1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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/markWord.hpp"
32 #include "oops/metadata.hpp"
33 #include "runtime/atomic.hpp"
34 #include "utilities/globalDefinitions.hpp"
35 #include "utilities/macros.hpp"
36 #include <type_traits>
37
38 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
39 // the format of Java objects so the fields can be accessed from C++.
40 // oopDesc is abstract.
41 // (see oopHierarchy for complete oop class hierarchy)
42 //
43 // no virtual functions allowed
44 //
45 // oopDesc::_mark - the "oop mark word" encoding to be found separately in markWord.hpp
46 //
47 // oopDesc::_metadata - encodes the object's klass pointer, as a raw pointer in "_klass"
48 // or compressed pointer in "_compressed_klass"
49 //
50 // The overall size of the _metadata field is dependent on "UseCompressedClassPointers",
51 // hence the terms "narrow" (32 bits) vs "wide" (64 bits).
52 //
53
54
55 // Forward declarations.
56 class OopClosure;
57 class FilteringClosure;
58
59 class PSPromotionManager;
60 class ParCompactionManager;
61
62 class oopDesc {
63 friend class VMStructs;
64 friend class JVMCIVMStructs;
65 private:
66 volatile markWord _mark;
67 union _metadata {
68 Klass* _klass;
69 narrowKlass _compressed_klass;
70 } _metadata;
71
72 // There may be ordering constraints on the initialization of fields that
73 // make use of the C++ copy/assign incorrect.
74 NONCOPYABLE(oopDesc);
75
76 public:
77 // Must be trivial; see verifying static assert after the class.
78 oopDesc() = default;
79
80 inline markWord mark() const;
81 inline markWord mark_acquire() const;
82 inline markWord* mark_addr() const;
83
84 inline void set_mark(markWord m);
85 static inline void 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 // Used only to re-initialize the mark word (e.g., of promoted
92 // objects during a GC) -- requires a valid klass pointer
93 inline void init_mark();
94
95 inline Klass* klass() const;
96 inline Klass* klass_or_null() const;
97 inline Klass* klass_or_null_acquire() const;
98 // Get the raw value without any checks.
99 inline Klass* klass_raw() const;
100
101 void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
102 inline void set_klass(Klass* k);
103 static inline void release_set_klass(HeapWord* mem, Klass* k);
104
105 // For klass field compression
106 static inline void set_klass_gap(HeapWord* mem, int z);
107
108 // size of object header, aligned to platform wordSize
109 static constexpr int header_size() { return sizeof(oopDesc)/HeapWordSize; }
110
111 // Returns whether this is an instance of k or an instance of a subclass of k
112 inline bool is_a(Klass* k) const;
113
114 // Returns the actual oop size of the object in machine words
115 inline size_t size();
116
117 // Sometimes (for complicated concurrency-related reasons), it is useful
118 // to be able to figure out the size of an object knowing its klass.
119 inline size_t size_given_klass(Klass* klass);
120
121 // type test operations (inlined in oop.inline.hpp)
122 inline bool is_instance() const;
123 inline bool is_inline_type() 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 inline bool is_flatArray() const;
130 inline bool is_null_free_array() const;
131
132 // type test operations that don't require inclusion of oop.inline.hpp.
133 bool is_instance_noinline() const;
134 bool is_instanceRef_noinline() const;
135 bool is_stackChunk_noinline() const;
136 bool is_array_noinline() const;
137 bool is_objArray_noinline() const;
138 bool is_typeArray_noinline() const;
139 bool is_flatArray_noinline() const;
140 bool is_null_free_array_noinline() const;
141
142 protected:
143 inline oop as_oop() const { return const_cast<oopDesc*>(this); }
144
145 public:
146 template<typename T>
147 inline T* field_addr(int offset) const;
148
149 template <typename T> inline size_t field_offset(T* p) const;
150
151 // Standard compare function returns negative value if o1 < o2
152 // 0 if o1 == o2
153 // positive value if o1 > o2
154 inline static int compare(oop o1, oop o2) {
155 void* o1_addr = (void*)o1;
156 void* o2_addr = (void*)o2;
157 if (o1_addr < o2_addr) {
158 return -1;
159 } else if (o1_addr > o2_addr) {
160 return 1;
161 } else {
162 return 0;
163 }
164 }
165
166 // Access to fields in a instanceOop through these methods.
167 template<DecoratorSet decorators>
168 oop obj_field_access(int offset) const;
169 oop obj_field(int offset) const;
170
171 void obj_field_put(int offset, oop value);
172 void obj_field_put_raw(int offset, oop value);
173 void obj_field_put_volatile(int offset, oop value);
174 template<DecoratorSet decorators>
175 void obj_field_put_access(int offset, oop value);
176
177 Metadata* metadata_field(int offset) const;
178 void metadata_field_put(int offset, Metadata* value);
179
180 Metadata* metadata_field_acquire(int offset) const;
181 void release_metadata_field_put(int offset, Metadata* value);
182
183 jbyte byte_field(int offset) const;
184 void byte_field_put(int offset, jbyte contents);
185
186 jchar char_field(int offset) const;
187 void char_field_put(int offset, jchar contents);
188
189 jboolean bool_field(int offset) const;
190 void bool_field_put(int offset, jboolean contents);
191 jboolean bool_field_volatile(int offset) const;
192 void bool_field_put_volatile(int offset, jboolean contents);
193
194 jint int_field(int offset) const;
195 void int_field_put(int offset, jint contents);
196
197 jshort short_field(int offset) const;
198 void short_field_put(int offset, jshort contents);
199
200 jlong long_field(int offset) const;
201 void long_field_put(int offset, jlong contents);
202
203 jfloat float_field(int offset) const;
204 void float_field_put(int offset, jfloat contents);
205
206 jdouble double_field(int offset) const;
207 void double_field_put(int offset, jdouble contents);
208
209 address address_field(int offset) const;
210 void address_field_put(int offset, address contents);
211
212 oop obj_field_acquire(int offset) const;
213 void release_obj_field_put(int offset, oop value);
214
215 jbyte byte_field_acquire(int offset) const;
216 void release_byte_field_put(int offset, jbyte contents);
217
218 jchar char_field_acquire(int offset) const;
219 void release_char_field_put(int offset, jchar contents);
220
221 jboolean bool_field_acquire(int offset) const;
222 void release_bool_field_put(int offset, jboolean contents);
223
224 jint int_field_acquire(int offset) const;
225 void release_int_field_put(int offset, jint contents);
226
227 jshort short_field_acquire(int offset) const;
228 void release_short_field_put(int offset, jshort contents);
229
230 jlong long_field_acquire(int offset) const;
231 void release_long_field_put(int offset, jlong contents);
232
233 jfloat float_field_acquire(int offset) const;
234 void release_float_field_put(int offset, jfloat contents);
235
236 jdouble double_field_acquire(int offset) const;
237 void release_double_field_put(int offset, jdouble contents);
238
239 address address_field_acquire(int offset) const;
240 void release_address_field_put(int offset, address contents);
241
242 // printing functions for VM debugging
243 void print_on(outputStream* st) const; // First level print
244 void print_value_on(outputStream* st) const; // Second level print.
245 void print_address_on(outputStream* st) const; // Address printing
246 void print_name_on(outputStream* st) const; // External name printing.
247
248 // printing on default output stream
249 void print();
250 void print_value();
251 void print_address();
252
253 // return the print strings
254 char* print_string();
255 char* print_value_string();
256
257 // verification operations
258 static void verify_on(outputStream* st, oopDesc* oop_desc);
259 static void verify(oopDesc* oopDesc);
260
261 // locking operations
262 inline bool is_locked() const;
263 inline bool is_unlocked() const;
264
265 // asserts and guarantees
266 static bool is_oop(oop obj, bool ignore_mark_word = false);
267 static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
268
269 // garbage collection
270 inline bool is_gc_marked() const;
271
272 // Forward pointer operations for scavenge
273 inline bool is_forwarded() const;
274
275 inline void forward_to(oop p);
276
277 // Like "forward_to", but inserts the forwarding pointer atomically.
278 // Exactly one thread succeeds in inserting the forwarding pointer, and
279 // this call returns null for that thread; any other thread has the
280 // value of the forwarding pointer returned and does not modify "this".
281 inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
282
283 inline oop forwardee() const;
284
285 // Age of object during scavenge
286 inline uint age() const;
287 inline void incr_age();
288
289 template <typename OopClosureType>
290 inline void oop_iterate(OopClosureType* cl);
291
292 template <typename OopClosureType>
293 inline void oop_iterate(OopClosureType* cl, MemRegion mr);
294
295 template <typename OopClosureType>
296 inline size_t oop_iterate_size(OopClosureType* cl);
297
298 template <typename OopClosureType>
299 inline size_t oop_iterate_size(OopClosureType* cl, MemRegion mr);
300
301 template <typename OopClosureType>
302 inline void oop_iterate_backwards(OopClosureType* cl);
303
304 template <typename OopClosureType>
305 inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
306
307 inline static bool is_instanceof_or_null(oop obj, Klass* klass);
308
309 // identity hash; returns the identity hash key (computes it if necessary)
310 inline intptr_t identity_hash();
311 intptr_t slow_identity_hash();
312 inline bool fast_no_hash_check();
313
314 // marks are forwarded to stack when object is locked
315 inline bool has_displaced_mark() const;
316 inline markWord displaced_mark() const;
317 inline void set_displaced_mark(markWord m);
318
319 // Checks if the mark word needs to be preserved
320 inline bool mark_must_be_preserved() const;
321 inline bool mark_must_be_preserved(markWord m) const;
322
323 static bool has_klass_gap();
324
325 // for code generation
326 static int mark_offset_in_bytes() { return offset_of(oopDesc, _mark); }
327 static int klass_offset_in_bytes() { return offset_of(oopDesc, _metadata._klass); }
328 static int klass_gap_offset_in_bytes() {
329 assert(has_klass_gap(), "only applicable to compressed klass pointers");
330 return klass_offset_in_bytes() + sizeof(narrowKlass);
331 }
332
333 // for error reporting
334 static void* load_klass_raw(oop obj);
335 static void* load_oop_raw(oop obj, int offset);
336
337 DEBUG_ONLY(bool size_might_change();)
338 };
339
340 // An oopDesc is not initialized via a constructor. Space is allocated in
341 // the Java heap, and static functions provided here on HeapWord* are used
342 // to fill in certain parts of that memory. The allocated memory is then
343 // treated as referring to an oopDesc. For that to be valid, the oopDesc
344 // class must have a trivial default constructor (C++14 3.8/1).
345 static_assert(std::is_trivially_default_constructible<oopDesc>::value, "required");
346
347 #endif // SHARE_OOPS_OOP_HPP