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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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 // Returns the prototype mark that should be used for this object.
76 inline markWord prototype_mark() const;
77
78 // Used only to re-initialize the mark word (e.g., of promoted
79 // objects during a GC) -- requires a valid klass pointer
80 inline void init_mark();
81
82 inline Klass* klass() const;
83 inline Klass* klass_or_null() const;
84 inline Klass* klass_or_null_acquire() const;
85
86 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
87 inline void set_klass(Klass* k);
88 static inline void release_set_klass(HeapWord* mem, Klass* k);
89
90 // For klass field compression
91 inline int klass_gap() const;
92 inline void set_klass_gap(int z);
93 static inline void set_klass_gap(HeapWord* mem, int z);
94
95 // size of object header, aligned to platform wordSize
96 static int header_size() {
97 #ifdef _LP64
98 if (UseCompactObjectHeaders) {
99 return sizeof(markWord) / HeapWordSize;
100 } else
101 #endif
102 return sizeof(oopDesc)/HeapWordSize;
103 }
104
105 // Returns whether this is an instance of k or an instance of a subclass of k
106 inline bool is_a(Klass* k) const;
107
108 // Returns the actual oop size of the object
109 inline int size();
110
111 // Sometimes (for complicated concurrency-related reasons), it is useful
112 // to be able to figure out the size of an object knowing its klass.
113 inline int size_given_klass(Klass* klass);
114
115 // The following set of methods is used to access the mark-word and related
116 // properties when the object may be forwarded. Be careful where and when
117 // using this method. It assumes that the forwardee is installed in
118 // the header as a plain pointer (or self-forwarded). In particular,
119 // those methods can not deal with the sliding-forwarding that is used
120 // in Serial, G1 and Shenandoah full-GCs.
121 private:
122 inline Klass* forward_safe_klass_impl(markWord m) const;
123 public:
124 inline Klass* forward_safe_klass() const;
125 inline size_t forward_safe_size();
126 inline Klass* forward_safe_klass(markWord m) const;
127 inline void forward_safe_init_mark();
128
129 // type test operations (inlined in oop.inline.hpp)
130 inline bool is_instance() const;
131 inline bool is_array() const;
132 inline bool is_objArray() const;
133 inline bool is_typeArray() const;
134
135 // type test operations that don't require inclusion of oop.inline.hpp.
136 bool is_instance_noinline() const;
137 bool is_array_noinline() const;
138 bool is_objArray_noinline() const;
139 bool is_typeArray_noinline() const;
140
141 protected:
142 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
143
144 public:
145 // field addresses in oop
146 inline void* field_addr(int offset) const;
147
148 // Need this as public for garbage collection.
149 template <class T> inline T* obj_field_addr(int offset) const;
150
151 template <typename T> inline size_t field_offset(T* p) const;
152
153 // Standard compare function returns negative value if o1 < o2
154 // 0 if o1 == o2
155 // positive value if o1 > o2
156 inline static int compare(oop o1, oop o2) {
157 void* o1_addr = (void*)o1;
158 void* o2_addr = (void*)o2;
159 if (o1_addr < o2_addr) {
160 return -1;
161 } else if (o1_addr > o2_addr) {
162 return 1;
163 } else {
164 return 0;
165 }
166 }
167
168 // Access to fields in a instanceOop through these methods.
169 template <DecoratorSet decorator>
170 oop obj_field_access(int offset) const;
171 oop obj_field(int offset) const;
172 void obj_field_put(int offset, oop value);
173 void obj_field_put_raw(int offset, oop value);
174 void obj_field_put_volatile(int offset, oop value);
175
176 Metadata* metadata_field(int offset) const;
177 Metadata* metadata_field_raw(int offset) const;
178 void metadata_field_put(int offset, Metadata* value);
179
180 Metadata* metadata_field_acquire(int offset) const;
181 void release_metadata_field_put(int offset, Metadata* value);
182
183 jbyte byte_field(int offset) const;
184 void byte_field_put(int offset, jbyte contents);
185
186 jchar char_field(int offset) const;
187 void char_field_put(int offset, jchar contents);
188
189 jboolean bool_field(int offset) const;
190 void bool_field_put(int offset, jboolean contents);
191 jboolean bool_field_volatile(int offset) const;
192 void bool_field_put_volatile(int offset, jboolean contents);
193
194 jint int_field(int offset) const;
195 jint int_field_raw(int offset) const;
196 void int_field_put(int offset, jint contents);
197
198 jshort short_field(int offset) const;
199 void short_field_put(int offset, jshort contents);
200
201 jlong long_field(int offset) const;
202 void long_field_put(int offset, jlong contents);
203
204 jfloat float_field(int offset) const;
205 void float_field_put(int offset, jfloat contents);
206
207 jdouble double_field(int offset) const;
208 void double_field_put(int offset, jdouble contents);
209
210 address address_field(int offset) const;
211 void address_field_put(int offset, address contents);
212
213 oop obj_field_acquire(int offset) const;
214 void release_obj_field_put(int offset, oop value);
215
216 jbyte byte_field_acquire(int offset) const;
217 void release_byte_field_put(int offset, jbyte contents);
218
219 jchar char_field_acquire(int offset) const;
220 void release_char_field_put(int offset, jchar contents);
221
222 jboolean bool_field_acquire(int offset) const;
223 void release_bool_field_put(int offset, jboolean contents);
224
225 jint int_field_acquire(int offset) const;
226 void release_int_field_put(int offset, jint contents);
227
228 jshort short_field_acquire(int offset) const;
229 void release_short_field_put(int offset, jshort contents);
230
231 jlong long_field_acquire(int offset) const;
232 void release_long_field_put(int offset, jlong contents);
233
234 jfloat float_field_acquire(int offset) const;
235 void release_float_field_put(int offset, jfloat contents);
236
237 jdouble double_field_acquire(int offset) const;
238 void release_double_field_put(int offset, jdouble contents);
239
240 address address_field_acquire(int offset) const;
241 void release_address_field_put(int offset, address contents);
242
243 // printing functions for VM debugging
244 void print_on(outputStream* st) const; // First level print
245 void print_value_on(outputStream* st) const; // Second level print.
246 void print_address_on(outputStream* st) const; // Address printing
247
248 // printing on default output stream
249 void print();
250 void print_value();
251 void print_address();
252
253 // return the print strings
254 char* print_string();
255 char* print_value_string();
256
257 // verification operations
258 static void verify_on(outputStream* st, oopDesc* oop_desc);
259 static void verify(oopDesc* oopDesc);
260
261 // locking operations
262 inline bool is_locked() const;
263 inline bool is_unlocked() const;
264 inline bool has_bias_pattern() const;
265
266 // asserts and guarantees
267 static bool is_oop(oop obj, bool ignore_mark_word = false);
268 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
269
270 // garbage collection
271 inline bool is_gc_marked() const;
272
273 // Forward pointer operations for scavenge
274 inline bool is_forwarded() const;
275
276 void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
277
278 inline void forward_to(oop p);
279 inline void forward_to_self();
280
281 // Like "forward_to", but inserts the forwarding pointer atomically.
282 // Exactly one thread succeeds in inserting the forwarding pointer, and
283 // this call returns "NULL" for that thread; any other thread has the
284 // value of the forwarding pointer returned and does not modify "this".
285 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
286 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
287
288 inline oop forwardee() const;
289 inline oop forwardee(markWord header) const;
290
291 // Age of object during scavenge
292 inline uint age() const;
293 inline void incr_age();
294
295 template <typename OopClosureType>
296 inline void oop_iterate(OopClosureType* cl);
297
298 template <typename OopClosureType>
299 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
300
301 template <typename OopClosureType>
302 inline int oop_iterate_size(OopClosureType* cl);
303
304 template <typename OopClosureType>
305 inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
306
307 template <typename OopClosureType>
308 inline void oop_iterate_backwards(OopClosureType* cl);
309
310 template <typename OopClosureType>
311 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
312
313 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
314
315 // identity hash; returns the identity hash key (computes it if necessary)
316 // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
317 // safepoint if called on a biased object. Calling code must be aware of that.
318 inline intptr_t identity_hash();
319 intptr_t slow_identity_hash();
320
321 // marks are forwarded to stack when object is locked
322 inline bool has_displaced_mark() const;
323 inline markWord displaced_mark() const;
324 inline void set_displaced_mark(markWord m);
325
326 // Checks if the mark word needs to be preserved
327 inline bool mark_must_be_preserved() const;
328 inline bool mark_must_be_preserved(markWord m) const;
329 inline bool mark_must_be_preserved_for_promotion_failure(markWord m) const;
330
331 static bool has_klass_gap();
332
333 // for code generation
334 static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
335 static int klass_gap_offset_in_bytes() {
336 assert(has_klass_gap(), "only applicable to compressed klass pointers");
337 assert(!UseCompactObjectHeaders, "don't use klass_offset_in_bytes() with compact headers");
338 return klass_offset_in_bytes() + sizeof(narrowKlass);
339 }
340
341 static int klass_offset_in_bytes() {
342 #ifdef _LP64
343 if (UseCompactObjectHeaders) {
344 STATIC_ASSERT(markWord::klass_shift % 8 == 0);
345 return mark_offset_in_bytes() + markWord::klass_shift / 8;
346 } else
347 #endif
348 return offset_of(oopDesc, _metadata._klass);
349 }
350
351 static int base_offset_in_bytes() {
352 #ifdef _LP64
353 if (UseCompactObjectHeaders) {
354 // With compact headers, the Klass* field is not used for the Klass*
355 // and is used for the object fields instead.
356 assert(sizeof(markWord) == 8, "sanity");
357 return sizeof(markWord);
358 } else if (UseCompressedClassPointers) {
359 return sizeof(markWord) + sizeof(narrowKlass);
360 } else
361 #endif
362 return sizeof(oopDesc);
363 }
364
365 // for error reporting
366 static void* load_klass_raw(oop obj);
367 static void* load_oop_raw(oop obj, int offset);
368
369 // Avoid include gc_globals.hpp in oop.inline.hpp
370 DEBUG_ONLY(bool get_UseParallelGC();)
371 DEBUG_ONLY(bool get_UseG1GC();)
372 };
373
374 #endif // SHARE_OOPS_OOP_HPP