1 /*
2 * Copyright (c) 1997, 2018, 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.
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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_OOP_HPP
26 #define SHARE_VM_OOPS_OOP_HPP
27
28 #include "memory/iterator.hpp"
29 #include "memory/memRegion.hpp"
30 #include "oops/access.hpp"
31 #include "oops/metadata.hpp"
32 #include "runtime/atomic.hpp"
33 #include "utilities/macros.hpp"
34
35 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
36 // the format of Java objects so the fields can be accessed from C++.
37 // oopDesc is abstract.
38 // (see oopHierarchy for complete oop class hierarchy)
39 //
40 // no virtual functions allowed
41
42 extern bool always_do_update_barrier;
43
44 // Forward declarations.
45 class OopClosure;
46 class ScanClosure;
47 class FastScanClosure;
48 class FilteringClosure;
49 class CMSIsAliveClosure;
50
51 class PSPromotionManager;
52 class ParCompactionManager;
53
54 class oopDesc {
55 friend class VMStructs;
56 friend class JVMCIVMStructs;
57 private:
58 volatile markOop _mark;
59 union _metadata {
60 Klass* _klass;
61 narrowKlass _compressed_klass;
62 } _metadata;
63
64 public:
65 inline markOop mark() const;
66 inline markOop mark_raw() const;
67 inline markOop* mark_addr_raw() const;
68
69 inline void set_mark(volatile markOop m);
70 inline void set_mark_raw(volatile markOop m);
71 static inline void set_mark_raw(HeapWord* mem, markOop m);
72
73 inline void release_set_mark(markOop m);
74 inline markOop cas_set_mark(markOop new_mark, markOop old_mark);
75 inline markOop cas_set_mark_raw(markOop new_mark, markOop old_mark, atomic_memory_order order = memory_order_conservative);
76
77 // Used only to re-initialize the mark word (e.g., of promoted
78 // objects during a GC) -- requires a valid klass pointer
79 inline void init_mark();
80 inline void init_mark_raw();
81
82 inline Klass* klass() const;
83 inline Klass* klass_or_null() const volatile;
84 inline Klass* klass_or_null_acquire() const volatile;
85 static inline Klass** klass_addr(HeapWord* mem);
86 static inline narrowKlass* compressed_klass_addr(HeapWord* mem);
87 inline Klass** klass_addr();
88 inline narrowKlass* compressed_klass_addr();
89
90 inline void set_klass(Klass* k);
91 static inline void release_set_klass(HeapWord* mem, Klass* klass);
92
93 // For klass field compression
94 inline int klass_gap() const;
95 inline void set_klass_gap(int z);
96 static inline void set_klass_gap(HeapWord* mem, int z);
97 // For when the klass pointer is being used as a linked list "next" field.
98 inline void set_klass_to_list_ptr(oop k);
99 inline oop list_ptr_from_klass();
100
101 // size of object header, aligned to platform wordSize
102 static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
103
104 // Returns whether this is an instance of k or an instance of a subclass of k
105 inline bool is_a(Klass* k) const;
106
107 // Returns the actual oop size of the object
108 inline int size();
109
110 // Sometimes (for complicated concurrency-related reasons), it is useful
111 // to be able to figure out the size of an object knowing its klass.
112 inline int size_given_klass(Klass* klass);
113
114 // type test operations (inlined in oop.inline.hpp)
115 inline bool is_instance() const;
116 inline bool is_array() const;
117 inline bool is_objArray() const;
118 inline bool is_typeArray() const;
119
120 // type test operations that don't require inclusion of oop.inline.hpp.
121 bool is_instance_noinline() const;
122 bool is_array_noinline() const;
123 bool is_objArray_noinline() const;
124 bool is_typeArray_noinline() const;
125
126 protected:
127 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
128
129 public:
130 // field addresses in oop
131 inline void* field_addr(int offset) const;
132 inline void* field_addr_raw(int offset) const;
133
134 // Need this as public for garbage collection.
135 template <class T> inline T* obj_field_addr_raw(int offset) const;
136
137 template <typename T> inline size_t field_offset(T* p) const;
138
139 // Standard compare function returns negative value if o1 < o2
140 // 0 if o1 == o2
141 // positive value if o1 > o2
142 inline static int compare(oop o1, oop o2) {
143 void* o1_addr = (void*)o1;
144 void* o2_addr = (void*)o2;
145 if (o1_addr < o2_addr) {
146 return -1;
147 } else if (o1_addr > o2_addr) {
148 return 1;
149 } else {
150 return 0;
151 }
152 }
153
154 inline static bool equals(oop o1, oop o2) { return Access<>::equals(o1, o2); }
155
156 inline static bool unsafe_equals(oop o1, oop o2) {
157 #ifdef CHECK_UNHANDLED_OOPS
158 return o1.obj() == o2.obj();
159 #else
160 return o1 == o2;
161 #endif
162 }
163
164 // Access to fields in a instanceOop through these methods.
165 template <DecoratorSet decorator>
166 oop obj_field_access(int offset) const;
167 oop obj_field(int offset) const;
168 void obj_field_put(int offset, oop value);
169 void obj_field_put_raw(int offset, oop value);
170 void obj_field_put_volatile(int offset, oop value);
171
172 Metadata* metadata_field(int offset) const;
173 void metadata_field_put(int offset, Metadata* value);
174
175 Metadata* metadata_field_acquire(int offset) const;
176 void release_metadata_field_put(int offset, Metadata* value);
177
178 jbyte byte_field(int offset) const;
179 void byte_field_put(int offset, jbyte contents);
180
181 jchar char_field(int offset) const;
182 void char_field_put(int offset, jchar contents);
183
184 jboolean bool_field(int offset) const;
185 void bool_field_put(int offset, jboolean contents);
186
187 jint int_field(int offset) const;
188 jint int_field_raw(int offset) const;
189 void int_field_put(int offset, jint contents);
190
191 jshort short_field(int offset) const;
192 void short_field_put(int offset, jshort contents);
193
194 jlong long_field(int offset) const;
195 void long_field_put(int offset, jlong contents);
196
197 jfloat float_field(int offset) const;
198 void float_field_put(int offset, jfloat contents);
199
200 jdouble double_field(int offset) const;
201 void double_field_put(int offset, jdouble contents);
202
203 address address_field(int offset) const;
204 void address_field_put(int offset, address contents);
205
206 oop obj_field_acquire(int offset) const;
207 void release_obj_field_put(int offset, oop value);
208
209 jbyte byte_field_acquire(int offset) const;
210 void release_byte_field_put(int offset, jbyte contents);
211
212 jchar char_field_acquire(int offset) const;
213 void release_char_field_put(int offset, jchar contents);
214
215 jboolean bool_field_acquire(int offset) const;
216 void release_bool_field_put(int offset, jboolean contents);
217
218 jint int_field_acquire(int offset) const;
219 void release_int_field_put(int offset, jint contents);
220
221 jshort short_field_acquire(int offset) const;
222 void release_short_field_put(int offset, jshort contents);
223
224 jlong long_field_acquire(int offset) const;
225 void release_long_field_put(int offset, jlong contents);
226
227 jfloat float_field_acquire(int offset) const;
228 void release_float_field_put(int offset, jfloat contents);
229
230 jdouble double_field_acquire(int offset) const;
231 void release_double_field_put(int offset, jdouble contents);
232
233 address address_field_acquire(int offset) const;
234 void release_address_field_put(int offset, address contents);
235
236 // printing functions for VM debugging
237 void print_on(outputStream* st) const; // First level print
238 void print_value_on(outputStream* st) const; // Second level print.
239 void print_address_on(outputStream* st) const; // Address printing
240
241 // printing on default output stream
242 void print();
243 void print_value();
244 void print_address();
245
246 // return the print strings
247 char* print_string();
248 char* print_value_string();
249
250 // verification operations
251 void verify_on(outputStream* st);
252 void verify();
253
254 // locking operations
255 inline bool is_locked() const;
256 inline bool is_unlocked() const;
257 inline bool has_bias_pattern() const;
258 inline bool has_bias_pattern_raw() const;
259
260 // asserts and guarantees
261 static bool is_oop(oop obj, bool ignore_mark_word = false);
262 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
263 #ifndef PRODUCT
264 inline bool is_unlocked_oop() const;
265 #endif
266
267 // garbage collection
268 inline bool is_gc_marked() const;
269
270 // Forward pointer operations for scavenge
271 inline bool is_forwarded() const;
272
273 inline void forward_to(oop p);
274 inline bool cas_forward_to(oop p, markOop compare, atomic_memory_order order = memory_order_conservative);
275
276 // Like "forward_to", but inserts the forwarding pointer atomically.
277 // Exactly one thread succeeds in inserting the forwarding pointer, and
278 // this call returns "NULL" for that thread; any other thread has the
279 // value of the forwarding pointer returned and does not modify "this".
280 inline oop forward_to_atomic(oop p, atomic_memory_order order = memory_order_conservative);
281
282 inline oop forwardee() const;
283 inline oop forwardee_acquire() const;
284
285 // Age of object during scavenge
286 inline uint age() const;
287 inline void incr_age();
288
289 // mark-sweep support
290 void follow_body(int begin, int end);
291
292 // Garbage Collection support
293
294 #if INCLUDE_PARALLELGC
295 // Parallel Compact
296 inline void pc_follow_contents(ParCompactionManager* cm);
297 inline void pc_update_contents(ParCompactionManager* cm);
298 // Parallel Scavenge
299 inline void ps_push_contents(PSPromotionManager* pm);
300 #endif
301
302 template <typename OopClosureType>
303 inline void oop_iterate(OopClosureType* cl);
304
305 template <typename OopClosureType>
306 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
307
308 template <typename OopClosureType>
309 inline int oop_iterate_size(OopClosureType* cl);
310
311 template <typename OopClosureType>
312 inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
313
314 template <typename OopClosureType>
315 inline void oop_iterate_backwards(OopClosureType* cl);
316
317 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
318
319 // identity hash; returns the identity hash key (computes it if necessary)
320 // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
321 // safepoint if called on a biased object. Calling code must be aware of that.
322 inline intptr_t identity_hash();
323 intptr_t slow_identity_hash();
324
325 // Alternate hashing code if string table is rehashed
326 unsigned int new_hash(juint seed);
327
328 // marks are forwarded to stack when object is locked
329 inline bool has_displaced_mark_raw() const;
330 inline markOop displaced_mark_raw() const;
331 inline void set_displaced_mark_raw(markOop m);
332
333 static bool has_klass_gap();
334
335 // for code generation
336 static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
337 static int klass_offset_in_bytes() { return offset_of(oopDesc, _metadata._klass); }
338 static int klass_gap_offset_in_bytes() {
339 assert(has_klass_gap(), "only applicable to compressed klass pointers");
340 return klass_offset_in_bytes() + sizeof(narrowKlass);
341 }
342 };
343
344 #endif // SHARE_VM_OOPS_OOP_HPP