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