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_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 CMSIsAliveClosure;
  50 
  51 class PSPromotionManager;
  52 class ParCompactionManager;
  53 
  54 class oopDesc {
  55   friend class VMStructs;
  56   friend class JVMCIVMStructs;
  57  private:
  58   volatile markOop _mark;
  59   union _metadata {
  60     Klass*      _klass;
  61     narrowKlass _compressed_klass;
  62   } _metadata;
  63 
  64  public:
  65   inline markOop  mark()          const;
  66   inline markOop  mark_raw()      const;
  67   inline markOop* mark_addr_raw() const;
  68 
  69   inline void set_mark(volatile markOop m);
  70   inline void set_mark_raw(volatile markOop m);
  71   static inline void set_mark_raw(HeapWord* mem, markOop m);
  72 
  73   inline void release_set_mark(markOop m);
  74   inline markOop cas_set_mark(markOop new_mark, markOop old_mark);
  75   inline markOop cas_set_mark_raw(markOop new_mark, markOop old_mark, atomic_memory_order order = memory_order_conservative);
  76 
  77   // Used only to re-initialize the mark word (e.g., of promoted
  78   // objects during a GC) -- requires a valid klass pointer
  79   inline void init_mark();
  80   inline void init_mark_raw();
  81 
  82   inline Klass* klass() const;
  83   inline Klass* klass_or_null() const volatile;
  84   inline Klass* klass_or_null_acquire() const volatile;
  85   static inline Klass** klass_addr(HeapWord* mem);
  86   static inline narrowKlass* compressed_klass_addr(HeapWord* mem);
  87   inline Klass** klass_addr();
  88   inline narrowKlass* compressed_klass_addr();
  89 
  90   inline void set_klass(Klass* k);
  91   static inline void release_set_klass(HeapWord* mem, Klass* klass);
  92 
  93   // For klass field compression
  94   inline int klass_gap() const;
  95   inline void set_klass_gap(int z);
  96   static inline void set_klass_gap(HeapWord* mem, int z);
  97   // For when the klass pointer is being used as a linked list "next" field.
  98   inline void set_klass_to_list_ptr(oop k);
  99   inline oop list_ptr_from_klass();
 100 
 101   // size of object header, aligned to platform wordSize
 102   static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
 103 
 104   // Returns whether this is an instance of k or an instance of a subclass of k
 105   inline bool is_a(Klass* k) const;
 106 
 107   // Returns the actual oop size of the object
 108   inline int size();
 109 
 110   // Sometimes (for complicated concurrency-related reasons), it is useful
 111   // to be able to figure out the size of an object knowing its klass.
 112   inline int size_given_klass(Klass* klass);
 113 
 114   // type test operations (inlined in oop.inline.hpp)
 115   inline bool is_instance()            const;
 116   inline bool is_array()               const;
 117   inline bool is_objArray()            const;
 118   inline bool is_typeArray()           const;
 119 
 120   // type test operations that don't require inclusion of oop.inline.hpp.
 121   bool is_instance_noinline()          const;
 122   bool is_array_noinline()             const;
 123   bool is_objArray_noinline()          const;
 124   bool is_typeArray_noinline()         const;
 125 
 126  protected:
 127   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
 128 
 129  public:
 130   // field addresses in oop
 131   inline void* field_addr(int offset)     const;
 132   inline void* field_addr_raw(int offset) const;
 133 
 134   // Need this as public for garbage collection.
 135   template <class T> inline T* obj_field_addr_raw(int offset) const;
 136 
 137   template <typename T> inline size_t field_offset(T* p) const;
 138 
 139   // Standard compare function returns negative value if o1 < o2
 140   //                                   0              if o1 == o2
 141   //                                   positive value if o1 > o2
 142   inline static int  compare(oop o1, oop o2) {
 143     void* o1_addr = (void*)o1;
 144     void* o2_addr = (void*)o2;
 145     if (o1_addr < o2_addr) {
 146       return -1;
 147     } else if (o1_addr > o2_addr) {
 148       return 1;
 149     } else {
 150       return 0;
 151     }
 152   }
 153 
 154   inline static bool equals(oop o1, oop o2) { return Access<>::equals(o1, o2); }
 155 
 156   inline static bool unsafe_equals(oop o1, oop o2) {
 157 #ifdef CHECK_UNHANDLED_OOPS
 158     return o1.obj() == o2.obj();
 159 #else
 160     return o1 == o2;
 161 #endif
 162   }
 163 
 164   // Access to fields in a instanceOop through these methods.
 165   template <DecoratorSet decorator>
 166   oop obj_field_access(int offset) const;
 167   oop obj_field(int offset) const;
 168   void obj_field_put(int offset, oop value);
 169   void obj_field_put_raw(int offset, oop value);
 170   void obj_field_put_volatile(int offset, oop value);
 171 
 172   Metadata* metadata_field(int offset) const;
 173   void metadata_field_put(int offset, Metadata* value);
 174 
 175   Metadata* metadata_field_acquire(int offset) const;
 176   void release_metadata_field_put(int offset, Metadata* value);
 177 
 178   jbyte byte_field(int offset) const;
 179   void byte_field_put(int offset, jbyte contents);
 180 
 181   jchar char_field(int offset) const;
 182   void char_field_put(int offset, jchar contents);
 183 
 184   jboolean bool_field(int offset) const;
 185   void bool_field_put(int offset, jboolean contents);
 186 
 187   jint int_field(int offset) const;
 188   void int_field_put(int offset, jint contents);
 189 
 190   jshort short_field(int offset) const;
 191   void short_field_put(int offset, jshort contents);
 192 
 193   jlong long_field(int offset) const;
 194   void long_field_put(int offset, jlong contents);
 195 
 196   jfloat float_field(int offset) const;
 197   void float_field_put(int offset, jfloat contents);
 198 
 199   jdouble double_field(int offset) const;
 200   void double_field_put(int offset, jdouble contents);
 201 
 202   address address_field(int offset) const;
 203   void address_field_put(int offset, address contents);
 204 
 205   oop obj_field_acquire(int offset) const;
 206   void release_obj_field_put(int offset, oop value);
 207 
 208   jbyte byte_field_acquire(int offset) const;
 209   void release_byte_field_put(int offset, jbyte contents);
 210 
 211   jchar char_field_acquire(int offset) const;
 212   void release_char_field_put(int offset, jchar contents);
 213 
 214   jboolean bool_field_acquire(int offset) const;
 215   void release_bool_field_put(int offset, jboolean contents);
 216 
 217   jint int_field_acquire(int offset) const;
 218   void release_int_field_put(int offset, jint contents);
 219 
 220   jshort short_field_acquire(int offset) const;
 221   void release_short_field_put(int offset, jshort contents);
 222 
 223   jlong long_field_acquire(int offset) const;
 224   void release_long_field_put(int offset, jlong contents);
 225 
 226   jfloat float_field_acquire(int offset) const;
 227   void release_float_field_put(int offset, jfloat contents);
 228 
 229   jdouble double_field_acquire(int offset) const;
 230   void release_double_field_put(int offset, jdouble contents);
 231 
 232   address address_field_acquire(int offset) const;
 233   void release_address_field_put(int offset, address contents);
 234 
 235   // printing functions for VM debugging
 236   void print_on(outputStream* st) const;         // First level print
 237   void print_value_on(outputStream* st) const;   // Second level print.
 238   void print_address_on(outputStream* st) const; // Address printing
 239 
 240   // printing on default output stream
 241   void print();
 242   void print_value();
 243   void print_address();
 244 
 245   // return the print strings
 246   char* print_string();
 247   char* print_value_string();
 248 
 249   // verification operations
 250   void verify_on(outputStream* st);
 251   void verify();
 252 
 253   // locking operations
 254   inline bool is_locked()   const;
 255   inline bool is_unlocked() const;
 256   inline bool has_bias_pattern() const;
 257   inline bool has_bias_pattern_raw() const;
 258 
 259   // asserts and guarantees
 260   static bool is_oop(oop obj, bool ignore_mark_word = false);
 261   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
 262 #ifndef PRODUCT
 263   inline bool is_unlocked_oop() const;
 264 #endif
 265 
 266   // garbage collection
 267   inline bool is_gc_marked() const;
 268 
 269   // Forward pointer operations for scavenge
 270   inline bool is_forwarded() const;
 271 
 272   inline void forward_to(oop p);
 273   inline bool cas_forward_to(oop p, markOop compare, atomic_memory_order order = memory_order_conservative);
 274 
 275   // Like "forward_to", but inserts the forwarding pointer atomically.
 276   // Exactly one thread succeeds in inserting the forwarding pointer, and
 277   // this call returns "NULL" for that thread; any other thread has the
 278   // value of the forwarding pointer returned and does not modify "this".
 279   inline oop forward_to_atomic(oop p, atomic_memory_order order = memory_order_conservative);
 280 
 281   inline oop forwardee() const;
 282   inline oop forwardee_acquire() const;
 283 
 284   // Age of object during scavenge
 285   inline uint age() const;
 286   inline void incr_age();
 287 
 288   // mark-sweep support
 289   void follow_body(int begin, int end);
 290 
 291   // Garbage Collection support
 292 
 293 #if INCLUDE_PARALLELGC
 294   // Parallel Compact
 295   inline void pc_follow_contents(ParCompactionManager* cm);
 296   inline void pc_update_contents(ParCompactionManager* cm);
 297   // Parallel Scavenge
 298   inline void ps_push_contents(PSPromotionManager* pm);
 299 #endif
 300 
 301   template <typename OopClosureType>
 302   inline void oop_iterate(OopClosureType* cl);
 303 
 304   template <typename OopClosureType>
 305   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
 306 
 307   template <typename OopClosureType>
 308   inline int oop_iterate_size(OopClosureType* cl);
 309 
 310   template <typename OopClosureType>
 311   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
 312 
 313   template <typename OopClosureType>
 314   inline void oop_iterate_backwards(OopClosureType* cl);
 315 
 316   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
 317 
 318   // identity hash; returns the identity hash key (computes it if necessary)
 319   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 320   // safepoint if called on a biased object. Calling code must be aware of that.
 321   inline intptr_t identity_hash();
 322   intptr_t slow_identity_hash();
 323 
 324   // Alternate hashing code if string table is rehashed
 325   unsigned int new_hash(juint seed);
 326 
 327   // marks are forwarded to stack when object is locked
 328   inline bool    has_displaced_mark_raw() const;
 329   inline markOop displaced_mark_raw() const;
 330   inline void    set_displaced_mark_raw(markOop m);
 331 
 332   static bool has_klass_gap();
 333 
 334   // for code generation
 335   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
 336   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
 337   static int klass_gap_offset_in_bytes() {
 338     assert(has_klass_gap(), "only applicable to compressed klass pointers");
 339     return klass_offset_in_bytes() + sizeof(narrowKlass);
 340   }
 341 
 342   // for error reporting
 343   static oop   decode_oop_raw(narrowOop narrow_oop);
 344   static void* load_klass_raw(oop obj);
 345   static void* load_oop_raw(oop obj, int offset);
 346   static bool  is_valid(oop obj);
 347   static oop   oop_or_null(address addr);
 348 };
 349 
 350 #endif // SHARE_VM_OOPS_OOP_HPP