1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_OOPS_OOP_HPP
26 #define SHARE_OOPS_OOP_HPP
27
28 #include "cppstdlib/type_traits.hpp"
29 #include "memory/iterator.hpp"
30 #include "memory/memRegion.hpp"
31 #include "oops/accessDecorators.hpp"
32 #include "oops/compressedKlass.hpp"
33 #include "oops/markWord.hpp"
34 #include "oops/metadata.hpp"
35 #include "oops/objLayout.hpp"
36 #include "runtime/atomicAccess.hpp"
37 #include "utilities/globalDefinitions.hpp"
38 #include "utilities/macros.hpp"
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 class oopDesc {
48 friend class VMStructs;
49 friend class JVMCIVMStructs;
50 private:
51 volatile markWord _mark;
52 union _metadata {
53 Klass* _klass;
54 narrowKlass _compressed_klass;
55 } _metadata;
56
57 // There may be ordering constraints on the initialization of fields that
58 // make use of the C++ copy/assign incorrect.
59 NONCOPYABLE(oopDesc);
60
61 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
62
63 public:
64 // Must be trivial; see verifying static assert after the class.
65 oopDesc() = default;
66
67 inline void* base_addr();
68 inline const void* base_addr() const;
69
70 inline markWord mark() const;
71 inline markWord mark_acquire() const;
72
73 inline void set_mark(markWord m);
74 static inline void set_mark(HeapWord* mem, markWord m);
75 static inline void release_set_mark(HeapWord* mem, markWord m);
76
77 inline void release_set_mark(markWord m);
78 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
79 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
80
81 // Returns the prototype mark that should be used for this object.
82 inline markWord prototype_mark() const;
83
84 // Used only to re-initialize the mark word (e.g., of promoted
85 // objects during a GC) -- requires a valid klass pointer
86 inline void init_mark();
87
88 inline Klass* klass() const;
89 inline Klass* klass_or_null() const;
90 inline Klass* klass_or_null_acquire() const;
91 // Get the klass without running any asserts.
92 inline Klass* klass_without_asserts() const;
93
94 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
95 inline narrowKlass narrow_klass() const;
96 inline void set_klass(Klass* k);
97 static inline void release_set_klass(HeapWord* mem, Klass* k);
98
99 // For klass field compression
100 static inline void set_klass_gap(HeapWord* mem, int z);
101
102 // Size of object header, aligned to platform wordSize
103 static int header_size() {
104 if (UseCompactObjectHeaders) {
105 return sizeof(markWord) / HeapWordSize;
106 } else {
107 return sizeof(oopDesc) / HeapWordSize;
108 }
109 }
110
111 // Returns whether this is an instance of k or an instance of a subclass of k
112 inline bool is_a(Klass* k) const;
113
114 // Returns the actual oop size of the object in machine words
115 inline size_t size();
116
117 // Sometimes (for complicated concurrency-related reasons), it is useful
118 // to be able to figure out the size of an object knowing its klass.
119 inline size_t size_given_klass(Klass* klass);
120
121 // type test operations (inlined in oop.inline.hpp)
122 inline bool is_instance() const;
123 inline bool is_instanceRef() const;
124 inline bool is_stackChunk() const;
125 inline bool is_array() const;
126 inline bool is_objArray() const;
127 inline bool is_typeArray() const;
128
129 // type test operations that don't require inclusion of oop.inline.hpp.
130 bool is_instance_noinline() const;
131 bool is_instanceRef_noinline() const;
132 bool is_stackChunk_noinline() const;
133 bool is_array_noinline() const;
134 bool is_objArray_noinline() const;
135 bool is_typeArray_noinline() const;
136
137 protected:
138 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
139
140 public:
141 template<typename T>
142 inline T* field_addr(int offset) const;
143
144 template <typename T> inline size_t field_offset(T* p) const;
145
146 // Standard compare function returns negative value if o1 < o2
147 // 0 if o1 == o2
148 // positive value if o1 > o2
149 inline static int compare(oop o1, oop o2) {
150 void* o1_addr = (void*)o1;
151 void* o2_addr = (void*)o2;
152 if (o1_addr < o2_addr) {
153 return -1;
154 } else if (o1_addr > o2_addr) {
155 return 1;
156 } else {
157 return 0;
158 }
159 }
160
161 // Access to fields in a instanceOop through these methods.
162 template<DecoratorSet decorators>
163 oop obj_field_access(int offset) const;
164 oop obj_field(int offset) const;
165
166 void obj_field_put(int offset, oop value);
167 void obj_field_put_raw(int offset, oop value);
168 void obj_field_put_volatile(int offset, oop value);
169 template<DecoratorSet decorators>
170 void obj_field_put_access(int offset, oop value);
171
172 Metadata* metadata_field(int offset) const;
173 void metadata_field_put(int offset, Metadata* value);
174
175 Metadata* metadata_field_acquire(int offset) const;
176 void release_metadata_field_put(int offset, Metadata* value);
177
178 jbyte byte_field(int offset) const;
179 void byte_field_put(int offset, jbyte contents);
180
181 jchar char_field(int offset) const;
182 void char_field_put(int offset, jchar contents);
183
184 jboolean bool_field(int offset) const;
185 void bool_field_put(int offset, jboolean contents);
186 jboolean bool_field_volatile(int offset) const;
187 void bool_field_put_volatile(int offset, jboolean contents);
188
189 jint int_field(int offset) const;
190 void int_field_put(int offset, jint contents);
191
192 jshort short_field(int offset) const;
193 void short_field_put(int offset, jshort contents);
194
195 jlong long_field(int offset) const;
196 void long_field_put(int offset, jlong contents);
197
198 jfloat float_field(int offset) const;
199 void float_field_put(int offset, jfloat contents);
200
201 jdouble double_field(int offset) const;
202 void double_field_put(int offset, jdouble contents);
203
204 address address_field(int offset) const;
205 void address_field_put(int offset, address contents);
206
207 oop obj_field_acquire(int offset) const;
208 void release_obj_field_put(int offset, oop value);
209
210 jbyte byte_field_acquire(int offset) const;
211 void release_byte_field_put(int offset, jbyte contents);
212
213 jchar char_field_acquire(int offset) const;
214 void release_char_field_put(int offset, jchar contents);
215
216 jboolean bool_field_acquire(int offset) const;
217 void release_bool_field_put(int offset, jboolean contents);
218
219 jint int_field_relaxed(int offset) const;
220 void int_field_put_relaxed(int offset, jint contents);
221 jint int_field_acquire(int offset) const;
222 void release_int_field_put(int offset, jint contents);
223
224 jshort short_field_acquire(int offset) const;
225 void release_short_field_put(int offset, jshort contents);
226
227 jlong long_field_acquire(int offset) const;
228 void release_long_field_put(int offset, jlong contents);
229
230 jfloat float_field_acquire(int offset) const;
231 void release_float_field_put(int offset, jfloat contents);
232
233 jdouble double_field_acquire(int offset) const;
234 void release_double_field_put(int offset, jdouble contents);
235
236 address address_field_acquire(int offset) const;
237 void release_address_field_put(int offset, address contents);
238
239 // printing functions for VM debugging
240 void print_on(outputStream* st) const; // First level print
241 void print_value_on(outputStream* st) const; // Second level print.
242 void print_address_on(outputStream* st) const; // Address printing
243 void print_name_on(outputStream* st) const; // External name printing.
244
245 // printing on default output stream
246 void print();
247 void print_value();
248 void print_address();
249
250 // return the print strings
251 char* print_string();
252 char* print_value_string();
253
254 // verification operations
255 static void verify_on(outputStream* st, oopDesc* oop_desc);
256 static void verify(oopDesc* oopDesc);
257
258 // locking operations
259 inline bool is_locked() const;
260 inline bool is_unlocked() const;
261
262 // asserts and guarantees
263 static bool is_oop(oop obj);
264 static bool is_oop_or_null(oop obj);
265
266 // garbage collection
267 inline bool is_gc_marked() const;
268
269 // Forward pointer operations for scavenge
270 inline bool is_forwarded() const;
271 inline bool is_self_forwarded() const;
272
273 inline void forward_to(oop p);
274 inline void forward_to_self();
275
276 // Like "forward_to", but inserts the forwarding pointer atomically.
277 // Exactly one thread succeeds in inserting the forwarding pointer, and
278 // this call returns null for that thread; any other thread has the
279 // value of the forwarding pointer returned and does not modify "this".
280 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
281 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
282
283 inline oop forwardee() const;
284 inline oop forwardee(markWord header) const;
285
286 inline void unset_self_forwarded();
287
288 // Age of object during scavenge
289 inline uint age() const;
290 inline void incr_age();
291
292 template <typename OopClosureType>
293 inline void oop_iterate(OopClosureType* cl);
294
295 template <typename OopClosureType>
296 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
297
298 template <typename OopClosureType>
299 inline size_t oop_iterate_size(OopClosureType* cl);
300
301 template <typename OopClosureType>
302 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
303
304 template <typename OopClosureType>
305 inline void oop_iterate_backwards(OopClosureType* cl);
306
307 template <typename OopClosureType>
308 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
309
310 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
311
312 // identity hash; returns the identity hash key (computes it if necessary)
313 inline intptr_t identity_hash();
314 intptr_t slow_identity_hash();
315 inline bool fast_no_hash_check();
316
317 // marks are forwarded to stack when object is locked
318 inline bool has_displaced_mark() const;
319 inline markWord displaced_mark() const;
320 inline void set_displaced_mark(markWord m);
321
322 // Checks if the mark word needs to be preserved
323 inline bool mark_must_be_preserved() const;
324 inline bool mark_must_be_preserved(markWord m) const;
325
326 inline static bool has_klass_gap() {
327 return ObjLayout::oop_has_klass_gap();
328 }
329
330 // for code generation
331 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
332 static int klass_offset_in_bytes() {
333 #ifdef _LP64
334 if (UseCompactObjectHeaders) {
335 // NOTE: The only places where this is used with compact headers are the C2
336 // compiler and JVMCI.
337 return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
338 } else
339 #endif
340 {
341 return (int)offset_of(oopDesc, _metadata._klass);
342 }
343 }
344 static int klass_gap_offset_in_bytes() {
345 assert(has_klass_gap(), "only applicable to compressed klass pointers");
346 return klass_offset_in_bytes() + sizeof(narrowKlass);
347 }
348
349 static int base_offset_in_bytes() {
350 return ObjLayout::oop_base_offset_in_bytes();
351 }
352
353 // for error reporting
354 static void* load_oop_raw(oop obj, int offset);
355 };
356
357 // An oopDesc is not initialized via a constructor. Space is allocated in
358 // the Java heap, and static functions provided here on HeapWord* are used
359 // to fill in certain parts of that memory. The allocated memory is then
360 // treated as referring to an oopDesc. For that to be valid, the oopDesc
361 // class must have a trivial default constructor (C++14 3.8/1).
362 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
363
364 #endif // SHARE_OOPS_OOP_HPP