1 /*
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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 // oopDesc::_mark - the "oop mark word" encoding to be found separately in markWord.hpp
48 //
49 // oopDesc::_metadata - encodes the object's klass pointer, as a raw pointer in "_klass"
50 // or compressed pointer in "_compressed_klass"
51 //
52 // The overall size of the _metadata field is dependent on "UseCompressedClassPointers",
53 // hence the terms "narrow" (32 bits) vs "wide" (64 bits).
54 //
55
56
57 class oopDesc {
58 friend class VMStructs;
59 friend class JVMCIVMStructs;
60 private:
61 volatile markWord _mark;
62 union _metadata {
63 Klass* _klass;
64 narrowKlass _compressed_klass;
65 } _metadata;
66
67 // There may be ordering constraints on the initialization of fields that
68 // make use of the C++ copy/assign incorrect.
69 NONCOPYABLE(oopDesc);
70
71 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
72
73 public:
74 // Must be trivial; see verifying static assert after the class.
75 oopDesc() = default;
76
77 inline markWord mark() const;
78 inline markWord mark_acquire() const;
79 inline markWord* mark_addr() const;
80
81 inline void set_mark(markWord m);
82 static inline void set_mark(HeapWord* mem, markWord m);
83 static inline void release_set_mark(HeapWord* mem, markWord m);
84
85 inline void release_set_mark(markWord m);
86 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
87 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
88
89 // Returns the prototype mark that should be used for this object.
90 inline markWord prototype_mark() const;
91
92 // Used only to re-initialize the mark word (e.g., of promoted
93 // objects during a GC) -- requires a valid klass pointer
94 inline void init_mark();
95
96 inline Klass* klass() const;
97 inline Klass* klass_or_null() const;
98 inline Klass* klass_or_null_acquire() const;
99 // Get the klass without running any asserts.
100 inline Klass* klass_without_asserts() const;
101
102 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
103 inline void set_klass(Klass* k);
104 static inline void release_set_klass(HeapWord* mem, Klass* k);
105
106 // For klass field compression
107 static inline void set_klass_gap(HeapWord* mem, int z);
108
109 // Size of object header, aligned to platform wordSize
110 static int header_size() {
111 if (UseCompactObjectHeaders) {
112 return sizeof(markWord) / HeapWordSize;
113 } else {
114 return sizeof(oopDesc) / HeapWordSize;
115 }
116 }
117
118 // Returns whether this is an instance of k or an instance of a subclass of k
119 inline bool is_a(Klass* k) const;
120
121 // Returns the actual oop size of the object in machine words
122 inline size_t size();
123
124 // Sometimes (for complicated concurrency-related reasons), it is useful
125 // to be able to figure out the size of an object knowing its klass.
126 inline size_t size_given_klass(Klass* klass);
127
128 // type test operations (inlined in oop.inline.hpp)
129 inline bool is_instance() const;
130 inline bool is_inline_type() const;
131 inline bool is_instanceRef() const;
132 inline bool is_stackChunk() const;
133 inline bool is_array() const;
134 inline bool is_objArray() const;
135 inline bool is_typeArray() const;
136 inline bool is_flatArray() const;
137 inline bool is_null_free_array() const;
138
139 // type test operations that don't require inclusion of oop.inline.hpp.
140 bool is_instance_noinline() const;
141 bool is_instanceRef_noinline() const;
142 bool is_stackChunk_noinline() const;
143 bool is_array_noinline() const;
144 bool is_objArray_noinline() const;
145 bool is_typeArray_noinline() const;
146 bool is_flatArray_noinline() const;
147 bool is_null_free_array_noinline() const;
148
149 protected:
150 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
151
152 public:
153 template<typename T>
154 inline T* field_addr(int offset) const;
155
156 template <typename T> inline size_t field_offset(T* p) const;
157
158 // Standard compare function returns negative value if o1 < o2
159 // 0 if o1 == o2
160 // positive value if o1 > o2
161 inline static int compare(oop o1, oop o2) {
162 void* o1_addr = (void*)o1;
163 void* o2_addr = (void*)o2;
164 if (o1_addr < o2_addr) {
165 return -1;
166 } else if (o1_addr > o2_addr) {
167 return 1;
168 } else {
169 return 0;
170 }
171 }
172
173 // Access to fields in a instanceOop through these methods.
174 template<DecoratorSet decorators>
175 oop obj_field_access(int offset) const;
176 oop obj_field(int offset) const;
177
178 void obj_field_put(int offset, oop value);
179 void obj_field_put_raw(int offset, oop value);
180 void obj_field_put_volatile(int offset, oop value);
181 template<DecoratorSet decorators>
182 void obj_field_put_access(int offset, oop value);
183
184 Metadata* metadata_field(int offset) const;
185 void metadata_field_put(int offset, Metadata* value);
186
187 Metadata* metadata_field_acquire(int offset) const;
188 void release_metadata_field_put(int offset, Metadata* value);
189
190 jbyte byte_field(int offset) const;
191 void byte_field_put(int offset, jbyte contents);
192
193 jchar char_field(int offset) const;
194 void char_field_put(int offset, jchar contents);
195
196 jboolean bool_field(int offset) const;
197 void bool_field_put(int offset, jboolean contents);
198 jboolean bool_field_volatile(int offset) const;
199 void bool_field_put_volatile(int offset, jboolean contents);
200
201 jint int_field(int offset) const;
202 void int_field_put(int offset, jint contents);
203
204 jshort short_field(int offset) const;
205 void short_field_put(int offset, jshort contents);
206
207 jlong long_field(int offset) const;
208 void long_field_put(int offset, jlong contents);
209
210 jfloat float_field(int offset) const;
211 void float_field_put(int offset, jfloat contents);
212
213 jdouble double_field(int offset) const;
214 void double_field_put(int offset, jdouble contents);
215
216 address address_field(int offset) const;
217 void address_field_put(int offset, address contents);
218
219 oop obj_field_acquire(int offset) const;
220 void release_obj_field_put(int offset, oop value);
221
222 jbyte byte_field_acquire(int offset) const;
223 void release_byte_field_put(int offset, jbyte contents);
224
225 jchar char_field_acquire(int offset) const;
226 void release_char_field_put(int offset, jchar contents);
227
228 jboolean bool_field_acquire(int offset) const;
229 void release_bool_field_put(int offset, jboolean contents);
230
231 jint int_field_relaxed(int offset) const;
232 void int_field_put_relaxed(int offset, jint contents);
233 jint int_field_acquire(int offset) const;
234 void release_int_field_put(int offset, jint contents);
235
236 jshort short_field_acquire(int offset) const;
237 void release_short_field_put(int offset, jshort contents);
238
239 jlong long_field_acquire(int offset) const;
240 void release_long_field_put(int offset, jlong contents);
241
242 jfloat float_field_acquire(int offset) const;
243 void release_float_field_put(int offset, jfloat contents);
244
245 jdouble double_field_acquire(int offset) const;
246 void release_double_field_put(int offset, jdouble contents);
247
248 address address_field_acquire(int offset) const;
249 void release_address_field_put(int offset, address contents);
250
251 // printing functions for VM debugging
252 void print_on(outputStream* st) const; // First level print
253 void print_value_on(outputStream* st) const; // Second level print.
254 void print_address_on(outputStream* st) const; // Address printing
255 void print_name_on(outputStream* st) const; // External name printing.
256
257 // printing on default output stream
258 void print();
259 void print_value();
260 void print_address();
261
262 // return the print strings
263 char* print_string();
264 char* print_value_string();
265
266 // verification operations
267 static void verify_on(outputStream* st, oopDesc* oop_desc);
268 static void verify(oopDesc* oopDesc);
269
270 // locking operations
271 inline bool is_locked() const;
272 inline bool is_unlocked() const;
273
274 // asserts and guarantees
275 static bool is_oop(oop obj, bool ignore_mark_word = false);
276 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
277
278 // garbage collection
279 inline bool is_gc_marked() const;
280
281 // Forward pointer operations for scavenge
282 inline bool is_forwarded() const;
283 inline bool is_self_forwarded() const;
284
285 inline void forward_to(oop p);
286 inline void forward_to_self();
287
288 // Like "forward_to", but inserts the forwarding pointer atomically.
289 // Exactly one thread succeeds in inserting the forwarding pointer, and
290 // this call returns null for that thread; any other thread has the
291 // value of the forwarding pointer returned and does not modify "this".
292 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
293 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
294
295 inline oop forwardee() const;
296 inline oop forwardee(markWord header) const;
297
298 inline void unset_self_forwarded();
299
300 // Age of object during scavenge
301 inline uint age() const;
302 inline void incr_age();
303
304 template <typename OopClosureType>
305 inline void oop_iterate(OopClosureType* cl);
306
307 template <typename OopClosureType>
308 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
309
310 template <typename OopClosureType>
311 inline size_t oop_iterate_size(OopClosureType* cl);
312
313 template <typename OopClosureType>
314 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
315
316 template <typename OopClosureType>
317 inline void oop_iterate_backwards(OopClosureType* cl);
318
319 template <typename OopClosureType>
320 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
321
322 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
323
324 // identity hash; returns the identity hash key (computes it if necessary)
325 inline intptr_t identity_hash();
326 intptr_t slow_identity_hash();
327 inline bool fast_no_hash_check();
328
329 // marks are forwarded to stack when object is locked
330 inline bool has_displaced_mark() const;
331 inline markWord displaced_mark() const;
332 inline void set_displaced_mark(markWord m);
333
334 // Checks if the mark word needs to be preserved
335 inline bool mark_must_be_preserved() const;
336 inline bool mark_must_be_preserved(markWord m) const;
337
338 inline static bool has_klass_gap() {
339 return ObjLayout::oop_has_klass_gap();
340 }
341
342 // for code generation
343 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
344 static int klass_offset_in_bytes() {
345 #ifdef _LP64
346 if (UseCompactObjectHeaders) {
347 // NOTE: The only places where this is used with compact headers are the C2
348 // compiler and JVMCI.
349 return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
350 } else
351 #endif
352 {
353 return (int)offset_of(oopDesc, _metadata._klass);
354 }
355 }
356 static int klass_gap_offset_in_bytes() {
357 assert(has_klass_gap(), "only applicable to compressed klass pointers");
358 return klass_offset_in_bytes() + sizeof(narrowKlass);
359 }
360
361 static int base_offset_in_bytes() {
362 return ObjLayout::oop_base_offset_in_bytes();
363 }
364
365 // for error reporting
366 static void* load_oop_raw(oop obj, int offset);
367 };
368
369 // An oopDesc is not initialized via a constructor. Space is allocated in
370 // the Java heap, and static functions provided here on HeapWord* are used
371 // to fill in certain parts of that memory. The allocated memory is then
372 // treated as referring to an oopDesc. For that to be valid, the oopDesc
373 // class must have a trivial default constructor (C++14 3.8/1).
374 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
375
376 #endif // SHARE_OOPS_OOP_HPP