1 /*
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  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  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
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 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
 20  * or visit www.oracle.com if you need additional information or have any
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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/macros.hpp"
 35 
 36 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
 37 // the format of Java objects so the fields can be accessed from C++.
 38 // oopDesc is abstract.
 39 // (see oopHierarchy for complete oop class hierarchy)
 40 //
 41 // no virtual functions allowed
 42 
 43 // Forward declarations.
 44 class OopClosure;
 45 class FilteringClosure;
 46 
 47 class PSPromotionManager;
 48 class ParCompactionManager;
 49 
 50 class oopDesc {
 51   friend class VMStructs;
 52   friend class JVMCIVMStructs;
 53  private:
 54   volatile markWord _mark;
 55   union _metadata {
 56     Klass*      _klass;
 57     narrowKlass _compressed_klass;
 58   } _metadata;
 59 
 60  public:
 61   inline markWord  mark()          const;
 62   inline markWord* mark_addr() const;
 63 
 64   inline void set_mark(markWord m);
 65   static inline void set_mark(HeapWord* mem, markWord m);
 66 
 67   inline void release_set_mark(markWord m);
 68   inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
 69   inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
 70 
 71   // Used only to re-initialize the mark word (e.g., of promoted
 72   // objects during a GC) -- requires a valid klass pointer
 73   inline void init_mark();
 74 
 75   inline Klass* klass() const;
 76   inline Klass* klass_or_null() const;
 77   inline Klass* klass_or_null_acquire() const;
 78 
 79   void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
 80   inline void set_klass(Klass* k);
 81   static inline void release_set_klass(HeapWord* mem, Klass* k);
 82 
 83   // For klass field compression
 84   inline int klass_gap() const;
 85   inline void set_klass_gap(int z);
 86   static inline void set_klass_gap(HeapWord* mem, int z);
 87 
 88   // size of object header, aligned to platform wordSize
 89   static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
 90 
 91   // Returns whether this is an instance of k or an instance of a subclass of k
 92   inline bool is_a(Klass* k) const;
 93 
 94   // Returns the actual oop size of the object
 95   inline int size();
 96 
 97   // Sometimes (for complicated concurrency-related reasons), it is useful
 98   // to be able to figure out the size of an object knowing its klass.
 99   inline int size_given_klass(Klass* klass);
100 
101   // type test operations (inlined in oop.inline.hpp)
102   inline bool is_instance()            const;
103   inline bool is_array()               const;
104   inline bool is_objArray()            const;
105   inline bool is_typeArray()           const;
106 
107   // type test operations that don't require inclusion of oop.inline.hpp.
108   bool is_instance_noinline()          const;
109   bool is_array_noinline()             const;
110   bool is_objArray_noinline()          const;
111   bool is_typeArray_noinline()         const;
112 
113  protected:
114   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
115 
116  public:
117   // field addresses in oop
118   inline void* field_addr(int offset) const;
119 
120   // Need this as public for garbage collection.
121   template <class T> inline T* obj_field_addr(int offset) const;
122 
123   template <typename T> inline size_t field_offset(T* p) const;
124 
125   // Standard compare function returns negative value if o1 < o2
126   //                                   0              if o1 == o2
127   //                                   positive value if o1 > o2
128   inline static int  compare(oop o1, oop o2) {
129     void* o1_addr = (void*)o1;
130     void* o2_addr = (void*)o2;
131     if (o1_addr < o2_addr) {
132       return -1;
133     } else if (o1_addr > o2_addr) {
134       return 1;
135     } else {
136       return 0;
137     }
138   }
139 
140   // Access to fields in a instanceOop through these methods.
141   template <DecoratorSet decorator>
142   oop obj_field_access(int offset) const;
143   oop obj_field(int offset) const;
144   void obj_field_put(int offset, oop value);
145   void obj_field_put_raw(int offset, oop value);
146   void obj_field_put_volatile(int offset, oop value);
147 
148   Metadata* metadata_field(int offset) const;
149   Metadata* metadata_field_raw(int offset) const;
150   void metadata_field_put(int offset, Metadata* value);
151 
152   Metadata* metadata_field_acquire(int offset) const;
153   void release_metadata_field_put(int offset, Metadata* value);
154 
155   jbyte byte_field(int offset) const;
156   void byte_field_put(int offset, jbyte contents);
157 
158   jchar char_field(int offset) const;
159   void char_field_put(int offset, jchar contents);
160 
161   jboolean bool_field(int offset) const;
162   void bool_field_put(int offset, jboolean contents);
163   jboolean bool_field_volatile(int offset) const;
164   void bool_field_put_volatile(int offset, jboolean contents);
165 
166   jint int_field(int offset) const;
167   jint int_field_raw(int offset) const;
168   void int_field_put(int offset, jint contents);
169 
170   jshort short_field(int offset) const;
171   void short_field_put(int offset, jshort contents);
172 
173   jlong long_field(int offset) const;
174   void long_field_put(int offset, jlong contents);
175 
176   jfloat float_field(int offset) const;
177   void float_field_put(int offset, jfloat contents);
178 
179   jdouble double_field(int offset) const;
180   void double_field_put(int offset, jdouble contents);
181 
182   address address_field(int offset) const;
183   void address_field_put(int offset, address contents);
184 
185   oop obj_field_acquire(int offset) const;
186   void release_obj_field_put(int offset, oop value);
187 
188   jbyte byte_field_acquire(int offset) const;
189   void release_byte_field_put(int offset, jbyte contents);
190 
191   jchar char_field_acquire(int offset) const;
192   void release_char_field_put(int offset, jchar contents);
193 
194   jboolean bool_field_acquire(int offset) const;
195   void release_bool_field_put(int offset, jboolean contents);
196 
197   jint int_field_acquire(int offset) const;
198   void release_int_field_put(int offset, jint contents);
199 
200   jshort short_field_acquire(int offset) const;
201   void release_short_field_put(int offset, jshort contents);
202 
203   jlong long_field_acquire(int offset) const;
204   void release_long_field_put(int offset, jlong contents);
205 
206   jfloat float_field_acquire(int offset) const;
207   void release_float_field_put(int offset, jfloat contents);
208 
209   jdouble double_field_acquire(int offset) const;
210   void release_double_field_put(int offset, jdouble contents);
211 
212   address address_field_acquire(int offset) const;
213   void release_address_field_put(int offset, address contents);
214 
215   // printing functions for VM debugging
216   void print_on(outputStream* st) const;        // First level print
217   void print_value_on(outputStream* st) const;  // Second level print.
218   void print_address_on(outputStream* st) const; // Address printing
219 
220   // printing on default output stream
221   void print();
222   void print_value();
223   void print_address();
224 
225   // return the print strings
226   char* print_string();
227   char* print_value_string();
228 
229   // verification operations
230   static void verify_on(outputStream* st, oopDesc* oop_desc);
231   static void verify(oopDesc* oopDesc);
232 
233   // locking operations
234   inline bool is_locked()   const;
235   inline bool is_unlocked() const;
236   inline bool has_bias_pattern() const;
237 
238   // asserts and guarantees
239   static bool is_oop(oop obj, bool ignore_mark_word = false);
240   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
241 
242   // garbage collection
243   inline bool is_gc_marked() const;
244 
245   // Forward pointer operations for scavenge
246   inline bool is_forwarded() const;
247 
248   void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
249 
250   inline void forward_to(oop p);
251   inline bool cas_forward_to(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
252 
253   // Like "forward_to", but inserts the forwarding pointer atomically.
254   // Exactly one thread succeeds in inserting the forwarding pointer, and
255   // this call returns "NULL" for that thread; any other thread has the
256   // value of the forwarding pointer returned and does not modify "this".
257   inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
258 
259   inline oop forwardee() const;
260 
261   // Age of object during scavenge
262   inline uint age() const;
263   inline void incr_age();
264 
265   template <typename OopClosureType>
266   inline void oop_iterate(OopClosureType* cl);
267 
268   template <typename OopClosureType>
269   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
270 
271   template <typename OopClosureType>
272   inline int oop_iterate_size(OopClosureType* cl);
273 
274   template <typename OopClosureType>
275   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
276 
277   template <typename OopClosureType>
278   inline void oop_iterate_backwards(OopClosureType* cl);
279 
280   template <typename OopClosureType>
281   inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
282 
283   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
284 
285   // identity hash; returns the identity hash key (computes it if necessary)
286   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
287   // safepoint if called on a biased object. Calling code must be aware of that.
288   inline intptr_t identity_hash();
289   intptr_t slow_identity_hash();
290 
291   // marks are forwarded to stack when object is locked
292   inline bool     has_displaced_mark() const;
293   inline markWord displaced_mark() const;
294   inline void     set_displaced_mark(markWord m);
295 
296   // Checks if the mark word needs to be preserved
297   inline bool mark_must_be_preserved() const;
298   inline bool mark_must_be_preserved(markWord m) const;
299   inline bool mark_must_be_preserved_for_promotion_failure(markWord m) const;
300 
301   static bool has_klass_gap();
302 
303   // for code generation
304   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
305   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
306   static int klass_gap_offset_in_bytes() {
307     assert(has_klass_gap(), "only applicable to compressed klass pointers");
308     return klass_offset_in_bytes() + sizeof(narrowKlass);
309   }
310 
311   // for error reporting
312   static void* load_klass_raw(oop obj);
313   static void* load_oop_raw(oop obj, int offset);
314 
315   // Avoid include gc_globals.hpp in oop.inline.hpp
316   DEBUG_ONLY(bool get_UseParallelGC();)
317   DEBUG_ONLY(bool get_UseG1GC();)
318 };
319 
320 #endif // SHARE_OOPS_OOP_HPP