1 /*
   2  * Copyright (c) 1997, 2015, 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.
  22  *
  23  */
  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 "memory/specialized_oop_closures.hpp"
  31 #include "oops/metadata.hpp"
  32 #include "utilities/macros.hpp"
  33 #include "utilities/top.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 // store into oop with store check
  43 template <class T> void oop_store(T* p, oop v);
  44 template <class T> void oop_store(volatile T* p, oop v);
  45 
  46 extern bool always_do_update_barrier;
  47 
  48 // Forward declarations.
  49 class OopClosure;
  50 class ScanClosure;
  51 class FastScanClosure;
  52 class FilteringClosure;
  53 class BarrierSet;
  54 class CMSIsAliveClosure;
  55 
  56 class PSPromotionManager;
  57 class ParCompactionManager;
  58 
  59 class oopDesc {
  60   friend class VMStructs;
  61  private:
  62   volatile markOop  _mark;
  63   union _metadata {
  64     Klass*      _klass;
  65     narrowKlass _compressed_klass;
  66   } _metadata;
  67 
  68   // Fast access to barrier set.  Must be initialized.
  69   static BarrierSet* _bs;
  70 
  71  public:
  72   markOop  mark() const         { return _mark; }
  73   markOop* mark_addr() const    { return (markOop*) &_mark; }
  74 
  75   void set_mark(volatile markOop m)      { _mark = m;   }
  76 
  77   void    release_set_mark(markOop m);
  78   markOop cas_set_mark(markOop new_mark, markOop old_mark);
  79 
  80   // Used only to re-initialize the mark word (e.g., of promoted
  81   // objects during a GC) -- requires a valid klass pointer
  82   void init_mark();
  83 
  84   Klass* klass() const;
  85   Klass* klass_or_null() const volatile;
  86   Klass** klass_addr();
  87   narrowKlass* compressed_klass_addr();
  88 
  89   void set_klass(Klass* k);
  90 
  91   // For klass field compression
  92   int klass_gap() const;
  93   void set_klass_gap(int z);
  94   // For when the klass pointer is being used as a linked list "next" field.
  95   void set_klass_to_list_ptr(oop k);
  96   oop list_ptr_from_klass();
  97 
  98   // size of object header, aligned to platform wordSize
  99   static int header_size()          { return sizeof(oopDesc)/HeapWordSize; }
 100 
 101   // Returns whether this is an instance of k or an instance of a subclass of k
 102   bool is_a(Klass* k)  const;
 103 
 104   // Returns the actual oop size of the object
 105   int size();
 106 
 107   // Sometimes (for complicated concurrency-related reasons), it is useful
 108   // to be able to figure out the size of an object knowing its klass.
 109   int size_given_klass(Klass* klass);
 110 
 111   // type test operations (inlined in oop.inline.hpp)
 112   bool is_instance()            const;
 113   bool is_instanceMirror()      const;
 114   bool is_instanceClassLoader() const;
 115   bool is_instanceRef()         const;
 116   bool is_array()               const;
 117   bool is_objArray()            const;
 118   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_instanceMirror_noinline()    const;
 123   bool is_instanceClassLoader_noline() const;
 124   bool is_instanceRef_noline()         const;
 125   bool is_array_noinline()             const;
 126   bool is_objArray_noinline()          const;
 127   bool is_typeArray_noinline()         const;
 128 
 129  private:
 130   // field addresses in oop
 131   void*     field_base(int offset)        const;
 132 
 133   jbyte*    byte_field_addr(int offset)   const;
 134   jchar*    char_field_addr(int offset)   const;
 135   jboolean* bool_field_addr(int offset)   const;
 136   jint*     int_field_addr(int offset)    const;
 137   jshort*   short_field_addr(int offset)  const;
 138   jlong*    long_field_addr(int offset)   const;
 139   jfloat*   float_field_addr(int offset)  const;
 140   jdouble*  double_field_addr(int offset) const;
 141   Metadata** metadata_field_addr(int offset) const;
 142 
 143  public:
 144   // Need this as public for garbage collection.
 145   template <class T> T* obj_field_addr(int offset) const;
 146 
 147   // Needed for javaClasses
 148   address*  address_field_addr(int offset) const;
 149 
 150   static bool is_null(oop obj);
 151   static bool is_null(narrowOop obj);
 152   static bool is_null(Klass* obj);
 153 
 154   // Decode an oop pointer from a narrowOop if compressed.
 155   // These are overloaded for oop and narrowOop as are the other functions
 156   // below so that they can be called in template functions.
 157   static oop decode_heap_oop_not_null(oop v);
 158   static oop decode_heap_oop_not_null(narrowOop v);
 159   static oop decode_heap_oop(oop v);
 160   static oop decode_heap_oop(narrowOop v);
 161 
 162   // Encode an oop pointer to a narrow oop.  The or_null versions accept
 163   // null oop pointer, others do not in order to eliminate the
 164   // null checking branches.
 165   static narrowOop encode_heap_oop_not_null(oop v);
 166   static narrowOop encode_heap_oop(oop v);
 167 
 168   // Load an oop out of the Java heap
 169   static narrowOop load_heap_oop(narrowOop* p);
 170   static oop       load_heap_oop(oop* p);
 171 
 172   // Load an oop out of Java heap and decode it to an uncompressed oop.
 173   static oop load_decode_heap_oop_not_null(narrowOop* p);
 174   static oop load_decode_heap_oop_not_null(oop* p);
 175   static oop load_decode_heap_oop(narrowOop* p);
 176   static oop load_decode_heap_oop(oop* p);
 177 
 178   // Store an oop into the heap.
 179   static void store_heap_oop(narrowOop* p, narrowOop v);
 180   static void store_heap_oop(oop* p, oop v);
 181 
 182   // Encode oop if UseCompressedOops and store into the heap.
 183   static void encode_store_heap_oop_not_null(narrowOop* p, oop v);
 184   static void encode_store_heap_oop_not_null(oop* p, oop v);
 185   static void encode_store_heap_oop(narrowOop* p, oop v);
 186   static void encode_store_heap_oop(oop* p, oop v);
 187 
 188   static void release_store_heap_oop(volatile narrowOop* p, narrowOop v);
 189   static void release_store_heap_oop(volatile oop* p, oop v);
 190 
 191   static void release_encode_store_heap_oop_not_null(volatile narrowOop* p, oop v);
 192   static void release_encode_store_heap_oop_not_null(volatile oop* p, oop v);
 193   static void release_encode_store_heap_oop(volatile narrowOop* p, oop v);
 194   static void release_encode_store_heap_oop(volatile oop* p, oop v);
 195 
 196   static oop atomic_exchange_oop(oop exchange_value, volatile HeapWord *dest);
 197   static oop atomic_compare_exchange_oop(oop exchange_value,
 198                                          volatile HeapWord *dest,
 199                                          oop compare_value,
 200                                          bool prebarrier = false);
 201 
 202   // Access to fields in a instanceOop through these methods.
 203   oop obj_field(int offset) const;
 204   void obj_field_put(int offset, oop value);
 205   void obj_field_put_raw(int offset, oop value);
 206   void obj_field_put_volatile(int offset, oop value);
 207 
 208   Metadata* metadata_field(int offset) const;
 209   void metadata_field_put(int offset, Metadata* value);
 210 
 211   jbyte byte_field(int offset) const;
 212   void byte_field_put(int offset, jbyte contents);
 213 
 214   jchar char_field(int offset) const;
 215   void char_field_put(int offset, jchar contents);
 216 
 217   jboolean bool_field(int offset) const;
 218   void bool_field_put(int offset, jboolean contents);
 219 
 220   jint int_field(int offset) const;
 221   void int_field_put(int offset, jint contents);
 222 
 223   jshort short_field(int offset) const;
 224   void short_field_put(int offset, jshort contents);
 225 
 226   jlong long_field(int offset) const;
 227   void long_field_put(int offset, jlong contents);
 228 
 229   jfloat float_field(int offset) const;
 230   void float_field_put(int offset, jfloat contents);
 231 
 232   jdouble double_field(int offset) const;
 233   void double_field_put(int offset, jdouble contents);
 234 
 235   address address_field(int offset) const;
 236   void address_field_put(int offset, address contents);
 237 
 238   oop obj_field_acquire(int offset) const;
 239   void release_obj_field_put(int offset, oop value);
 240 
 241   jbyte byte_field_acquire(int offset) const;
 242   void release_byte_field_put(int offset, jbyte contents);
 243 
 244   jchar char_field_acquire(int offset) const;
 245   void release_char_field_put(int offset, jchar contents);
 246 
 247   jboolean bool_field_acquire(int offset) const;
 248   void release_bool_field_put(int offset, jboolean contents);
 249 
 250   jint int_field_acquire(int offset) const;
 251   void release_int_field_put(int offset, jint contents);
 252 
 253   jshort short_field_acquire(int offset) const;
 254   void release_short_field_put(int offset, jshort contents);
 255 
 256   jlong long_field_acquire(int offset) const;
 257   void release_long_field_put(int offset, jlong contents);
 258 
 259   jfloat float_field_acquire(int offset) const;
 260   void release_float_field_put(int offset, jfloat contents);
 261 
 262   jdouble double_field_acquire(int offset) const;
 263   void release_double_field_put(int offset, jdouble contents);
 264 
 265   address address_field_acquire(int offset) const;
 266   void release_address_field_put(int offset, address contents);
 267 
 268   // printing functions for VM debugging
 269   void print_on(outputStream* st) const;         // First level print
 270   void print_value_on(outputStream* st) const;   // Second level print.
 271   void print_address_on(outputStream* st) const; // Address printing
 272 
 273   // printing on default output stream
 274   void print();
 275   void print_value();
 276   void print_address();
 277 
 278   // return the print strings
 279   char* print_string();
 280   char* print_value_string();
 281 
 282   // verification operations
 283   void verify_on(outputStream* st);
 284   void verify();
 285 
 286   // locking operations
 287   bool is_locked()   const;
 288   bool is_unlocked() const;
 289   bool has_bias_pattern() const;
 290 
 291   // asserts
 292   bool is_oop(bool ignore_mark_word = false) const;
 293   bool is_oop_or_null(bool ignore_mark_word = false) const;
 294 #ifndef PRODUCT
 295   bool is_unlocked_oop() const;
 296 #endif
 297 
 298   // garbage collection
 299   bool is_gc_marked() const;
 300 
 301   bool is_scavengable() const;
 302 
 303   // Forward pointer operations for scavenge
 304   bool is_forwarded() const;
 305 
 306   void forward_to(oop p);
 307   bool cas_forward_to(oop p, markOop compare);
 308 
 309 #if INCLUDE_ALL_GCS
 310   // Like "forward_to", but inserts the forwarding pointer atomically.
 311   // Exactly one thread succeeds in inserting the forwarding pointer, and
 312   // this call returns "NULL" for that thread; any other thread has the
 313   // value of the forwarding pointer returned and does not modify "this".
 314   oop forward_to_atomic(oop p);
 315 #endif // INCLUDE_ALL_GCS
 316 
 317   oop forwardee() const;
 318 
 319   // Age of object during scavenge
 320   uint age() const;
 321   void incr_age();
 322 
 323 
 324   // mark-sweep support
 325   void follow_body(int begin, int end);
 326 
 327   // Fast access to barrier set
 328   static BarrierSet* bs()            { return _bs; }
 329   static void set_bs(BarrierSet* bs) { _bs = bs; }
 330 
 331   // Garbage Collection support
 332 
 333   // Mark Sweep
 334   void ms_follow_contents();
 335   // Adjust all pointers in this object to point at it's forwarded location and
 336   // return the size of this oop.  This is used by the MarkSweep collector.
 337   int  ms_adjust_pointers();
 338 #if INCLUDE_ALL_GCS
 339   // Parallel Compact
 340   void pc_follow_contents(ParCompactionManager* pc);
 341   void pc_update_contents();
 342   // Parallel Scavenge
 343   void ps_push_contents(PSPromotionManager* pm);
 344 #endif
 345 
 346 
 347   // iterators, returns size of object
 348 #define OOP_ITERATE_DECL(OopClosureType, nv_suffix)                      \
 349   int oop_iterate(OopClosureType* blk);                                  \
 350   int oop_iterate(OopClosureType* blk, MemRegion mr);  // Only in mr.
 351 
 352   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_DECL)
 353   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_DECL)
 354 
 355 #if INCLUDE_ALL_GCS
 356 
 357 #define OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)            \
 358   int oop_iterate_backwards(OopClosureType* blk);
 359 
 360   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_BACKWARDS_DECL)
 361   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_BACKWARDS_DECL)
 362 #endif
 363 
 364   int oop_iterate_no_header(OopClosure* bk);
 365   int oop_iterate_no_header(OopClosure* bk, MemRegion mr);
 366 
 367   // identity hash; returns the identity hash key (computes it if necessary)
 368   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 369   // safepoint if called on a biased object. Calling code must be aware of that.
 370   intptr_t identity_hash();
 371   intptr_t slow_identity_hash();
 372 
 373   // Alternate hashing code if string table is rehashed
 374   unsigned int new_hash(juint seed);
 375 
 376   // marks are forwarded to stack when object is locked
 377   bool     has_displaced_mark() const;
 378   markOop  displaced_mark() const;
 379   void     set_displaced_mark(markOop m);
 380 
 381   static bool has_klass_gap();
 382 
 383   // for code generation
 384   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
 385   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
 386   static int klass_gap_offset_in_bytes() {
 387     assert(has_klass_gap(), "only applicable to compressed klass pointers");
 388     return klass_offset_in_bytes() + sizeof(narrowKlass);
 389   }
 390 };
 391 
 392 #endif // SHARE_VM_OOPS_OOP_HPP