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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 inline void set_mark_full(markWord m);
79 static inline void release_set_mark(HeapWord* mem, markWord m);
80
81 inline void release_set_mark(markWord m);
82 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
83 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
84
85 // Returns the prototype mark that should be used for this object.
86 inline markWord prototype_mark() const;
87
88 // Used only to re-initialize the mark word (e.g., of promoted
89 // objects during a GC) -- requires a valid klass pointer
90 inline void init_mark();
91
92 inline Klass* klass() const;
93 inline Klass* klass_or_null() const;
94 inline Klass* klass_or_null_acquire() const;
95 // Get the klass without running any asserts.
96 inline Klass* klass_without_asserts() const;
97
98 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
99 inline void set_klass(Klass* k);
100 static inline void release_set_klass(HeapWord* mem, Klass* k);
101
102 // For klass field compression
103 static inline void set_klass_gap(HeapWord* mem, int z);
104
105 // Size of object header, aligned to platform wordSize
106 static int header_size() {
107 if (UseCompactObjectHeaders) {
108 return sizeof(markWord) / HeapWordSize;
109 } else {
110 return sizeof(oopDesc) / HeapWordSize;
111 }
112 }
113
114 // Returns whether this is an instance of k or an instance of a subclass of k
115 inline bool is_a(Klass* k) const;
116
117 // Returns the actual oop size of the object in machine words
118 inline size_t size();
119
120 // Returns the size that a copy of this object requires, in machine words.
121 // It can be 1 word larger than its current size to accomodate
122 // an additional 4-byte-field for the identity hash-code.
123 //
124 // size: the current size of this object, we're passing this here for performance
125 // reasons, because all callers compute this anyway, and we want to avoid
126 // recomputing it.
127 // mark: the mark-word of this object. Some callers (e.g. G1ParScanThreadState::do_copy_to_survivor_space())
128 // need to use a known markWord because of racing GC threads that can change
129 // the markWord at any time.
130 inline size_t copy_size(size_t size, markWord mark) const;
131 // Special version to deal with scratch classes in CDS. There we allocate
132 // temporary scratch classes (which are skeleton versions of InstanceMirrorKlass,
133 // which represent java.lang.Class objects in the CDS archive). At that point, we
134 // don't know whether or not the final archived version will be hashed or expanded,
135 // and therefore we allocate them in the special state not-hashed-but-expanded.
136 // When creating the final copy of those objects, we either populate the hidden hash
137 // field and make the object 'expanded', or we turn it back to 'not-hashed'
138 // and reduce the object's size. We do this by providing a separate method for CDS
139 // so that we don't affect GC performance.
140 inline size_t copy_size_cds(size_t size, markWord mark) const;
141
142 // Sometimes (for complicated concurrency-related reasons), it is useful
143 // to be able to figure out the size of an object knowing its klass.
144 inline size_t base_size_given_klass(markWord m, const Klass* klass);
145 inline size_t size_given_mark_and_klass(markWord mrk, const Klass* kls);
146
147 // type test operations (inlined in oop.inline.hpp)
148 inline bool is_instance() const;
149 inline bool is_instanceRef() const;
150 inline bool is_stackChunk() const;
151 inline bool is_array() const;
152 inline bool is_objArray() const;
153 inline bool is_typeArray() const;
154
155 // type test operations that don't require inclusion of oop.inline.hpp.
156 bool is_instance_noinline() const;
157 bool is_instanceRef_noinline() const;
158 bool is_stackChunk_noinline() const;
159 bool is_array_noinline() const;
160 bool is_objArray_noinline() const;
161 bool is_typeArray_noinline() const;
162
163 protected:
164 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
165
166 public:
167 template<typename T>
168 inline T* field_addr(int offset) const;
169
170 template <typename T> inline size_t field_offset(T* p) const;
171
172 // Standard compare function returns negative value if o1 < o2
173 // 0 if o1 == o2
174 // positive value if o1 > o2
175 inline static int compare(oop o1, oop o2) {
176 void* o1_addr = (void*)o1;
177 void* o2_addr = (void*)o2;
178 if (o1_addr < o2_addr) {
179 return -1;
180 } else if (o1_addr > o2_addr) {
181 return 1;
182 } else {
183 return 0;
184 }
185 }
186
187 // Access to fields in a instanceOop through these methods.
188 template<DecoratorSet decorators>
189 oop obj_field_access(int offset) const;
190 oop obj_field(int offset) const;
191
192 void obj_field_put(int offset, oop value);
193 void obj_field_put_raw(int offset, oop value);
194 void obj_field_put_volatile(int offset, oop value);
195 template<DecoratorSet decorators>
196 void obj_field_put_access(int offset, oop value);
197
198 Metadata* metadata_field(int offset) const;
199 void metadata_field_put(int offset, Metadata* value);
200
201 Metadata* metadata_field_acquire(int offset) const;
202 void release_metadata_field_put(int offset, Metadata* value);
203
204 jbyte byte_field(int offset) const;
205 void byte_field_put(int offset, jbyte contents);
206
207 jchar char_field(int offset) const;
208 void char_field_put(int offset, jchar contents);
209
210 jboolean bool_field(int offset) const;
211 void bool_field_put(int offset, jboolean contents);
212 jboolean bool_field_volatile(int offset) const;
213 void bool_field_put_volatile(int offset, jboolean contents);
214
215 jint int_field(int offset) const;
216 void int_field_put(int offset, jint contents);
217
218 jshort short_field(int offset) const;
219 void short_field_put(int offset, jshort contents);
220
221 jlong long_field(int offset) const;
222 void long_field_put(int offset, jlong contents);
223
224 jfloat float_field(int offset) const;
225 void float_field_put(int offset, jfloat contents);
226
227 jdouble double_field(int offset) const;
228 void double_field_put(int offset, jdouble contents);
229
230 address address_field(int offset) const;
231 void address_field_put(int offset, address contents);
232
233 oop obj_field_acquire(int offset) const;
234 void release_obj_field_put(int offset, oop value);
235
236 jbyte byte_field_acquire(int offset) const;
237 void release_byte_field_put(int offset, jbyte contents);
238
239 jchar char_field_acquire(int offset) const;
240 void release_char_field_put(int offset, jchar contents);
241
242 jboolean bool_field_acquire(int offset) const;
243 void release_bool_field_put(int offset, jboolean contents);
244
245 jint int_field_relaxed(int offset) const;
246 void int_field_put_relaxed(int offset, jint contents);
247 jint int_field_acquire(int offset) const;
248 void release_int_field_put(int offset, jint contents);
249
250 jshort short_field_acquire(int offset) const;
251 void release_short_field_put(int offset, jshort contents);
252
253 jlong long_field_acquire(int offset) const;
254 void release_long_field_put(int offset, jlong contents);
255
256 jfloat float_field_acquire(int offset) const;
257 void release_float_field_put(int offset, jfloat contents);
258
259 jdouble double_field_acquire(int offset) const;
260 void release_double_field_put(int offset, jdouble contents);
261
262 address address_field_acquire(int offset) const;
263 void release_address_field_put(int offset, address contents);
264
265 // printing functions for VM debugging
266 void print_on(outputStream* st) const; // First level print
267 void print_value_on(outputStream* st) const; // Second level print.
268 void print_address_on(outputStream* st) const; // Address printing
269 void print_name_on(outputStream* st) const; // External name printing.
270
271 // printing on default output stream
272 void print();
273 void print_value();
274 void print_address();
275
276 // return the print strings
277 char* print_string();
278 char* print_value_string();
279
280 // verification operations
281 static void verify_on(outputStream* st, oopDesc* oop_desc);
282 static void verify(oopDesc* oopDesc);
283
284 // locking operations
285 inline bool is_locked() const;
286 inline bool is_unlocked() const;
287
288 // asserts and guarantees
289 static bool is_oop(oop obj, bool ignore_mark_word = false);
290 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
291
292 // garbage collection
293 inline bool is_gc_marked() const;
294
295 // Forward pointer operations for scavenge
296 inline bool is_forwarded() const;
297 inline bool is_self_forwarded() const;
298
299 inline void forward_to(oop p);
300 inline void forward_to_self();
301
302 // Like "forward_to", but inserts the forwarding pointer atomically.
303 // Exactly one thread succeeds in inserting the forwarding pointer, and
304 // this call returns null for that thread; any other thread has the
305 // value of the forwarding pointer returned and does not modify "this".
306 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
307 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
308
309 inline oop forwardee() const;
310 inline oop forwardee(markWord header) const;
311
312 inline void unset_self_forwarded();
313
314 // Age of object during scavenge
315 inline uint age() const;
316 inline void incr_age();
317
318 template <typename OopClosureType>
319 inline void oop_iterate(OopClosureType* cl);
320
321 template <typename OopClosureType>
322 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
323
324 template <typename OopClosureType>
325 inline size_t oop_iterate_size(OopClosureType* cl);
326
327 template <typename OopClosureType>
328 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
329
330 template <typename OopClosureType>
331 inline void oop_iterate_backwards(OopClosureType* cl);
332
333 template <typename OopClosureType>
334 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
335
336 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
337
338 // identity hash; returns the identity hash key (computes it if necessary)
339 inline intptr_t identity_hash();
340 intptr_t slow_identity_hash();
341 inline bool fast_no_hash_check();
342
343 // Initialize identity hash code in hash word of object copy from original object.
344 // Returns true if the object has been expanded, false otherwise.
345 inline void initialize_hash_if_necessary(oop obj);
346 // For CDS only.
347 void initialize_hash_if_necessary(oop obj, Klass* k, markWord m);
348
349 // marks are forwarded to stack when object is locked
350 inline bool has_displaced_mark() const;
351 inline markWord displaced_mark() const;
352 inline void set_displaced_mark(markWord m);
353
354 // Checks if the mark word needs to be preserved
355 inline bool mark_must_be_preserved() const;
356 inline bool mark_must_be_preserved(markWord m) const;
357
358 inline static bool has_klass_gap() {
359 return ObjLayout::oop_has_klass_gap();
360 }
361
362 // for code generation
363 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
364 static int klass_offset_in_bytes() {
365 assert(!UseCompactObjectHeaders, "don't use this with compact headers");
366 return (int)offset_of(oopDesc, _metadata._klass);
367 }
368 static int klass_gap_offset_in_bytes() {
369 assert(has_klass_gap(), "only applicable to compressed klass pointers");
370 if (UseCompactObjectHeaders) {
371 return base_offset_in_bytes();
372 } else {
373 return klass_offset_in_bytes() + sizeof(narrowKlass);
374 }
375 }
376
377 static int base_offset_in_bytes() {
378 return ObjLayout::oop_base_offset_in_bytes();
379 }
380
381 // for error reporting
382 static void* load_oop_raw(oop obj, int offset);
383 };
384
385 // An oopDesc is not initialized via a constructor. Space is allocated in
386 // the Java heap, and static functions provided here on HeapWord* are used
387 // to fill in certain parts of that memory. The allocated memory is then
388 // treated as referring to an oopDesc. For that to be valid, the oopDesc
389 // class must have a trivial default constructor (C++14 3.8/1).
390 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
391
392 #endif // SHARE_OOPS_OOP_HPP