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