1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   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
  21  * questions.
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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   void metadata_field_put(int offset, Metadata* value);
 167 
 168   Metadata* metadata_field_acquire(int offset) const;
 169   void release_metadata_field_put(int offset, Metadata* value);
 170 
 171   jbyte byte_field(int offset) const;
 172   void byte_field_put(int offset, jbyte contents);
 173 
 174   jchar char_field(int offset) const;
 175   void char_field_put(int offset, jchar contents);
 176 
 177   jboolean bool_field(int offset) const;
 178   void bool_field_put(int offset, jboolean contents);
 179 
 180   jint int_field(int offset) const;
 181   void int_field_put(int offset, jint contents);
 182 
 183   jshort short_field(int offset) const;
 184   void short_field_put(int offset, jshort contents);
 185 
 186   jlong long_field(int offset) const;
 187   void long_field_put(int offset, jlong contents);
 188 
 189   jfloat float_field(int offset) const;
 190   void float_field_put(int offset, jfloat contents);
 191 
 192   jdouble double_field(int offset) const;
 193   void double_field_put(int offset, jdouble contents);
 194 
 195   address address_field(int offset) const;
 196   void address_field_put(int offset, address contents);
 197 
 198   oop obj_field_acquire(int offset) const;
 199   void release_obj_field_put(int offset, oop value);
 200 
 201   jbyte byte_field_acquire(int offset) const;
 202   void release_byte_field_put(int offset, jbyte contents);
 203 
 204   jchar char_field_acquire(int offset) const;
 205   void release_char_field_put(int offset, jchar contents);
 206 
 207   jboolean bool_field_acquire(int offset) const;
 208   void release_bool_field_put(int offset, jboolean contents);
 209 
 210   jint int_field_acquire(int offset) const;
 211   void release_int_field_put(int offset, jint contents);
 212 
 213   jshort short_field_acquire(int offset) const;
 214   void release_short_field_put(int offset, jshort contents);
 215 
 216   jlong long_field_acquire(int offset) const;
 217   void release_long_field_put(int offset, jlong contents);
 218 
 219   jfloat float_field_acquire(int offset) const;
 220   void release_float_field_put(int offset, jfloat contents);
 221 
 222   jdouble double_field_acquire(int offset) const;
 223   void release_double_field_put(int offset, jdouble contents);
 224 
 225   address address_field_acquire(int offset) const;
 226   void release_address_field_put(int offset, address contents);
 227 
 228   // printing functions for VM debugging
 229   void print_on(outputStream* st) const;         // First level print
 230   void print_value_on(outputStream* st) const;   // Second level print.
 231   void print_address_on(outputStream* st) const; // Address printing
 232 
 233   // printing on default output stream
 234   void print();
 235   void print_value();
 236   void print_address();
 237 
 238   // return the print strings
 239   char* print_string();
 240   char* print_value_string();
 241 
 242   // verification operations
 243   void verify_on(outputStream* st);
 244   void verify();
 245 
 246   // locking operations
 247   inline bool is_locked()   const;
 248   inline bool is_unlocked() const;
 249   inline bool has_bias_pattern() const;
 250   inline bool has_bias_pattern_raw() const;
 251 
 252   // asserts and guarantees
 253   static bool is_oop(oop obj, bool ignore_mark_word = false);
 254   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
 255 #ifndef PRODUCT
 256   inline bool is_unlocked_oop() const;
 257 #endif
 258 
 259   // garbage collection
 260   inline bool is_gc_marked() const;
 261 
 262   // Forward pointer operations for scavenge
 263   inline bool is_forwarded() const;
 264 
 265   inline void forward_to(oop p);
 266   inline bool cas_forward_to(oop p, markOop compare, atomic_memory_order order = memory_order_conservative);
 267 
 268   // Like "forward_to", but inserts the forwarding pointer atomically.
 269   // Exactly one thread succeeds in inserting the forwarding pointer, and
 270   // this call returns "NULL" for that thread; any other thread has the
 271   // value of the forwarding pointer returned and does not modify "this".
 272   inline oop forward_to_atomic(oop p, atomic_memory_order order = memory_order_conservative);
 273 
 274   inline oop forwardee() const;
 275   inline oop forwardee_acquire() const;
 276 
 277   // Age of object during scavenge
 278   inline uint age() const;
 279   inline void incr_age();
 280 
 281   // mark-sweep support
 282   void follow_body(int begin, int end);
 283 
 284   // Garbage Collection support
 285 
 286 #if INCLUDE_PARALLELGC
 287   // Parallel Compact
 288   inline void pc_follow_contents(ParCompactionManager* cm);
 289   inline void pc_update_contents(ParCompactionManager* cm);
 290   // Parallel Scavenge
 291   inline void ps_push_contents(PSPromotionManager* pm);
 292 #endif
 293 
 294   template <typename OopClosureType>
 295   inline void oop_iterate(OopClosureType* cl);
 296 
 297   template <typename OopClosureType>
 298   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
 299 
 300   template <typename OopClosureType>
 301   inline int oop_iterate_size(OopClosureType* cl);
 302 
 303   template <typename OopClosureType>
 304   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
 305 
 306   template <typename OopClosureType>
 307   inline void oop_iterate_backwards(OopClosureType* cl);
 308 
 309   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
 310 
 311   // identity hash; returns the identity hash key (computes it if necessary)
 312   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 313   // safepoint if called on a biased object. Calling code must be aware of that.
 314   inline intptr_t identity_hash();
 315   intptr_t slow_identity_hash();
 316 
 317   // Alternate hashing code if string table is rehashed
 318   unsigned int new_hash(juint seed);
 319 
 320   // marks are forwarded to stack when object is locked
 321   inline bool    has_displaced_mark_raw() const;
 322   inline markOop displaced_mark_raw() const;
 323   inline void    set_displaced_mark_raw(markOop m);
 324 
 325   static bool has_klass_gap();
 326 
 327   // for code generation
 328   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
 329   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
 330   static int klass_gap_offset_in_bytes() {
 331     assert(has_klass_gap(), "only applicable to compressed klass pointers");
 332     return klass_offset_in_bytes() + sizeof(narrowKlass);
 333   }
 334 
 335   // for error reporting
 336   static oop   decode_oop_raw(narrowOop narrow_oop);
 337   static void* load_klass_raw(oop obj);
 338   static void* load_oop_raw(oop obj, int offset);
 339   static bool  is_valid(oop obj);
 340   static oop   oop_or_null(address addr);
 341 };
 342 
 343 #endif // SHARE_VM_OOPS_OOP_HPP