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 static inline void release_set_mark(HeapWord* mem, markWord m);
70 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
71 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
72
73 inline markWord resolve_mark() const;
74
75 // Used only to re-initialize the mark word (e.g., of promoted
76 // objects during a GC) -- requires a valid klass pointer
77 inline void init_mark();
78
79 inline Klass* klass() const;
80 inline Klass* klass_or_null() const;
81 inline Klass* klass_or_null_acquire() const;
82
83 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
84 inline void set_klass(Klass* k);
85 static inline void release_set_klass(HeapWord* mem, Klass* k);
86
87 // For klass field compression
88 static inline void set_klass_gap(HeapWord* mem, int z);
89
90 // size of object header, aligned to platform wordSize
91 static int header_size() {
92 #ifdef _LP64
93 if (UseCompactObjectHeaders) {
94 return sizeof(markWord) / HeapWordSize;
95 } else
96 #endif
97 return sizeof(oopDesc)/HeapWordSize;
98 }
99
100 // Returns whether this is an instance of k or an instance of a subclass of k
101 inline bool is_a(Klass* k) const;
102
103 // Returns the actual oop size of the object
104 inline int size();
105
106 // Sometimes (for complicated concurrency-related reasons), it is useful
107 // to be able to figure out the size of an object knowing its klass.
108 inline int size_given_klass(Klass* klass);
109
110 // type test operations (inlined in oop.inline.hpp)
111 inline bool is_instance() const;
112 inline bool is_array() const;
113 inline bool is_objArray() const;
114 inline bool is_typeArray() const;
115
116 // type test operations that don't require inclusion of oop.inline.hpp.
117 bool is_instance_noinline() const;
118 bool is_array_noinline() const;
119 bool is_objArray_noinline() const;
120 bool is_typeArray_noinline() const;
121
122 protected:
123 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
124
125 public:
126 // field addresses in oop
127 inline void* field_addr(int offset) const;
128
129 // Need this as public for garbage collection.
130 template <class T> inline T* obj_field_addr(int offset) const;
131
132 template <typename T> inline size_t field_offset(T* p) const;
133
134 // Standard compare function returns negative value if o1 < o2
135 // 0 if o1 == o2
136 // positive value if o1 > o2
137 inline static int compare(oop o1, oop o2) {
138 void* o1_addr = (void*)o1;
139 void* o2_addr = (void*)o2;
140 if (o1_addr < o2_addr) {
141 return -1;
142 } else if (o1_addr > o2_addr) {
143 return 1;
144 } else {
145 return 0;
146 }
147 }
148
149 // Access to fields in a instanceOop through these methods.
150 template <DecoratorSet decorator>
151 oop obj_field_access(int offset) const;
152 oop obj_field(int offset) const;
153 void obj_field_put(int offset, oop value);
154 void obj_field_put_raw(int offset, oop value);
155 void obj_field_put_volatile(int offset, oop value);
156
157 Metadata* metadata_field(int offset) const;
158 Metadata* metadata_field_raw(int offset) const;
159 void metadata_field_put(int offset, Metadata* value);
160
161 Metadata* metadata_field_acquire(int offset) const;
162 void release_metadata_field_put(int offset, Metadata* value);
163
164 jbyte byte_field(int offset) const;
165 void byte_field_put(int offset, jbyte contents);
166
167 jchar char_field(int offset) const;
168 void char_field_put(int offset, jchar contents);
169
170 jboolean bool_field(int offset) const;
171 void bool_field_put(int offset, jboolean contents);
172 jboolean bool_field_volatile(int offset) const;
173 void bool_field_put_volatile(int offset, jboolean contents);
174
175 jint int_field(int offset) const;
176 jint int_field_raw(int offset) const;
177 void int_field_put(int offset, jint contents);
178
179 jshort short_field(int offset) const;
180 void short_field_put(int offset, jshort contents);
181
182 jlong long_field(int offset) const;
183 void long_field_put(int offset, jlong contents);
184
185 jfloat float_field(int offset) const;
186 void float_field_put(int offset, jfloat contents);
187
188 jdouble double_field(int offset) const;
189 void double_field_put(int offset, jdouble contents);
190
191 address address_field(int offset) const;
192 void address_field_put(int offset, address contents);
193
194 oop obj_field_acquire(int offset) const;
195 void release_obj_field_put(int offset, oop value);
196
197 jbyte byte_field_acquire(int offset) const;
198 void release_byte_field_put(int offset, jbyte contents);
199
200 jchar char_field_acquire(int offset) const;
201 void release_char_field_put(int offset, jchar contents);
202
203 jboolean bool_field_acquire(int offset) const;
204 void release_bool_field_put(int offset, jboolean contents);
205
206 jint int_field_acquire(int offset) const;
207 void release_int_field_put(int offset, jint contents);
208
209 jshort short_field_acquire(int offset) const;
210 void release_short_field_put(int offset, jshort contents);
211
212 jlong long_field_acquire(int offset) const;
213 void release_long_field_put(int offset, jlong contents);
214
215 jfloat float_field_acquire(int offset) const;
216 void release_float_field_put(int offset, jfloat contents);
217
218 jdouble double_field_acquire(int offset) const;
219 void release_double_field_put(int offset, jdouble contents);
220
221 address address_field_acquire(int offset) const;
222 void release_address_field_put(int offset, address contents);
223
224 // printing functions for VM debugging
225 void print_on(outputStream* st) const; // First level print
226 void print_value_on(outputStream* st) const; // Second level print.
227 void print_address_on(outputStream* st) const; // Address printing
228
229 // printing on default output stream
230 void print();
231 void print_value();
232 void print_address();
233
234 // return the print strings
235 char* print_string();
236 char* print_value_string();
237
238 // verification operations
239 static void verify_on(outputStream* st, oopDesc* oop_desc);
240 static void verify(oopDesc* oopDesc);
241
242 // locking operations
243 inline bool is_locked() const;
244 inline bool is_unlocked() const;
245 inline bool has_bias_pattern() const;
246
247 // asserts and guarantees
248 static bool is_oop(oop obj, bool ignore_mark_word = false);
249 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
250
251 // garbage collection
252 inline bool is_gc_marked() const;
253
254 // Forward pointer operations for scavenge
255 inline bool is_forwarded() const;
256
257 void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
258
259 inline void forward_to(oop p);
260 inline bool cas_forward_to(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
261 inline void forward_to_self();
262
263 // Like "forward_to", but inserts the forwarding pointer atomically.
264 // Exactly one thread succeeds in inserting the forwarding pointer, and
265 // this call returns "NULL" for that thread; any other thread has the
266 // value of the forwarding pointer returned and does not modify "this".
267 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
268 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
269
270 inline oop forwardee() const;
271 inline oop forwardee(markWord header) const;
272
273 // Age of object during scavenge
274 inline uint age() const;
275 inline void incr_age();
276
277 template <typename OopClosureType>
278 inline void oop_iterate(OopClosureType* cl);
279
280 template <typename OopClosureType>
281 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
282
283 template <typename OopClosureType>
284 inline int oop_iterate_size(OopClosureType* cl);
285
286 template <typename OopClosureType>
287 inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
288
289 template <typename OopClosureType>
290 inline void oop_iterate_backwards(OopClosureType* cl);
291
292 template <typename OopClosureType>
293 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
294
295 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
296
297 // identity hash; returns the identity hash key (computes it if necessary)
298 // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
299 // safepoint if called on a biased object. Calling code must be aware of that.
300 inline intptr_t identity_hash();
301 intptr_t slow_identity_hash();
302
303 // marks are forwarded to stack when object is locked
304 inline bool has_displaced_mark() const;
305 inline markWord displaced_mark() const;
306 inline void set_displaced_mark(markWord m);
307
308 // Checks if the mark word needs to be preserved
309 inline bool mark_must_be_preserved() const;
310 inline bool mark_must_be_preserved(markWord m) const;
311 inline bool mark_must_be_preserved_for_promotion_failure(markWord m) const;
312
313 static bool has_klass_gap();
314
315 // for code generation
316 static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
317 static int klass_gap_offset_in_bytes() {
318 assert(has_klass_gap(), "only applicable to compressed klass pointers");
319 assert(!UseCompactObjectHeaders, "don't use klass_offset_in_bytes() with compact headers");
320 return klass_offset_in_bytes() + sizeof(narrowKlass);
321 }
322
323 static int klass_offset_in_bytes() {
324 #ifdef _LP64
325 if (UseCompactObjectHeaders) {
326 STATIC_ASSERT(markWord::klass_shift % 8 == 0);
327 return mark_offset_in_bytes() + markWord::klass_shift / 8;
328 } else
329 #endif
330 return offset_of(oopDesc, _metadata._klass);
331 }
332
333 static int base_offset_in_bytes() {
334 #ifdef _LP64
335 if (UseCompactObjectHeaders) {
336 // With compact headers, the Klass* field is not used for the Klass*
337 // and is used for the object fields instead.
338 assert(sizeof(markWord) == 8, "sanity");
339 return sizeof(markWord);
340 } else if (UseCompressedClassPointers) {
341 return sizeof(markWord) + sizeof(narrowKlass);
342 } else
343 #endif
344 return sizeof(oopDesc);
345 }
346
347 // for error reporting
348 static void* load_klass_raw(oop obj);
349 static void* load_oop_raw(oop obj, int offset);
350
351 // Avoid include gc_globals.hpp in oop.inline.hpp
352 DEBUG_ONLY(bool get_UseParallelGC();)
353 DEBUG_ONLY(bool get_UseG1GC();)
354 };
355
356 #endif // SHARE_OOPS_OOP_HPP