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