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 "runtime/atomic.hpp"
35 #include "utilities/globalDefinitions.hpp"
36 #include "utilities/macros.hpp"
37 #include <type_traits>
38
39 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
40 // the format of Java objects so the fields can be accessed from C++.
41 // oopDesc is abstract.
42 // (see oopHierarchy for complete oop class hierarchy)
43 //
44 // no virtual functions allowed
45
46 // Forward declarations.
47 class OopClosure;
48 class FilteringClosure;
49
50 class PSPromotionManager;
51 class ParCompactionManager;
52
53 class oopDesc {
54 friend class VMStructs;
55 friend class JVMCIVMStructs;
56 private:
57 volatile markWord _mark;
58 union _metadata {
59 Klass* _klass;
60 narrowKlass _compressed_klass;
61 } _metadata;
62
63 // There may be ordering constraints on the initialization of fields that
64 // make use of the C++ copy/assign incorrect.
65 NONCOPYABLE(oopDesc);
66
67 public:
68 // Must be trivial; see verifying static assert after the class.
69 oopDesc() = default;
70
71 inline markWord mark() const;
72 inline markWord mark_acquire() const;
73 inline markWord* mark_addr() const;
74
75 inline void set_mark(markWord m);
76 static inline void set_mark(HeapWord* mem, markWord m);
77
78 inline void release_set_mark(markWord m);
79 static inline void release_set_mark(HeapWord* mem, markWord m);
80 inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
81 inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
82
83 inline markWord resolve_mark() const;
84
85 // Used only to re-initialize the mark word (e.g., of promoted
86 // objects during a GC) -- requires a valid klass pointer
87 inline void init_mark();
88
89 inline Klass* klass() const;
90 inline Klass* klass_or_null() const;
91 inline Klass* klass_or_null_acquire() const;
92 // Get the raw value without any checks.
93 inline Klass* klass_raw() const;
94
95 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
96 inline void set_klass(Klass* k);
97 static inline void release_set_klass(HeapWord* mem, Klass* k);
98
99 // For klass field compression
100 static inline void set_klass_gap(HeapWord* mem, int z);
101
102 // size of object header, aligned to platform wordSize
103 static int header_size() {
104 #ifdef _LP64
105 if (UseCompactObjectHeaders) {
106 return sizeof(markWord) / HeapWordSize;
107 } else
108 #endif
109 return sizeof(oopDesc)/HeapWordSize;
110 }
111
112 // Returns whether this is an instance of k or an instance of a subclass of k
113 inline bool is_a(Klass* k) const;
114
115 // Returns the actual oop size of the object in machine words
116 inline size_t size();
117
118 // Sometimes (for complicated concurrency-related reasons), it is useful
119 // to be able to figure out the size of an object knowing its klass.
120 inline size_t size_given_klass(Klass* klass);
121
122 // type test operations (inlined in oop.inline.hpp)
123 inline bool is_instance() const;
124 inline bool is_instanceRef() const;
125 inline bool is_stackChunk() const;
126 inline bool is_array() const;
127 inline bool is_objArray() const;
128 inline bool is_typeArray() const;
129
130 // type test operations that don't require inclusion of oop.inline.hpp.
131 bool is_instance_noinline() const;
132 bool is_instanceRef_noinline() const;
133 bool is_stackChunk_noinline() const;
134 bool is_array_noinline() const;
135 bool is_objArray_noinline() const;
136 bool is_typeArray_noinline() const;
137
138 protected:
139 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
140
141 public:
142 template<typename T>
143 inline T* field_addr(int offset) const;
144
145 template <typename T> inline size_t field_offset(T* p) const;
146
147 // Standard compare function returns negative value if o1 < o2
148 // 0 if o1 == o2
149 // positive value if o1 > o2
150 inline static int compare(oop o1, oop o2) {
151 void* o1_addr = (void*)o1;
152 void* o2_addr = (void*)o2;
153 if (o1_addr < o2_addr) {
154 return -1;
155 } else if (o1_addr > o2_addr) {
156 return 1;
157 } else {
158 return 0;
159 }
160 }
161
162 // Access to fields in a instanceOop through these methods.
163 template<DecoratorSet decorators>
164 oop obj_field_access(int offset) const;
165 oop obj_field(int offset) const;
166
167 void obj_field_put(int offset, oop value);
168 void obj_field_put_raw(int offset, oop value);
169 void obj_field_put_volatile(int offset, oop value);
170 template<DecoratorSet decorators>
171 void obj_field_put_access(int offset, oop value);
172
173 Metadata* metadata_field(int offset) const;
174 void metadata_field_put(int offset, Metadata* value);
175
176 Metadata* metadata_field_acquire(int offset) const;
177 void release_metadata_field_put(int offset, Metadata* value);
178
179 jbyte byte_field(int offset) const;
180 void byte_field_put(int offset, jbyte contents);
181
182 jchar char_field(int offset) const;
183 void char_field_put(int offset, jchar contents);
184
185 jboolean bool_field(int offset) const;
186 void bool_field_put(int offset, jboolean contents);
187 jboolean bool_field_volatile(int offset) const;
188 void bool_field_put_volatile(int offset, jboolean contents);
189
190 jint int_field(int offset) const;
191 void int_field_put(int offset, jint contents);
192
193 jshort short_field(int offset) const;
194 void short_field_put(int offset, jshort contents);
195
196 jlong long_field(int offset) const;
197 void long_field_put(int offset, jlong contents);
198
199 jfloat float_field(int offset) const;
200 void float_field_put(int offset, jfloat contents);
201
202 jdouble double_field(int offset) const;
203 void double_field_put(int offset, jdouble contents);
204
205 address address_field(int offset) const;
206 void address_field_put(int offset, address contents);
207
208 oop obj_field_acquire(int offset) const;
209 void release_obj_field_put(int offset, oop value);
210
211 jbyte byte_field_acquire(int offset) const;
212 void release_byte_field_put(int offset, jbyte contents);
213
214 jchar char_field_acquire(int offset) const;
215 void release_char_field_put(int offset, jchar contents);
216
217 jboolean bool_field_acquire(int offset) const;
218 void release_bool_field_put(int offset, jboolean contents);
219
220 jint int_field_acquire(int offset) const;
221 void release_int_field_put(int offset, jint contents);
222
223 jshort short_field_acquire(int offset) const;
224 void release_short_field_put(int offset, jshort contents);
225
226 jlong long_field_acquire(int offset) const;
227 void release_long_field_put(int offset, jlong contents);
228
229 jfloat float_field_acquire(int offset) const;
230 void release_float_field_put(int offset, jfloat contents);
231
232 jdouble double_field_acquire(int offset) const;
233 void release_double_field_put(int offset, jdouble contents);
234
235 address address_field_acquire(int offset) const;
236 void release_address_field_put(int offset, address contents);
237
238 // printing functions for VM debugging
239 void print_on(outputStream* st) const; // First level print
240 void print_value_on(outputStream* st) const; // Second level print.
241 void print_address_on(outputStream* st) const; // Address printing
242 void print_name_on(outputStream* st) const; // External name printing.
243
244 // printing on default output stream
245 void print();
246 void print_value();
247 void print_address();
248
249 // return the print strings
250 char* print_string();
251 char* print_value_string();
252
253 // verification operations
254 static void verify_on(outputStream* st, oopDesc* oop_desc);
255 static void verify(oopDesc* oopDesc);
256
257 // locking operations
258 inline bool is_locked() const;
259 inline bool is_unlocked() const;
260
261 // asserts and guarantees
262 static bool is_oop(oop obj, bool ignore_mark_word = false);
263 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
264
265 // garbage collection
266 inline bool is_gc_marked() const;
267
268 // Forward pointer operations for scavenge
269 inline bool is_forwarded() const;
270
271 void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
272
273 inline void forward_to(oop p);
274 inline void forward_to_self();
275
276 // Like "forward_to", but inserts the forwarding pointer atomically.
277 // Exactly one thread succeeds in inserting the forwarding pointer, and
278 // this call returns null for that thread; any other thread has the
279 // value of the forwarding pointer returned and does not modify "this".
280 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
281 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
282
283 inline oop forwardee() const;
284 inline oop forwardee(markWord header) const;
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 static bool has_klass_gap();
325
326 // for code generation
327 static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
328 static int klass_gap_offset_in_bytes() {
329 assert(has_klass_gap(), "only applicable to compressed klass pointers");
330 assert(!UseCompactObjectHeaders, "don't use klass_offset_in_bytes() with compact headers");
331 return klass_offset_in_bytes() + sizeof(narrowKlass);
332 }
333
334 static int klass_offset_in_bytes() {
335 #ifdef _LP64
336 if (UseCompactObjectHeaders) {
337 STATIC_ASSERT(markWord::klass_shift % 8 == 0);
338 return mark_offset_in_bytes() + markWord::klass_shift / 8;
339 } else
340 #endif
341 return offset_of(oopDesc, _metadata._klass);
342 }
343
344 static int base_offset_in_bytes() {
345 #ifdef _LP64
346 if (UseCompactObjectHeaders) {
347 // With compact headers, the Klass* field is not used for the Klass*
348 // and is used for the object fields instead.
349 assert(sizeof(markWord) == 8, "sanity");
350 return sizeof(markWord);
351 } else if (UseCompressedClassPointers) {
352 return sizeof(markWord) + sizeof(narrowKlass);
353 } else
354 #endif
355 return sizeof(oopDesc);
356 }
357
358 // for error reporting
359 static void* load_klass_raw(oop obj);
360 static void* load_oop_raw(oop obj, int offset);
361
362 DEBUG_ONLY(bool size_might_change();)
363 };
364
365 // An oopDesc is not initialized via a constructor. Space is allocated in
366 // the Java heap, and static functions provided here on HeapWord* are used
367 // to fill in certain parts of that memory. The allocated memory is then
368 // treated as referring to an oopDesc. For that to be valid, the oopDesc
369 // class must have a trivial default constructor (C++14 3.8/1).
370 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
371
372 #endif // SHARE_OOPS_OOP_HPP