1 /*
2 * Copyright (c) 1997, 2021, 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/accessDecorators.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 FilteringClosure;
46
47 class PSPromotionManager;
48 class ParCompactionManager;
49
50 class oopDesc {
51 friend class VMStructs;
52 friend class JVMCIVMStructs;
53 private:
54 volatile markWord _mark;
55 union _metadata {
56 Klass* _klass;
57 narrowKlass _compressed_klass;
58 } _metadata;
59
60 public:
61 inline markWord mark() const;
62 inline markWord mark_acquire() const;
63 inline markWord* mark_addr() const;
64
65 inline void set_mark(markWord m);
66 static inline void set_mark(HeapWord* mem, markWord m);
67
68 inline void release_set_mark(markWord m);
69 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
70 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
71
72 // Used only to re-initialize the mark word (e.g., of promoted
73 // objects during a GC) -- requires a valid klass pointer
74 inline void init_mark();
75
76 inline Klass* klass() const;
77 inline Klass* klass_or_null() const;
78 inline Klass* klass_or_null_acquire() const;
79
80 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
81 inline void set_klass(Klass* k);
82 static inline void release_set_klass(HeapWord* mem, Klass* k);
83
84 // For klass field compression
85 inline int klass_gap() const;
86 inline void set_klass_gap(int z);
87 static inline void set_klass_gap(HeapWord* mem, int z);
88
89 // size of object header, aligned to platform wordSize
90 static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
91
92 // Returns whether this is an instance of k or an instance of a subclass of k
93 inline bool is_a(Klass* k) const;
94
95 // Returns the actual oop size of the object
96 inline int size();
97
98 // Sometimes (for complicated concurrency-related reasons), it is useful
99 // to be able to figure out the size of an object knowing its klass.
100 inline int size_given_klass(Klass* klass);
101
102 // type test operations (inlined in oop.inline.hpp)
103 inline bool is_instance() const;
104 inline bool is_array() const;
105 inline bool is_objArray() const;
106 inline bool is_typeArray() const;
107
108 // type test operations that don't require inclusion of oop.inline.hpp.
109 bool is_instance_noinline() const;
110 bool is_array_noinline() const;
111 bool is_objArray_noinline() const;
112 bool is_typeArray_noinline() const;
113
114 protected:
115 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
116
117 public:
118 // field addresses in oop
119 inline void* field_addr(int offset) const;
120
121 // Need this as public for garbage collection.
122 template <class T> inline T* obj_field_addr(int offset) const;
123
124 template <typename T> inline size_t field_offset(T* p) const;
125
126 // Standard compare function returns negative value if o1 < o2
127 // 0 if o1 == o2
128 // positive value if o1 > o2
129 inline static int compare(oop o1, oop o2) {
130 void* o1_addr = (void*)o1;
131 void* o2_addr = (void*)o2;
132 if (o1_addr < o2_addr) {
133 return -1;
134 } else if (o1_addr > o2_addr) {
135 return 1;
136 } else {
137 return 0;
138 }
139 }
140
141 // Access to fields in a instanceOop through these methods.
142 template <DecoratorSet decorator>
143 oop obj_field_access(int offset) const;
144 oop obj_field(int offset) const;
145 void obj_field_put(int offset, oop value);
146 void obj_field_put_raw(int offset, oop value);
147 void obj_field_put_volatile(int offset, oop value);
148
149 Metadata* metadata_field(int offset) const;
150 Metadata* metadata_field_raw(int offset) const;
151 void metadata_field_put(int offset, Metadata* value);
152
153 Metadata* metadata_field_acquire(int offset) const;
154 void release_metadata_field_put(int offset, Metadata* value);
155
156 jbyte byte_field(int offset) const;
157 void byte_field_put(int offset, jbyte contents);
158
159 jchar char_field(int offset) const;
160 void char_field_put(int offset, jchar contents);
161
162 jboolean bool_field(int offset) const;
163 void bool_field_put(int offset, jboolean contents);
164 jboolean bool_field_volatile(int offset) const;
165 void bool_field_put_volatile(int offset, jboolean contents);
166
167 jint int_field(int offset) const;
168 jint int_field_raw(int offset) const;
169 void int_field_put(int offset, jint contents);
170
171 jshort short_field(int offset) const;
172 void short_field_put(int offset, jshort contents);
173
174 jlong long_field(int offset) const;
175 void long_field_put(int offset, jlong contents);
176
177 jfloat float_field(int offset) const;
178 void float_field_put(int offset, jfloat contents);
179
180 jdouble double_field(int offset) const;
181 void double_field_put(int offset, jdouble contents);
182
183 address address_field(int offset) const;
184 void address_field_put(int offset, address contents);
185
186 oop obj_field_acquire(int offset) const;
187 void release_obj_field_put(int offset, oop value);
188
189 jbyte byte_field_acquire(int offset) const;
190 void release_byte_field_put(int offset, jbyte contents);
191
192 jchar char_field_acquire(int offset) const;
193 void release_char_field_put(int offset, jchar contents);
194
195 jboolean bool_field_acquire(int offset) const;
196 void release_bool_field_put(int offset, jboolean contents);
197
198 jint int_field_acquire(int offset) const;
199 void release_int_field_put(int offset, jint contents);
200
201 jshort short_field_acquire(int offset) const;
202 void release_short_field_put(int offset, jshort contents);
203
204 jlong long_field_acquire(int offset) const;
205 void release_long_field_put(int offset, jlong contents);
206
207 jfloat float_field_acquire(int offset) const;
208 void release_float_field_put(int offset, jfloat contents);
209
210 jdouble double_field_acquire(int offset) const;
211 void release_double_field_put(int offset, jdouble contents);
212
213 address address_field_acquire(int offset) const;
214 void release_address_field_put(int offset, address contents);
215
216 // printing functions for VM debugging
217 void print_on(outputStream* st) const; // First level print
218 void print_value_on(outputStream* st) const; // Second level print.
219 void print_address_on(outputStream* st) const; // Address printing
220
221 // printing on default output stream
222 void print();
223 void print_value();
224 void print_address();
225
226 // return the print strings
227 char* print_string();
228 char* print_value_string();
229
230 // verification operations
231 static void verify_on(outputStream* st, oopDesc* oop_desc);
232 static void verify(oopDesc* oopDesc);
233
234 // locking operations
235 inline bool is_locked() const;
236 inline bool is_unlocked() const;
237 inline bool has_bias_pattern() const;
238
239 // asserts and guarantees
240 static bool is_oop(oop obj, bool ignore_mark_word = false);
241 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
242
243 // garbage collection
244 inline bool is_gc_marked() const;
245
246 // Forward pointer operations for scavenge
247 inline bool is_forwarded() const;
248
249 void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
250
251 inline void forward_to(oop p);
252 inline bool cas_forward_to(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
253
254 // Like "forward_to", but inserts the forwarding pointer atomically.
255 // Exactly one thread succeeds in inserting the forwarding pointer, and
256 // this call returns "NULL" for that thread; any other thread has the
257 // value of the forwarding pointer returned and does not modify "this".
258 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
259
260 inline oop forwardee() const;
261
262 // Age of object during scavenge
263 inline uint age() const;
264 inline void incr_age();
265
266 template <typename OopClosureType>
267 inline void oop_iterate(OopClosureType* cl);
268
269 template <typename OopClosureType>
270 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
271
272 template <typename OopClosureType>
273 inline int oop_iterate_size(OopClosureType* cl);
274
275 template <typename OopClosureType>
276 inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
277
278 template <typename OopClosureType>
279 inline void oop_iterate_backwards(OopClosureType* cl);
280
281 template <typename OopClosureType>
282 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
283
284 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
285
286 // identity hash; returns the identity hash key (computes it if necessary)
287 // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
288 // safepoint if called on a biased object. Calling code must be aware of that.
289 inline intptr_t identity_hash();
290 intptr_t slow_identity_hash();
291
292 // marks are forwarded to stack when object is locked
293 inline bool has_displaced_mark() const;
294 inline markWord displaced_mark() const;
295 inline void set_displaced_mark(markWord m);
296
297 // Checks if the mark word needs to be preserved
298 inline bool mark_must_be_preserved() const;
299 inline bool mark_must_be_preserved(markWord m) const;
300 inline bool mark_must_be_preserved_for_promotion_failure(markWord m) const;
301
302 static bool has_klass_gap();
303
304 // for code generation
305 static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
306 static int klass_offset_in_bytes() { return offset_of(oopDesc, _metadata._klass); }
307 static int klass_gap_offset_in_bytes() {
308 assert(has_klass_gap(), "only applicable to compressed klass pointers");
309 return klass_offset_in_bytes() + sizeof(narrowKlass);
310 }
311
312 // for error reporting
313 static void* load_klass_raw(oop obj);
314 static void* load_oop_raw(oop obj, int offset);
315
316 // Avoid include gc_globals.hpp in oop.inline.hpp
317 DEBUG_ONLY(bool get_UseParallelGC();)
318 DEBUG_ONLY(bool get_UseG1GC();)
319 };
320
321 #endif // SHARE_OOPS_OOP_HPP