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