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
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
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 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 24 
 25 #ifndef SHARE_VM_OOPS_OOP_HPP
 26 #define SHARE_VM_OOPS_OOP_HPP
 27 
 28 #include "memory/iterator.hpp"
 29 #include "memory/memRegion.hpp"
 30 #include "oops/access.hpp"
 31 #include "oops/metadata.hpp"
 32 #include "runtime/atomic.hpp"
 33 #include "utilities/macros.hpp"
 34 
 35 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
 36 // the format of Java objects so the fields can be accessed from C++.
 37 // oopDesc is abstract.
 38 // (see oopHierarchy for complete oop class hierarchy)
 39 //
 40 // no virtual functions allowed
 41 
 42 extern bool always_do_update_barrier;
 43 
 44 // Forward declarations.
 45 class OopClosure;
 46 class ScanClosure;
 47 class FastScanClosure;
 48 class FilteringClosure;
 49 class BarrierSet;
 50 class CMSIsAliveClosure;
 51 
 52 class PSPromotionManager;
 53 class ParCompactionManager;
 54 
 55 class oopDesc {
 56   friend class VMStructs;
 57   friend class JVMCIVMStructs;
 58  private:
 59   volatile markOop _mark;
 60   union _metadata {
 61     Klass*      _klass;
 62     narrowKlass _compressed_klass;
 63   } _metadata;
 64 
 65  public:
 66   inline markOop  mark()          const;
 67   inline markOop  mark_raw()      const;
 68   inline markOop* mark_addr_raw() const;
 69 
 70   inline void set_mark(volatile markOop m);
 71   inline void set_mark_raw(volatile markOop m);
 72   static inline void set_mark_raw(HeapWord* mem, markOop m);
 73 
 74   inline void release_set_mark(markOop m);
 75   inline markOop cas_set_mark(markOop new_mark, markOop old_mark);
 76   inline markOop cas_set_mark_raw(markOop new_mark, markOop old_mark, atomic_memory_order order = memory_order_conservative);
 77 
 78   // Used only to re-initialize the mark word (e.g., of promoted
 79   // objects during a GC) -- requires a valid klass pointer
 80   inline void init_mark();
 81   inline void init_mark_raw();
 82 
 83   inline Klass* klass() const;
 84   inline Klass* klass_or_null() const volatile;
 85   inline Klass* klass_or_null_acquire() const volatile;
 86   static inline Klass** klass_addr(HeapWord* mem);
 87   static inline narrowKlass* compressed_klass_addr(HeapWord* mem);
 88   inline Klass** klass_addr();
 89   inline narrowKlass* compressed_klass_addr();
 90 
 91   inline void set_klass(Klass* k);
 92   static inline void release_set_klass(HeapWord* mem, Klass* klass);
 93 
 94   // For klass field compression
 95   inline int klass_gap() const;
 96   inline void set_klass_gap(int z);
 97   static inline void set_klass_gap(HeapWord* mem, int z);
 98   // For when the klass pointer is being used as a linked list "next" field.
 99   inline void set_klass_to_list_ptr(oop k);
100   inline oop list_ptr_from_klass();
101 
102   // size of object header, aligned to platform wordSize
103   static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
104 
105   // Returns whether this is an instance of k or an instance of a subclass of k
106   inline bool is_a(Klass* k) const;
107 
108   // Returns the actual oop size of the object
109   inline int size();
110 
111   // Sometimes (for complicated concurrency-related reasons), it is useful
112   // to be able to figure out the size of an object knowing its klass.
113   inline int size_given_klass(Klass* klass);
114 
115   // type test operations (inlined in oop.inline.hpp)
116   inline bool is_instance()            const;
117   inline bool is_array()               const;
118   inline bool is_objArray()            const;
119   inline bool is_typeArray()           const;
120 
121   // type test operations that don't require inclusion of oop.inline.hpp.
122   bool is_instance_noinline()          const;
123   bool is_array_noinline()             const;
124   bool is_objArray_noinline()          const;
125   bool is_typeArray_noinline()         const;
126 
127  protected:
128   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
129 
130  public:
131   // field addresses in oop
132   inline void* field_addr(int offset)     const;
133   inline void* field_addr_raw(int offset) const;
134 
135   // Need this as public for garbage collection.
136   template <class T> inline T* obj_field_addr_raw(int offset) const;
137 
138   template <typename T> inline size_t field_offset(T* p) const;
139 
140   // Standard compare function returns negative value if o1 < o2
141   //                                   0              if o1 == o2
142   //                                   positive value if o1 > o2
143   inline static int  compare(oop o1, oop o2) {
144     void* o1_addr = (void*)o1;
145     void* o2_addr = (void*)o2;
146     if (o1_addr < o2_addr) {
147       return -1;
148     } else if (o1_addr > o2_addr) {
149       return 1;
150     } else {
151       return 0;
152     }
153   }
154 
155   inline static bool equals(oop o1, oop o2) { return Access<>::equals(o1, o2); }
156 
157   // Access to fields in a instanceOop through these methods.
158   template <DecoratorSet decorator>
159   oop obj_field_access(int offset) const;
160   oop obj_field(int offset) const;
161   void obj_field_put(int offset, oop value);
162   void obj_field_put_raw(int offset, oop value);
163   void obj_field_put_volatile(int offset, oop value);
164 
165   Metadata* metadata_field(int offset) const;
166   Metadata* metadata_field_raw(int offset) const;
167   void metadata_field_put(int offset, Metadata* value);
168 
169   Metadata* metadata_field_acquire(int offset) const;
170   void release_metadata_field_put(int offset, Metadata* value);
171 
172   jbyte byte_field(int offset) const;
173   void byte_field_put(int offset, jbyte contents);
174 
175   jchar char_field(int offset) const;
176   void char_field_put(int offset, jchar contents);
177 
178   jboolean bool_field(int offset) const;
179   void bool_field_put(int offset, jboolean contents);
180 
181   jint int_field(int offset) const;
182   jint int_field_raw(int offset) const;
183   void int_field_put(int offset, jint contents);
184 
185   jshort short_field(int offset) const;
186   void short_field_put(int offset, jshort contents);
187 
188   jlong long_field(int offset) const;
189   void long_field_put(int offset, jlong contents);
190 
191   jfloat float_field(int offset) const;
192   void float_field_put(int offset, jfloat contents);
193 
194   jdouble double_field(int offset) const;
195   void double_field_put(int offset, jdouble contents);
196 
197   address address_field(int offset) const;
198   void address_field_put(int offset, address contents);
199 
200   oop obj_field_acquire(int offset) const;
201   void release_obj_field_put(int offset, oop value);
202 
203   jbyte byte_field_acquire(int offset) const;
204   void release_byte_field_put(int offset, jbyte contents);
205 
206   jchar char_field_acquire(int offset) const;
207   void release_char_field_put(int offset, jchar contents);
208 
209   jboolean bool_field_acquire(int offset) const;
210   void release_bool_field_put(int offset, jboolean contents);
211 
212   jint int_field_acquire(int offset) const;
213   void release_int_field_put(int offset, jint contents);
214 
215   jshort short_field_acquire(int offset) const;
216   void release_short_field_put(int offset, jshort contents);
217 
218   jlong long_field_acquire(int offset) const;
219   void release_long_field_put(int offset, jlong contents);
220 
221   jfloat float_field_acquire(int offset) const;
222   void release_float_field_put(int offset, jfloat contents);
223 
224   jdouble double_field_acquire(int offset) const;
225   void release_double_field_put(int offset, jdouble contents);
226 
227   address address_field_acquire(int offset) const;
228   void release_address_field_put(int offset, address contents);
229 
230   // printing functions for VM debugging
231   void print_on(outputStream* st) const;        // First level print
232   void print_value_on(outputStream* st) const;  // Second level print.
233   void print_address_on(outputStream* st) const; // Address printing
234 
235   // printing on default output stream
236   void print();
237   void print_value();
238   void print_address();
239 
240   // return the print strings
241   char* print_string();
242   char* print_value_string();
243 
244   // verification operations
245   static void verify_on(outputStream* st, oopDesc* oop_desc);
246   static void verify(oopDesc* oopDesc);
247 
248   // locking operations
249   inline bool is_locked()   const;
250   inline bool is_unlocked() const;
251   inline bool has_bias_pattern() const;
252   inline bool has_bias_pattern_raw() const;
253 
254   // asserts and guarantees
255   static bool is_oop(oop obj, bool ignore_mark_word = false);
256   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
257 #ifndef PRODUCT
258   inline bool is_unlocked_oop() const;
259   static bool is_archive_object(oop p) NOT_CDS_JAVA_HEAP_RETURN_(false);
260 #endif
261 
262   // garbage collection
263   inline bool is_gc_marked() const;
264 
265   // Forward pointer operations for scavenge
266   inline bool is_forwarded() const;
267 
268   inline void forward_to(oop p);
269   inline bool cas_forward_to(oop p, markOop compare, atomic_memory_order order = memory_order_conservative);
270 
271   // Like "forward_to", but inserts the forwarding pointer atomically.
272   // Exactly one thread succeeds in inserting the forwarding pointer, and
273   // this call returns "NULL" for that thread; any other thread has the
274   // value of the forwarding pointer returned and does not modify "this".
275   inline oop forward_to_atomic(oop p, atomic_memory_order order = memory_order_conservative);
276 
277   inline oop forwardee() const;
278   inline oop forwardee_acquire() const;
279 
280   // Age of object during scavenge
281   inline uint age() const;
282   inline void incr_age();
283 
284   // mark-sweep support
285   void follow_body(int begin, int end);
286 
287   template <typename OopClosureType>
288   inline void oop_iterate(OopClosureType* cl);
289 
290   template <typename OopClosureType>
291   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
292 
293   template <typename OopClosureType>
294   inline int oop_iterate_size(OopClosureType* cl);
295 
296   template <typename OopClosureType>
297   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
298 
299   template <typename OopClosureType>
300   inline void oop_iterate_backwards(OopClosureType* cl);
301 
302   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
303 
304   // identity hash; returns the identity hash key (computes it if necessary)
305   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
306   // safepoint if called on a biased object. Calling code must be aware of that.
307   inline intptr_t identity_hash();
308   intptr_t slow_identity_hash();
309 
310   // Alternate hashing code if string table is rehashed
311   unsigned int new_hash(juint seed);
312 
313   // marks are forwarded to stack when object is locked
314   inline bool    has_displaced_mark_raw() const;
315   inline markOop displaced_mark_raw() const;
316   inline void    set_displaced_mark_raw(markOop m);
317 
318   static bool has_klass_gap();
319 
320   // for code generation
321   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
322   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
323   static int klass_gap_offset_in_bytes() {
324     assert(has_klass_gap(), "only applicable to compressed klass pointers");
325     return klass_offset_in_bytes() + sizeof(narrowKlass);
326   }
327 };
328 
329 #endif // SHARE_VM_OOPS_OOP_HPP