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.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_OOPS_OOP_HPP
  26 #define SHARE_VM_OOPS_OOP_HPP
  27 
  28 #include "gc/shared/specialized_oop_closures.hpp"
  29 #include "memory/iterator.hpp"
  30 #include "memory/memRegion.hpp"
  31 #include "oops/access.hpp"
  32 #include "oops/metadata.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   markOop  mark()      const { return _mark; }
  67   markOop* mark_addr() const { return (markOop*) &_mark; }
  68 
  69   void set_mark(volatile markOop m) { _mark = m; }
  70 
  71   inline void release_set_mark(markOop m);
  72   inline markOop cas_set_mark(markOop new_mark, markOop old_mark);
  73 
  74   // Used only to re-initialize the mark word (e.g., of promoted
  75   // objects during a GC) -- requires a valid klass pointer
  76   inline void init_mark();
  77 
  78   inline Klass* klass() const;
  79   inline Klass* klass_or_null() const volatile;
  80   inline Klass* klass_or_null_acquire() const volatile;
  81   inline Klass** klass_addr();
  82   inline narrowKlass* compressed_klass_addr();
  83 
  84   inline void set_klass(Klass* k);
  85   inline void release_set_klass(Klass* k);
  86 
  87   // For klass field compression
  88   inline int klass_gap() const;
  89   inline void set_klass_gap(int z);
  90   // For when the klass pointer is being used as a linked list "next" field.
  91   inline void set_klass_to_list_ptr(oop k);
  92   inline oop list_ptr_from_klass();
  93 
  94   // size of object header, aligned to platform wordSize
  95   static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
  96 
  97   // Returns whether this is an instance of k or an instance of a subclass of k
  98   inline bool is_a(Klass* k) const;
  99 
 100   // Returns the actual oop size of the object
 101   inline int size();
 102 
 103   // Sometimes (for complicated concurrency-related reasons), it is useful
 104   // to be able to figure out the size of an object knowing its klass.
 105   inline int size_given_klass(Klass* klass);
 106 
 107   // type test operations (inlined in oop.inline.hpp)
 108   inline bool is_instance()            const;
 109   inline bool is_array()               const;
 110   inline bool is_objArray()            const;
 111   inline bool is_typeArray()           const;
 112   inline bool is_value()               const;
 113   inline bool is_valueArray()          const;
 114 
 115   // type test operations that don't require inclusion of oop.inline.hpp.
 116   bool is_instance_noinline()          const;
 117   bool is_array_noinline()             const;
 118   bool is_objArray_noinline()          const;
 119   bool is_typeArray_noinline()         const;
 120   bool is_value_noinline()             const;
 121   bool is_valueArray_noinline()        const;
 122 
 123  protected:
 124   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
 125 
 126  public:
 127   // field addresses in oop
 128   inline void* field_addr(int offset)     const;
 129   inline void* field_addr_raw(int offset) const;
 130 
 131   // Need this as public for garbage collection.
 132   template <class T> inline T* obj_field_addr_raw(int offset) const;
 133 
 134   inline static bool is_null(oop obj)       { return obj == NULL; }
 135   inline static bool is_null(narrowOop obj) { return obj == 0; }
 136 
 137   // Standard compare function returns negative value if o1 < o2
 138   //                                   0              if o1 == o2
 139   //                                   positive value if o1 > o2
 140   inline static int  compare(oop o1, oop o2) {
 141     void* o1_addr = (void*)o1;
 142     void* o2_addr = (void*)o2;
 143     if (o1_addr < o2_addr) {
 144       return -1;
 145     } else if (o1_addr > o2_addr) {
 146       return 1;
 147     } else {
 148       return 0;
 149     }
 150   }
 151 
 152   // Decode an oop pointer from a narrowOop if compressed.
 153   // These are overloaded for oop and narrowOop as are the other functions
 154   // below so that they can be called in template functions.
 155   static inline oop decode_heap_oop_not_null(oop v) { return v; }
 156   static inline oop decode_heap_oop_not_null(narrowOop v);
 157   static inline oop decode_heap_oop(oop v) { return v; }
 158   static inline oop decode_heap_oop(narrowOop v);
 159 
 160   // Encode an oop pointer to a narrow oop. The or_null versions accept
 161   // null oop pointer, others do not in order to eliminate the
 162   // null checking branches.
 163   static inline narrowOop encode_heap_oop_not_null(oop v);
 164   static inline narrowOop encode_heap_oop(oop v);
 165 
 166   // Load an oop out of the Java heap as is without decoding.
 167   // Called by GC to check for null before decoding.
 168   static inline narrowOop load_heap_oop(narrowOop* p);
 169   static inline oop       load_heap_oop(oop* p);
 170 
 171   // Load an oop out of Java heap and decode it to an uncompressed oop.
 172   static inline oop load_decode_heap_oop_not_null(narrowOop* p);
 173   static inline oop load_decode_heap_oop_not_null(oop* p);
 174   static inline oop load_decode_heap_oop(narrowOop* p);
 175   static inline oop load_decode_heap_oop(oop* p);
 176 
 177   // Store already encoded heap oop into the heap.
 178   static inline void store_heap_oop(narrowOop* p, narrowOop v);
 179   static inline void store_heap_oop(oop* p, oop v);
 180 
 181   // Encode oop if UseCompressedOops and store into the heap.
 182   static inline void encode_store_heap_oop_not_null(narrowOop* p, oop v);
 183   static inline void encode_store_heap_oop_not_null(oop* p, oop v);
 184   static inline void encode_store_heap_oop(narrowOop* p, oop v);
 185   static inline void encode_store_heap_oop(oop* p, oop v);
 186 
 187   // Access to fields in a instanceOop through these methods.
 188   template <DecoratorSet decorator>
 189   oop obj_field_access(int offset) const;
 190   oop obj_field(int offset) const;
 191   void obj_field_put(int offset, oop value);
 192   void obj_field_put_raw(int offset, oop value);
 193   void obj_field_put_volatile(int offset, oop value);
 194 
 195   Metadata* metadata_field(int offset) const;
 196   void metadata_field_put(int offset, Metadata* value);
 197 
 198   Metadata* metadata_field_acquire(int offset) const;
 199   void release_metadata_field_put(int offset, Metadata* value);
 200 
 201   jbyte byte_field(int offset) const;
 202   void byte_field_put(int offset, jbyte contents);
 203 
 204   jchar char_field(int offset) const;
 205   void char_field_put(int offset, jchar contents);
 206 
 207   jboolean bool_field(int offset) const;
 208   void bool_field_put(int offset, jboolean contents);
 209 
 210   jint int_field(int offset) const;
 211   void int_field_put(int offset, jint contents);
 212 
 213   jshort short_field(int offset) const;
 214   void short_field_put(int offset, jshort contents);
 215 
 216   jlong long_field(int offset) const;
 217   void long_field_put(int offset, jlong contents);
 218 
 219   jfloat float_field(int offset) const;
 220   void float_field_put(int offset, jfloat contents);
 221 
 222   jdouble double_field(int offset) const;
 223   void double_field_put(int offset, jdouble contents);
 224 
 225   address address_field(int offset) const;
 226   void address_field_put(int offset, address contents);
 227 
 228   oop obj_field_acquire(int offset) const;
 229   void release_obj_field_put(int offset, oop value);
 230 
 231   jbyte byte_field_acquire(int offset) const;
 232   void release_byte_field_put(int offset, jbyte contents);
 233 
 234   jchar char_field_acquire(int offset) const;
 235   void release_char_field_put(int offset, jchar contents);
 236 
 237   jboolean bool_field_acquire(int offset) const;
 238   void release_bool_field_put(int offset, jboolean contents);
 239 
 240   jint int_field_acquire(int offset) const;
 241   void release_int_field_put(int offset, jint contents);
 242 
 243   jshort short_field_acquire(int offset) const;
 244   void release_short_field_put(int offset, jshort contents);
 245 
 246   jlong long_field_acquire(int offset) const;
 247   void release_long_field_put(int offset, jlong contents);
 248 
 249   jfloat float_field_acquire(int offset) const;
 250   void release_float_field_put(int offset, jfloat contents);
 251 
 252   jdouble double_field_acquire(int offset) const;
 253   void release_double_field_put(int offset, jdouble contents);
 254 
 255   address address_field_acquire(int offset) const;
 256   void release_address_field_put(int offset, address contents);
 257 
 258   // printing functions for VM debugging
 259   void print_on(outputStream* st) const;         // First level print
 260   void print_value_on(outputStream* st) const;   // Second level print.
 261   void print_address_on(outputStream* st) const; // Address printing
 262 
 263   // printing on default output stream
 264   void print();
 265   void print_value();
 266   void print_address();
 267 
 268   // return the print strings
 269   char* print_string();
 270   char* print_value_string();
 271 
 272   // verification operations
 273   void verify_on(outputStream* st);
 274   void verify();
 275 
 276   // locking operations
 277   inline bool is_locked()   const;
 278   inline bool is_unlocked() const;
 279   inline bool has_bias_pattern() const;
 280 
 281   // asserts and guarantees
 282   static bool is_oop(oop obj, bool ignore_mark_word = false);
 283   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
 284 #ifndef PRODUCT
 285   inline bool is_unlocked_oop() const;
 286 #endif
 287 
 288   // garbage collection
 289   inline bool is_gc_marked() const;
 290 
 291   inline bool is_scavengable() const;
 292 
 293   // Forward pointer operations for scavenge
 294   inline bool is_forwarded() const;
 295 
 296   inline void forward_to(oop p);
 297   inline bool cas_forward_to(oop p, markOop compare);
 298 
 299 #if INCLUDE_ALL_GCS
 300   // Like "forward_to", but inserts the forwarding pointer atomically.
 301   // Exactly one thread succeeds in inserting the forwarding pointer, and
 302   // this call returns "NULL" for that thread; any other thread has the
 303   // value of the forwarding pointer returned and does not modify "this".
 304   inline oop forward_to_atomic(oop p);
 305 #endif // INCLUDE_ALL_GCS
 306 
 307   inline oop forwardee() const;
 308 
 309   // Age of object during scavenge
 310   inline uint age() const;
 311   inline void incr_age();
 312 
 313   // mark-sweep support
 314   void follow_body(int begin, int end);
 315 
 316   // Garbage Collection support
 317 
 318 #if INCLUDE_ALL_GCS
 319   // Parallel Compact
 320   inline void pc_follow_contents(ParCompactionManager* cm);
 321   inline void pc_update_contents(ParCompactionManager* cm);
 322   // Parallel Scavenge
 323   inline void ps_push_contents(PSPromotionManager* pm);
 324 #endif
 325 
 326 
 327   // iterators, returns size of object
 328 #define OOP_ITERATE_DECL(OopClosureType, nv_suffix)                     \
 329   inline void oop_iterate(OopClosureType* blk);                         \
 330   inline void oop_iterate(OopClosureType* blk, MemRegion mr);  // Only in mr.
 331 
 332   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_DECL)
 333   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_DECL)
 334 
 335 #define OOP_ITERATE_SIZE_DECL(OopClosureType, nv_suffix)                \
 336   inline int oop_iterate_size(OopClosureType* blk);                     \
 337   inline int oop_iterate_size(OopClosureType* blk, MemRegion mr);  // Only in mr.
 338 
 339   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_SIZE_DECL)
 340   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_SIZE_DECL)
 341 
 342 
 343 #if INCLUDE_ALL_GCS
 344 
 345 #define OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)  \
 346   inline void oop_iterate_backwards(OopClosureType* blk);
 347 
 348   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_BACKWARDS_DECL)
 349   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_BACKWARDS_DECL)
 350 
 351 #endif // INCLUDE_ALL_GCS
 352 
 353   inline int oop_iterate_no_header(OopClosure* bk);
 354   inline int oop_iterate_no_header(OopClosure* bk, MemRegion mr);
 355 
 356   // identity hash; returns the identity hash key (computes it if necessary)
 357   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 358   // safepoint if called on a biased object. Calling code must be aware of that.
 359   inline intptr_t identity_hash();
 360   intptr_t slow_identity_hash();
 361 
 362   // Alternate hashing code if string table is rehashed
 363   unsigned int new_hash(juint seed);
 364 
 365   // marks are forwarded to stack when object is locked
 366   inline bool    has_displaced_mark() const;
 367   inline markOop displaced_mark() const;
 368   inline void    set_displaced_mark(markOop m);
 369 
 370   static bool has_klass_gap();
 371 
 372   // for code generation
 373   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
 374   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
 375   static int klass_gap_offset_in_bytes() {
 376     assert(has_klass_gap(), "only applicable to compressed klass pointers");
 377     return klass_offset_in_bytes() + sizeof(narrowKlass);
 378   }
 379 
 380   static bool is_archive_object(oop p) NOT_CDS_JAVA_HEAP_RETURN_(false);
 381 };
 382 
 383 #endif // SHARE_VM_OOPS_OOP_HPP