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
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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_acquire()  const;
 63   inline markWord* mark_addr() const;
 64 
 65   inline void set_mark(markWord m);
 66   static inline void set_mark(HeapWord* mem, markWord m);
 67 
 68   inline void release_set_mark(markWord m);
 69   static inline void release_set_mark(HeapWord* mem, markWord m);
 70   inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
 71   inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
 72 
 73   inline markWord resolve_mark() const;
 74 
 75   // Used only to re-initialize the mark word (e.g., of promoted
 76   // objects during a GC) -- requires a valid klass pointer
 77   inline void init_mark();
 78 
 79   inline Klass* klass() const;
 80   inline Klass* klass_or_null() const;
 81   inline Klass* klass_or_null_acquire() const;
 82 
 83   void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
 84   inline void set_klass(Klass* k);
 85   static inline void release_set_klass(HeapWord* mem, Klass* k);
 86 
 87   // For klass field compression
 88   static inline void set_klass_gap(HeapWord* mem, int z);
 89 
 90   // size of object header, aligned to platform wordSize
 91   static int header_size() {
 92 #ifdef _LP64
 93     if (UseCompactObjectHeaders) {
 94       return sizeof(markWord) / HeapWordSize;
 95     } else
 96 #endif
 97     return sizeof(oopDesc)/HeapWordSize;
 98   }
 99 
100   // Returns whether this is an instance of k or an instance of a subclass of k
101   inline bool is_a(Klass* k) const;
102 
103   // Returns the actual oop size of the object
104   inline int size();
105 
106   // Sometimes (for complicated concurrency-related reasons), it is useful
107   // to be able to figure out the size of an object knowing its klass.
108   inline int size_given_klass(Klass* klass);
109 
110   // type test operations (inlined in oop.inline.hpp)
111   inline bool is_instance()            const;
112   inline bool is_array()               const;
113   inline bool is_objArray()            const;
114   inline bool is_typeArray()           const;
115 
116   // type test operations that don't require inclusion of oop.inline.hpp.
117   bool is_instance_noinline()          const;
118   bool is_array_noinline()             const;
119   bool is_objArray_noinline()          const;
120   bool is_typeArray_noinline()         const;
121 
122  protected:
123   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
124 
125  public:
126   // field addresses in oop
127   inline void* field_addr(int offset) const;
128 
129   // Need this as public for garbage collection.
130   template <class T> inline T* obj_field_addr(int offset) const;
131 
132   template <typename T> inline size_t field_offset(T* p) const;
133 
134   // Standard compare function returns negative value if o1 < o2
135   //                                   0              if o1 == o2
136   //                                   positive value if o1 > o2
137   inline static int  compare(oop o1, oop o2) {
138     void* o1_addr = (void*)o1;
139     void* o2_addr = (void*)o2;
140     if (o1_addr < o2_addr) {
141       return -1;
142     } else if (o1_addr > o2_addr) {
143       return 1;
144     } else {
145       return 0;
146     }
147   }
148 
149   // Access to fields in a instanceOop through these methods.
150   template <DecoratorSet decorator>
151   oop obj_field_access(int offset) const;
152   oop obj_field(int offset) const;
153   void obj_field_put(int offset, oop value);
154   void obj_field_put_raw(int offset, oop value);
155   void obj_field_put_volatile(int offset, oop value);
156 
157   Metadata* metadata_field(int offset) const;
158   Metadata* metadata_field_raw(int offset) const;
159   void metadata_field_put(int offset, Metadata* value);
160 
161   Metadata* metadata_field_acquire(int offset) const;
162   void release_metadata_field_put(int offset, Metadata* value);
163 
164   jbyte byte_field(int offset) const;
165   void byte_field_put(int offset, jbyte contents);
166 
167   jchar char_field(int offset) const;
168   void char_field_put(int offset, jchar contents);
169 
170   jboolean bool_field(int offset) const;
171   void bool_field_put(int offset, jboolean contents);
172   jboolean bool_field_volatile(int offset) const;
173   void bool_field_put_volatile(int offset, jboolean contents);
174 
175   jint int_field(int offset) const;
176   jint int_field_raw(int offset) const;
177   void int_field_put(int offset, jint contents);
178 
179   jshort short_field(int offset) const;
180   void short_field_put(int offset, jshort contents);
181 
182   jlong long_field(int offset) const;
183   void long_field_put(int offset, jlong contents);
184 
185   jfloat float_field(int offset) const;
186   void float_field_put(int offset, jfloat contents);
187 
188   jdouble double_field(int offset) const;
189   void double_field_put(int offset, jdouble contents);
190 
191   address address_field(int offset) const;
192   void address_field_put(int offset, address contents);
193 
194   oop obj_field_acquire(int offset) const;
195   void release_obj_field_put(int offset, oop value);
196 
197   jbyte byte_field_acquire(int offset) const;
198   void release_byte_field_put(int offset, jbyte contents);
199 
200   jchar char_field_acquire(int offset) const;
201   void release_char_field_put(int offset, jchar contents);
202 
203   jboolean bool_field_acquire(int offset) const;
204   void release_bool_field_put(int offset, jboolean contents);
205 
206   jint int_field_acquire(int offset) const;
207   void release_int_field_put(int offset, jint contents);
208 
209   jshort short_field_acquire(int offset) const;
210   void release_short_field_put(int offset, jshort contents);
211 
212   jlong long_field_acquire(int offset) const;
213   void release_long_field_put(int offset, jlong contents);
214 
215   jfloat float_field_acquire(int offset) const;
216   void release_float_field_put(int offset, jfloat contents);
217 
218   jdouble double_field_acquire(int offset) const;
219   void release_double_field_put(int offset, jdouble contents);
220 
221   address address_field_acquire(int offset) const;
222   void release_address_field_put(int offset, address contents);
223 
224   // printing functions for VM debugging
225   void print_on(outputStream* st) const;        // First level print
226   void print_value_on(outputStream* st) const;  // Second level print.
227   void print_address_on(outputStream* st) const; // Address printing
228 
229   // printing on default output stream
230   void print();
231   void print_value();
232   void print_address();
233 
234   // return the print strings
235   char* print_string();
236   char* print_value_string();
237 
238   // verification operations
239   static void verify_on(outputStream* st, oopDesc* oop_desc);
240   static void verify(oopDesc* oopDesc);
241 
242   // locking operations
243   inline bool is_locked()   const;
244   inline bool is_unlocked() const;
245   inline bool has_bias_pattern() const;
246 
247   // asserts and guarantees
248   static bool is_oop(oop obj, bool ignore_mark_word = false);
249   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
250 
251   // garbage collection
252   inline bool is_gc_marked() const;
253 
254   // Forward pointer operations for scavenge
255   inline bool is_forwarded() const;
256 
257   void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
258 
259   inline void forward_to(oop p);
260   inline bool cas_forward_to(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
261   inline void forward_to_self();
262 
263   // Like "forward_to", but inserts the forwarding pointer atomically.
264   // Exactly one thread succeeds in inserting the forwarding pointer, and
265   // this call returns "NULL" for that thread; any other thread has the
266   // value of the forwarding pointer returned and does not modify "this".
267   inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
268   inline oop forward_to_self_atomic(markWord compare, atomic_memory_order order = memory_order_conservative);
269 
270   inline oop forwardee() const;
271   inline oop forwardee(markWord header) const;
272 
273   // Age of object during scavenge
274   inline uint age() const;
275   inline void incr_age();
276 
277   template <typename OopClosureType>
278   inline void oop_iterate(OopClosureType* cl);
279 
280   template <typename OopClosureType>
281   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
282 
283   template <typename OopClosureType>
284   inline int oop_iterate_size(OopClosureType* cl);
285 
286   template <typename OopClosureType>
287   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
288 
289   template <typename OopClosureType>
290   inline void oop_iterate_backwards(OopClosureType* cl);
291 
292   template <typename OopClosureType>
293   inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
294 
295   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
296 
297   // identity hash; returns the identity hash key (computes it if necessary)
298   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
299   // safepoint if called on a biased object. Calling code must be aware of that.
300   inline intptr_t identity_hash();
301   intptr_t slow_identity_hash();
302 
303   // marks are forwarded to stack when object is locked
304   inline bool     has_displaced_mark() const;
305   inline markWord displaced_mark() const;
306   inline void     set_displaced_mark(markWord m);
307 
308   // Checks if the mark word needs to be preserved
309   inline bool mark_must_be_preserved() const;
310   inline bool mark_must_be_preserved(markWord m) const;
311   inline bool mark_must_be_preserved_for_promotion_failure(markWord m) const;
312 
313   static bool has_klass_gap();
314 
315   // for code generation
316   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
317   static int klass_gap_offset_in_bytes() {
318     assert(has_klass_gap(), "only applicable to compressed klass pointers");
319     assert(!UseCompactObjectHeaders, "don't use klass_offset_in_bytes() with compact headers");
320     return klass_offset_in_bytes() + sizeof(narrowKlass);
321   }
322 
323   static int klass_offset_in_bytes()     {
324 #ifdef _LP64
325     if (UseCompactObjectHeaders) {
326       STATIC_ASSERT(markWord::klass_shift % 8 == 0);
327       return mark_offset_in_bytes() + markWord::klass_shift / 8;
328     } else
329 #endif
330     return offset_of(oopDesc, _metadata._klass);
331   }
332 
333   static int base_offset_in_bytes() {
334 #ifdef _LP64
335     if (UseCompactObjectHeaders) {
336       // With compact headers, the Klass* field is not used for the Klass*
337       // and is used for the object fields instead.
338       assert(sizeof(markWord) == 8, "sanity");
339       return sizeof(markWord);
340     } else if (UseCompressedClassPointers) {
341       return sizeof(markWord) + sizeof(narrowKlass);
342     } else
343 #endif
344     return sizeof(oopDesc);
345   }
346 
347   // for error reporting
348   static void* load_klass_raw(oop obj);
349   static void* load_oop_raw(oop obj, int offset);
350 
351   // Avoid include gc_globals.hpp in oop.inline.hpp
352   DEBUG_ONLY(bool get_UseParallelGC();)
353   DEBUG_ONLY(bool get_UseG1GC();)
354 };
355 
356 #endif // SHARE_OOPS_OOP_HPP