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
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
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
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