1 /*
2 * Copyright (c) 1997, 2019, 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.
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23 */
24
25 #ifndef SHARE_OOPS_OOP_HPP
26 #define SHARE_OOPS_OOP_HPP
27
28 #include "memory/iterator.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/access.hpp"
31 #include "oops/arrayStorageProperties.hpp"
32 #include "oops/metadata.hpp"
33 #include "runtime/atomic.hpp"
34 #include "utilities/macros.hpp"
35
36 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
37 // the format of Java objects so the fields can be accessed from C++.
38 // oopDesc is abstract.
39 // (see oopHierarchy for complete oop class hierarchy)
40 //
41 // no virtual functions allowed
42 //
43 // oopDesc::_mark - the "oop mark word" encoding to be found separately in markOop.hpp
44 //
45 // oopDesc::_metadata - encodes both the object's klass pointer and potentially
46 // "storage properties" (currently confined to arrays in the form of
47 // ArrayStorageProperties). Storage properties are peculiar to the
48 // *instance*, and not necessarily the "type".
49 //
50 // The overall size of the _metadata field is dependent on "UseCompressedClassPointers",
51 // hence the terms "narrow" (32 bits) vs "wide" (64 bits).
52 //
53 // "Wide" encoding of _metadata:
54 // bit number |63 0|
55 // bit length |--3|-----61-----|
56 // --------------------------------------
57 // _klass [xxx| Klass* ]
58 // _wide_storage_props [ sp| ]
59 // --------------------------------------
60 // with:
61 // xxx = klass_mask(), Klass* = Klass pointer to be masked
62 // sp = storage properties, bit number: wide_storage_props_shift
63 //
64 // "Narrow" encoding of _metadata:
65 // bit number |31 0|
66 // bit length |--3|-----29-----|
67 // ----------------------------------------
68 // _compressed_klass [xxx| narrowKlass]
69 // _narrow_storage_props [ sp| ]
70 // ----------------------------------------
71 // with:
72 // xxx = compressed_klass_mask(), narrowKlass = compressed Klass pointer to be masked
73 // narrowKlass may be further decoded (Klass::decode_klass()) to produce Klass*
74 // sp = storage properties, bit number: narrow_storage_props_shift
75 //
76 // Storage properties encodings are current confined to arrayStorageProperties.hpp
77
78
79 extern bool always_do_update_barrier;
80
81 // Forward declarations.
82 class OopClosure;
83 class ScanClosure;
84 class FastScanClosure;
85 class FilteringClosure;
86 class CMSIsAliveClosure;
87
88 class PSPromotionManager;
89 class ParCompactionManager;
90
91 class oopDesc {
92 friend class VMStructs;
93 friend class JVMCIVMStructs;
94 private:
95 volatile markOop _mark;
96 union _metadata {
97 Klass* _klass;
98 narrowKlass _compressed_klass;
99 uintptr_t _wide_storage_props;
100 uint32_t _narrow_storage_props;
101 } _metadata;
102
103 public:
104 inline markOop mark() const;
105 inline markOop mark_raw() const;
106 inline markOop* mark_addr_raw() const;
107
108 inline void set_mark(volatile markOop m);
109 inline void set_mark_raw(volatile markOop m);
110 static inline void set_mark_raw(HeapWord* mem, markOop m);
111
112 inline void release_set_mark(markOop m);
113 inline markOop cas_set_mark(markOop new_mark, markOop old_mark);
114 inline markOop cas_set_mark_raw(markOop new_mark, markOop old_mark, atomic_memory_order order = memory_order_conservative);
115
116 // Used only to re-initialize the mark word (e.g., of promoted
117 // objects during a GC) -- requires a valid klass pointer
118 inline void init_mark();
119 inline void init_mark_raw();
120
121 enum {
122 storage_props_nof_bits = LogKlassAlignmentInBytes, // This alignment gives us some "free bits"
123 narrow_storage_props_shift = (sizeof(narrowKlass) << 3) - storage_props_nof_bits,
124 wide_storage_props_shift = (sizeof(Klass*) << 3) - storage_props_nof_bits,
125 };
126
127 static inline narrowKlass compressed_klass_mask();
128 static inline narrowKlass compressed_klass_masked(narrowKlass raw);
129 static inline uintptr_t klass_mask();
130 static inline Klass* klass_masked(uintptr_t raw);
131
132 inline Klass* klass() const;
133 inline Klass* klass_or_null() const volatile;
134 inline Klass* klass_or_null_acquire() const volatile;
135 static inline Klass** klass_addr(HeapWord* mem);
136 static inline narrowKlass* compressed_klass_addr(HeapWord* mem);
137 inline Klass** klass_addr();
138 inline narrowKlass* compressed_klass_addr();
139
140 inline void set_klass(Klass* k);
141 static inline void release_set_klass(HeapWord* mem, Klass* klass);
142
143 // Extra container metadata specific to arrays (encoded into high bits of _metadata)
144 static inline uintptr_t* wide_metadata_addr(HeapWord* mem);
145 inline ArrayStorageProperties array_storage_properties() const;
146 inline void set_metadata(ArrayStorageProperties storage_props, Klass* k);
147 static inline void release_set_metadata(HeapWord* mem, ArrayStorageProperties storage_props, Klass* klass);
148
149
150 // For klass field compression
151 inline int klass_gap() const;
152 inline void set_klass_gap(int z);
153 static inline void set_klass_gap(HeapWord* mem, int z);
154 // For when the klass pointer is being used as a linked list "next" field.
155 inline void set_klass_to_list_ptr(oop k);
156 inline oop list_ptr_from_klass();
157
158 // size of object header, aligned to platform wordSize
159 static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
160
161 // Returns whether this is an instance of k or an instance of a subclass of k
162 inline bool is_a(Klass* k) const;
163
164 // Returns the actual oop size of the object
165 inline int size();
166
167 // Sometimes (for complicated concurrency-related reasons), it is useful
168 // to be able to figure out the size of an object knowing its klass.
169 inline int size_given_klass(Klass* klass);
170
171 // type test operations (inlined in oop.inline.hpp)
172 inline bool is_instance() const;
173 inline bool is_array() const;
174 inline bool is_objArray() const;
175 inline bool is_typeArray() const;
176 inline bool is_value() const;
177 inline bool is_valueArray() const;
178
179 // type test operations that don't require inclusion of oop.inline.hpp.
180 bool is_instance_noinline() const;
181 bool is_array_noinline() const;
182 bool is_objArray_noinline() const;
183 bool is_typeArray_noinline() const;
184 bool is_value_noinline() const;
185 bool is_valueArray_noinline() const;
186
187 protected:
188 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
189
190 public:
191 // field addresses in oop
192 inline void* field_addr(int offset) const;
193 inline void* field_addr_raw(int offset) const;
194
195 // Need this as public for garbage collection.
196 template <class T> inline T* obj_field_addr_raw(int offset) const;
197
198 template <typename T> inline size_t field_offset(T* p) const;
199
200 // Standard compare function returns negative value if o1 < o2
201 // 0 if o1 == o2
202 // positive value if o1 > o2
203 inline static int compare(oop o1, oop o2) {
204 void* o1_addr = (void*)o1;
205 void* o2_addr = (void*)o2;
206 if (o1_addr < o2_addr) {
207 return -1;
208 } else if (o1_addr > o2_addr) {
209 return 1;
210 } else {
211 return 0;
212 }
213 }
214
215 inline static bool equals(oop o1, oop o2) { return Access<>::equals(o1, o2); }
216
217 inline static bool equals_raw(oop o1, oop o2) { return RawAccess<>::equals(o1, o2); }
218
219 // Access to fields in a instanceOop through these methods.
220 template <DecoratorSet decorator>
221 oop obj_field_access(int offset) const;
222 oop obj_field(int offset) const;
223 void obj_field_put(int offset, oop value);
224 void obj_field_put_raw(int offset, oop value);
225 void obj_field_put_volatile(int offset, oop value);
226
227 Metadata* metadata_field(int offset) const;
228 Metadata* metadata_field_raw(int offset) const;
229 void metadata_field_put(int offset, Metadata* value);
230
231 Metadata* metadata_field_acquire(int offset) const;
232 void release_metadata_field_put(int offset, Metadata* value);
233
234 jbyte byte_field(int offset) const;
235 void byte_field_put(int offset, jbyte contents);
236
237 jchar char_field(int offset) const;
238 void char_field_put(int offset, jchar contents);
239
240 jboolean bool_field(int offset) const;
241 void bool_field_put(int offset, jboolean contents);
242
243 jint int_field(int offset) const;
244 jint int_field_raw(int offset) const;
245 void int_field_put(int offset, jint contents);
246
247 jshort short_field(int offset) const;
248 void short_field_put(int offset, jshort contents);
249
250 jlong long_field(int offset) const;
251 void long_field_put(int offset, jlong contents);
252
253 jfloat float_field(int offset) const;
254 void float_field_put(int offset, jfloat contents);
255
256 jdouble double_field(int offset) const;
257 void double_field_put(int offset, jdouble contents);
258
259 address address_field(int offset) const;
260 void address_field_put(int offset, address contents);
261
262 oop obj_field_acquire(int offset) const;
263 void release_obj_field_put(int offset, oop value);
264
265 jbyte byte_field_acquire(int offset) const;
266 void release_byte_field_put(int offset, jbyte contents);
267
268 jchar char_field_acquire(int offset) const;
269 void release_char_field_put(int offset, jchar contents);
270
271 jboolean bool_field_acquire(int offset) const;
272 void release_bool_field_put(int offset, jboolean contents);
273
274 jint int_field_acquire(int offset) const;
275 void release_int_field_put(int offset, jint contents);
276
277 jshort short_field_acquire(int offset) const;
278 void release_short_field_put(int offset, jshort contents);
279
280 jlong long_field_acquire(int offset) const;
281 void release_long_field_put(int offset, jlong contents);
282
283 jfloat float_field_acquire(int offset) const;
284 void release_float_field_put(int offset, jfloat contents);
285
286 jdouble double_field_acquire(int offset) const;
287 void release_double_field_put(int offset, jdouble contents);
288
289 address address_field_acquire(int offset) const;
290 void release_address_field_put(int offset, address contents);
291
292 // printing functions for VM debugging
293 void print_on(outputStream* st) const; // First level print
294 void print_value_on(outputStream* st) const; // Second level print.
295 void print_address_on(outputStream* st) const; // Address printing
296
297 // printing on default output stream
298 void print();
299 void print_value();
300 void print_address();
301
302 // return the print strings
303 char* print_string();
304 char* print_value_string();
305
306 // verification operations
307 static void verify_on(outputStream* st, oopDesc* oop_desc);
308 static void verify(oopDesc* oopDesc);
309
310 // locking operations
311 inline bool is_locked() const;
312 inline bool is_unlocked() const;
313 inline bool has_bias_pattern() const;
314 inline bool has_bias_pattern_raw() const;
315
316 // asserts and guarantees
317 static bool is_oop(oop obj, bool ignore_mark_word = false);
318 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
319 #ifndef PRODUCT
320 inline bool is_unlocked_oop() const;
321 static bool is_archived_object(oop p) NOT_CDS_JAVA_HEAP_RETURN_(false);
322 #endif
323
324 // garbage collection
325 inline bool is_gc_marked() const;
326
327 // Forward pointer operations for scavenge
328 inline bool is_forwarded() const;
329
330 inline void forward_to(oop p);
331 inline bool cas_forward_to(oop p, markOop compare, atomic_memory_order order = memory_order_conservative);
332
333 // Like "forward_to", but inserts the forwarding pointer atomically.
334 // Exactly one thread succeeds in inserting the forwarding pointer, and
335 // this call returns "NULL" for that thread; any other thread has the
336 // value of the forwarding pointer returned and does not modify "this".
337 inline oop forward_to_atomic(oop p, markOop compare, atomic_memory_order order = memory_order_conservative);
338
339 inline oop forwardee() const;
340 inline oop forwardee_acquire() const;
341
342 // Age of object during scavenge
343 inline uint age() const;
344 inline void incr_age();
345
346 // mark-sweep support
347 void follow_body(int begin, int end);
348
349 template <typename OopClosureType>
350 inline void oop_iterate(OopClosureType* cl);
351
352 template <typename OopClosureType>
353 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
354
355 template <typename OopClosureType>
356 inline int oop_iterate_size(OopClosureType* cl);
357
358 template <typename OopClosureType>
359 inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
360
361 template <typename OopClosureType>
362 inline void oop_iterate_backwards(OopClosureType* cl);
363
364 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
365
366 // identity hash; returns the identity hash key (computes it if necessary)
367 // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
368 // safepoint if called on a biased object. Calling code must be aware of that.
369 inline intptr_t identity_hash();
370 intptr_t slow_identity_hash();
371
372 // marks are forwarded to stack when object is locked
373 inline bool has_displaced_mark_raw() const;
374 inline markOop displaced_mark_raw() const;
375 inline void set_displaced_mark_raw(markOop m);
376
377 static bool has_klass_gap();
378
379 // for code generation
380 static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
381 static int klass_offset_in_bytes() { return offset_of(oopDesc, _metadata._klass); }
382 static int klass_gap_offset_in_bytes() {
383 assert(has_klass_gap(), "only applicable to compressed klass pointers");
384 return klass_offset_in_bytes() + sizeof(narrowKlass);
385 }
386
387 // for error reporting
388 static oop decode_oop_raw(narrowOop narrow_oop);
389 static void* load_klass_raw(oop obj);
390 static void* load_oop_raw(oop obj, int offset);
391 static bool is_valid(oop obj);
392 static oop oop_or_null(address addr);
393 };
394
395 #endif // SHARE_OOPS_OOP_HPP