1 /*
   2  * Copyright (c) 1997, 2014, 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_or_null_acquire() const volatile;
  87   Klass** klass_addr();
  88   narrowKlass* compressed_klass_addr();
  89 
  90   void set_klass(Klass* k);
  91   void release_set_klass(Klass* k);
  92 
  93   // For klass field compression
  94   int klass_gap() const;
  95   void set_klass_gap(int z);
  96   // For when the klass pointer is being used as a linked list "next" field.
  97   void set_klass_to_list_ptr(oop k);
  98   oop list_ptr_from_klass();
  99 
 100   // size of object header, aligned to platform wordSize
 101   static int header_size()          { return sizeof(oopDesc)/HeapWordSize; }
 102 
 103   // Returns whether this is an instance of k or an instance of a subclass of k
 104   bool is_a(Klass* k)  const;
 105 
 106   // Returns the actual oop size of the object
 107   int size();
 108 
 109   // Sometimes (for complicated concurrency-related reasons), it is useful
 110   // to be able to figure out the size of an object knowing its klass.
 111   int size_given_klass(Klass* klass);
 112 
 113   // type test operations (inlined in oop.inline.h)
 114   bool is_instance()            const;
 115   bool is_instanceMirror()      const;
 116   bool is_instanceClassLoader() const;
 117   bool is_instanceRef()         const;
 118   bool is_array()               const;
 119   bool is_objArray()            const;
 120   bool is_typeArray()           const;
 121 
 122  private:
 123   // field addresses in oop
 124   void*     field_base(int offset)        const;
 125 
 126   jbyte*    byte_field_addr(int offset)   const;
 127   jchar*    char_field_addr(int offset)   const;
 128   jboolean* bool_field_addr(int offset)   const;
 129   jint*     int_field_addr(int offset)    const;
 130   jshort*   short_field_addr(int offset)  const;
 131   jlong*    long_field_addr(int offset)   const;
 132   jfloat*   float_field_addr(int offset)  const;
 133   jdouble*  double_field_addr(int offset) const;
 134   Metadata** metadata_field_addr(int offset) const;
 135 
 136  public:
 137   // Need this as public for garbage collection.
 138   template <class T> T* obj_field_addr(int offset) const;
 139 
 140   // Needed for javaClasses
 141   address*  address_field_addr(int offset) const;
 142 
 143   static bool is_null(oop obj);
 144   static bool is_null(narrowOop obj);
 145   static bool is_null(Klass* obj);
 146 
 147   // Decode an oop pointer from a narrowOop if compressed.
 148   // These are overloaded for oop and narrowOop as are the other functions
 149   // below so that they can be called in template functions.
 150   static oop decode_heap_oop_not_null(oop v);
 151   static oop decode_heap_oop_not_null(narrowOop v);
 152   static oop decode_heap_oop(oop v);
 153   static oop decode_heap_oop(narrowOop v);
 154 
 155   // Encode an oop pointer to a narrow oop.  The or_null versions accept
 156   // null oop pointer, others do not in order to eliminate the
 157   // null checking branches.
 158   static narrowOop encode_heap_oop_not_null(oop v);
 159   static narrowOop encode_heap_oop(oop v);
 160 
 161   // Load an oop out of the Java heap
 162   static narrowOop load_heap_oop(narrowOop* p);
 163   static oop       load_heap_oop(oop* p);
 164 
 165   // Load an oop out of Java heap and decode it to an uncompressed oop.
 166   static oop load_decode_heap_oop_not_null(narrowOop* p);
 167   static oop load_decode_heap_oop_not_null(oop* p);
 168   static oop load_decode_heap_oop(narrowOop* p);
 169   static oop load_decode_heap_oop(oop* p);
 170 
 171   // Store an oop into the heap.
 172   static void store_heap_oop(narrowOop* p, narrowOop v);
 173   static void store_heap_oop(oop* p, oop v);
 174 
 175   // Encode oop if UseCompressedOops and store into the heap.
 176   static void encode_store_heap_oop_not_null(narrowOop* p, oop v);
 177   static void encode_store_heap_oop_not_null(oop* p, oop v);
 178   static void encode_store_heap_oop(narrowOop* p, oop v);
 179   static void encode_store_heap_oop(oop* p, oop v);
 180 
 181   static void release_store_heap_oop(volatile narrowOop* p, narrowOop v);
 182   static void release_store_heap_oop(volatile oop* p, oop v);
 183 
 184   static void release_encode_store_heap_oop_not_null(volatile narrowOop* p, oop v);
 185   static void release_encode_store_heap_oop_not_null(volatile oop* p, oop v);
 186   static void release_encode_store_heap_oop(volatile narrowOop* p, oop v);
 187   static void release_encode_store_heap_oop(volatile oop* p, oop v);
 188 
 189   static oop atomic_exchange_oop(oop exchange_value, volatile HeapWord *dest);
 190   static oop atomic_compare_exchange_oop(oop exchange_value,
 191                                          volatile HeapWord *dest,
 192                                          oop compare_value,
 193                                          bool prebarrier = false);
 194 
 195   // Access to fields in a instanceOop through these methods.
 196   oop obj_field(int offset) const;
 197   volatile oop obj_field_volatile(int offset) const;
 198   void obj_field_put(int offset, oop value);
 199   void obj_field_put_raw(int offset, oop value);
 200   void obj_field_put_volatile(int offset, oop value);
 201 
 202   Metadata* metadata_field(int offset) const;
 203   void metadata_field_put(int offset, Metadata* value);
 204 
 205   jbyte byte_field(int offset) const;
 206   void byte_field_put(int offset, jbyte contents);
 207 
 208   jchar char_field(int offset) const;
 209   void char_field_put(int offset, jchar contents);
 210 
 211   jboolean bool_field(int offset) const;
 212   void bool_field_put(int offset, jboolean contents);
 213 
 214   jint int_field(int offset) const;
 215   void int_field_put(int offset, jint contents);

 216 
 217   jshort short_field(int offset) const;
 218   void short_field_put(int offset, jshort contents);
 219 
 220   jlong long_field(int offset) const;
 221   void long_field_put(int offset, jlong contents);
 222 
 223   jfloat float_field(int offset) const;
 224   void float_field_put(int offset, jfloat contents);
 225 
 226   jdouble double_field(int offset) const;
 227   void double_field_put(int offset, jdouble contents);
 228 
 229   address address_field(int offset) const;
 230   void address_field_put(int offset, address contents);
 231 
 232   oop obj_field_acquire(int offset) const;
 233   void release_obj_field_put(int offset, oop value);
 234 
 235   jbyte byte_field_acquire(int offset) const;
 236   void release_byte_field_put(int offset, jbyte contents);
 237 
 238   jchar char_field_acquire(int offset) const;
 239   void release_char_field_put(int offset, jchar contents);
 240 
 241   jboolean bool_field_acquire(int offset) const;
 242   void release_bool_field_put(int offset, jboolean contents);
 243 
 244   jint int_field_acquire(int offset) const;
 245   void release_int_field_put(int offset, jint contents);
 246 
 247   jshort short_field_acquire(int offset) const;
 248   void release_short_field_put(int offset, jshort contents);
 249 
 250   jlong long_field_acquire(int offset) const;
 251   void release_long_field_put(int offset, jlong contents);
 252 
 253   jfloat float_field_acquire(int offset) const;
 254   void release_float_field_put(int offset, jfloat contents);
 255 
 256   jdouble double_field_acquire(int offset) const;
 257   void release_double_field_put(int offset, jdouble contents);
 258 
 259   address address_field_acquire(int offset) const;
 260   void release_address_field_put(int offset, address contents);
 261 
 262   // printing functions for VM debugging
 263   void print_on(outputStream* st) const;         // First level print
 264   void print_value_on(outputStream* st) const;   // Second level print.
 265   void print_address_on(outputStream* st) const; // Address printing
 266 
 267   // printing on default output stream
 268   void print();
 269   void print_value();
 270   void print_address();
 271 
 272   // return the print strings
 273   char* print_string();
 274   char* print_value_string();
 275 
 276   // verification operations
 277   void verify_on(outputStream* st);
 278   void verify();
 279 
 280   // locking operations
 281   bool is_locked()   const;
 282   bool is_unlocked() const;
 283   bool has_bias_pattern() const;
 284 
 285   // asserts
 286   bool is_oop(bool ignore_mark_word = false) const;
 287   bool is_oop_or_null(bool ignore_mark_word = false) const;
 288 #ifndef PRODUCT
 289   bool is_unlocked_oop() const;
 290 #endif
 291 
 292   // garbage collection
 293   bool is_gc_marked() const;
 294   // Apply "MarkSweep::mark_and_push" to (the address of) every non-NULL
 295   // reference field in "this".
 296   void follow_contents(void);
 297 
 298 #if INCLUDE_ALL_GCS
 299   // Parallel Scavenge
 300   void push_contents(PSPromotionManager* pm);
 301 
 302   // Parallel Old
 303   void update_contents(ParCompactionManager* cm);
 304 
 305   void follow_contents(ParCompactionManager* cm);
 306 #endif // INCLUDE_ALL_GCS
 307 
 308   bool is_scavengable() const;
 309 
 310   // Forward pointer operations for scavenge
 311   bool is_forwarded() const;
 312 
 313   void forward_to(oop p);
 314   bool cas_forward_to(oop p, markOop compare);
 315 
 316 #if INCLUDE_ALL_GCS
 317   // Like "forward_to", but inserts the forwarding pointer atomically.
 318   // Exactly one thread succeeds in inserting the forwarding pointer, and
 319   // this call returns "NULL" for that thread; any other thread has the
 320   // value of the forwarding pointer returned and does not modify "this".
 321   oop forward_to_atomic(oop p);
 322 #endif // INCLUDE_ALL_GCS
 323 
 324   oop forwardee() const;
 325 
 326   // Age of object during scavenge
 327   uint age() const;
 328   void incr_age();
 329 
 330   // Adjust all pointers in this object to point at it's forwarded location and
 331   // return the size of this oop.  This is used by the MarkSweep collector.
 332   int adjust_pointers();
 333 
 334   // mark-sweep support
 335   void follow_body(int begin, int end);
 336 
 337   // Fast access to barrier set
 338   static BarrierSet* bs()            { return _bs; }
 339   static void set_bs(BarrierSet* bs) { _bs = bs; }
 340 
 341   // iterators, returns size of object
 342 #define OOP_ITERATE_DECL(OopClosureType, nv_suffix)                      \
 343   int oop_iterate(OopClosureType* blk);                                  \
 344   int oop_iterate(OopClosureType* blk, MemRegion mr);  // Only in mr.
 345 
 346   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_DECL)
 347   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_DECL)
 348 
 349 #if INCLUDE_ALL_GCS
 350 
 351 #define OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)            \
 352   int oop_iterate_backwards(OopClosureType* blk);
 353 
 354   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_BACKWARDS_DECL)
 355   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_BACKWARDS_DECL)
 356 #endif
 357 
 358   int oop_iterate_no_header(OopClosure* bk);
 359   int oop_iterate_no_header(OopClosure* bk, MemRegion mr);
 360 
 361   // identity hash; returns the identity hash key (computes it if necessary)
 362   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 363   // safepoint if called on a biased object. Calling code must be aware of that.
 364   intptr_t identity_hash();
 365   intptr_t slow_identity_hash();
 366 
 367   // Alternate hashing code if string table is rehashed
 368   unsigned int new_hash(juint seed);
 369 
 370   // marks are forwarded to stack when object is locked
 371   bool     has_displaced_mark() const;
 372   markOop  displaced_mark() const;
 373   void     set_displaced_mark(markOop m);
 374 
 375   // for code generation
 376   static int mark_offset_in_bytes()    { return offset_of(oopDesc, _mark); }
 377   static int klass_offset_in_bytes()   { return offset_of(oopDesc, _metadata._klass); }
 378   static int klass_gap_offset_in_bytes();
 379 };
 380 
 381 #endif // SHARE_VM_OOPS_OOP_HPP
--- EOF ---