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.
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   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/access.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 ScanClosure;
  46 class FastScanClosure;
  47 class FilteringClosure;
  48 
  49 class PSPromotionManager;
  50 class ParCompactionManager;
  51 
  52 class oopDesc {
  53   friend class VMStructs;
  54   friend class JVMCIVMStructs;
  55  private:
  56   volatile markWord _mark;
  57   union _metadata {
  58     Klass*      _klass;
  59     narrowKlass _compressed_klass;
  60   } _metadata;
  61 
  62  public:
  63   inline markWord  mark()          const;
  64   inline markWord  mark_raw()      const;
  65   inline markWord* mark_addr_raw() const;
  66 
  67   inline void set_mark(markWord m);
  68   inline void set_mark_raw(markWord m);
  69   static inline void set_mark_raw(HeapWord* mem, markWord m);
  70 
  71   inline void release_set_mark(markWord m);
  72   inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
  73   inline markWord cas_set_mark_raw(markWord new_mark, markWord old_mark, atomic_memory_order order = memory_order_conservative);
  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   inline void init_mark_raw();
  79 
  80   inline Klass* klass() const;
  81   inline Klass* klass_or_null() const;
  82   inline Klass* klass_or_null_acquire() const;
  83   static inline Klass** klass_addr(HeapWord* mem);
  84   static inline narrowKlass* compressed_klass_addr(HeapWord* mem);
  85   inline Klass** klass_addr();
  86   inline narrowKlass* compressed_klass_addr();
  87 
  88   inline void set_klass(Klass* k);
  89   static inline void release_set_klass(HeapWord* mem, Klass* klass);
  90 
  91   // For klass field compression
  92   inline int klass_gap() const;
  93   inline void set_klass_gap(int z);
  94   static inline void set_klass_gap(HeapWord* mem, int z);
  95 
  96   // size of object header, aligned to platform wordSize
  97   static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
  98 
  99   // Returns whether this is an instance of k or an instance of a subclass of k
 100   inline bool is_a(Klass* k) const;
 101 
 102   // Returns the actual oop size of the object
 103   inline int size();
 104 
 105   // Sometimes (for complicated concurrency-related reasons), it is useful
 106   // to be able to figure out the size of an object knowing its klass.
 107   inline int size_given_klass(Klass* klass);
 108 
 109   // type test operations (inlined in oop.inline.hpp)
 110   inline bool is_instance()            const;
 111   inline bool is_array()               const;
 112   inline bool is_objArray()            const;
 113   inline bool is_typeArray()           const;
 114 
 115   // type test operations that don't require inclusion of oop.inline.hpp.
 116   bool is_instance_noinline()          const;
 117   bool is_array_noinline()             const;
 118   bool is_objArray_noinline()          const;
 119   bool is_typeArray_noinline()         const;
 120 
 121  protected:
 122   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
 123 
 124  public:
 125   // field addresses in oop
 126   inline void* field_addr(int offset)     const;
 127   inline void* field_addr_raw(int offset) const;
 128 
 129   // Need this as public for garbage collection.
 130   template <class T> inline T* obj_field_addr_raw(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   inline bool has_bias_pattern_raw() const;
 247 
 248   // asserts and guarantees
 249   static bool is_oop(oop obj, bool ignore_mark_word = false);
 250   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
 251 
 252   // garbage collection
 253   inline bool is_gc_marked() const;
 254 
 255   // Forward pointer operations for scavenge
 256   inline bool is_forwarded() const;
 257 
 258   void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
 259 
 260   inline void forward_to(oop p);
 261   inline bool cas_forward_to(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
 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 
 269   inline oop forwardee() const;
 270   inline oop forwardee_acquire() const;
 271 
 272   // Age of object during scavenge
 273   inline uint age() const;
 274   inline void incr_age();
 275 
 276   // mark-sweep support
 277   void follow_body(int begin, int end);
 278 
 279   template <typename OopClosureType>
 280   inline void oop_iterate(OopClosureType* cl);
 281 
 282   template <typename OopClosureType>
 283   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
 284 
 285   template <typename OopClosureType>
 286   inline int oop_iterate_size(OopClosureType* cl);
 287 
 288   template <typename OopClosureType>
 289   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
 290 
 291   template <typename OopClosureType>
 292   inline void oop_iterate_backwards(OopClosureType* cl);
 293 
 294   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
 295 
 296   // identity hash; returns the identity hash key (computes it if necessary)
 297   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 298   // safepoint if called on a biased object. Calling code must be aware of that.
 299   inline intptr_t identity_hash();
 300   intptr_t slow_identity_hash();
 301 
 302   // marks are forwarded to stack when object is locked
 303   inline bool     has_displaced_mark_raw() const;
 304   inline markWord displaced_mark_raw() const;
 305   inline void     set_displaced_mark_raw(markWord m);
 306 
 307   // Checks if the mark word needs to be preserved
 308   inline bool mark_must_be_preserved() const;
 309   inline bool mark_must_be_preserved(markWord m) const;
 310   inline bool mark_must_be_preserved_for_promotion_failure(markWord m) const;
 311 
 312   static bool has_klass_gap();
 313 
 314   // for code generation
 315   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
 316   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
 317   static int klass_gap_offset_in_bytes() {
 318     assert(has_klass_gap(), "only applicable to compressed klass pointers");
 319     return klass_offset_in_bytes() + sizeof(narrowKlass);
 320   }
 321 
 322   // for error reporting
 323   static void* load_klass_raw(oop obj);
 324   static void* load_oop_raw(oop obj, int offset);
 325 };
 326 
 327 #endif // SHARE_OOPS_OOP_HPP