1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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/compressedKlass.hpp"
31 #include "oops/accessDecorators.hpp"
32 #include "oops/markWord.hpp"
33 #include "oops/metadata.hpp"
34 #include "oops/objLayout.hpp"
35 #include "runtime/atomic.hpp"
36 #include "utilities/globalDefinitions.hpp"
37 #include "utilities/macros.hpp"
38 #include <type_traits>
39
40 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
41 // the format of Java objects so the fields can be accessed from C++.
42 // oopDesc is abstract.
43 // (see oopHierarchy for complete oop class hierarchy)
44 //
45 // no virtual functions allowed
46
47 // Forward declarations.
48 class OopClosure;
49 class PSPromotionManager;
50 class ParCompactionManager;
51
52 class oopDesc {
53 friend class VMStructs;
54 friend class JVMCIVMStructs;
55 private:
56 volatile markWord _mark;
57 union _metadata {
58 Klass* _klass;
59 narrowKlass _compressed_klass;
60 } _metadata;
61
62 // There may be ordering constraints on the initialization of fields that
63 // make use of the C++ copy/assign incorrect.
64 NONCOPYABLE(oopDesc);
65
66 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
67
68 public:
69 // Must be trivial; see verifying static assert after the class.
70 oopDesc() = default;
71
72 inline markWord mark() const;
73 inline markWord mark_acquire() const;
74 inline markWord* mark_addr() const;
75
76 inline void set_mark(markWord m);
77 static inline void set_mark(HeapWord* mem, markWord m);
78 static inline void release_set_mark(HeapWord* mem, markWord m);
79
80 inline void release_set_mark(markWord m);
81 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
82 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
83
84 // Returns the prototype mark that should be used for this object.
85 inline markWord prototype_mark() const;
86
87 // Used only to re-initialize the mark word (e.g., of promoted
88 // objects during a GC) -- requires a valid klass pointer
89 inline void init_mark();
90
91 inline Klass* klass() const;
92 inline Klass* klass_or_null() const;
93 inline Klass* klass_or_null_acquire() const;
94 // Get the klass without running any asserts.
95 inline Klass* klass_without_asserts() const;
96
97 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
98 inline void set_klass(Klass* k);
99 static inline void release_set_klass(HeapWord* mem, Klass* k);
100
101 // For klass field compression
102 static inline void set_klass_gap(HeapWord* mem, int z);
103
104 // Size of object header, aligned to platform wordSize
105 static int header_size() {
106 if (UseCompactObjectHeaders) {
107 return sizeof(markWord) / HeapWordSize;
108 } else {
109 return sizeof(oopDesc) / HeapWordSize;
110 }
111 }
112
113 // Returns whether this is an instance of k or an instance of a subclass of k
114 inline bool is_a(Klass* k) const;
115
116 // Returns the actual oop size of the object in machine words
117 inline size_t size();
118
119 // Sometimes (for complicated concurrency-related reasons), it is useful
120 // to be able to figure out the size of an object knowing its klass.
121 inline size_t size_given_klass(Klass* klass);
122
123 // type test operations (inlined in oop.inline.hpp)
124 inline bool is_instance() const;
125 inline bool is_instanceRef() const;
126 inline bool is_stackChunk() const;
127 inline bool is_array() const;
128 inline bool is_objArray() const;
129 inline bool is_typeArray() const;
130
131 // type test operations that don't require inclusion of oop.inline.hpp.
132 bool is_instance_noinline() const;
133 bool is_instanceRef_noinline() const;
134 bool is_stackChunk_noinline() const;
135 bool is_array_noinline() const;
136 bool is_objArray_noinline() const;
137 bool is_typeArray_noinline() const;
138
139 protected:
140 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
141
142 public:
143 template<typename T>
144 inline T* field_addr(int offset) const;
145
146 template <typename T> inline size_t field_offset(T* p) const;
147
148 // Standard compare function returns negative value if o1 < o2
149 // 0 if o1 == o2
150 // positive value if o1 > o2
151 inline static int compare(oop o1, oop o2) {
152 void* o1_addr = (void*)o1;
153 void* o2_addr = (void*)o2;
154 if (o1_addr < o2_addr) {
155 return -1;
156 } else if (o1_addr > o2_addr) {
157 return 1;
158 } else {
159 return 0;
160 }
161 }
162
163 // Access to fields in a instanceOop through these methods.
164 template<DecoratorSet decorators>
165 oop obj_field_access(int offset) const;
166 oop obj_field(int offset) const;
167
168 void obj_field_put(int offset, oop value);
169 void obj_field_put_raw(int offset, oop value);
170 void obj_field_put_volatile(int offset, oop value);
171 template<DecoratorSet decorators>
172 void obj_field_put_access(int offset, oop value);
173
174 Metadata* metadata_field(int offset) const;
175 void metadata_field_put(int offset, Metadata* value);
176
177 Metadata* metadata_field_acquire(int offset) const;
178 void release_metadata_field_put(int offset, Metadata* value);
179
180 jbyte byte_field(int offset) const;
181 void byte_field_put(int offset, jbyte contents);
182
183 jchar char_field(int offset) const;
184 void char_field_put(int offset, jchar contents);
185
186 jboolean bool_field(int offset) const;
187 void bool_field_put(int offset, jboolean contents);
188 jboolean bool_field_volatile(int offset) const;
189 void bool_field_put_volatile(int offset, jboolean contents);
190
191 jint int_field(int offset) const;
192 void int_field_put(int offset, jint contents);
193
194 jshort short_field(int offset) const;
195 void short_field_put(int offset, jshort contents);
196
197 jlong long_field(int offset) const;
198 void long_field_put(int offset, jlong contents);
199
200 jfloat float_field(int offset) const;
201 void float_field_put(int offset, jfloat contents);
202
203 jdouble double_field(int offset) const;
204 void double_field_put(int offset, jdouble contents);
205
206 address address_field(int offset) const;
207 void address_field_put(int offset, address contents);
208
209 oop obj_field_acquire(int offset) const;
210 void release_obj_field_put(int offset, oop value);
211
212 jbyte byte_field_acquire(int offset) const;
213 void release_byte_field_put(int offset, jbyte contents);
214
215 jchar char_field_acquire(int offset) const;
216 void release_char_field_put(int offset, jchar contents);
217
218 jboolean bool_field_acquire(int offset) const;
219 void release_bool_field_put(int offset, jboolean contents);
220
221 jint int_field_relaxed(int offset) const;
222 void int_field_put_relaxed(int offset, jint contents);
223 jint int_field_acquire(int offset) const;
224 void release_int_field_put(int offset, jint contents);
225
226 jshort short_field_acquire(int offset) const;
227 void release_short_field_put(int offset, jshort contents);
228
229 jlong long_field_acquire(int offset) const;
230 void release_long_field_put(int offset, jlong contents);
231
232 jfloat float_field_acquire(int offset) const;
233 void release_float_field_put(int offset, jfloat contents);
234
235 jdouble double_field_acquire(int offset) const;
236 void release_double_field_put(int offset, jdouble contents);
237
238 address address_field_acquire(int offset) const;
239 void release_address_field_put(int offset, address contents);
240
241 // printing functions for VM debugging
242 void print_on(outputStream* st) const; // First level print
243 void print_value_on(outputStream* st) const; // Second level print.
244 void print_address_on(outputStream* st) const; // Address printing
245 void print_name_on(outputStream* st) const; // External name printing.
246
247 // printing on default output stream
248 void print();
249 void print_value();
250 void print_address();
251
252 // return the print strings
253 char* print_string();
254 char* print_value_string();
255
256 // verification operations
257 static void verify_on(outputStream* st, oopDesc* oop_desc);
258 static void verify(oopDesc* oopDesc);
259
260 // locking operations
261 inline bool is_locked() const;
262 inline bool is_unlocked() const;
263
264 // asserts and guarantees
265 static bool is_oop(oop obj, bool ignore_mark_word = false);
266 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
267
268 // garbage collection
269 inline bool is_gc_marked() const;
270
271 // Forward pointer operations for scavenge
272 inline bool is_forwarded() const;
273 inline bool is_self_forwarded() const;
274
275 inline void forward_to(oop p);
276 inline void forward_to_self();
277
278 // Like "forward_to", but inserts the forwarding pointer atomically.
279 // Exactly one thread succeeds in inserting the forwarding pointer, and
280 // this call returns null for that thread; any other thread has the
281 // value of the forwarding pointer returned and does not modify "this".
282 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
283 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
284
285 inline oop forwardee() const;
286 inline oop forwardee(markWord header) const;
287
288 inline void unset_self_forwarded();
289
290 // Age of object during scavenge
291 inline uint age() const;
292 inline void incr_age();
293
294 template <typename OopClosureType>
295 inline void oop_iterate(OopClosureType* cl);
296
297 template <typename OopClosureType>
298 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
299
300 template <typename OopClosureType>
301 inline size_t oop_iterate_size(OopClosureType* cl);
302
303 template <typename OopClosureType>
304 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
305
306 template <typename OopClosureType>
307 inline void oop_iterate_backwards(OopClosureType* cl);
308
309 template <typename OopClosureType>
310 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
311
312 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
313
314 // identity hash; returns the identity hash key (computes it if necessary)
315 inline intptr_t identity_hash();
316 intptr_t slow_identity_hash();
317 inline bool fast_no_hash_check();
318
319 // marks are forwarded to stack when object is locked
320 inline bool has_displaced_mark() const;
321 inline markWord displaced_mark() const;
322 inline void set_displaced_mark(markWord m);
323
324 // Checks if the mark word needs to be preserved
325 inline bool mark_must_be_preserved() const;
326 inline bool mark_must_be_preserved(markWord m) const;
327
328 inline static bool has_klass_gap() {
329 return ObjLayout::oop_has_klass_gap();
330 }
331
332 // for code generation
333 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
334 static int klass_offset_in_bytes() {
335 #ifdef _LP64
336 if (UseCompactObjectHeaders) {
337 // NOTE: The only places where this is used with compact headers are the C2
338 // compiler and JVMCI.
339 return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
340 } else
341 #endif
342 {
343 return (int)offset_of(oopDesc, _metadata._klass);
344 }
345 }
346 static int klass_gap_offset_in_bytes() {
347 assert(has_klass_gap(), "only applicable to compressed klass pointers");
348 return klass_offset_in_bytes() + sizeof(narrowKlass);
349 }
350
351 static int base_offset_in_bytes() {
352 return ObjLayout::oop_base_offset_in_bytes();
353 }
354
355 // for error reporting
356 static void* load_oop_raw(oop obj, int offset);
357 };
358
359 // An oopDesc is not initialized via a constructor. Space is allocated in
360 // the Java heap, and static functions provided here on HeapWord* are used
361 // to fill in certain parts of that memory. The allocated memory is then
362 // treated as referring to an oopDesc. For that to be valid, the oopDesc
363 // class must have a trivial default constructor (C++14 3.8/1).
364 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
365
366 #endif // SHARE_OOPS_OOP_HPP