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_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.h)
 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  private:
 121   // field addresses in oop
 122   void*     field_base(int offset)        const;
 123 
 124   jbyte*    byte_field_addr(int offset)   const;
 125   jchar*    char_field_addr(int offset)   const;
 126   jboolean* bool_field_addr(int offset)   const;
 127   jint*     int_field_addr(int offset)    const;
 128   jshort*   short_field_addr(int offset)  const;
 129   jlong*    long_field_addr(int offset)   const;
 130   jfloat*   float_field_addr(int offset)  const;
 131   jdouble*  double_field_addr(int offset) const;
 132   Metadata** metadata_field_addr(int offset) const;
 133 
 134  public:
 135   // Need this as public for garbage collection.
 136   template <class T> T* obj_field_addr(int offset) const;
 137 
 138   // Needed for javaClasses
 139   address*  address_field_addr(int offset) const;
 140 
 141   static bool is_null(oop obj);
 142   static bool is_null(narrowOop obj);
 143   static bool is_null(Klass* obj);
 144 
 145   // Decode an oop pointer from a narrowOop if compressed.
 146   // These are overloaded for oop and narrowOop as are the other functions
 147   // below so that they can be called in template functions.
 148   static oop decode_heap_oop_not_null(oop v);
 149   static oop decode_heap_oop_not_null(narrowOop v);
 150   static oop decode_heap_oop(oop v);
 151   static oop decode_heap_oop(narrowOop v);
 152 
 153   // Encode an oop pointer to a narrow oop.  The or_null versions accept
 154   // null oop pointer, others do not in order to eliminate the
 155   // null checking branches.
 156   static narrowOop encode_heap_oop_not_null(oop v);
 157   static narrowOop encode_heap_oop(oop v);
 158 
 159   // Load an oop out of the Java heap
 160   static narrowOop load_heap_oop(narrowOop* p);
 161   static oop       load_heap_oop(oop* p);
 162 
 163   // Load an oop out of Java heap and decode it to an uncompressed oop.
 164   static oop load_decode_heap_oop_not_null(narrowOop* p);
 165   static oop load_decode_heap_oop_not_null(oop* p);
 166   static oop load_decode_heap_oop(narrowOop* p);
 167   static oop load_decode_heap_oop(oop* p);
 168 
 169   // Store an oop into the heap.
 170   static void store_heap_oop(narrowOop* p, narrowOop v);
 171   static void store_heap_oop(oop* p, oop v);
 172 
 173   // Encode oop if UseCompressedOops and store into the heap.
 174   static void encode_store_heap_oop_not_null(narrowOop* p, oop v);
 175   static void encode_store_heap_oop_not_null(oop* p, oop v);
 176   static void encode_store_heap_oop(narrowOop* p, oop v);
 177   static void encode_store_heap_oop(oop* p, oop v);
 178 
 179   static void release_store_heap_oop(volatile narrowOop* p, narrowOop v);
 180   static void release_store_heap_oop(volatile oop* p, oop v);
 181 
 182   static void release_encode_store_heap_oop_not_null(volatile narrowOop* p, oop v);
 183   static void release_encode_store_heap_oop_not_null(volatile oop* p, oop v);
 184   static void release_encode_store_heap_oop(volatile narrowOop* p, oop v);
 185   static void release_encode_store_heap_oop(volatile oop* p, oop v);
 186 
 187   static oop atomic_exchange_oop(oop exchange_value, volatile HeapWord *dest);
 188   static oop atomic_compare_exchange_oop(oop exchange_value,
 189                                          volatile HeapWord *dest,
 190                                          oop compare_value,
 191                                          bool prebarrier = false);
 192 
 193   // Access to fields in a instanceOop through these methods.
 194   oop obj_field(int offset) const;
 195   volatile oop obj_field_volatile(int offset) const;
 196   void obj_field_put(int offset, oop value);
 197   void obj_field_put_raw(int offset, oop value);
 198   void obj_field_put_volatile(int offset, oop value);
 199 
 200   Metadata* metadata_field(int offset) const;
 201   void metadata_field_put(int offset, Metadata* value);
 202 
 203   jbyte byte_field(int offset) const;
 204   void byte_field_put(int offset, jbyte contents);
 205 
 206   jchar char_field(int offset) const;
 207   void char_field_put(int offset, jchar contents);
 208 
 209   jboolean bool_field(int offset) const;
 210   void bool_field_put(int offset, jboolean contents);
 211 
 212   jint int_field(int offset) const;
 213   void int_field_put(int offset, jint contents);
 214   void int_field_put_raw(int offset, jint contents);
 215 
 216   jshort short_field(int offset) const;
 217   void short_field_put(int offset, jshort contents);
 218 
 219   jlong long_field(int offset) const;
 220   void long_field_put(int offset, jlong contents);
 221 
 222   jfloat float_field(int offset) const;
 223   void float_field_put(int offset, jfloat contents);
 224 
 225   jdouble double_field(int offset) const;
 226   void double_field_put(int offset, jdouble contents);
 227 
 228   address address_field(int offset) const;
 229   void address_field_put(int offset, address contents);
 230 
 231   oop obj_field_acquire(int offset) const;
 232   void release_obj_field_put(int offset, oop value);
 233 
 234   jbyte byte_field_acquire(int offset) const;
 235   void release_byte_field_put(int offset, jbyte contents);
 236 
 237   jchar char_field_acquire(int offset) const;
 238   void release_char_field_put(int offset, jchar contents);
 239 
 240   jboolean bool_field_acquire(int offset) const;
 241   void release_bool_field_put(int offset, jboolean contents);
 242 
 243   jint int_field_acquire(int offset) const;
 244   void release_int_field_put(int offset, jint contents);
 245 
 246   jshort short_field_acquire(int offset) const;
 247   void release_short_field_put(int offset, jshort contents);
 248 
 249   jlong long_field_acquire(int offset) const;
 250   void release_long_field_put(int offset, jlong contents);
 251 
 252   jfloat float_field_acquire(int offset) const;
 253   void release_float_field_put(int offset, jfloat contents);
 254 
 255   jdouble double_field_acquire(int offset) const;
 256   void release_double_field_put(int offset, jdouble contents);
 257 
 258   address address_field_acquire(int offset) const;
 259   void release_address_field_put(int offset, address contents);
 260 
 261   // printing functions for VM debugging
 262   void print_on(outputStream* st) const;         // First level print
 263   void print_value_on(outputStream* st) const;   // Second level print.
 264   void print_address_on(outputStream* st) const; // Address printing
 265 
 266   // printing on default output stream
 267   void print();
 268   void print_value();
 269   void print_address();
 270 
 271   // return the print strings
 272   char* print_string();
 273   char* print_value_string();
 274 
 275   // verification operations
 276   void verify_on(outputStream* st);
 277   void verify();
 278 
 279   // locking operations
 280   bool is_locked()   const;
 281   bool is_unlocked() const;
 282   bool has_bias_pattern() const;
 283 
 284   // asserts
 285   bool is_oop(bool ignore_mark_word = false) const;
 286   bool is_oop_or_null(bool ignore_mark_word = false) const;
 287 #ifndef PRODUCT
 288   bool is_unlocked_oop() const;
 289 #endif
 290 
 291   // garbage collection
 292   bool is_gc_marked() const;
 293   // Apply "MarkSweep::mark_and_push" to (the address of) every non-NULL
 294   // reference field in "this".
 295   void follow_contents(void);
 296 
 297 #if INCLUDE_ALL_GCS
 298   // Parallel Scavenge
 299   void push_contents(PSPromotionManager* pm);
 300 
 301   // Parallel Old
 302   void update_contents(ParCompactionManager* cm);
 303 
 304   void follow_contents(ParCompactionManager* cm);
 305 #endif // INCLUDE_ALL_GCS
 306 
 307   bool is_scavengable() const;
 308 
 309   // Forward pointer operations for scavenge
 310   bool is_forwarded() const;
 311 
 312   void forward_to(oop p);
 313   bool cas_forward_to(oop p, markOop compare);
 314 
 315 #if INCLUDE_ALL_GCS
 316   // Like "forward_to", but inserts the forwarding pointer atomically.
 317   // Exactly one thread succeeds in inserting the forwarding pointer, and
 318   // this call returns "NULL" for that thread; any other thread has the
 319   // value of the forwarding pointer returned and does not modify "this".
 320   oop forward_to_atomic(oop p);
 321 #endif // INCLUDE_ALL_GCS
 322 
 323   oop forwardee() const;
 324 
 325   // Age of object during scavenge
 326   uint age() const;
 327   void incr_age();
 328 
 329   // Adjust all pointers in this object to point at it's forwarded location and
 330   // return the size of this oop.  This is used by the MarkSweep collector.
 331   int adjust_pointers();
 332 
 333   // mark-sweep support
 334   void follow_body(int begin, int end);
 335 
 336   // Fast access to barrier set
 337   static BarrierSet* bs()            { return _bs; }
 338   static void set_bs(BarrierSet* bs) { _bs = bs; }
 339 
 340   // iterators, returns size of object
 341 #define OOP_ITERATE_DECL(OopClosureType, nv_suffix)                      \
 342   int oop_iterate(OopClosureType* blk);                                  \
 343   int oop_iterate(OopClosureType* blk, MemRegion mr);  // Only in mr.
 344 
 345   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_DECL)
 346   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_DECL)
 347 
 348 #if INCLUDE_ALL_GCS
 349 
 350 #define OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)            \
 351   int oop_iterate_backwards(OopClosureType* blk);
 352 
 353   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_BACKWARDS_DECL)
 354   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_BACKWARDS_DECL)
 355 #endif
 356 
 357   int oop_iterate_no_header(OopClosure* bk);
 358   int oop_iterate_no_header(OopClosure* bk, MemRegion mr);
 359 
 360   // identity hash; returns the identity hash key (computes it if necessary)
 361   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 362   // safepoint if called on a biased object. Calling code must be aware of that.
 363   intptr_t identity_hash();
 364   intptr_t slow_identity_hash();
 365 
 366   // Alternate hashing code if string table is rehashed
 367   unsigned int new_hash(juint seed);
 368 
 369   // marks are forwarded to stack when object is locked
 370   bool     has_displaced_mark() const;
 371   markOop  displaced_mark() const;
 372   void     set_displaced_mark(markOop m);
 373 
 374   // for code generation
 375   static int mark_offset_in_bytes()    { return offset_of(oopDesc, _mark); }
 376   static int klass_offset_in_bytes()   { return offset_of(oopDesc, _metadata._klass); }
 377   static int klass_gap_offset_in_bytes();
 378 };
 379 
 380 #endif // SHARE_VM_OOPS_OOP_HPP