1 /*
2 * Copyright (c) 1997, 2012, 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
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23 */
24
25 #ifndef SHARE_VM_OOPS_KLASS_HPP
26 #define SHARE_VM_OOPS_KLASS_HPP
27
28 #include "memory/genOopClosures.hpp"
29 #include "memory/iterator.hpp"
30 #include "memory/memRegion.hpp"
31 #include "memory/specialized_oop_closures.hpp"
32 #include "oops/klassPS.hpp"
33 #include "oops/metadata.hpp"
34 #include "oops/oop.hpp"
35 #include "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
95 class Klass : public Metadata {
96 friend class VMStructs;
97 protected:
98 // note: put frequently-used fields together at start of klass structure
99 // for better cache behavior (may not make much of a difference but sure won't hurt)
100 enum { _primary_super_limit = 8 };
101
102 // The "layout helper" is a combined descriptor of object layout.
103 // For klasses which are neither instance nor array, the value is zero.
104 //
105 // For instances, layout helper is a positive number, the instance size.
106 // This size is already passed through align_object_size and scaled to bytes.
107 // The low order bit is set if instances of this class cannot be
108 // allocated using the fastpath.
109 //
110 // For arrays, layout helper is a negative number, containing four
111 // distinct bytes, as follows:
112 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
113 // where:
114 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
115 // hsz is array header size in bytes (i.e., offset of first element)
116 // ebt is the BasicType of the elements
117 // esz is the element size in bytes
118 // This packed word is arranged so as to be quickly unpacked by the
119 // various fast paths that use the various subfields.
120 //
121 // The esz bits can be used directly by a SLL instruction, without masking.
122 //
123 // Note that the array-kind tag looks like 0x00 for instance klasses,
124 // since their length in bytes is always less than 24Mb.
125 //
126 // Final note: This comes first, immediately after C++ vtable,
127 // because it is frequently queried.
128 jint _layout_helper;
129
130 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
131 // and _primary_supers all help make fast subtype checks. See big discussion
132 // in doc/server_compiler/checktype.txt
133 //
134 // Where to look to observe a supertype (it is &_secondary_super_cache for
135 // secondary supers, else is &_primary_supers[depth()].
136 juint _super_check_offset;
137
138 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
139 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
140 Symbol* _name;
141
142 // Cache of last observed secondary supertype
143 Klass* _secondary_super_cache;
144 // Array of all secondary supertypes
145 Array<Klass*>* _secondary_supers;
146 // Ordered list of all primary supertypes
147 Klass* _primary_supers[_primary_super_limit];
148 // java/lang/Class instance mirroring this class
149 oop _java_mirror;
150 // Superclass
151 Klass* _super;
152 // First subclass (NULL if none); _subklass->next_sibling() is next one
153 Klass* _subklass;
154 // Sibling link (or NULL); links all subklasses of a klass
155 Klass* _next_sibling;
156
157 // All klasses loaded by a class loader are chained through these links
158 Klass* _next_link;
159
160 // The VM's representation of the ClassLoader used to load this class.
161 // Provide access the corresponding instance java.lang.ClassLoader.
162 ClassLoaderData* _class_loader_data;
163
164 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
165 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
166
167 #ifndef PRODUCT
168 int _verify_count; // to avoid redundant verifies
169 #endif
170
171 juint _alloc_count; // allocation profiling support
172
173 // Biased locking implementation and statistics
174 // (the 64-bit chunk goes first, to avoid some fragmentation)
175 jlong _last_biased_lock_bulk_revocation_time;
176 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type
177 jint _biased_lock_revocation_count;
178
179 TRACE_DEFINE_KLASS_TRACE_ID;
180
181 // Remembered sets support for the oops in the klasses.
182 jbyte _modified_oops; // Card Table Equivalent (YC/CMS support)
183 jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
184
185 // Constructor
186 Klass();
187
188 void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS);
189
190 public:
191 bool is_klass() const volatile { return true; }
192
193 // super
194 Klass* super() const { return _super; }
195 void set_super(Klass* k) { _super = k; }
196
197 // initializes _super link, _primary_supers & _secondary_supers arrays
198 void initialize_supers(Klass* k, TRAPS);
199 void initialize_supers_impl1(Klass* k);
200 void initialize_supers_impl2(Klass* k);
201
202 // klass-specific helper for initializing _secondary_supers
203 virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
204
205 // java_super is the Java-level super type as specified by Class.getSuperClass.
206 virtual Klass* java_super() const { return NULL; }
207
208 juint super_check_offset() const { return _super_check_offset; }
209 void set_super_check_offset(juint o) { _super_check_offset = o; }
210
211 Klass* secondary_super_cache() const { return _secondary_super_cache; }
212 void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
213
214 Array<Klass*>* secondary_supers() const { return _secondary_supers; }
215 void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
216
217 // Return the element of the _super chain of the given depth.
218 // If there is no such element, return either NULL or this.
219 Klass* primary_super_of_depth(juint i) const {
220 assert(i < primary_super_limit(), "oob");
221 Klass* super = _primary_supers[i];
222 assert(super == NULL || super->super_depth() == i, "correct display");
223 return super;
224 }
225
226 // Can this klass be a primary super? False for interfaces and arrays of
227 // interfaces. False also for arrays or classes with long super chains.
228 bool can_be_primary_super() const {
229 const juint secondary_offset = in_bytes(secondary_super_cache_offset());
230 return super_check_offset() != secondary_offset;
231 }
232 virtual bool can_be_primary_super_slow() const;
233
234 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
235 juint super_depth() const {
236 if (!can_be_primary_super()) {
237 return primary_super_limit();
238 } else {
239 juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
240 assert(d < primary_super_limit(), "oob");
241 assert(_primary_supers[d] == this, "proper init");
242 return d;
243 }
244 }
245
246 // store an oop into a field of a Klass
247 void klass_oop_store(oop* p, oop v);
248 void klass_oop_store(volatile oop* p, oop v);
249
250 // java mirror
251 oop java_mirror() const { return _java_mirror; }
252 void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
253
254 // modifier flags
255 jint modifier_flags() const { return _modifier_flags; }
256 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
257
258 // size helper
259 int layout_helper() const { return _layout_helper; }
260 void set_layout_helper(int lh) { _layout_helper = lh; }
261
262 // Note: for instances layout_helper() may include padding.
263 // Use InstanceKlass::contains_field_offset to classify field offsets.
264
265 // sub/superklass links
266 InstanceKlass* superklass() const;
267 Klass* subklass() const;
268 Klass* next_sibling() const;
269 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
270
271 void set_next_link(Klass* k) { _next_link = k; }
272 Klass* next_link() const { return _next_link; } // The next klass defined by the class loader.
273
274 // class loader data
275 ClassLoaderData* class_loader_data() const { return _class_loader_data; }
276 void set_class_loader_data(ClassLoaderData* loader_data) { _class_loader_data = loader_data; }
277
278 // The Klasses are not placed in the Heap, so the Card Table or
279 // the Mod Union Table can't be used to mark when klasses have modified oops.
280 // The CT and MUT bits saves this information for the individual Klasses.
281 void record_modified_oops() { _modified_oops = 1; }
282 void clear_modified_oops() { _modified_oops = 0; }
283 bool has_modified_oops() { return _modified_oops == 1; }
284
285 void accumulate_modified_oops() { if (has_modified_oops()) _accumulated_modified_oops = 1; }
286 void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
287 bool has_accumulated_modified_oops() { return _accumulated_modified_oops == 1; }
288
289 protected: // internal accessors
290 Klass* subklass_oop() const { return _subklass; }
291 Klass* next_sibling_oop() const { return _next_sibling; }
292 void set_subklass(Klass* s);
293 void set_next_sibling(Klass* s);
294
295 public:
296 // Allocation profiling support
297 juint alloc_count() const { return _alloc_count; }
298 void set_alloc_count(juint n) { _alloc_count = n; }
299 virtual juint alloc_size() const = 0;
300 virtual void set_alloc_size(juint n) = 0;
301
302 // Compiler support
303 static ByteSize super_offset() { return in_ByteSize(offset_of(Klass, _super)); }
304 static ByteSize super_check_offset_offset() { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
305 static ByteSize primary_supers_offset() { return in_ByteSize(offset_of(Klass, _primary_supers)); }
306 static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
307 static ByteSize secondary_supers_offset() { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
308 static ByteSize java_mirror_offset() { return in_ByteSize(offset_of(Klass, _java_mirror)); }
309 static ByteSize modifier_flags_offset() { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
310 static ByteSize layout_helper_offset() { return in_ByteSize(offset_of(Klass, _layout_helper)); }
311 static ByteSize access_flags_offset() { return in_ByteSize(offset_of(Klass, _access_flags)); }
312
313 // Unpacking layout_helper:
314 enum {
315 _lh_neutral_value = 0, // neutral non-array non-instance value
316 _lh_instance_slow_path_bit = 0x01,
317 _lh_log2_element_size_shift = BitsPerByte*0,
318 _lh_log2_element_size_mask = BitsPerLong-1,
319 _lh_element_type_shift = BitsPerByte*1,
320 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
321 _lh_header_size_shift = BitsPerByte*2,
322 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
323 _lh_array_tag_bits = 2,
324 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
325 _lh_array_tag_type_value = ~0x00, // 0xC0000000 >> 30
326 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30
327 };
328
329 static int layout_helper_size_in_bytes(jint lh) {
330 assert(lh > (jint)_lh_neutral_value, "must be instance");
331 return (int) lh & ~_lh_instance_slow_path_bit;
332 }
333 static bool layout_helper_needs_slow_path(jint lh) {
334 assert(lh > (jint)_lh_neutral_value, "must be instance");
335 return (lh & _lh_instance_slow_path_bit) != 0;
336 }
337 static bool layout_helper_is_instance(jint lh) {
338 return (jint)lh > (jint)_lh_neutral_value;
339 }
340 static bool layout_helper_is_array(jint lh) {
341 return (jint)lh < (jint)_lh_neutral_value;
342 }
343 static bool layout_helper_is_typeArray(jint lh) {
344 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
345 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
346 }
347 static bool layout_helper_is_objArray(jint lh) {
348 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
349 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
350 }
351 static int layout_helper_header_size(jint lh) {
352 assert(lh < (jint)_lh_neutral_value, "must be array");
353 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
354 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
355 return hsize;
356 }
357 static BasicType layout_helper_element_type(jint lh) {
358 assert(lh < (jint)_lh_neutral_value, "must be array");
359 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
360 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
361 return (BasicType) btvalue;
362 }
363 static int layout_helper_log2_element_size(jint lh) {
364 assert(lh < (jint)_lh_neutral_value, "must be array");
365 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
366 assert(l2esz <= LogBitsPerLong, "sanity");
367 return l2esz;
368 }
369 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
370 return (tag << _lh_array_tag_shift)
371 | (hsize << _lh_header_size_shift)
372 | ((int)etype << _lh_element_type_shift)
373 | (log2_esize << _lh_log2_element_size_shift);
374 }
375 static jint instance_layout_helper(jint size, bool slow_path_flag) {
376 return (size << LogHeapWordSize)
377 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
378 }
379 static int layout_helper_to_size_helper(jint lh) {
380 assert(lh > (jint)_lh_neutral_value, "must be instance");
381 // Note that the following expression discards _lh_instance_slow_path_bit.
382 return lh >> LogHeapWordSize;
383 }
384 // Out-of-line version computes everything based on the etype:
385 static jint array_layout_helper(BasicType etype);
386
387 // What is the maximum number of primary superclasses any klass can have?
388 #ifdef PRODUCT
389 static juint primary_super_limit() { return _primary_super_limit; }
390 #else
391 static juint primary_super_limit() {
392 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
393 return FastSuperclassLimit;
394 }
395 #endif
396
397 // vtables
398 virtual klassVtable* vtable() const { return NULL; }
399
400 // subclass check
401 bool is_subclass_of(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 Method* uncached_lookup_method(Symbol* name, Symbol* signature) const;
434 public:
435 Method* lookup_method(Symbol* name, Symbol* signature) const {
436 return uncached_lookup_method(name, signature);
437 }
438
439 // array class with specific rank
440 Klass* array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
441
442 // array class with this klass as element type
443 Klass* array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
444
445 // These will return NULL instead of allocating on the heap:
446 // NB: these can block for a mutex, like other functions with TRAPS arg.
447 Klass* array_klass_or_null(int rank);
448 Klass* array_klass_or_null();
449
450 virtual oop protection_domain() { return NULL; }
451
452 oop class_loader() const;
453
454 virtual oop klass_holder() const { return class_loader(); }
455
456 protected:
457 virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
458 virtual Klass* array_klass_impl(bool or_null, TRAPS);
459
460 public:
461 // CDS support - remove and restore oops from metadata. Oops are not shared.
462 virtual void remove_unshareable_info();
463 virtual void restore_unshareable_info(TRAPS);
464
465 protected:
466 // computes the subtype relationship
467 virtual bool compute_is_subtype_of(Klass* k);
468 public:
469 // subclass accessor (here for convenience; undefined for non-klass objects)
470 virtual bool is_leaf_class() const { fatal("not a class"); return false; }
471 public:
472 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
473 // These functions describe behavior for the oop not the KLASS.
474
475 // actual oop size of obj in memory
476 virtual int oop_size(oop obj) const = 0;
477
478 // Size of klass in word size.
479 virtual int size() const = 0;
480
481 // Returns the Java name for a class (Resource allocated)
482 // For arrays, this returns the name of the element with a leading '['.
483 // For classes, this returns the name with the package separators
484 // turned into '.'s.
485 const char* external_name() const;
486 // Returns the name for a class (Resource allocated) as the class
487 // would appear in a signature.
488 // For arrays, this returns the name of the element with a leading '['.
489 // For classes, this returns the name with a leading 'L' and a trailing ';'
490 // and the package separators as '/'.
491 virtual const char* signature_name() const;
492
493 // garbage collection support
494 virtual void oop_follow_contents(oop obj) = 0;
495 virtual int oop_adjust_pointers(oop obj) = 0;
496
497 // Parallel Scavenge and Parallel Old
498 PARALLEL_GC_DECLS_PV
499
500 // type testing operations
501 protected:
502 virtual bool oop_is_instance_slow() const { return false; }
503 virtual bool oop_is_array_slow() const { return false; }
504 virtual bool oop_is_objArray_slow() const { return false; }
505 virtual bool oop_is_typeArray_slow() const { return false; }
506 public:
507 virtual bool oop_is_instanceMirror() const { return false; }
508 virtual bool oop_is_instanceRef() const { return false; }
509
510 // Fast non-virtual versions
511 #ifndef ASSERT
512 #define assert_same_query(xval, xcheck) xval
513 #else
514 private:
515 static bool assert_same_query(bool xval, bool xslow) {
516 assert(xval == xslow, "slow and fast queries agree");
517 return xval;
518 }
519 public:
520 #endif
521 inline bool oop_is_instance() const { return assert_same_query(
522 layout_helper_is_instance(layout_helper()),
523 oop_is_instance_slow()); }
524 inline bool oop_is_array() const { return assert_same_query(
525 layout_helper_is_array(layout_helper()),
526 oop_is_array_slow()); }
527 inline bool oop_is_objArray() const { return assert_same_query(
528 layout_helper_is_objArray(layout_helper()),
529 oop_is_objArray_slow()); }
530 inline bool oop_is_typeArray() const { return assert_same_query(
531 layout_helper_is_typeArray(layout_helper()),
532 oop_is_typeArray_slow()); }
533 #undef assert_same_query
534
535 // Access flags
536 AccessFlags access_flags() const { return _access_flags; }
537 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
538
539 bool is_public() const { return _access_flags.is_public(); }
540 bool is_final() const { return _access_flags.is_final(); }
541 bool is_interface() const { return _access_flags.is_interface(); }
542 bool is_abstract() const { return _access_flags.is_abstract(); }
543 bool is_super() const { return _access_flags.is_super(); }
544 bool is_synthetic() const { return _access_flags.is_synthetic(); }
545 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
546 bool has_finalizer() const { return _access_flags.has_finalizer(); }
547 bool has_final_method() const { return _access_flags.has_final_method(); }
548 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
549 void set_has_final_method() { _access_flags.set_has_final_method(); }
550 bool is_cloneable() const { return _access_flags.is_cloneable(); }
551 void set_is_cloneable() { _access_flags.set_is_cloneable(); }
552 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
553 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
554 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
555 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
556
557 // Biased locking support
558 // Note: the prototype header is always set up to be at least the
559 // prototype markOop. If biased locking is enabled it may further be
560 // biasable and have an epoch.
561 markOop prototype_header() const { return _prototype_header; }
562 // NOTE: once instances of this klass are floating around in the
563 // system, this header must only be updated at a safepoint.
564 // NOTE 2: currently we only ever set the prototype header to the
565 // biasable prototype for instanceKlasses. There is no technical
566 // reason why it could not be done for arrayKlasses aside from
567 // wanting to reduce the initial scope of this optimization. There
568 // are potential problems in setting the bias pattern for
569 // JVM-internal oops.
570 inline void set_prototype_header(markOop header);
571 static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
572
573 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
574 // Atomically increments biased_lock_revocation_count and returns updated value
575 int atomic_incr_biased_lock_revocation_count();
576 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
577 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
578 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
579
580 TRACE_DEFINE_KLASS_METHODS;
581
582 // garbage collection support
583 virtual void oops_do(OopClosure* cl);
584
585 // Iff the class loader (or mirror for anonymous classes) is alive the
586 // Klass is considered alive.
587 // The is_alive closure passed in depends on the Garbage Collector used.
588 bool is_loader_alive(BoolObjectClosure* is_alive);
589
590 static void clean_weak_klass_links(BoolObjectClosure* is_alive);
591
592 // Prefetch within oop iterators. This is a macro because we
593 // can't guarantee that the compiler will inline it. In 64-bit
594 // it generally doesn't. Signature is
595 //
596 // static void prefetch_beyond(oop* const start,
597 // oop* const end,
598 // const intx foffset,
599 // const Prefetch::style pstyle);
600 #define prefetch_beyond(start, end, foffset, pstyle) { \
601 const intx foffset_ = (foffset); \
602 const Prefetch::style pstyle_ = (pstyle); \
603 assert(foffset_ > 0, "prefetch beyond, not behind"); \
604 if (pstyle_ != Prefetch::do_none) { \
605 oop* ref = (start); \
606 if (ref < (end)) { \
607 switch (pstyle_) { \
608 case Prefetch::do_read: \
609 Prefetch::read(*ref, foffset_); \
610 break; \
611 case Prefetch::do_write: \
612 Prefetch::write(*ref, foffset_); \
613 break; \
614 default: \
615 ShouldNotReachHere(); \
616 break; \
617 } \
618 } \
619 } \
620 }
621
622 // iterators
623 virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0;
624 virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) {
625 return oop_oop_iterate(obj, blk);
626 }
627
628 #ifndef SERIALGC
629 // In case we don't have a specialized backward scanner use forward
630 // iteration.
631 virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) {
632 return oop_oop_iterate_v(obj, blk);
633 }
634 #endif // !SERIALGC
635
636 // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
637 // (I don't see why the _m should be required, but without it the Solaris
638 // C++ gives warning messages about overridings of the "oop_oop_iterate"
639 // defined above "hiding" this virtual function. (DLD, 6/20/00)) */
640 virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0;
641 virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
642 return oop_oop_iterate_m(obj, blk, mr);
643 }
644
645 // Versions of the above iterators specialized to particular subtypes
646 // of OopClosure, to avoid closure virtual calls.
647 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
648 virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) { \
649 /* Default implementation reverts to general version. */ \
650 return oop_oop_iterate(obj, blk); \
651 } \
652 \
653 /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
654 (I don't see why the _m should be required, but without it the Solaris \
655 C++ gives warning messages about overridings of the "oop_oop_iterate" \
656 defined above "hiding" this virtual function. (DLD, 6/20/00)) */ \
657 virtual int oop_oop_iterate##nv_suffix##_m(oop obj, \
658 OopClosureType* blk, \
659 MemRegion mr) { \
660 return oop_oop_iterate_m(obj, blk, mr); \
661 }
662
663 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
664 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
665
666 #ifndef SERIALGC
667 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
668 virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, \
669 OopClosureType* blk) { \
670 /* Default implementation reverts to general version. */ \
671 return oop_oop_iterate_backwards_v(obj, blk); \
672 }
673
674 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
675 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
676 #endif // !SERIALGC
677
678 virtual void array_klasses_do(void f(Klass* k)) {}
679 virtual void with_array_klasses_do(void f(Klass* k));
680
681 // Return self, except for abstract classes with exactly 1
682 // implementor. Then return the 1 concrete implementation.
683 Klass *up_cast_abstract();
684
685 // klass name
686 Symbol* name() const { return _name; }
687 void set_name(Symbol* n);
688
689 public:
690 // jvm support
691 virtual jint compute_modifier_flags(TRAPS) const;
692
693 // JVMTI support
694 virtual jint jvmti_class_status() const;
695
696 // Printing
697 virtual void print_on(outputStream* st) const;
698
699 virtual void oop_print_value_on(oop obj, outputStream* st);
700 virtual void oop_print_on (oop obj, outputStream* st);
701
702 virtual const char* internal_name() const = 0;
703
704 // Verification
705 virtual void verify_on(outputStream* st);
706 void verify() { verify_on(tty); }
707
708 #ifndef PRODUCT
709 void verify_vtable_index(int index);
710 #endif
711
712 virtual void oop_verify_on(oop obj, outputStream* st);
713
714 private:
715 // barriers used by klass_oop_store
716 void klass_update_barrier_set(oop v);
717 void klass_update_barrier_set_pre(void* p, oop v);
718 };
719
720 #endif // SHARE_VM_OOPS_KLASS_HPP