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 // oopDesc::_mark - the "oop mark word" encoding to be found separately in markWord.hpp
48 //
49 // oopDesc::_metadata - encodes the object's klass pointer, as a raw pointer in "_klass"
50 // or compressed pointer in "_compressed_klass"
51 //
52 // The overall size of the _metadata field is dependent on "UseCompressedClassPointers",
53 // hence the terms "narrow" (32 bits) vs "wide" (64 bits).
54 //
55
56
57 class oopDesc {
58 friend class VMStructs;
59 friend class JVMCIVMStructs;
60 private:
61 volatile markWord _mark;
62 union _metadata {
63 Klass* _klass;
64 narrowKlass _compressed_klass;
65 } _metadata;
66
67 // There may be ordering constraints on the initialization of fields that
68 // make use of the C++ copy/assign incorrect.
69 NONCOPYABLE(oopDesc);
70
71 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
72
73 public:
74 // Must be trivial; see verifying static assert after the class.
75 oopDesc() = default;
76
77 inline void* base_addr();
78 inline const void* base_addr() const;
79
80 inline markWord mark() const;
81 inline markWord mark_acquire() const;
82
83 inline void set_mark(markWord m);
84 static inline void set_mark(HeapWord* mem, markWord m);
85 static inline void release_set_mark(HeapWord* mem, markWord m);
86
87 inline void release_set_mark(markWord m);
88 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
89 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
90
91 // Returns the prototype mark that should be used for this object.
92 inline markWord prototype_mark() const;
93
94 // Used only to re-initialize the mark word (e.g., of promoted
95 // objects during a GC) -- requires a valid klass pointer
96 inline void init_mark();
97 inline void reinit_mark(); // special for parallelGC
98
99 inline Klass* klass() const;
100 inline Klass* klass_or_null() const;
101 inline Klass* klass_or_null_acquire() const;
102 // Get the klass without running any asserts.
103 inline Klass* klass_without_asserts() const;
104
105 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
106 inline narrowKlass narrow_klass() const;
107 inline void set_klass(Klass* k);
108 static inline void release_set_klass(HeapWord* mem, Klass* k);
109
110 // For klass field compression
111 static inline void set_klass_gap(HeapWord* mem, int z);
112
113 // Size of object header, aligned to platform wordSize
114 static int header_size() {
115 if (UseCompactObjectHeaders) {
116 return sizeof(markWord) / HeapWordSize;
117 } else {
118 return sizeof(oopDesc) / HeapWordSize;
119 }
120 }
121
122 // Returns whether this is an instance of k or an instance of a subclass of k
123 inline bool is_a(Klass* k) const;
124
125 // Returns the actual oop size of the object in machine words
126 inline size_t size();
127
128 // Sometimes (for complicated concurrency-related reasons), it is useful
129 // to be able to figure out the size of an object knowing its klass.
130 inline size_t size_given_klass(Klass* klass);
131
132 // type test operations (inlined in oop.inline.hpp)
133 inline bool is_instance() const;
134 inline bool is_inline_type() const;
135 inline bool is_instanceRef() const;
136 inline bool is_stackChunk() const;
137 inline bool is_array() const;
138 inline bool is_objArray() const;
139 inline bool is_typeArray() const;
140 inline bool is_flatArray() const;
141 inline bool is_refArray() const;
142 inline bool is_null_free_array() const;
143 inline bool is_refined_objArray() const;
144
145 // type test operations that don't require inclusion of oop.inline.hpp.
146 bool is_instance_noinline() const;
147 bool is_instanceRef_noinline() const;
148 bool is_stackChunk_noinline() const;
149 bool is_array_noinline() const;
150 bool is_objArray_noinline() const;
151 bool is_refArray_noinline() const;
152 bool is_typeArray_noinline() const;
153 bool is_flatArray_noinline() const;
154 bool is_null_free_array_noinline() const;
155
156 protected:
157 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
158
159 public:
160 template<typename T>
161 inline T* field_addr(int offset) const;
162
163 template <typename T> inline size_t field_offset(T* p) const;
164
165 // Standard compare function returns negative value if o1 < o2
166 // 0 if o1 == o2
167 // positive value if o1 > o2
168 inline static int compare(oop o1, oop o2) {
169 void* o1_addr = (void*)o1;
170 void* o2_addr = (void*)o2;
171 if (o1_addr < o2_addr) {
172 return -1;
173 } else if (o1_addr > o2_addr) {
174 return 1;
175 } else {
176 return 0;
177 }
178 }
179
180 // Access to fields in a instanceOop through these methods.
181 template<DecoratorSet decorators>
182 oop obj_field_access(int offset) const;
183 oop obj_field(int offset) const;
184
185 void obj_field_put(int offset, oop value);
186 void obj_field_put_raw(int offset, oop value);
187 void obj_field_put_volatile(int offset, oop value);
188 template<DecoratorSet decorators>
189 void obj_field_put_access(int offset, oop value);
190
191 Metadata* metadata_field(int offset) const;
192 void metadata_field_put(int offset, Metadata* value);
193
194 Metadata* metadata_field_acquire(int offset) const;
195 void release_metadata_field_put(int offset, Metadata* value);
196
197 jbyte byte_field(int offset) const;
198 void byte_field_put(int offset, jbyte contents);
199
200 jchar char_field(int offset) const;
201 void char_field_put(int offset, jchar contents);
202
203 jboolean bool_field(int offset) const;
204 void bool_field_put(int offset, jboolean contents);
205 jboolean bool_field_volatile(int offset) const;
206 void bool_field_put_volatile(int offset, jboolean contents);
207
208 jint int_field(int offset) const;
209 void int_field_put(int offset, jint contents);
210
211 jshort short_field(int offset) const;
212 void short_field_put(int offset, jshort contents);
213
214 jlong long_field(int offset) const;
215 void long_field_put(int offset, jlong contents);
216
217 jfloat float_field(int offset) const;
218 void float_field_put(int offset, jfloat contents);
219
220 jdouble double_field(int offset) const;
221 void double_field_put(int offset, jdouble contents);
222
223 address address_field(int offset) const;
224 void address_field_put(int offset, address contents);
225
226 oop obj_field_acquire(int offset) const;
227 void release_obj_field_put(int offset, oop value);
228
229 jbyte byte_field_acquire(int offset) const;
230 void release_byte_field_put(int offset, jbyte contents);
231
232 jchar char_field_acquire(int offset) const;
233 void release_char_field_put(int offset, jchar contents);
234
235 jboolean bool_field_acquire(int offset) const;
236 void release_bool_field_put(int offset, jboolean contents);
237
238 jint int_field_relaxed(int offset) const;
239 void int_field_put_relaxed(int offset, jint contents);
240 jint int_field_acquire(int offset) const;
241 void release_int_field_put(int offset, jint contents);
242
243 jshort short_field_acquire(int offset) const;
244 void release_short_field_put(int offset, jshort contents);
245
246 jlong long_field_acquire(int offset) const;
247 void release_long_field_put(int offset, jlong contents);
248
249 jfloat float_field_acquire(int offset) const;
250 void release_float_field_put(int offset, jfloat contents);
251
252 jdouble double_field_acquire(int offset) const;
253 void release_double_field_put(int offset, jdouble contents);
254
255 address address_field_acquire(int offset) const;
256 void release_address_field_put(int offset, address contents);
257
258 // printing functions for VM debugging
259 void print_on(outputStream* st) const; // First level print
260 void print_value_on(outputStream* st) const; // Second level print.
261 void print_address_on(outputStream* st) const; // Address printing
262 void print_name_on(outputStream* st) const; // External name printing.
263
264 // printing on default output stream
265 void print();
266 void print_value();
267 void print_address();
268
269 // return the print strings
270 char* print_string();
271 char* print_value_string();
272
273 // verification operations
274 static void verify_on(outputStream* st, oopDesc* oop_desc);
275 static void verify(oopDesc* oopDesc);
276
277 // locking operations
278 inline bool is_locked() const;
279 inline bool is_unlocked() const;
280
281 // asserts and guarantees
282 static bool is_oop(oop obj);
283 static bool is_oop_or_null(oop obj);
284
285 // garbage collection
286 inline bool is_gc_marked() const;
287
288 // Forward pointer operations for scavenge
289 inline bool is_forwarded() const;
290 inline bool is_self_forwarded() const;
291
292 inline void forward_to(oop p);
293 inline void forward_to_self();
294
295 // Like "forward_to", but inserts the forwarding pointer atomically.
296 // Exactly one thread succeeds in inserting the forwarding pointer, and
297 // this call returns null for that thread; any other thread has the
298 // value of the forwarding pointer returned and does not modify "this".
299 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
300 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
301
302 inline oop forwardee() const;
303 inline oop forwardee(markWord header) const;
304
305 inline void unset_self_forwarded();
306
307 // Age of object during scavenge
308 inline uint age() const;
309 inline void incr_age();
310
311 template <typename OopClosureType>
312 inline void oop_iterate(OopClosureType* cl);
313
314 template <typename OopClosureType>
315 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
316
317 template <typename OopClosureType>
318 inline size_t oop_iterate_size(OopClosureType* cl);
319
320 template <typename OopClosureType>
321 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
322
323 template <typename OopClosureType>
324 inline void oop_iterate_backwards(OopClosureType* cl);
325
326 template <typename OopClosureType>
327 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
328
329 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
330
331 // identity hash; returns the identity hash key (computes it if necessary)
332 inline intptr_t identity_hash();
333 intptr_t slow_identity_hash();
334 inline bool fast_no_hash_check();
335
336 // marks are forwarded to stack when object is locked
337 inline bool has_displaced_mark() const;
338 inline markWord displaced_mark() const;
339 inline void set_displaced_mark(markWord m);
340
341 // Checks if the mark word needs to be preserved
342 inline bool mark_must_be_preserved() const;
343 inline bool mark_must_be_preserved(markWord m) const;
344
345 inline static bool has_klass_gap() {
346 return ObjLayout::oop_has_klass_gap();
347 }
348
349 // for code generation
350 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
351 static int klass_offset_in_bytes() {
352 #ifdef _LP64
353 if (UseCompactObjectHeaders) {
354 // NOTE: The only places where this is used with compact headers are the C2
355 // compiler and JVMCI.
356 return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
357 } else
358 #endif
359 {
360 return (int)offset_of(oopDesc, _metadata._klass);
361 }
362 }
363 static int klass_gap_offset_in_bytes() {
364 assert(has_klass_gap(), "only applicable to compressed klass pointers");
365 return klass_offset_in_bytes() + sizeof(narrowKlass);
366 }
367
368 static int base_offset_in_bytes() {
369 return ObjLayout::oop_base_offset_in_bytes();
370 }
371
372 // for error reporting
373 static void* load_oop_raw(oop obj, int offset);
374 };
375
376 // An oopDesc is not initialized via a constructor. Space is allocated in
377 // the Java heap, and static functions provided here on HeapWord* are used
378 // to fill in certain parts of that memory. The allocated memory is then
379 // treated as referring to an oopDesc. For that to be valid, the oopDesc
380 // class must have a trivial default constructor (C++14 3.8/1).
381 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
382
383 #endif // SHARE_OOPS_OOP_HPP