1 /*
2 * Copyright (c) 1997, 2009, 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 // A Klass is the part of the klassOop that provides:
26 // 1: language level class object (method dictionary etc.)
27 // 2: provide vm dispatch behavior for the object
28 // Both functions are combined into one C++ class. The toplevel class "Klass"
29 // implements purpose 1 whereas all subclasses provide extra virtual functions
30 // for purpose 2.
31
32 // One reason for the oop/klass dichotomy in the implementation is
33 // that we don't want a C++ vtbl pointer in every object. Thus,
34 // normal oops don't have any virtual functions. Instead, they
35 // forward all "virtual" functions to their klass, which does have
36 // a vtbl and does the C++ dispatch depending on the object's
37 // actual type. (See oop.inline.hpp for some of the forwarding code.)
38 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
39
40 // Klass layout:
41 // [header ] klassOop
42 // [klass pointer ] klassOop
43 // [C++ vtbl ptr ] (contained in Klass_vtbl)
44 // [layout_helper ]
45 // [super_check_offset ] for fast subtype checks
46 // [secondary_super_cache] for fast subtype checks
47 // [secondary_supers ] array of 2ndary supertypes
48 // [primary_supers 0]
49 // [primary_supers 1]
50 // [primary_supers 2]
51 // ...
52 // [primary_supers 7]
53 // [java_mirror ]
54 // [super ]
55 // [name ]
56 // [first subklass]
57 // [next_sibling ] link to chain additional subklasses
58 // [modifier_flags]
59 // [access_flags ]
60 // [verify_count ] - not in product
61 // [alloc_count ]
62 // [last_biased_lock_bulk_revocation_time] (64 bits)
63 // [prototype_header]
64 // [biased_lock_revocation_count]
65
66
67 // Forward declarations.
68 class klassVtable;
69 class KlassHandle;
70 class OrderAccess;
71
72 // Holder (or cage) for the C++ vtable of each kind of Klass.
73 // We want to tightly constrain the location of the C++ vtable in the overall layout.
74 class Klass_vtbl {
75 protected:
76 // The following virtual exists only to force creation of a C++ vtable,
77 // so that this class truly is the location of the vtable of all Klasses.
78 virtual void unused_initial_virtual() { }
79
80 public:
81 // The following virtual makes Klass_vtbl play a second role as a
82 // factory protocol for subclasses of Klass ("sub-Klasses").
83 // Here's how it works....
84 //
85 // This VM uses metaobjects as factories for their instances.
86 //
87 // In order to initialize the C++ vtable of a new instance, its
88 // metaobject is forced to use the C++ placed new operator to
89 // allocate the instance. In a typical C++-based system, each
90 // sub-class would have its own factory routine which
91 // directly uses the placed new operator on the desired class,
92 // and then calls the appropriate chain of C++ constructors.
93 //
94 // However, this system uses shared code to performs the first
95 // allocation and initialization steps for all sub-Klasses.
96 // (See base_create_klass() and base_create_array_klass().)
97 // This does not factor neatly into a hierarchy of C++ constructors.
98 // Each caller of these shared "base_create" routines knows
99 // exactly which sub-Klass it is creating, but the shared routine
100 // does not, even though it must perform the actual allocation.
101 //
102 // Therefore, the caller of the shared "base_create" must wrap
103 // the specific placed new call in a virtual function which
104 // performs the actual allocation and vtable set-up. That
105 // virtual function is here, Klass_vtbl::allocate_permanent.
106 //
107 // The arguments to Universe::allocate_permanent() are passed
108 // straight through the placed new operator, which in turn
109 // obtains them directly from this virtual call.
110 //
111 // This virtual is called on a temporary "example instance" of the
112 // sub-Klass being instantiated, a C++ auto variable. The "real"
113 // instance created by this virtual is on the VM heap, where it is
114 // equipped with a klassOopDesc header.
115 //
116 // It is merely an accident of implementation that we use "example
117 // instances", but that is why the virtual function which implements
118 // each sub-Klass factory happens to be defined by the same sub-Klass
119 // for which it creates instances.
120 //
121 // The vtbl_value() call (see below) is used to strip away the
122 // accidental Klass-ness from an "example instance" and present it as
123 // a factory. Think of each factory object as a mere container of the
124 // C++ vtable for the desired sub-Klass. Since C++ does not allow
125 // direct references to vtables, the factory must also be delegated
126 // the task of allocating the instance, but the essential point is
127 // that the factory knows how to initialize the C++ vtable with the
128 // right pointer value. All other common initializations are handled
129 // by the shared "base_create" subroutines.
130 //
131 virtual void* allocate_permanent(KlassHandle& klass, int size, TRAPS) const = 0;
132 void post_new_init_klass(KlassHandle& klass, klassOop obj, int size) const;
133
134 // Every subclass on which vtbl_value is called must include this macro.
135 // Delay the installation of the klassKlass pointer until after the
136 // the vtable for a new klass has been installed (after the call to new()).
137 #define DEFINE_ALLOCATE_PERMANENT(thisKlass) \
138 void* allocate_permanent(KlassHandle& klass_klass, int size, TRAPS) const { \
139 void* result = new(klass_klass, size, THREAD) thisKlass(); \
140 if (HAS_PENDING_EXCEPTION) return NULL; \
141 klassOop new_klass = ((Klass*) result)->as_klassOop(); \
142 OrderAccess::storestore(); \
143 post_new_init_klass(klass_klass, new_klass, size); \
144 return result; \
145 }
146
147 bool null_vtbl() { return *(intptr_t*)this == 0; }
148
149 protected:
150 void* operator new(size_t ignored, KlassHandle& klass, int size, TRAPS);
151 };
152
153
154 class Klass : public Klass_vtbl {
155 friend class VMStructs;
156 protected:
157 // note: put frequently-used fields together at start of klass structure
158 // for better cache behavior (may not make much of a difference but sure won't hurt)
159 enum { _primary_super_limit = 8 };
160
161 // The "layout helper" is a combined descriptor of object layout.
162 // For klasses which are neither instance nor array, the value is zero.
163 //
164 // For instances, layout helper is a positive number, the instance size.
165 // This size is already passed through align_object_size and scaled to bytes.
166 // The low order bit is set if instances of this class cannot be
167 // allocated using the fastpath.
168 //
169 // For arrays, layout helper is a negative number, containing four
170 // distinct bytes, as follows:
171 // MSB:[tag, hsz, ebt, log2(esz)]:LSB
172 // where:
173 // tag is 0x80 if the elements are oops, 0xC0 if non-oops
174 // hsz is array header size in bytes (i.e., offset of first element)
175 // ebt is the BasicType of the elements
176 // esz is the element size in bytes
177 // This packed word is arranged so as to be quickly unpacked by the
178 // various fast paths that use the various subfields.
179 //
180 // The esz bits can be used directly by a SLL instruction, without masking.
181 //
182 // Note that the array-kind tag looks like 0x00 for instance klasses,
183 // since their length in bytes is always less than 24Mb.
184 //
185 // Final note: This comes first, immediately after Klass_vtbl,
186 // because it is frequently queried.
187 jint _layout_helper;
188
189 // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
190 // and _primary_supers all help make fast subtype checks. See big discussion
191 // in doc/server_compiler/checktype.txt
192 //
193 // Where to look to observe a supertype (it is &_secondary_super_cache for
194 // secondary supers, else is &_primary_supers[depth()].
195 juint _super_check_offset;
196
197 public:
198 oop* oop_block_beg() const { return adr_secondary_super_cache(); }
199 oop* oop_block_end() const { return adr_next_sibling() + 1; }
200
201 protected:
202 //
203 // The oop block. All oop fields must be declared here and only oop fields
204 // may be declared here. In addition, the first and last fields in this block
205 // must remain first and last, unless oop_block_beg() and/or oop_block_end()
206 // are updated. Grouping the oop fields in a single block simplifies oop
207 // iteration.
208 //
209
210 // Cache of last observed secondary supertype
211 klassOop _secondary_super_cache;
212 // Array of all secondary supertypes
213 objArrayOop _secondary_supers;
214 // Ordered list of all primary supertypes
215 klassOop _primary_supers[_primary_super_limit];
216 // java/lang/Class instance mirroring this class
217 oop _java_mirror;
218 // Superclass
219 klassOop _super;
220 // Class name. Instance classes: java/lang/String, etc. Array classes: [I,
221 // [Ljava/lang/String;, etc. Set to zero for all other kinds of classes.
222 symbolOop _name;
223 // First subclass (NULL if none); _subklass->next_sibling() is next one
224 klassOop _subklass;
225 // Sibling link (or NULL); links all subklasses of a klass
226 klassOop _next_sibling;
227
228 //
229 // End of the oop block.
230 //
231
232 jint _modifier_flags; // Processed access flags, for use by Class.getModifiers.
233 AccessFlags _access_flags; // Access flags. The class/interface distinction is stored here.
234
235 #ifndef PRODUCT
236 int _verify_count; // to avoid redundant verifies
237 #endif
238
239 juint _alloc_count; // allocation profiling support - update klass_size_in_bytes() if moved/deleted
240
241 // Biased locking implementation and statistics
242 // (the 64-bit chunk goes first, to avoid some fragmentation)
243 jlong _last_biased_lock_bulk_revocation_time;
244 markOop _prototype_header; // Used when biased locking is both enabled and disabled for this type
245 jint _biased_lock_revocation_count;
246
247 public:
248
249 // returns the enclosing klassOop
250 klassOop as_klassOop() const {
251 // see klassOop.hpp for layout.
252 return (klassOop) (((char*) this) - sizeof(klassOopDesc));
253 }
254
255 public:
256 // Allocation
257 const Klass_vtbl& vtbl_value() const { return *this; } // used only on "example instances"
258 static KlassHandle base_create_klass(KlassHandle& klass, int size, const Klass_vtbl& vtbl, TRAPS);
259 static klassOop base_create_klass_oop(KlassHandle& klass, int size, const Klass_vtbl& vtbl, TRAPS);
260
261 // super
262 klassOop super() const { return _super; }
263 void set_super(klassOop k) { oop_store_without_check((oop*) &_super, (oop) k); }
264
265 // initializes _super link, _primary_supers & _secondary_supers arrays
266 void initialize_supers(klassOop k, TRAPS);
267 void initialize_supers_impl1(klassOop k);
268 void initialize_supers_impl2(klassOop k);
269
270 // klass-specific helper for initializing _secondary_supers
271 virtual objArrayOop compute_secondary_supers(int num_extra_slots, TRAPS);
272
273 // java_super is the Java-level super type as specified by Class.getSuperClass.
274 virtual klassOop java_super() const { return NULL; }
275
276 juint super_check_offset() const { return _super_check_offset; }
277 void set_super_check_offset(juint o) { _super_check_offset = o; }
278
279 klassOop secondary_super_cache() const { return _secondary_super_cache; }
280 void set_secondary_super_cache(klassOop k) { oop_store_without_check((oop*) &_secondary_super_cache, (oop) k); }
281
282 objArrayOop secondary_supers() const { return _secondary_supers; }
283 void set_secondary_supers(objArrayOop k) { oop_store_without_check((oop*) &_secondary_supers, (oop) k); }
284
285 // Return the element of the _super chain of the given depth.
286 // If there is no such element, return either NULL or this.
287 klassOop primary_super_of_depth(juint i) const {
288 assert(i < primary_super_limit(), "oob");
289 klassOop super = _primary_supers[i];
290 assert(super == NULL || super->klass_part()->super_depth() == i, "correct display");
291 return super;
292 }
293
294 // Can this klass be a primary super? False for interfaces and arrays of
295 // interfaces. False also for arrays or classes with long super chains.
296 bool can_be_primary_super() const {
297 const juint secondary_offset = secondary_super_cache_offset_in_bytes() + sizeof(oopDesc);
298 return super_check_offset() != secondary_offset;
299 }
300 virtual bool can_be_primary_super_slow() const;
301
302 // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
303 juint super_depth() const {
304 if (!can_be_primary_super()) {
305 return primary_super_limit();
306 } else {
307 juint d = (super_check_offset() - (primary_supers_offset_in_bytes() + sizeof(oopDesc))) / sizeof(klassOop);
308 assert(d < primary_super_limit(), "oob");
309 assert(_primary_supers[d] == as_klassOop(), "proper init");
310 return d;
311 }
312 }
313
314 // java mirror
315 oop java_mirror() const { return _java_mirror; }
316 void set_java_mirror(oop m) { oop_store((oop*) &_java_mirror, m); }
317
318 // modifier flags
319 jint modifier_flags() const { return _modifier_flags; }
320 void set_modifier_flags(jint flags) { _modifier_flags = flags; }
321
322 // size helper
323 int layout_helper() const { return _layout_helper; }
324 void set_layout_helper(int lh) { _layout_helper = lh; }
325
326 // Note: for instances layout_helper() may include padding.
327 // Use instanceKlass::contains_field_offset to classify field offsets.
328
329 // sub/superklass links
330 instanceKlass* superklass() const;
331 Klass* subklass() const;
332 Klass* next_sibling() const;
333 void append_to_sibling_list(); // add newly created receiver to superklass' subklass list
334 void remove_from_sibling_list(); // remove receiver from sibling list
335 protected: // internal accessors
336 klassOop subklass_oop() const { return _subklass; }
337 klassOop next_sibling_oop() const { return _next_sibling; }
338 void set_subklass(klassOop s);
339 void set_next_sibling(klassOop s);
340
341 oop* adr_super() const { return (oop*)&_super; }
342 oop* adr_primary_supers() const { return (oop*)&_primary_supers[0]; }
343 oop* adr_secondary_super_cache() const { return (oop*)&_secondary_super_cache; }
344 oop* adr_secondary_supers()const { return (oop*)&_secondary_supers; }
345 oop* adr_java_mirror() const { return (oop*)&_java_mirror; }
346 oop* adr_name() const { return (oop*)&_name; }
347 oop* adr_subklass() const { return (oop*)&_subklass; }
348 oop* adr_next_sibling() const { return (oop*)&_next_sibling; }
349
350 public:
351 // Allocation profiling support
352 juint alloc_count() const { return _alloc_count; }
353 void set_alloc_count(juint n) { _alloc_count = n; }
354 virtual juint alloc_size() const = 0;
355 virtual void set_alloc_size(juint n) = 0;
356
357 // Compiler support
358 static int super_offset_in_bytes() { return offset_of(Klass, _super); }
359 static int super_check_offset_offset_in_bytes() { return offset_of(Klass, _super_check_offset); }
360 static int primary_supers_offset_in_bytes(){ return offset_of(Klass, _primary_supers); }
361 static int secondary_super_cache_offset_in_bytes() { return offset_of(Klass, _secondary_super_cache); }
362 static int secondary_supers_offset_in_bytes() { return offset_of(Klass, _secondary_supers); }
363 static int java_mirror_offset_in_bytes() { return offset_of(Klass, _java_mirror); }
364 static int modifier_flags_offset_in_bytes(){ return offset_of(Klass, _modifier_flags); }
365 static int layout_helper_offset_in_bytes() { return offset_of(Klass, _layout_helper); }
366 static int access_flags_offset_in_bytes() { return offset_of(Klass, _access_flags); }
367
368 // Unpacking layout_helper:
369 enum {
370 _lh_neutral_value = 0, // neutral non-array non-instance value
371 _lh_instance_slow_path_bit = 0x01,
372 _lh_log2_element_size_shift = BitsPerByte*0,
373 _lh_log2_element_size_mask = BitsPerLong-1,
374 _lh_element_type_shift = BitsPerByte*1,
375 _lh_element_type_mask = right_n_bits(BitsPerByte), // shifted mask
376 _lh_header_size_shift = BitsPerByte*2,
377 _lh_header_size_mask = right_n_bits(BitsPerByte), // shifted mask
378 _lh_array_tag_bits = 2,
379 _lh_array_tag_shift = BitsPerInt - _lh_array_tag_bits,
380 _lh_array_tag_type_value = ~0x00, // 0xC0000000 >> 30
381 _lh_array_tag_obj_value = ~0x01 // 0x80000000 >> 30
382 };
383
384 static int layout_helper_size_in_bytes(jint lh) {
385 assert(lh > (jint)_lh_neutral_value, "must be instance");
386 return (int) lh & ~_lh_instance_slow_path_bit;
387 }
388 static bool layout_helper_needs_slow_path(jint lh) {
389 assert(lh > (jint)_lh_neutral_value, "must be instance");
390 return (lh & _lh_instance_slow_path_bit) != 0;
391 }
392 static bool layout_helper_is_instance(jint lh) {
393 return (jint)lh > (jint)_lh_neutral_value;
394 }
395 static bool layout_helper_is_javaArray(jint lh) {
396 return (jint)lh < (jint)_lh_neutral_value;
397 }
398 static bool layout_helper_is_typeArray(jint lh) {
399 // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
400 return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
401 }
402 static bool layout_helper_is_objArray(jint lh) {
403 // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
404 return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
405 }
406 static int layout_helper_header_size(jint lh) {
407 assert(lh < (jint)_lh_neutral_value, "must be array");
408 int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
409 assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
410 return hsize;
411 }
412 static BasicType layout_helper_element_type(jint lh) {
413 assert(lh < (jint)_lh_neutral_value, "must be array");
414 int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
415 assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
416 return (BasicType) btvalue;
417 }
418 static int layout_helper_log2_element_size(jint lh) {
419 assert(lh < (jint)_lh_neutral_value, "must be array");
420 int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
421 assert(l2esz <= LogBitsPerLong, "sanity");
422 return l2esz;
423 }
424 static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
425 return (tag << _lh_array_tag_shift)
426 | (hsize << _lh_header_size_shift)
427 | ((int)etype << _lh_element_type_shift)
428 | (log2_esize << _lh_log2_element_size_shift);
429 }
430 static jint instance_layout_helper(jint size, bool slow_path_flag) {
431 return (size << LogHeapWordSize)
432 | (slow_path_flag ? _lh_instance_slow_path_bit : 0);
433 }
434 static int layout_helper_to_size_helper(jint lh) {
435 assert(lh > (jint)_lh_neutral_value, "must be instance");
436 // Note that the following expression discards _lh_instance_slow_path_bit.
437 return lh >> LogHeapWordSize;
438 }
439 // Out-of-line version computes everything based on the etype:
440 static jint array_layout_helper(BasicType etype);
441
442 // What is the maximum number of primary superclasses any klass can have?
443 #ifdef PRODUCT
444 static juint primary_super_limit() { return _primary_super_limit; }
445 #else
446 static juint primary_super_limit() {
447 assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
448 return FastSuperclassLimit;
449 }
450 #endif
451
452 // vtables
453 virtual klassVtable* vtable() const { return NULL; }
454
455 static int klass_size_in_bytes() { return offset_of(Klass, _alloc_count) + sizeof(juint); } // all "visible" fields
456
457 // subclass check
458 bool is_subclass_of(klassOop k) const;
459 // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
460 bool is_subtype_of(klassOop k) const {
461 juint off = k->klass_part()->super_check_offset();
462 klassOop sup = *(klassOop*)( (address)as_klassOop() + off );
463 const juint secondary_offset = secondary_super_cache_offset_in_bytes() + sizeof(oopDesc);
464 if (sup == k) {
465 return true;
466 } else if (off != secondary_offset) {
467 return false;
468 } else {
469 return search_secondary_supers(k);
470 }
471 }
472 bool search_secondary_supers(klassOop k) const;
473
474 // Find LCA in class hierarchy
475 Klass *LCA( Klass *k );
476
477 // Check whether reflection/jni/jvm code is allowed to instantiate this class;
478 // if not, throw either an Error or an Exception.
479 virtual void check_valid_for_instantiation(bool throwError, TRAPS);
480
481 // Casting
482 static Klass* cast(klassOop k) {
483 assert(k->is_klass(), "cast to Klass");
484 return k->klass_part();
485 }
486
487 // array copying
488 virtual void copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
489
490 // tells if the class should be initialized
491 virtual bool should_be_initialized() const { return false; }
492 // initializes the klass
493 virtual void initialize(TRAPS);
494 // lookup operation for MethodLookupCache
495 friend class MethodLookupCache;
496 virtual methodOop uncached_lookup_method(symbolOop name, symbolOop signature) const;
497 public:
498 methodOop lookup_method(symbolOop name, symbolOop signature) const {
499 return uncached_lookup_method(name, signature);
500 }
501
502 // array class with specific rank
503 klassOop array_klass(int rank, TRAPS) { return array_klass_impl(false, rank, THREAD); }
504
505 // array class with this klass as element type
506 klassOop array_klass(TRAPS) { return array_klass_impl(false, THREAD); }
507
508 // These will return NULL instead of allocating on the heap:
509 // NB: these can block for a mutex, like other functions with TRAPS arg.
510 klassOop array_klass_or_null(int rank);
511 klassOop array_klass_or_null();
512
513 virtual oop protection_domain() { return NULL; }
514 virtual oop class_loader() const { return NULL; }
515
516 protected:
517 virtual klassOop array_klass_impl(bool or_null, int rank, TRAPS);
518 virtual klassOop array_klass_impl(bool or_null, TRAPS);
519
520 public:
521 virtual void remove_unshareable_info();
522
523 protected:
524 // computes the subtype relationship
525 virtual bool compute_is_subtype_of(klassOop k);
526 public:
527 // subclass accessor (here for convenience; undefined for non-klass objects)
528 virtual bool is_leaf_class() const { fatal("not a class"); return false; }
529 public:
530 // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
531 // These functions describe behavior for the oop not the KLASS.
532
533 // actual oop size of obj in memory
534 virtual int oop_size(oop obj) const = 0;
535
536 // actual oop size of this klass in memory
537 virtual int klass_oop_size() const = 0;
538
539 // Returns the Java name for a class (Resource allocated)
540 // For arrays, this returns the name of the element with a leading '['.
541 // For classes, this returns the name with the package separators
542 // turned into '.'s.
543 const char* external_name() const;
544 // Returns the name for a class (Resource allocated) as the class
545 // would appear in a signature.
546 // For arrays, this returns the name of the element with a leading '['.
547 // For classes, this returns the name with a leading 'L' and a trailing ';'
548 // and the package separators as '/'.
549 virtual const char* signature_name() const;
550
551 // garbage collection support
552 virtual void oop_follow_contents(oop obj) = 0;
553 virtual int oop_adjust_pointers(oop obj) = 0;
554
555 // Parallel Scavenge and Parallel Old
556 PARALLEL_GC_DECLS_PV
557
558 public:
559 // type testing operations
560 virtual bool oop_is_instance_slow() const { return false; }
561 virtual bool oop_is_instanceRef() const { return false; }
562 virtual bool oop_is_array() const { return false; }
563 virtual bool oop_is_objArray_slow() const { return false; }
564 virtual bool oop_is_symbol() const { return false; }
565 virtual bool oop_is_klass() const { return false; }
566 virtual bool oop_is_thread() const { return false; }
567 virtual bool oop_is_method() const { return false; }
568 virtual bool oop_is_constMethod() const { return false; }
569 virtual bool oop_is_methodData() const { return false; }
570 virtual bool oop_is_constantPool() const { return false; }
571 virtual bool oop_is_constantPoolCache() const { return false; }
572 virtual bool oop_is_typeArray_slow() const { return false; }
573 virtual bool oop_is_arrayKlass() const { return false; }
574 virtual bool oop_is_objArrayKlass() const { return false; }
575 virtual bool oop_is_typeArrayKlass() const { return false; }
576 virtual bool oop_is_compiledICHolder() const { return false; }
577 virtual bool oop_is_instanceKlass() const { return false; }
578
579 bool oop_is_javaArray_slow() const {
580 return oop_is_objArray_slow() || oop_is_typeArray_slow();
581 }
582
583 // Fast non-virtual versions, used by oop.inline.hpp and elsewhere:
584 #ifndef ASSERT
585 #define assert_same_query(xval, xcheck) xval
586 #else
587 private:
588 static bool assert_same_query(bool xval, bool xslow) {
589 assert(xval == xslow, "slow and fast queries agree");
590 return xval;
591 }
592 public:
593 #endif
594 inline bool oop_is_instance() const { return assert_same_query(
595 layout_helper_is_instance(layout_helper()),
596 oop_is_instance_slow()); }
597 inline bool oop_is_javaArray() const { return assert_same_query(
598 layout_helper_is_javaArray(layout_helper()),
599 oop_is_javaArray_slow()); }
600 inline bool oop_is_objArray() const { return assert_same_query(
601 layout_helper_is_objArray(layout_helper()),
602 oop_is_objArray_slow()); }
603 inline bool oop_is_typeArray() const { return assert_same_query(
604 layout_helper_is_typeArray(layout_helper()),
605 oop_is_typeArray_slow()); }
606 #undef assert_same_query
607
608 // Unless overridden, oop is parsable if it has a klass pointer.
609 // Parsability of an object is object specific.
610 virtual bool oop_is_parsable(oop obj) const { return true; }
611
612 // Unless overridden, oop is safe for concurrent GC processing
613 // after its allocation is complete. The exception to
614 // this is the case where objects are changed after allocation.
615 // Class redefinition is one of the known exceptions. During
616 // class redefinition, an allocated class can changed in order
617 // order to create a merged class (the combiniation of the
618 // old class definition that has to be perserved and the new class
619 // definition which is being created.
620 virtual bool oop_is_conc_safe(oop obj) const { return true; }
621
622 // Access flags
623 AccessFlags access_flags() const { return _access_flags; }
624 void set_access_flags(AccessFlags flags) { _access_flags = flags; }
625
626 bool is_public() const { return _access_flags.is_public(); }
627 bool is_final() const { return _access_flags.is_final(); }
628 bool is_interface() const { return _access_flags.is_interface(); }
629 bool is_abstract() const { return _access_flags.is_abstract(); }
630 bool is_super() const { return _access_flags.is_super(); }
631 bool is_synthetic() const { return _access_flags.is_synthetic(); }
632 void set_is_synthetic() { _access_flags.set_is_synthetic(); }
633 bool has_finalizer() const { return _access_flags.has_finalizer(); }
634 bool has_final_method() const { return _access_flags.has_final_method(); }
635 void set_has_finalizer() { _access_flags.set_has_finalizer(); }
636 void set_has_final_method() { _access_flags.set_has_final_method(); }
637 bool is_cloneable() const { return _access_flags.is_cloneable(); }
638 void set_is_cloneable() { _access_flags.set_is_cloneable(); }
639 bool has_vanilla_constructor() const { return _access_flags.has_vanilla_constructor(); }
640 void set_has_vanilla_constructor() { _access_flags.set_has_vanilla_constructor(); }
641 bool has_miranda_methods () const { return access_flags().has_miranda_methods(); }
642 void set_has_miranda_methods() { _access_flags.set_has_miranda_methods(); }
643
644 // Biased locking support
645 // Note: the prototype header is always set up to be at least the
646 // prototype markOop. If biased locking is enabled it may further be
647 // biasable and have an epoch.
648 markOop prototype_header() const { return _prototype_header; }
649 // NOTE: once instances of this klass are floating around in the
650 // system, this header must only be updated at a safepoint.
651 // NOTE 2: currently we only ever set the prototype header to the
652 // biasable prototype for instanceKlasses. There is no technical
653 // reason why it could not be done for arrayKlasses aside from
654 // wanting to reduce the initial scope of this optimization. There
655 // are potential problems in setting the bias pattern for
656 // JVM-internal oops.
657 inline void set_prototype_header(markOop header);
658 static int prototype_header_offset_in_bytes() { return offset_of(Klass, _prototype_header); }
659
660 int biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
661 // Atomically increments biased_lock_revocation_count and returns updated value
662 int atomic_incr_biased_lock_revocation_count();
663 void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
664 jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
665 void set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
666
667
668 // garbage collection support
669 virtual void follow_weak_klass_links(
670 BoolObjectClosure* is_alive, OopClosure* keep_alive);
671
672 // Prefetch within oop iterators. This is a macro because we
673 // can't guarantee that the compiler will inline it. In 64-bit
674 // it generally doesn't. Signature is
675 //
676 // static void prefetch_beyond(oop* const start,
677 // oop* const end,
678 // const intx foffset,
679 // const Prefetch::style pstyle);
680 #define prefetch_beyond(start, end, foffset, pstyle) { \
681 const intx foffset_ = (foffset); \
682 const Prefetch::style pstyle_ = (pstyle); \
683 assert(foffset_ > 0, "prefetch beyond, not behind"); \
684 if (pstyle_ != Prefetch::do_none) { \
685 oop* ref = (start); \
686 if (ref < (end)) { \
687 switch (pstyle_) { \
688 case Prefetch::do_read: \
689 Prefetch::read(*ref, foffset_); \
690 break; \
691 case Prefetch::do_write: \
692 Prefetch::write(*ref, foffset_); \
693 break; \
694 default: \
695 ShouldNotReachHere(); \
696 break; \
697 } \
698 } \
699 } \
700 }
701
702 // iterators
703 virtual int oop_oop_iterate(oop obj, OopClosure* blk) = 0;
704 virtual int oop_oop_iterate_v(oop obj, OopClosure* blk) {
705 return oop_oop_iterate(obj, blk);
706 }
707
708 #ifndef SERIALGC
709 // In case we don't have a specialized backward scanner use forward
710 // iteration.
711 virtual int oop_oop_iterate_backwards_v(oop obj, OopClosure* blk) {
712 return oop_oop_iterate_v(obj, blk);
713 }
714 #endif // !SERIALGC
715
716 // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
717 // (I don't see why the _m should be required, but without it the Solaris
718 // C++ gives warning messages about overridings of the "oop_oop_iterate"
719 // defined above "hiding" this virtual function. (DLD, 6/20/00)) */
720 virtual int oop_oop_iterate_m(oop obj, OopClosure* blk, MemRegion mr) = 0;
721 virtual int oop_oop_iterate_v_m(oop obj, OopClosure* blk, MemRegion mr) {
722 return oop_oop_iterate_m(obj, blk, mr);
723 }
724
725 // Versions of the above iterators specialized to particular subtypes
726 // of OopClosure, to avoid closure virtual calls.
727 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \
728 virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) { \
729 /* Default implementation reverts to general version. */ \
730 return oop_oop_iterate(obj, blk); \
731 } \
732 \
733 /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
734 (I don't see why the _m should be required, but without it the Solaris \
735 C++ gives warning messages about overridings of the "oop_oop_iterate" \
736 defined above "hiding" this virtual function. (DLD, 6/20/00)) */ \
737 virtual int oop_oop_iterate##nv_suffix##_m(oop obj, \
738 OopClosureType* blk, \
739 MemRegion mr) { \
740 return oop_oop_iterate_m(obj, blk, mr); \
741 }
742
743 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
744 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
745
746 #ifndef SERIALGC
747 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
748 virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, \
749 OopClosureType* blk) { \
750 /* Default implementation reverts to general version. */ \
751 return oop_oop_iterate_backwards_v(obj, blk); \
752 }
753
754 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
755 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
756 #endif // !SERIALGC
757
758 virtual void array_klasses_do(void f(klassOop k)) {}
759 virtual void with_array_klasses_do(void f(klassOop k));
760
761 // Return self, except for abstract classes with exactly 1
762 // implementor. Then return the 1 concrete implementation.
763 Klass *up_cast_abstract();
764
765 // klass name
766 symbolOop name() const { return _name; }
767 void set_name(symbolOop n) { oop_store_without_check((oop*) &_name, (oop) n); }
768
769 friend class klassKlass;
770
771 public:
772 // jvm support
773 virtual jint compute_modifier_flags(TRAPS) const;
774
775 // JVMTI support
776 virtual jint jvmti_class_status() const;
777
778 // Printing
779 virtual void oop_print_value_on(oop obj, outputStream* st);
780 virtual void oop_print_on (oop obj, outputStream* st);
781
782 // Verification
783 virtual const char* internal_name() const = 0;
784 virtual void oop_verify_on(oop obj, outputStream* st);
785 virtual void oop_verify_old_oop(oop obj, oop* p, bool allow_dirty);
786 virtual void oop_verify_old_oop(oop obj, narrowOop* p, bool allow_dirty);
787 // tells whether obj is partially constructed (gc during class loading)
788 virtual bool oop_partially_loaded(oop obj) const { return false; }
789 virtual void oop_set_partially_loaded(oop obj) {};
790
791 #ifndef PRODUCT
792 void verify_vtable_index(int index);
793 #endif
794 };