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