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/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 // 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 void* base_addr();
79 inline const void* base_addr() const;
80
81 inline markWord mark() const;
82 inline markWord mark_acquire() const;
83
84 inline void set_mark(markWord m);
85 static inline void set_mark(HeapWord* mem, markWord m);
86 static inline void release_set_mark(HeapWord* mem, markWord m);
87
88 inline void release_set_mark(markWord m);
89 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
90 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
91
92 // Returns the prototype mark that should be used for this object.
93 inline markWord prototype_mark() const;
94
95 // Used only to re-initialize the mark word (e.g., of promoted
96 // objects during a GC) -- requires a valid klass pointer
97 inline void init_mark();
98 inline void reinit_mark(); // special for parallelGC
99
100 inline Klass* klass() const;
101 inline Klass* klass_or_null() const;
102 inline Klass* klass_or_null_acquire() const;
103 // Get the klass without running any asserts.
104 inline Klass* klass_without_asserts() const;
105
106 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
107 inline narrowKlass narrow_klass() const;
108 inline void set_klass(Klass* k);
109 static inline void release_set_klass(HeapWord* mem, Klass* k);
110
111 // For klass field compression
112 static inline void set_klass_gap(HeapWord* mem, int z);
113
114 // Size of object header, aligned to platform wordSize
115 static int header_size() {
116 if (UseCompactObjectHeaders) {
117 return sizeof(markWord) / HeapWordSize;
118 } else {
119 return sizeof(oopDesc) / HeapWordSize;
120 }
121 }
122
123 // Returns whether this is an instance of k or an instance of a subclass of k
124 inline bool is_a(Klass* k) const;
125
126 // Returns the actual oop size of the object in machine words
127 inline size_t size();
128
129 // Sometimes (for complicated concurrency-related reasons), it is useful
130 // to be able to figure out the size of an object knowing its klass.
131 inline size_t size_given_klass(Klass* klass);
132
133 // type test operations (inlined in oop.inline.hpp)
134 inline bool is_instance() const;
135 inline bool is_inline_type() const;
136 inline bool is_instanceRef() const;
137 inline bool is_stackChunk() const;
138 inline bool is_array() const;
139 inline bool is_objArray() const;
140 inline bool is_typeArray() const;
141 inline bool is_flatArray() const;
142 inline bool is_refArray() const;
143 inline bool is_null_free_array() const;
144 inline bool is_refined_objArray() const;
145
146 // type test operations that don't require inclusion of oop.inline.hpp.
147 bool is_instance_noinline() const;
148 bool is_instanceRef_noinline() const;
149 bool is_stackChunk_noinline() const;
150 bool is_array_noinline() const;
151 bool is_objArray_noinline() const;
152 bool is_refArray_noinline() const;
153 bool is_typeArray_noinline() const;
154 bool is_flatArray_noinline() const;
155 bool is_null_free_array_noinline() const;
156
157 protected:
158 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
159
160 public:
161 template<typename T>
162 inline T* field_addr(int offset) const;
163
164 template <typename T> inline size_t field_offset(T* p) const;
165
166 // Standard compare function returns negative value if o1 < o2
167 // 0 if o1 == o2
168 // positive value if o1 > o2
169 inline static int compare(oop o1, oop o2) {
170 void* o1_addr = (void*)o1;
171 void* o2_addr = (void*)o2;
172 if (o1_addr < o2_addr) {
173 return -1;
174 } else if (o1_addr > o2_addr) {
175 return 1;
176 } else {
177 return 0;
178 }
179 }
180
181 // Access to fields in a instanceOop through these methods.
182 template<DecoratorSet decorators>
183 oop obj_field_access(int offset) const;
184 oop obj_field(int offset) const;
185
186 void obj_field_put(int offset, oop value);
187 void obj_field_put_raw(int offset, oop value);
188 void obj_field_put_volatile(int offset, oop value);
189 template<DecoratorSet decorators>
190 void obj_field_put_access(int offset, oop value);
191
192 Metadata* metadata_field(int offset) const;
193 void metadata_field_put(int offset, Metadata* value);
194
195 Metadata* metadata_field_acquire(int offset) const;
196 void release_metadata_field_put(int offset, Metadata* value);
197
198 jbyte byte_field(int offset) const;
199 void byte_field_put(int offset, jbyte contents);
200
201 jchar char_field(int offset) const;
202 void char_field_put(int offset, jchar contents);
203
204 jboolean bool_field(int offset) const;
205 void bool_field_put(int offset, jboolean contents);
206 jboolean bool_field_volatile(int offset) const;
207 void bool_field_put_volatile(int offset, jboolean contents);
208
209 jint int_field(int offset) const;
210 void int_field_put(int offset, jint contents);
211
212 jshort short_field(int offset) const;
213 void short_field_put(int offset, jshort contents);
214
215 jlong long_field(int offset) const;
216 void long_field_put(int offset, jlong contents);
217
218 jfloat float_field(int offset) const;
219 void float_field_put(int offset, jfloat contents);
220
221 jdouble double_field(int offset) const;
222 void double_field_put(int offset, jdouble contents);
223
224 address address_field(int offset) const;
225 void address_field_put(int offset, address contents);
226
227 oop obj_field_acquire(int offset) const;
228 void release_obj_field_put(int offset, oop value);
229
230 jbyte byte_field_acquire(int offset) const;
231 void release_byte_field_put(int offset, jbyte contents);
232
233 jchar char_field_acquire(int offset) const;
234 void release_char_field_put(int offset, jchar contents);
235
236 jboolean bool_field_acquire(int offset) const;
237 void release_bool_field_put(int offset, jboolean contents);
238
239 jint int_field_relaxed(int offset) const;
240 void int_field_put_relaxed(int offset, jint contents);
241 jint int_field_acquire(int offset) const;
242 void release_int_field_put(int offset, jint contents);
243
244 jshort short_field_acquire(int offset) const;
245 void release_short_field_put(int offset, jshort contents);
246
247 jlong long_field_acquire(int offset) const;
248 void release_long_field_put(int offset, jlong contents);
249
250 jfloat float_field_acquire(int offset) const;
251 void release_float_field_put(int offset, jfloat contents);
252
253 jdouble double_field_acquire(int offset) const;
254 void release_double_field_put(int offset, jdouble contents);
255
256 address address_field_acquire(int offset) const;
257 void release_address_field_put(int offset, address contents);
258
259 // printing functions for VM debugging
260 void print_on(outputStream* st) const; // First level print
261 void print_value_on(outputStream* st) const; // Second level print.
262 void print_address_on(outputStream* st) const; // Address printing
263 void print_name_on(outputStream* st) const; // External name printing.
264
265 // printing on default output stream
266 void print();
267 void print_value();
268 void print_address();
269
270 // return the print strings
271 char* print_string();
272 char* print_value_string();
273
274 // verification operations
275 static void verify_on(outputStream* st, oopDesc* oop_desc);
276 static void verify(oopDesc* oopDesc);
277
278 // locking operations
279 inline bool is_locked() const;
280 inline bool is_unlocked() const;
281
282 // asserts and guarantees
283 static bool is_oop(oop obj);
284 static bool is_oop_or_null(oop obj);
285
286 // garbage collection
287 inline bool is_gc_marked() const;
288
289 // Forward pointer operations for scavenge
290 inline bool is_forwarded() const;
291 inline bool is_self_forwarded() const;
292
293 inline void forward_to(oop p);
294 inline void forward_to_self();
295
296 // Like "forward_to", but inserts the forwarding pointer atomically.
297 // Exactly one thread succeeds in inserting the forwarding pointer, and
298 // this call returns null for that thread; any other thread has the
299 // value of the forwarding pointer returned and does not modify "this".
300 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
301 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
302
303 inline oop forwardee() const;
304 inline oop forwardee(markWord header) const;
305
306 inline void unset_self_forwarded();
307
308 // Age of object during scavenge
309 inline uint age() const;
310 inline void incr_age();
311
312 template <typename OopClosureType>
313 inline void oop_iterate(OopClosureType* cl);
314
315 template <typename OopClosureType>
316 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
317
318 template <typename OopClosureType>
319 inline size_t oop_iterate_size(OopClosureType* cl);
320
321 template <typename OopClosureType>
322 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
323
324 template <typename OopClosureType>
325 inline void oop_iterate_backwards(OopClosureType* cl);
326
327 template <typename OopClosureType>
328 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
329
330 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
331
332 // identity hash; returns the identity hash key (computes it if necessary)
333 inline intptr_t identity_hash();
334 intptr_t slow_identity_hash();
335 inline bool fast_no_hash_check();
336
337 // marks are forwarded to stack when object is locked
338 inline bool has_displaced_mark() const;
339 inline markWord displaced_mark() const;
340 inline void set_displaced_mark(markWord m);
341
342 // Checks if the mark word needs to be preserved
343 inline bool mark_must_be_preserved() const;
344 inline bool mark_must_be_preserved(markWord m) const;
345
346 inline static bool has_klass_gap() {
347 return ObjLayout::oop_has_klass_gap();
348 }
349
350 // for code generation
351 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
352 static int klass_offset_in_bytes() {
353 #ifdef _LP64
354 if (UseCompactObjectHeaders) {
355 // NOTE: The only places where this is used with compact headers are the C2
356 // compiler and JVMCI.
357 return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
358 } else
359 #endif
360 {
361 return (int)offset_of(oopDesc, _metadata._klass);
362 }
363 }
364 static int klass_gap_offset_in_bytes() {
365 assert(has_klass_gap(), "only applicable to compressed klass pointers");
366 return klass_offset_in_bytes() + sizeof(narrowKlass);
367 }
368
369 static int base_offset_in_bytes() {
370 return ObjLayout::oop_base_offset_in_bytes();
371 }
372
373 // for error reporting
374 static void* load_oop_raw(oop obj, int offset);
375 };
376
377 // An oopDesc is not initialized via a constructor. Space is allocated in
378 // the Java heap, and static functions provided here on HeapWord* are used
379 // to fill in certain parts of that memory. The allocated memory is then
380 // treated as referring to an oopDesc. For that to be valid, the oopDesc
381 // class must have a trivial default constructor (C++14 3.8/1).
382 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
383
384 #endif // SHARE_OOPS_OOP_HPP