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;
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
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
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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;
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
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 inline void reset_forwarded();
314
315 // Age of object during scavenge
316 inline uint age() const;
317 inline void incr_age();
318
319 template <typename OopClosureType>
320 inline void oop_iterate(OopClosureType* cl);
321
322 template <typename OopClosureType>
323 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
324
325 template <typename OopClosureType>
326 inline size_t oop_iterate_size(OopClosureType* cl);
327
328 template <typename OopClosureType>
329 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
330
331 template <typename OopClosureType>
332 inline void oop_iterate_backwards(OopClosureType* cl);
333
334 template <typename OopClosureType>
335 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
336
337 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
338
339 // identity hash; returns the identity hash key (computes it if necessary)
340 inline intptr_t identity_hash();
341 intptr_t slow_identity_hash();
342 inline bool fast_no_hash_check();
343
344 // Initialize identity hash code in hash word of object copy from original object.
345 // Returns true if the object has been expanded, false otherwise.
346 inline void initialize_hash_if_necessary(oop obj);
347 // For CDS only.
348 void initialize_hash_if_necessary(oop obj, Klass* k, markWord m);
349
350 // marks are forwarded to stack when object is locked
351 inline bool has_displaced_mark() const;
352 inline markWord displaced_mark() const;
353 inline void set_displaced_mark(markWord m);
354
355 // Checks if the mark word needs to be preserved
356 inline bool mark_must_be_preserved() const;
357 inline bool mark_must_be_preserved(markWord m) const;
358
359 inline static bool has_klass_gap() {
360 return ObjLayout::oop_has_klass_gap();
361 }
362
363 // for code generation
364 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
365 static int klass_offset_in_bytes() {
366 assert(!UseCompactObjectHeaders, "don't use this with compact headers");
367 return (int)offset_of(oopDesc, _metadata._klass);
368 }
369 static int klass_gap_offset_in_bytes() {
370 assert(has_klass_gap(), "only applicable to compressed klass pointers");
371 if (UseCompactObjectHeaders) {
372 return base_offset_in_bytes();
373 } else {
374 return klass_offset_in_bytes() + sizeof(narrowKlass);
375 }
376 }
377
378 static int base_offset_in_bytes() {
379 return ObjLayout::oop_base_offset_in_bytes();
380 }
381
382 // for error reporting
383 static void* load_oop_raw(oop obj, int offset);
384 };
385
386 // An oopDesc is not initialized via a constructor. Space is allocated in
387 // the Java heap, and static functions provided here on HeapWord* are used
388 // to fill in certain parts of that memory. The allocated memory is then
389 // treated as referring to an oopDesc. For that to be valid, the oopDesc
390 // class must have a trivial default constructor (C++14 3.8/1).
391 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
392
393 #endif // SHARE_OOPS_OOP_HPP
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