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/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/atomic.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 // oopDesc::_mark - the "oop mark word" encoding to be found separately in markWord.hpp
49 //
50 // oopDesc::_metadata - encodes the object's klass pointer, as a raw pointer in "_klass"
51 // or compressed pointer in "_compressed_klass"
52 //
53 // The overall size of the _metadata field is dependent on "UseCompressedClassPointers",
54 // hence the terms "narrow" (32 bits) vs "wide" (64 bits).
55 //
56
57
58 class oopDesc {
59 friend class VMStructs;
60 friend class JVMCIVMStructs;
61 private:
62 volatile markWord _mark;
63 union _metadata {
64 Klass* _klass;
65 narrowKlass _compressed_klass;
66 } _metadata;
67
68 // There may be ordering constraints on the initialization of fields that
69 // make use of the C++ copy/assign incorrect.
70 NONCOPYABLE(oopDesc);
71
72 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
73
74 public:
75 // Must be trivial; see verifying static assert after the class.
76 oopDesc() = default;
77
78 inline markWord mark() const;
79 inline markWord mark_acquire() const;
80 inline markWord* mark_addr() const;
81
82 inline void set_mark(markWord m);
83 static inline void set_mark(HeapWord* mem, markWord m);
84 static inline void release_set_mark(HeapWord* mem, markWord m);
85
86 inline void release_set_mark(markWord m);
87 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
88 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
89
90 // Returns the prototype mark that should be used for this object.
91 inline markWord prototype_mark() const;
92
93 // Used only to re-initialize the mark word (e.g., of promoted
94 // objects during a GC) -- requires a valid klass pointer
95 inline void init_mark();
96 inline void reinit_mark(); // special for parallelGC
97
98 inline Klass* klass() const;
99 inline Klass* klass_or_null() const;
100 inline Klass* klass_or_null_acquire() const;
101 // Get the klass without running any asserts.
102 inline Klass* klass_without_asserts() const;
103
104 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
105 inline narrowKlass narrow_klass() const;
106 inline void set_klass(Klass* k);
107 static inline void release_set_klass(HeapWord* mem, Klass* k);
108
109 // For klass field compression
110 static inline void set_klass_gap(HeapWord* mem, int z);
111
112 // Size of object header, aligned to platform wordSize
113 static int header_size() {
114 if (UseCompactObjectHeaders) {
115 return sizeof(markWord) / HeapWordSize;
116 } else {
117 return sizeof(oopDesc) / HeapWordSize;
118 }
119 }
120
121 // Returns whether this is an instance of k or an instance of a subclass of k
122 inline bool is_a(Klass* k) const;
123
124 // Returns the actual oop size of the object in machine words
125 inline size_t size();
126
127 // Sometimes (for complicated concurrency-related reasons), it is useful
128 // to be able to figure out the size of an object knowing its klass.
129 inline size_t size_given_klass(Klass* klass);
130
131 // type test operations (inlined in oop.inline.hpp)
132 inline bool is_instance() const;
133 inline bool is_inline_type() const;
134 inline bool is_instanceRef() const;
135 inline bool is_stackChunk() const;
136 inline bool is_array() const;
137 inline bool is_objArray() const;
138 inline bool is_typeArray() const;
139 inline bool is_flatArray() const;
140 inline bool is_refArray() const;
141 inline bool is_null_free_array() const;
142 inline bool is_refined_objArray() const;
143
144 // type test operations that don't require inclusion of oop.inline.hpp.
145 bool is_instance_noinline() const;
146 bool is_instanceRef_noinline() const;
147 bool is_stackChunk_noinline() const;
148 bool is_array_noinline() const;
149 bool is_objArray_noinline() const;
150 bool is_refArray_noinline() const;
151 bool is_typeArray_noinline() const;
152 bool is_flatArray_noinline() const;
153 bool is_null_free_array_noinline() const;
154
155 protected:
156 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
157
158 public:
159 template<typename T>
160 inline T* field_addr(int offset) const;
161
162 template <typename T> inline size_t field_offset(T* p) const;
163
164 // Standard compare function returns negative value if o1 < o2
165 // 0 if o1 == o2
166 // positive value if o1 > o2
167 inline static int compare(oop o1, oop o2) {
168 void* o1_addr = (void*)o1;
169 void* o2_addr = (void*)o2;
170 if (o1_addr < o2_addr) {
171 return -1;
172 } else if (o1_addr > o2_addr) {
173 return 1;
174 } else {
175 return 0;
176 }
177 }
178
179 // Access to fields in a instanceOop through these methods.
180 template<DecoratorSet decorators>
181 oop obj_field_access(int offset) const;
182 oop obj_field(int offset) const;
183
184 void obj_field_put(int offset, oop value);
185 void obj_field_put_raw(int offset, oop value);
186 void obj_field_put_volatile(int offset, oop value);
187 template<DecoratorSet decorators>
188 void obj_field_put_access(int offset, oop value);
189
190 Metadata* metadata_field(int offset) const;
191 void metadata_field_put(int offset, Metadata* value);
192
193 Metadata* metadata_field_acquire(int offset) const;
194 void release_metadata_field_put(int offset, Metadata* value);
195
196 jbyte byte_field(int offset) const;
197 void byte_field_put(int offset, jbyte contents);
198
199 jchar char_field(int offset) const;
200 void char_field_put(int offset, jchar contents);
201
202 jboolean bool_field(int offset) const;
203 void bool_field_put(int offset, jboolean contents);
204 jboolean bool_field_volatile(int offset) const;
205 void bool_field_put_volatile(int offset, jboolean contents);
206
207 jint int_field(int offset) const;
208 void int_field_put(int offset, jint contents);
209
210 jshort short_field(int offset) const;
211 void short_field_put(int offset, jshort contents);
212
213 jlong long_field(int offset) const;
214 void long_field_put(int offset, jlong contents);
215
216 jfloat float_field(int offset) const;
217 void float_field_put(int offset, jfloat contents);
218
219 jdouble double_field(int offset) const;
220 void double_field_put(int offset, jdouble contents);
221
222 address address_field(int offset) const;
223 void address_field_put(int offset, address contents);
224
225 oop obj_field_acquire(int offset) const;
226 void release_obj_field_put(int offset, oop value);
227
228 jbyte byte_field_acquire(int offset) const;
229 void release_byte_field_put(int offset, jbyte contents);
230
231 jchar char_field_acquire(int offset) const;
232 void release_char_field_put(int offset, jchar contents);
233
234 jboolean bool_field_acquire(int offset) const;
235 void release_bool_field_put(int offset, jboolean contents);
236
237 jint int_field_relaxed(int offset) const;
238 void int_field_put_relaxed(int offset, jint contents);
239 jint int_field_acquire(int offset) const;
240 void release_int_field_put(int offset, jint contents);
241
242 jshort short_field_acquire(int offset) const;
243 void release_short_field_put(int offset, jshort contents);
244
245 jlong long_field_acquire(int offset) const;
246 void release_long_field_put(int offset, jlong contents);
247
248 jfloat float_field_acquire(int offset) const;
249 void release_float_field_put(int offset, jfloat contents);
250
251 jdouble double_field_acquire(int offset) const;
252 void release_double_field_put(int offset, jdouble contents);
253
254 address address_field_acquire(int offset) const;
255 void release_address_field_put(int offset, address contents);
256
257 // printing functions for VM debugging
258 void print_on(outputStream* st) const; // First level print
259 void print_value_on(outputStream* st) const; // Second level print.
260 void print_address_on(outputStream* st) const; // Address printing
261 void print_name_on(outputStream* st) const; // External name printing.
262
263 // printing on default output stream
264 void print();
265 void print_value();
266 void print_address();
267
268 // return the print strings
269 char* print_string();
270 char* print_value_string();
271
272 // verification operations
273 static void verify_on(outputStream* st, oopDesc* oop_desc);
274 static void verify(oopDesc* oopDesc);
275
276 // locking operations
277 inline bool is_locked() const;
278 inline bool is_unlocked() const;
279
280 // asserts and guarantees
281 static bool is_oop(oop obj, bool ignore_mark_word = false);
282 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
283
284 // garbage collection
285 inline bool is_gc_marked() const;
286
287 // Forward pointer operations for scavenge
288 inline bool is_forwarded() const;
289 inline bool is_self_forwarded() const;
290
291 inline void forward_to(oop p);
292 inline void forward_to_self();
293
294 // Like "forward_to", but inserts the forwarding pointer atomically.
295 // Exactly one thread succeeds in inserting the forwarding pointer, and
296 // this call returns null for that thread; any other thread has the
297 // value of the forwarding pointer returned and does not modify "this".
298 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
299 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
300
301 inline oop forwardee() const;
302 inline oop forwardee(markWord header) const;
303
304 inline void unset_self_forwarded();
305
306 // Age of object during scavenge
307 inline uint age() const;
308 inline void incr_age();
309
310 template <typename OopClosureType>
311 inline void oop_iterate(OopClosureType* cl);
312
313 template <typename OopClosureType>
314 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
315
316 template <typename OopClosureType>
317 inline size_t oop_iterate_size(OopClosureType* cl);
318
319 template <typename OopClosureType>
320 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
321
322 template <typename OopClosureType>
323 inline void oop_iterate_backwards(OopClosureType* cl);
324
325 template <typename OopClosureType>
326 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
327
328 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
329
330 // identity hash; returns the identity hash key (computes it if necessary)
331 inline intptr_t identity_hash();
332 intptr_t slow_identity_hash();
333 inline bool fast_no_hash_check();
334
335 // marks are forwarded to stack when object is locked
336 inline bool has_displaced_mark() const;
337 inline markWord displaced_mark() const;
338 inline void set_displaced_mark(markWord m);
339
340 // Checks if the mark word needs to be preserved
341 inline bool mark_must_be_preserved() const;
342 inline bool mark_must_be_preserved(markWord m) const;
343
344 inline static bool has_klass_gap() {
345 return ObjLayout::oop_has_klass_gap();
346 }
347
348 // for code generation
349 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
350 static int klass_offset_in_bytes() {
351 #ifdef _LP64
352 if (UseCompactObjectHeaders) {
353 // NOTE: The only places where this is used with compact headers are the C2
354 // compiler and JVMCI.
355 return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
356 } else
357 #endif
358 {
359 return (int)offset_of(oopDesc, _metadata._klass);
360 }
361 }
362 static int klass_gap_offset_in_bytes() {
363 assert(has_klass_gap(), "only applicable to compressed klass pointers");
364 return klass_offset_in_bytes() + sizeof(narrowKlass);
365 }
366
367 static int base_offset_in_bytes() {
368 return ObjLayout::oop_base_offset_in_bytes();
369 }
370
371 // for error reporting
372 static void* load_oop_raw(oop obj, int offset);
373 };
374
375 // An oopDesc is not initialized via a constructor. Space is allocated in
376 // the Java heap, and static functions provided here on HeapWord* are used
377 // to fill in certain parts of that memory. The allocated memory is then
378 // treated as referring to an oopDesc. For that to be valid, the oopDesc
379 // class must have a trivial default constructor (C++14 3.8/1).
380 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
381
382 #endif // SHARE_OOPS_OOP_HPP