51 narrowKlass _compressed_klass;
52
53 // There may be ordering constraints on the initialization of fields that
54 // make use of the C++ copy/assign incorrect.
55 NONCOPYABLE(oopDesc);
56
57 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
58
59 public:
60 // Must be trivial; see verifying static assert after the class.
61 oopDesc() = default;
62
63 inline void* base_addr();
64 inline const void* base_addr() const;
65
66 inline markWord mark() const;
67 inline markWord mark_acquire() const;
68
69 inline void set_mark(markWord m);
70 static inline void set_mark(HeapWord* mem, markWord m);
71 static inline void release_set_mark(HeapWord* mem, markWord m);
72
73 inline void release_set_mark(markWord m);
74 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
75 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
76
77 // Returns the prototype mark that should be used for this object.
78 inline markWord prototype_mark() const;
79
80 // Used only to re-initialize the mark word (e.g., of promoted
81 // objects during a GC) -- requires a valid klass pointer
82 inline void init_mark();
83
84 inline Klass* klass() const;
85 inline Klass* klass_or_null() const;
86 inline Klass* klass_or_null_acquire() const;
87 // Get the klass without running any asserts.
88 inline Klass* klass_without_asserts() const;
89
90 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
91 inline narrowKlass narrow_klass() const;
92 inline narrowKlass narrow_klass_acquire() const;
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
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 place where this is used with compact headers is C2.
333 return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
334 } else
335 #endif
336 {
337 return (int)offset_of(oopDesc, _compressed_klass);
338 }
339 }
340 static int klass_gap_offset_in_bytes() {
341 assert(has_klass_gap(), "only applicable to compressed klass pointers");
342 return klass_offset_in_bytes() + sizeof(narrowKlass);
343 }
344
345 static int base_offset_in_bytes() {
346 return ObjLayout::oop_base_offset_in_bytes();
347 }
348
349 // for error reporting
350 static void* load_oop_raw(oop obj, int offset);
351 };
352
353 // An oopDesc is not initialized via a constructor. Space is allocated in
354 // the Java heap, and static functions provided here on HeapWord* are used
355 // to fill in certain parts of that memory. The allocated memory is then
356 // treated as referring to an oopDesc. For that to be valid, the oopDesc
357 // class must have a trivial default constructor (C++14 3.8/1).
358 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
359
360 #endif // SHARE_OOPS_OOP_HPP
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51 narrowKlass _compressed_klass;
52
53 // There may be ordering constraints on the initialization of fields that
54 // make use of the C++ copy/assign incorrect.
55 NONCOPYABLE(oopDesc);
56
57 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
58
59 public:
60 // Must be trivial; see verifying static assert after the class.
61 oopDesc() = default;
62
63 inline void* base_addr();
64 inline const void* base_addr() const;
65
66 inline markWord mark() const;
67 inline markWord mark_acquire() const;
68
69 inline void set_mark(markWord m);
70 static inline void set_mark(HeapWord* mem, markWord m);
71 inline void set_mark_full(markWord m);
72 static inline void release_set_mark(HeapWord* mem, markWord m);
73
74 inline void release_set_mark(markWord m);
75 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
76 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
77
78 // Returns the prototype mark that should be used for this object.
79 inline markWord prototype_mark() const;
80
81 // Initializes the mark word of an object (typically an object copy)
82 // to the prototype mark -- requires a valid klass pointer.
83 // This completely resets the mark-word, except for the
84 // Klass bits.
85 // This is typically used by clone() routines, where the copy of
86 // the object is a new object identity.
87 inline void init_mark();
88
89 // Re-initializes the mark word of an object (typically an object copy)
90 // to the prototype mark -- requires a valid klass pointer.
91 // This completely resets the mark-word, except for the
92 // Klass bits and the hashcode, which are preserved.
93 // This is typically used by GCs when they copy object to new locations,
94 // where the copy of the object preserves the previous identity.
95 inline void reinit_mark();
96
97 inline Klass* klass() const;
98 inline Klass* klass_or_null() const;
99 inline Klass* klass_or_null_acquire() const;
100 // Get the klass without running any asserts.
101 inline Klass* klass_without_asserts() const;
102
103 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
104 inline narrowKlass narrow_klass() const;
105 inline narrowKlass narrow_klass_acquire() const;
106 inline void set_klass(Klass* k);
107 static inline void release_set_klass(HeapWord* mem, Klass* k);
108
109 // For klass field compression
110 static inline void set_klass_gap(HeapWord* mem, int z);
111
112 // Size of object header, aligned to platform wordSize
113 static int header_size() {
114 if (UseCompactObjectHeaders) {
115 return sizeof(markWord) / HeapWordSize;
116 } else {
117 return sizeof(oopDesc) / HeapWordSize;
118 }
119 }
120
121 // Returns whether this is an instance of k or an instance of a subclass of k
122 inline bool is_a(Klass* k) const;
123
124 // Returns the actual oop size of the object in machine words
125 inline size_t size();
126
127 // Returns hash expanded size for given words, assuming it uses 1 word to accommodate the identity hash-code.
128 static size_t hash_expanded_size(size_t words) { return align_object_size(words + 1); }
129
130 // Returns the size that a copy of this object requires, in machine words.
131 // It can be 1 word larger than its current size to accommodate
132 // an additional 4-byte-field for the identity hash-code.
133 //
134 // size: the current size of this object, we're passing this here for performance
135 // reasons, because all callers compute this anyway, and we want to avoid
136 // recomputing it.
137 // mark: the mark-word of this object. Some callers (e.g. G1ParScanThreadState::do_copy_to_survivor_space())
138 // need to use a known markWord because of racing GC threads that can change
139 // the markWord at any time.
140 inline size_t copy_size(size_t size, markWord mark) const;
141 // Special version to deal with scratch classes in CDS. There we allocate
142 // temporary scratch classes (which are skeleton versions of InstanceMirrorKlass,
143 // which represent java.lang.Class objects in the CDS archive). At that point, we
144 // don't know whether or not the final archived version will be hashed or expanded,
145 // and therefore we allocate them in the special state not-hashed-but-expanded.
146 // When creating the final copy of those objects, we either populate the hidden hash
147 // field and make the object 'expanded', or we turn it back to 'not-hashed'
148 // and reduce the object's size. We do this by providing a separate method for CDS
149 // so that we don't affect GC performance.
150 inline size_t copy_size_cds(size_t size, markWord mark) const;
151
152 // Sometimes (for complicated concurrency-related reasons), it is useful
153 // to be able to figure out the size of an object knowing its klass.
154 inline size_t base_size_given_klass(markWord m, const Klass* klass);
155 inline size_t size_given_mark_and_klass(markWord mrk, const Klass* kls);
156
157 // Returns the size of a forwarded object in its original (source) space.
158 // Only valid for scavenge-style forwarding (oopDesc::forward_to(/_atomic)).
159 inline size_t size_forwarded();
160
161 // type test operations (inlined in oop.inline.hpp)
162 inline bool is_instance() const;
163 inline bool is_instanceRef() const;
164 inline bool is_stackChunk() const;
165 inline bool is_array() const;
166 inline bool is_objArray() const;
167 inline bool is_typeArray() const;
168
169 // type test operations that don't require inclusion of oop.inline.hpp.
170 bool is_instance_noinline() const;
171 bool is_instanceRef_noinline() const;
172 bool is_stackChunk_noinline() const;
173 bool is_array_noinline() const;
174 bool is_objArray_noinline() const;
175 bool is_typeArray_noinline() const;
176
177 protected:
178 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
179
307 inline bool is_gc_marked() const;
308
309 // Forward pointer operations for scavenge
310 inline bool is_forwarded() const;
311 inline bool is_self_forwarded() const;
312
313 inline void forward_to(oop p);
314 inline void forward_to_self();
315
316 // Like "forward_to", but inserts the forwarding pointer atomically.
317 // Exactly one thread succeeds in inserting the forwarding pointer, and
318 // this call returns null for that thread; any other thread has the
319 // value of the forwarding pointer returned and does not modify "this".
320 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
321 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
322
323 inline oop forwardee() const;
324 inline oop forwardee(markWord header) const;
325
326 inline void unset_self_forwarded();
327 inline void reset_forwarded();
328
329 // Age of object during scavenge
330 inline uint age() const;
331 inline void incr_age();
332
333 template <typename OopClosureType>
334 inline void oop_iterate(OopClosureType* cl);
335
336 template <typename OopClosureType>
337 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
338
339 template <typename OopClosureType>
340 inline size_t oop_iterate_size(OopClosureType* cl);
341
342 template <typename OopClosureType>
343 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
344
345 template <typename OopClosureType>
346 inline void oop_iterate_backwards(OopClosureType* cl);
347
348 template <typename OopClosureType>
349 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
350
351 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
352
353 // identity hash; returns the identity hash key (computes it if necessary)
354 inline intptr_t identity_hash();
355 intptr_t slow_identity_hash();
356 inline bool fast_no_hash_check();
357
358 // Initialize identity hash code in hash word of object copy from original object.
359 // Returns true if the object has been expanded, false otherwise.
360 inline void initialize_hash_if_necessary(oop obj);
361 // For CDS only.
362 markWord initialize_hash_if_necessary(oop obj, Klass* k, markWord m);
363
364 // marks are forwarded to stack when object is locked
365 inline bool has_displaced_mark() const;
366 inline markWord displaced_mark() const;
367 inline void set_displaced_mark(markWord m);
368
369 // Checks if the mark word needs to be preserved
370 inline bool mark_must_be_preserved() const;
371 inline bool mark_must_be_preserved(markWord m) const;
372
373 inline static bool has_klass_gap() {
374 return ObjLayout::oop_has_klass_gap();
375 }
376
377 // for code generation
378 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
379 static int klass_offset_in_bytes() {
380 assert(!UseCompactObjectHeaders, "don't use this with compact headers");
381 return (int)offset_of(oopDesc, _compressed_klass);
382 }
383 static int klass_gap_offset_in_bytes() {
384 assert(has_klass_gap(), "only applicable to compressed klass pointers");
385 if (UseCompactObjectHeaders) {
386 return base_offset_in_bytes();
387 } else {
388 return klass_offset_in_bytes() + sizeof(narrowKlass);
389 }
390 }
391
392 static int base_offset_in_bytes() {
393 return ObjLayout::oop_base_offset_in_bytes();
394 }
395
396 // for error reporting
397 static void* load_oop_raw(oop obj, int offset);
398 };
399
400 // An oopDesc is not initialized via a constructor. Space is allocated in
401 // the Java heap, and static functions provided here on HeapWord* are used
402 // to fill in certain parts of that memory. The allocated memory is then
403 // treated as referring to an oopDesc. For that to be valid, the oopDesc
404 // class must have a trivial default constructor (C++14 3.8/1).
405 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
406
407 #endif // SHARE_OOPS_OOP_HPP
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