specific helper for initializing _secondary_supers
204 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
205
206 // java_super is the Java-level super type as specified by Class.getSuperClass.
207 virtual Klass* java_super() const { return NULL; }
208
209 juint super_check_offset() const { return _super_check_offset; }
210 void set_super_check_offset(juint o) { _super_check_offset = o; }
211
212 Klass* secondary_super_cache() const { return _secondary_super_cache; }
213 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
214
215 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
216 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
217
218 // Return the element of the _super chain of the given depth.
219 // If there is no such element, return either NULL or this.
220 Klass* primary_super_of_depth(juint i) const {
221 assert(i < primary_super_limit(), "oob");
222 Klass* super = _primary_supers[i];
223 assert(super == NULL || super->super_depth() == i, "correct display");
224 return super;
225 }
226
227 // Can this klass be a primary super? False for interfaces and arrays of
228 // interfaces. False also for arrays or classes with long super chains.
229 bool can_be_primary_super() const {
230 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
231 return super_check_offset() != secondary_offset;
232 }
233 virtual bool can_be_primary_super_slow() const;
234
235 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
236 juint super_depth() const {
237 if (!can_be_primary_super()) {
238 return primary_super_limit();
239 } else {
240 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
241 assert(d < primary_super_limit(), "oob");
242 assert(_primary_supers[d] == this, "proper init");
243 return d;
244 }
245 }
246
247 // store an oop into a field of a Klass
248 void klass_oop_store(oop* p, oop v);
249 void klass_oop_store(volatile oop* p, oop v);
250
251 // java mirror
252 oop java_mirror() const { return _java_mirror; }
253 void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
254
255 // modifier flags
256 jint modifier_flags() const { return _modifier_flags; }
257 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
258
259 // size helper
260 int layout_helper() const { return _layout_helper; }
261 void set_layout_helper(int lh) { _layout_helper = lh; }
262
263 // Note: for instances layout_helper() may include padding.
264 // Use InstanceKlass::contains_field_offset to classify field offsets.
265
266 // sub/superklass links
267 InstanceKlass* superklass() const;
268 Klass* subklass() const;
269 Klass* next_sibling() const;
270 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
271
272 void set_next_link(Klass* k) { _next_link = k; }
273 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
274
275 // class loader data
276 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
277 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
278
279 // The Klasses are not placed in the Heap, so the Card Table or
280 // the Mod Union Table can't be used to mark when klasses have modified oops.
281 // The CT and MUT bits saves this information for the individual Klasses.
282 void record_modified_oops() { _modified_oops = 1; }
283 void clear_modified_oops() { _modified_oops = 0; }
284 bool has_modified_oops() { return _modified_oops == 1; }
285
286 void accumulate_modified_oops() { if (has_modified_oops()) _accumulated_modified_oops = 1; }
287 void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
288 bool has_accumulated_modified_oops() { return _accumulated_modified_oops == 1; }
289
290 protected: // internal accessors
291 Klass* subklass_oop() const { return _subklass; }
292 Klass* next_sibling_oop() const { return _next_sibling; }
293 void set_subklass(Klass* s);
294 void set_next_sibling(Klass* s);
295
296 public:
297 // Allocation profiling support
298 juint alloc_count() const { return _alloc_count; }
299 void set_alloc_count(juint n) { _alloc_count = n; }
300 virtual juint alloc_size() const = 0;
301 virtual void set_alloc_size(juint n) = 0;
302
303 // Compiler support
304 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
305 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
306 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
307 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
308 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
309 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
310 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
311 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
312 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
313
314 // Unpacking layout_helper:
315 enum {
316 _lh_neutral_value = 0, // neutral non-array non-instance value
317 _lh_instance_slow_path_bit = 0x01,
318 _lh_log2_element_size_shift = BitsPerByte*0,
319 _lh_log2_element_size_mask = BitsPerLong-1,
320 _lh_element_type_shift = BitsPerByte*1,
321 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
322 _lh_header_size_shift = BitsPerByte*2,
323 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
324 _lh_array_tag_bits = 2,
325 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
326 _lh_array_tag_type_value = ~0x00, // 0xC0000000 >> 30
327 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30
328 };
329
330 static int layout_helper_size_in_bytes(jint lh) {
331 assert(lh > (jint)_lh_neutral_value, "must be instance");
332 return (int) lh & ~_lh_instance_slow_path_bit;
333 }
334 static bool layout_helper_needs_slow_path(jint lh) {
335 assert(lh > (jint)_lh_neutral_value, "must be instance");
336 return (lh & _lh_instance_slow_path_bit) != 0;
337 }
338 static bool layout_helper_is_instance(jint lh) {
339 return (jint)lh > (jint)_lh_neutral_value;
340 }
341 static bool layout_helper_is_array(jint lh) {
342 return (jint)lh < (jint)_lh_neutral_value;
343 }
344 static bool layout_helper_is_typeArray(jint lh) {
345 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
346 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
347 }
348 static bool layout_helper_is_objArray(jint lh) {
349 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
350 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
351 }
352 static int layout_helper_header_size(jint lh) {
353 assert(lh < (jint)_lh_neutral_value, "must be array");
354 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
355 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
356 return hsize;
357 }
358 static BasicType layout_helper_element_type(jint lh) {
359 assert(lh < (jint)_lh_neutral_value, "must be array");
360 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
361 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
362 return (BasicType) btvalue;
363 }
364 static int layout_helper_log2_element_size(jint lh) {
365 assert(lh < (jint)_lh_neutral_value, "must be array");
366 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
367 assert(l2esz <= LogBitsPerLong, "sanity");
368 return l2esz;
369 }
370 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
371 return (tag << _lh_array_tag_shift)
372 | (hsize << _lh_header_size_shift)
373 | ((int)etype << _lh_element_type_shift)
374 | (log2_esize << _lh_log2_element_size_shift);
375 }
376 static jint instance_layout_helper(jint size, bool slow_path_flag) {
377 return (size << LogHeapWordSize)
378 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
379 }
380 static int layout_helper_to_size_helper(jint lh) {
381 assert(lh > (jint)_lh_neutral_value, "must be instance");
382 // Note that the following expression discards _lh_instance_slow_path_bit.
383 return lh >> LogHeapWordSize;
384 }
385 // Out-of-line version computes everything based on the etype:
386 static jint array_layout_helper(BasicType etype);
387
388 // What is the maximum number of primary superclasses any klass can have?
389 #ifdef PRODUCT
390 static juint primary_super_limit() { return _primary_super_limit; }
391 #else
392 static juint primary_super_limit() {
393 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
394 return FastSuperclassLimit;
395 }
396 #endif
397
398 // vtables
399 virtual klassVtable* vtable() const { return NULL; }
400
401 // subclass check
402 bool is_subclass_of(Klass* k) const;
403 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
404 bool is_subtype_of(Klass* k) const {
405 juint off = k->super_check_offset();
406 Klass* sup = *(Klass**)( (address)this + off );
407 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
408 if (sup == k) {
409 return true;
410 } else if (off != secondary_offset) {
411 return false;
412 } else {
413 return search_secondary_supers(k);
414 }
415 }
416 bool search_secondary_supers(Klass* k) const;
417
418 // Find LCA in class hierarchy
419 Klass *LCA( Klass *k );
420
421 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
422 // if not, throw either an Error or an Exception.
423 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
424
425 // array copying
426 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
427
428 // tells if the class should be initialized
429 virtual bool should_be_initialized() const { return false; }
430 // initializes the klass
431 virtual void initialize(TRAPS);
432 // lookup operation for MethodLookupCache
433 friend class MethodLookupCache;
434 virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature) const;
435 public:
436 Method* lookup_method(Symbol* name, Symbol* signature) const {
437 return uncached_lookup_method(name, signature);
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() { return NULL; }
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 public:
462 // CDS support - remove and restore oops from metadata. Oops are not shared.
463 virtual void remove_unshareable_info();
464 virtual void restore_unshareable_info(TRAPS);
465
466 protected:
467 // computes the subtype relationship
468 virtual bool compute_is_subtype_of(Klass* k);
469 public:
470 // subclass accessor (here for convenience; undefined for non-klass objects)
471 virtual bool is_leaf_class() const { fatal("not a class"); return false; }
472 public:
473 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
474 // These functions describe behavior for the oop not the KLASS.
475
476 // actual oop size of obj in memory
477 virtual int oop_size(oop obj) const = 0;
478
479 // Size of klass in word size.
480 virtual int size() const = 0;
481 #if INCLUDE_SERVICES
482 virtual void collect_statistics(KlassSizeStats *sz) const;
483 #endif
484
485 // Returns the Java name for a class (Resource allocated)
486 // For arrays, this returns the name of the element with a leading '['.
487 // For classes, this returns the name with the package separators
488 // turned into '.'s.
489 const char* external_name() const;
490 // Returns the name for a class (Resource allocated) as the class
491 // would appear in a signature.
492 // For arrays, this returns the name of the element with a leading '['.
493 // For classes, this returns the name with a leading 'L' and a trailing ';'
494 // and the package separators as '/'.
495 virtual const char* signature_name() const;
496
497 // garbage collection support
498 virtual void oop_follow_contents(oop obj) = 0;
499 virtual int oop_adjust_pointers(oop obj) = 0;
500
501 // Parallel Scavenge and Parallel Old
502 PARALLEL_GC_DECLS_PV
503
504 // type testing operations
505 protected:
506 virtual bool oop_is_instance_slow() const { return false; }
507 virtual bool oop_is_array_slow() const { return false; }
508 virtual bool oop_is_objArray_slow() const { return false; }
509 virtual bool oop_is_typeArray_slow() const { return false; }
510 public:
511 virtual bool oop_is_instanceMirror() const { return false; }
512 virtual bool oop_is_instanceRef() const { return false; }
513
514 // Fast non-virtual versions
515 #ifndef ASSERT
516 #define assert_same_query(xval, xcheck) xval
517 #else
518 private:
519 static bool assert_same_query(bool xval, bool xslow) {
520 assert(xval == xslow, "slow and fast queries agree");
521 return xval;
522 }
523 public:
524 #endif
525 inline bool oop_is_instance() const { return assert_same_query(
526 layout_helper_is_instance(layout_helper()),
527 oop_is_instance_slow()); }
528 inline bool oop_is_array() const { return assert_same_query(
529 layout_helper_is_array(layout_helper()),
530 oop_is_array_slow()); }
531 inline bool oop_is_objArray() const { return assert_same_query(
532 layout_helper_is_objArray(layout_helper()),
533 oop_is_objArray_slow()); }
534 inline bool oop_is_typeArray() const { return assert_same_query(
535 layout_helper_is_typeArray(layout_helper()),
536 oop_is_typeArray_slow()); }
537 #undef assert_same_query
538
539 // Access flags
540 AccessFlags access_flags() const { return _access_flags; }
541 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
542
543 bool is_public() const { return _access_flags.is_public(); }
544 bool is_final() const { return _access_flags.is_final(); }
545 bool is_interface() const { return _access_flags.is_interface(); }
546 bool is_abstract() const { return _access_flags.is_abstract(); }
547 bool is_super() const { return _access_flags.is_super(); }
548 bool is_synthetic() const { return _access_flags.is_synthetic(); }
549 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
550 bool has_finalizer() const { return _access_flags.has_finalizer(); }
551 bool has_final_method() const { return _access_flags.has_final_method(); }
552 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
553 void set_has_final_method() { _access_flags.set_has_final_method(); }
554 bool is_cloneable() const { return _access_flags.is_cloneable(); }
555 void set_is_cloneable() { _access_flags.set_is_cloneable(); }
556 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
557 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
558 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
559 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
560
561 // Biased locking support
562 // Note: the prototype header is always set up to be at least the
563 // prototype markOop. If biased locking is enabled it may further be
564 // biasable and have an epoch.
565 markOop prototype_header() const { return _prototype_header; }
566 // NOTE: once instances of this klass are floating around in the
567 // system, this header must only be updated at a safepoint.
568 // NOTE 2: currently we only ever set the prototype header to the
569 // biasable prototype for instanceKlasses. There is no technical
570 // reason why it could not be done for arrayKlasses aside from
571 // wanting to reduce the initial scope of this optimization. There
572 // are potential problems in setting the bias pattern for
573 // JVM-internal oops.
574 inline void set_prototype_header(markOop header);
575 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
576
577 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
578 // Atomically increments biased_lock_revocation_count and returns updated value
579 int atomic_incr_biased_lock_revocation_count();
580 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
581 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
582 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
583
584 TRACE_DEFINE_KLASS_METHODS;
585
586 // garbage collection support
587 virtual void oops_do(OopClosure* cl);
588
589 // Iff the class loader (or mirror for anonymous classes) is alive the
590 // Klass is considered alive.
591 // The is_alive closure passed in depends on the Garbage Collector used.
592 bool is_loader_alive(BoolObjectClosure* is_alive);
593
594 static void clean_weak_klass_links(BoolObjectClosure* is_alive);
595
596 // Prefetch within oop iterators. This is a macro because we
597 // can't guarantee that the compiler will inline it. In 64-bit
598 // it generally doesn't. Signature is
599 //
600 // static void prefetch_beyond(oop* const start,
601 // oop* const end,
602 // const intx foffset,
603 // const Prefetch::style pstyle);
604 #define prefetch_beyond(start, end, foffset, pstyle) { \
605 const intx foffset_ = (foffset); \
606 const Prefetch::style pstyle_ = (pstyle); \
607 assert(foffset_ > 0, "prefetch beyond, not behind"); \
608 if (pstyle_ != Prefetch::do_none) { \
609 oop* ref = (start); \
610 if (ref < (end)) { \
611 switch (pstyle_) { \
612 case Prefetch::do_read: \
613 Prefetch::read(*ref, foffset_); \
614 break; \
615 case Prefetch::do_write: \
616 Prefetch::write(*ref, foffset_); \
617 break; \
618 default: \
619 ShouldNotReachHere(); \
620 break; \
621 } \
622 } \
623 } \
624 }
625
626 // iterators
627 virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0;
628 virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) {
629 return oop_oop_iterate(obj, blk);
630 }
631
632 #ifndef SERIALGC
633 // In case we don't have a specialized backward scanner use forward
634 // iteration.
635 virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) {
636 return oop_oop_iterate_v(obj, blk);
637 }
638 #endif // !SERIALGC
639
640 // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
641 // (I don't see why the _m should be required, but without it the Solaris
642 // C++ gives warning messages about overridings of the "oop_oop_iterate"
643 // defined above "hiding" this virtual function. (DLD, 6/20/00)) */
644 virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0;
645 virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
646 return oop_oop_iterate_m(obj, blk, mr);
647 }
648
649 // Versions of the above iterators specialized to particular subtypes
650 // of OopClosure, to avoid closure virtual calls.
651 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
652 virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) { \
653 /* Default implementation reverts to general version. */ \
654 return oop_oop_iterate(obj, blk); \
655 } \
656 \
657 /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
658 (I don't see why the _m should be required, but without it the Solaris \
659 C++ gives warning messages about overridings of the "oop_oop_iterate" \
660 defined above "hiding" this virtual function. (DLD, 6/20/00)) */ \
661 virtual int oop_oop_iterate##nv_suffix##_m(oop obj, \
662 OopClosureType* blk, \
663 MemRegion mr) { \
664 return oop_oop_iterate_m(obj, blk, mr); \
665 }
666
667 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
668 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
669
670 #ifndef SERIALGC
671 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
672 virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, \
673 OopClosureType* blk) { \
674 /* Default implementation reverts to general version. */ \
675 return oop_oop_iterate_backwards_v(obj, blk); \
676 }
677
678 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
679 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
680 #endif // !SERIALGC
681
682 virtual void array_klasses_do(void f(Klass* k)) {}
683 virtual void with_array_klasses_do(void f(Klass* k));
684
685 // Return self, except for abstract classes with exactly 1
686 // implementor. Then return the 1 concrete implementation.
687 Klass *up_cast_abstract();
688
689 // klass name
690 Symbol* name() const { return _name; }
691 void set_name(Symbol* n);
692
693 public:
694 // jvm support
695 virtual jint compute_modifier_flags(TRAPS) const;
696
697 // JVMTI support
698 virtual jint jvmti_class_status() const;
699
700 // Printing
701 virtual void print_on(outputStream* st) const;
702
703 virtual void oop_print_value_on(oop obj, outputStream* st);
704 virtual void oop_print_on (oop obj, outputStream* st);
705
706 virtual const char* internal_name() const = 0;
707
708 // Verification
709 virtual void verify_on(outputStream* st);
710 void verify() { verify_on(tty); }
711
712 #ifndef PRODUCT
713 void verify_vtable_index(int index);
714 #endif
715
716 virtual void oop_verify_on(oop obj, outputStream* st);
717
718 private:
719 // barriers used by klass_oop_store
720 void klass_update_barrier_set(oop v);
721 void klass_update_barrier_set_pre(void* p, oop v);
722 };
723
724 #endif // SHARE_VM_OOPS_KLASS_HPP