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