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/compressedKlass.hpp"
31 #include "oops/accessDecorators.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 PSPromotionManager;
49 class ParCompactionManager;
50
51 class oopDesc {
52 friend class VMStructs;
53 friend class JVMCIVMStructs;
54 private:
55 volatile markWord _mark;
56 union _metadata {
57 Klass* _klass;
58 narrowKlass _compressed_klass;
59 } _metadata;
60
61 // There may be ordering constraints on the initialization of fields that
62 // make use of the C++ copy/assign incorrect.
63 NONCOPYABLE(oopDesc);
64
65 inline oop cas_set_forwardee(markWord new_mark, markWord old_mark, atomic_memory_order order);
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 static inline void release_set_mark(HeapWord* mem, markWord m);
78
79 inline void release_set_mark(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 // Returns the prototype mark that should be used for this object.
86 inline markWord prototype_mark() const;
87
88 // Used only to re-initialize the mark word (e.g., of promoted
89 // objects during a GC) -- requires a valid klass pointer
90 inline void init_mark();
91
92 inline Klass* klass() const;
93 inline Klass* klass_or_null() const;
94 inline Klass* klass_or_null_acquire() const;
95 // Get the klass without running any asserts.
96 inline Klass* klass_without_asserts() const;
97
98 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
99 inline void set_klass(Klass* k);
100 static inline void release_set_klass(HeapWord* mem, Klass* k);
101
102 // For klass field compression
103 static inline void set_klass_gap(HeapWord* mem, int z);
104
105 // size of object header, aligned to platform wordSize
106 static int header_size() {
107 if (UseCompactObjectHeaders) {
108 return sizeof(markWord) / HeapWordSize;
109 } else {
110 return sizeof(oopDesc)/HeapWordSize;
111 }
112 }
113
114 // Returns whether this is an instance of k or an instance of a subclass of k
115 inline bool is_a(Klass* k) const;
116
117 // Returns the actual oop size of the object in machine words
118 inline size_t size();
119
120 // Sometimes (for complicated concurrency-related reasons), it is useful
121 // to be able to figure out the size of an object knowing its klass.
122 inline size_t size_given_klass(Klass* klass);
123
124 // The following set of methods is used to access the mark-word and related
125 // properties when the object may be forwarded. Be careful where and when
126 // using this method. It assumes that the forwardee is installed in
127 // the header as a plain pointer (or self-forwarded). In particular,
128 // those methods can not deal with the sliding-forwarding that is used
129 // in Serial, G1 and Shenandoah full-GCs.
130 private:
131 inline Klass* forward_safe_klass_impl(markWord m) const;
132 public:
133 inline Klass* forward_safe_klass() const;
134 inline Klass* forward_safe_klass(markWord m) const;
135 inline size_t forward_safe_size();
136 inline void forward_safe_init_mark();
137
138 // type test operations (inlined in oop.inline.hpp)
139 inline bool is_instance() const;
140 inline bool is_instanceRef() const;
141 inline bool is_stackChunk() const;
142 inline bool is_array() const;
143 inline bool is_objArray() const;
144 inline bool is_typeArray() 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_typeArray_noinline() const;
153
154 protected:
155 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
156
157 public:
158 template<typename T>
159 inline T* field_addr(int offset) const;
160
161 template <typename T> inline size_t field_offset(T* p) const;
162
163 // Standard compare function returns negative value if o1 < o2
164 // 0 if o1 == o2
165 // positive value if o1 > o2
166 inline static int compare(oop o1, oop o2) {
167 void* o1_addr = (void*)o1;
168 void* o2_addr = (void*)o2;
169 if (o1_addr < o2_addr) {
170 return -1;
171 } else if (o1_addr > o2_addr) {
172 return 1;
173 } else {
174 return 0;
175 }
176 }
177
178 // Access to fields in a instanceOop through these methods.
179 template<DecoratorSet decorators>
180 oop obj_field_access(int offset) const;
181 oop obj_field(int offset) const;
182
183 void obj_field_put(int offset, oop value);
184 void obj_field_put_raw(int offset, oop value);
185 void obj_field_put_volatile(int offset, oop value);
186 template<DecoratorSet decorators>
187 void obj_field_put_access(int offset, oop value);
188
189 Metadata* metadata_field(int offset) const;
190 void metadata_field_put(int offset, Metadata* value);
191
192 Metadata* metadata_field_acquire(int offset) const;
193 void release_metadata_field_put(int offset, Metadata* value);
194
195 jbyte byte_field(int offset) const;
196 void byte_field_put(int offset, jbyte contents);
197
198 jchar char_field(int offset) const;
199 void char_field_put(int offset, jchar contents);
200
201 jboolean bool_field(int offset) const;
202 void bool_field_put(int offset, jboolean contents);
203 jboolean bool_field_volatile(int offset) const;
204 void bool_field_put_volatile(int offset, jboolean contents);
205
206 jint int_field(int offset) const;
207 void int_field_put(int offset, jint contents);
208
209 jshort short_field(int offset) const;
210 void short_field_put(int offset, jshort contents);
211
212 jlong long_field(int offset) const;
213 void long_field_put(int offset, jlong contents);
214
215 jfloat float_field(int offset) const;
216 void float_field_put(int offset, jfloat contents);
217
218 jdouble double_field(int offset) const;
219 void double_field_put(int offset, jdouble contents);
220
221 address address_field(int offset) const;
222 void address_field_put(int offset, address contents);
223
224 oop obj_field_acquire(int offset) const;
225 void release_obj_field_put(int offset, oop value);
226
227 jbyte byte_field_acquire(int offset) const;
228 void release_byte_field_put(int offset, jbyte contents);
229
230 jchar char_field_acquire(int offset) const;
231 void release_char_field_put(int offset, jchar contents);
232
233 jboolean bool_field_acquire(int offset) const;
234 void release_bool_field_put(int offset, jboolean contents);
235
236 jint int_field_relaxed(int offset) const;
237 void int_field_put_relaxed(int offset, jint contents);
238 jint int_field_acquire(int offset) const;
239 void release_int_field_put(int offset, jint contents);
240
241 jshort short_field_acquire(int offset) const;
242 void release_short_field_put(int offset, jshort contents);
243
244 jlong long_field_acquire(int offset) const;
245 void release_long_field_put(int offset, jlong contents);
246
247 jfloat float_field_acquire(int offset) const;
248 void release_float_field_put(int offset, jfloat contents);
249
250 jdouble double_field_acquire(int offset) const;
251 void release_double_field_put(int offset, jdouble contents);
252
253 address address_field_acquire(int offset) const;
254 void release_address_field_put(int offset, address contents);
255
256 // printing functions for VM debugging
257 void print_on(outputStream* st) const; // First level print
258 void print_value_on(outputStream* st) const; // Second level print.
259 void print_address_on(outputStream* st) const; // Address printing
260 void print_name_on(outputStream* st) const; // External name printing.
261
262 // printing on default output stream
263 void print();
264 void print_value();
265 void print_address();
266
267 // return the print strings
268 char* print_string();
269 char* print_value_string();
270
271 // verification operations
272 static void verify_on(outputStream* st, oopDesc* oop_desc);
273 static void verify(oopDesc* oopDesc);
274
275 // locking operations
276 inline bool is_locked() const;
277 inline bool is_unlocked() const;
278
279 // asserts and guarantees
280 static bool is_oop(oop obj, bool ignore_mark_word = false);
281 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
282
283 // garbage collection
284 inline bool is_gc_marked() const;
285
286 // Forward pointer operations for scavenge
287 inline bool is_forwarded() const;
288 inline bool is_self_forwarded() const;
289
290 inline void forward_to(oop p);
291 inline void forward_to_self();
292
293 // Like "forward_to", but inserts the forwarding pointer atomically.
294 // Exactly one thread succeeds in inserting the forwarding pointer, and
295 // this call returns null for that thread; any other thread has the
296 // value of the forwarding pointer returned and does not modify "this".
297 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
298 inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
299
300 inline oop forwardee() const;
301 inline oop forwardee(markWord header) const;
302
303 inline void unset_self_forwarded();
304
305 // Age of object during scavenge
306 inline uint age() const;
307 inline void incr_age();
308
309 template <typename OopClosureType>
310 inline void oop_iterate(OopClosureType* cl);
311
312 template <typename OopClosureType>
313 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
314
315 template <typename OopClosureType>
316 inline size_t oop_iterate_size(OopClosureType* cl);
317
318 template <typename OopClosureType>
319 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
320
321 template <typename OopClosureType>
322 inline void oop_iterate_backwards(OopClosureType* cl);
323
324 template <typename OopClosureType>
325 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
326
327 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
328
329 // identity hash; returns the identity hash key (computes it if necessary)
330 inline intptr_t identity_hash();
331 intptr_t slow_identity_hash();
332 inline bool fast_no_hash_check();
333
334 // marks are forwarded to stack when object is locked
335 inline bool has_displaced_mark() const;
336 inline markWord displaced_mark() const;
337 inline void set_displaced_mark(markWord m);
338
339 // Checks if the mark word needs to be preserved
340 inline bool mark_must_be_preserved() const;
341 inline bool mark_must_be_preserved(markWord m) const;
342
343 static bool has_klass_gap();
344
345 // for code generation
346 static int mark_offset_in_bytes() { return (int)offset_of(oopDesc, _mark); }
347 static int klass_offset_in_bytes() {
348 #ifdef _LP64
349 if (UseCompactObjectHeaders) {
350 constexpr int load_shift = markWord::klass_load_shift;
351 STATIC_ASSERT(load_shift % 8 == 0);
352 return mark_offset_in_bytes() + load_shift / 8;
353 } else
354 #endif
355 {
356 return (int)offset_of(oopDesc, _metadata._klass);
357 }
358 }
359 static int klass_gap_offset_in_bytes() {
360 assert(has_klass_gap(), "only applicable to compressed klass pointers");
361 assert(!UseCompactObjectHeaders, "don't use klass_offset_in_bytes() with compact headers");
362 return klass_offset_in_bytes() + sizeof(narrowKlass);
363 }
364
365 static int base_offset_in_bytes() {
366 #ifdef _LP64
367 if (UseCompactObjectHeaders) {
368 // With compact headers, the Klass* field is not used for the Klass*
369 // and is used for the object fields instead.
370 STATIC_ASSERT(sizeof(markWord) == 8);
371 return sizeof(markWord);
372 } else if (UseCompressedClassPointers) {
373 return sizeof(markWord) + sizeof(narrowKlass);
374 } else
375 #endif
376 {
377 return sizeof(oopDesc);
378 }
379 }
380
381 // for error reporting
382 static void* load_oop_raw(oop obj, int offset);
383
384 DEBUG_ONLY(bool size_might_change(Klass* klass);)
385 };
386
387 // An oopDesc is not initialized via a constructor. Space is allocated in
388 // the Java heap, and static functions provided here on HeapWord* are used
389 // to fill in certain parts of that memory. The allocated memory is then
390 // treated as referring to an oopDesc. For that to be valid, the oopDesc
391 // class must have a trivial default constructor (C++14 3.8/1).
392 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
393
394 #endif // SHARE_OOPS_OOP_HPP