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/accessDecorators.hpp"
31 #include "oops/compressedKlass.hpp"
32 #include "oops/markWord.hpp"
33 #include "oops/metadata.hpp"
34 #include "oops/objLayout.hpp"
35 #include "runtime/atomicAccess.hpp"
36 #include "utilities/globalDefinitions.hpp"
37 #include "utilities/macros.hpp"
38
39 #include <type_traits>
40
41 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
42 // the format of Java objects so the fields can be accessed from C++.
43 // oopDesc is abstract.
44 // (see oopHierarchy for complete oop class hierarchy)
45 //
46 // no virtual functions allowed
47
48 class oopDesc {
49 friend class VMStructs;
50 friend class JVMCIVMStructs;
51 private:
52 volatile markWord _mark;
53 union _metadata {
54 Klass* _klass;
55 narrowKlass _compressed_klass;
56 } _metadata;
57
58 // There may be ordering constraints on the initialization of fields that
59 // make use of the C++ copy/assign incorrect.
60 NONCOPYABLE(oopDesc);
61
62 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
63
64 public:
65 // Must be trivial; see verifying static assert after the class.
66 oopDesc() = default;
67
68 inline void* base_addr();
69 inline const void* base_addr() const;
70
71 inline markWord mark() const;
72 inline markWord mark_acquire() const;
73
74 inline void set_mark(markWord m);
75 static inline void set_mark(HeapWord* mem, markWord m);
76 static inline void release_set_mark(HeapWord* mem, markWord m);
77
78 inline void release_set_mark(markWord m);
79 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
80 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
81
82 // Returns the prototype mark that should be used for this object.
83 inline markWord prototype_mark() const;
84
85 // Used only to re-initialize the mark word (e.g., of promoted
86 // objects during a GC) -- requires a valid klass pointer
87 inline void init_mark();
88
89 inline Klass* klass() const;
90 inline Klass* klass_or_null() const;
91 inline Klass* klass_or_null_acquire() const;
92 // Get the klass without running any asserts.
93 inline Klass* klass_without_asserts() const;
94
95 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
96 inline narrowKlass narrow_klass() const;
97 inline void set_klass(Klass* k);
98 static inline void release_set_klass(HeapWord* mem, Klass* k);
99
100 // For klass field compression
101 static inline void set_klass_gap(HeapWord* mem, int z);
102
103 // Size of object header, aligned to platform wordSize
104 static int header_size() {
105 if (UseCompactObjectHeaders) {
106 return sizeof(markWord) / HeapWordSize;
107 } else {
108 return sizeof(oopDesc) / HeapWordSize;
109 }
110 }
111
112 // Returns whether this is an instance of k or an instance of a subclass of k
113 inline bool is_a(Klass* k) const;
114
115 // Returns the actual oop size of the object in machine words
116 inline size_t size();
117
118 // Sometimes (for complicated concurrency-related reasons), it is useful
119 // to be able to figure out the size of an object knowing its klass.
120 inline size_t size_given_klass(Klass* klass);
121
122 // type test operations (inlined in oop.inline.hpp)
123 inline bool is_instance() const;
124 inline bool is_instanceRef() const;
125 inline bool is_stackChunk() const;
126 inline bool is_array() const;
127 inline bool is_objArray() const;
128 inline bool is_typeArray() const;
129
130 // type test operations that don't require inclusion of oop.inline.hpp.
131 bool is_instance_noinline() const;
132 bool is_instanceRef_noinline() const;
133 bool is_stackChunk_noinline() const;
134 bool is_array_noinline() const;
135 bool is_objArray_noinline() const;
136 bool is_typeArray_noinline() const;
137
138 protected:
139 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
140
141 public:
142 template<typename T>
143 inline T* field_addr(int offset) const;
144
145 template <typename T> inline size_t field_offset(T* p) const;
146
147 // Standard compare function returns negative value if o1 < o2
148 // 0 if o1 == o2
149 // positive value if o1 > o2
150 inline static int compare(oop o1, oop o2) {
151 void* o1_addr = (void*)o1;
152 void* o2_addr = (void*)o2;
153 if (o1_addr < o2_addr) {
154 return -1;
155 } else if (o1_addr > o2_addr) {
156 return 1;
157 } else {
158 return 0;
159 }
160 }
161
162 // Access to fields in a instanceOop through these methods.
163 template<DecoratorSet decorators>
164 oop obj_field_access(int offset) const;
165 oop obj_field(int offset) const;
166
167 void obj_field_put(int offset, oop value);
168 void obj_field_put_raw(int offset, oop value);
169 void obj_field_put_volatile(int offset, oop value);
170 template<DecoratorSet decorators>
171 void obj_field_put_access(int offset, oop value);
172
173 Metadata* metadata_field(int offset) const;
174 void metadata_field_put(int offset, Metadata* value);
175
176 Metadata* metadata_field_acquire(int offset) const;
177 void release_metadata_field_put(int offset, Metadata* value);
178
179 jbyte byte_field(int offset) const;
180 void byte_field_put(int offset, jbyte contents);
181
182 jchar char_field(int offset) const;
183 void char_field_put(int offset, jchar contents);
184
185 jboolean bool_field(int offset) const;
186 void bool_field_put(int offset, jboolean contents);
187 jboolean bool_field_volatile(int offset) const;
188 void bool_field_put_volatile(int offset, jboolean contents);
189
190 jint int_field(int offset) const;
191 void int_field_put(int offset, jint contents);
192
193 jshort short_field(int offset) const;
194 void short_field_put(int offset, jshort contents);
195
196 jlong long_field(int offset) const;
197 void long_field_put(int offset, jlong contents);
198
199 jfloat float_field(int offset) const;
200 void float_field_put(int offset, jfloat contents);
201
202 jdouble double_field(int offset) const;
203 void double_field_put(int offset, jdouble contents);
204
205 address address_field(int offset) const;
206 void address_field_put(int offset, address contents);
207
208 oop obj_field_acquire(int offset) const;
209 void release_obj_field_put(int offset, oop value);
210
211 jbyte byte_field_acquire(int offset) const;
212 void release_byte_field_put(int offset, jbyte contents);
213
214 jchar char_field_acquire(int offset) const;
215 void release_char_field_put(int offset, jchar contents);
216
217 jboolean bool_field_acquire(int offset) const;
218 void release_bool_field_put(int offset, jboolean contents);
219
220 jint int_field_relaxed(int offset) const;
221 void int_field_put_relaxed(int offset, jint contents);
222 jint int_field_acquire(int offset) const;
223 void release_int_field_put(int offset, jint contents);
224
225 jshort short_field_acquire(int offset) const;
226 void release_short_field_put(int offset, jshort contents);
227
228 jlong long_field_acquire(int offset) const;
229 void release_long_field_put(int offset, jlong contents);
230
231 jfloat float_field_acquire(int offset) const;
232 void release_float_field_put(int offset, jfloat contents);
233
234 jdouble double_field_acquire(int offset) const;
235 void release_double_field_put(int offset, jdouble contents);
236
237 address address_field_acquire(int offset) const;
238 void release_address_field_put(int offset, address contents);
239
240 // printing functions for VM debugging
241 void print_on(outputStream* st) const; // First level print
242 void print_value_on(outputStream* st) const; // Second level print.
243 void print_address_on(outputStream* st) const; // Address printing
244 void print_name_on(outputStream* st) const; // External name printing.
245
246 // printing on default output stream
247 void print();
248 void print_value();
249 void print_address();
250
251 // return the print strings
252 char* print_string();
253 char* print_value_string();
254
255 // verification operations
256 static void verify_on(outputStream* st, oopDesc* oop_desc);
257 static void verify(oopDesc* oopDesc);
258
259 // locking operations
260 inline bool is_locked() const;
261 inline bool is_unlocked() const;
262
263 // asserts and guarantees
264 static bool is_oop(oop obj);
265 static bool is_oop_or_null(oop obj);
266
267 // garbage collection
268 inline bool is_gc_marked() const;
269
270 // Forward pointer operations for scavenge
271 inline bool is_forwarded() const;
272 inline bool is_self_forwarded() const;
273
274 inline void forward_to(oop p);
275 inline void forward_to_self();
276
277 // Like "forward_to", but inserts the forwarding pointer atomically.
278 // Exactly one thread succeeds in inserting the forwarding pointer, and
279 // this call returns null for that thread; any other thread has the
280 // value of the forwarding pointer returned and does not modify "this".
281 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
282 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
283
284 inline oop forwardee() const;
285 inline oop forwardee(markWord header) const;
286
287 inline void unset_self_forwarded();
288
289 // Age of object during scavenge
290 inline uint age() const;
291 inline void incr_age();
292
293 template <typename OopClosureType>
294 inline void oop_iterate(OopClosureType* cl);
295
296 template <typename OopClosureType>
297 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
298
299 template <typename OopClosureType>
300 inline size_t oop_iterate_size(OopClosureType* cl);
301
302 template <typename OopClosureType>
303 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
304
305 template <typename OopClosureType>
306 inline void oop_iterate_backwards(OopClosureType* cl);
307
308 template <typename OopClosureType>
309 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
310
311 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
312
313 // identity hash; returns the identity hash key (computes it if necessary)
314 inline intptr_t identity_hash();
315 intptr_t slow_identity_hash();
316 inline bool fast_no_hash_check();
317
318 // marks are forwarded to stack when object is locked
319 inline bool has_displaced_mark() const;
320 inline markWord displaced_mark() const;
321 inline void set_displaced_mark(markWord m);
322
323 // Checks if the mark word needs to be preserved
324 inline bool mark_must_be_preserved() const;
325 inline bool mark_must_be_preserved(markWord m) const;
326
327 inline static bool has_klass_gap() {
328 return ObjLayout::oop_has_klass_gap();
329 }
330
331 // for code generation
332 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
333 static int klass_offset_in_bytes() {
334 #ifdef _LP64
335 if (UseCompactObjectHeaders) {
336 // NOTE: The only places where this is used with compact headers are the C2
337 // compiler and JVMCI.
338 return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
339 } else
340 #endif
341 {
342 return (int)offset_of(oopDesc, _metadata._klass);
343 }
344 }
345 static int klass_gap_offset_in_bytes() {
346 assert(has_klass_gap(), "only applicable to compressed klass pointers");
347 return klass_offset_in_bytes() + sizeof(narrowKlass);
348 }
349
350 static int base_offset_in_bytes() {
351 return ObjLayout::oop_base_offset_in_bytes();
352 }
353
354 // for error reporting
355 static void* load_oop_raw(oop obj, int offset);
356 };
357
358 // An oopDesc is not initialized via a constructor. Space is allocated in
359 // the Java heap, and static functions provided here on HeapWord* are used
360 // to fill in certain parts of that memory. The allocated memory is then
361 // treated as referring to an oopDesc. For that to be valid, the oopDesc
362 // class must have a trivial default constructor (C++14 3.8/1).
363 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
364
365 #endif // SHARE_OOPS_OOP_HPP