1 /*
   2  * Copyright (c) 1997, 2019, 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.
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  23  */
  24 
  25 #ifndef SHARE_OOPS_OOP_HPP
  26 #define SHARE_OOPS_OOP_HPP
  27 
  28 #include "memory/iterator.hpp"
  29 #include "memory/memRegion.hpp"
  30 #include "oops/access.hpp"
  31 #include "oops/arrayStorageProperties.hpp"
  32 #include "oops/metadata.hpp"
  33 #include "runtime/atomic.hpp"
  34 #include "utilities/macros.hpp"
  35 
  36 // oopDesc is the top baseclass for objects classes. The {name}Desc classes describe
  37 // the format of Java objects so the fields can be accessed from C++.
  38 // oopDesc is abstract.
  39 // (see oopHierarchy for complete oop class hierarchy)
  40 //
  41 // no virtual functions allowed
  42 //
  43 // oopDesc::_mark - the "oop mark word" encoding to be found separately in markOop.hpp
  44 //
  45 // oopDesc::_metadata - encodes both the object's klass pointer and potentially
  46 //                      "storage properties" (currently confined to arrays in the form of
  47 //                      ArrayStorageProperties). Storage properties are peculiar to the
  48 //                      *instance*, and not necessarily the "type".
  49 //
  50 // The overall size of the _metadata field is dependent on "UseCompressedClassPointers",
  51 // hence the terms "narrow" (32 bits) vs "wide" (64 bits).
  52 //
  53 // "Wide" encoding of _metadata:
  54 // bit number          |63             0|
  55 // bit length          |--3|-----61-----|
  56 // --------------------------------------
  57 // _klass              [xxx| Klass*     ]
  58 // _wide_storage_props [ sp|            ]
  59 // --------------------------------------
  60 // with:
  61 //    xxx = klass_mask(), Klass* = Klass pointer to be masked
  62 //    sp = storage properties, bit number: wide_storage_props_shift
  63 //
  64 // "Narrow" encoding of _metadata:
  65 // bit number            |31             0|
  66 // bit length            |--3|-----29-----|
  67 // ----------------------------------------
  68 // _compressed_klass     [xxx| narrowKlass]
  69 // _narrow_storage_props [ sp|            ]
  70 // ----------------------------------------
  71 // with:
  72 //   xxx = compressed_klass_mask(), narrowKlass = compressed Klass pointer to be masked
  73 //         narrowKlass may be further decoded (Klass::decode_klass()) to produce Klass*
  74 //   sp = storage properties, bit number: narrow_storage_props_shift
  75 //
  76 // Storage properties encodings are current confined to arrayStorageProperties.hpp
  77 
  78 
  79 extern bool always_do_update_barrier;
  80 
  81 // Forward declarations.
  82 class OopClosure;
  83 class ScanClosure;
  84 class FastScanClosure;
  85 class FilteringClosure;
  86 class CMSIsAliveClosure;
  87 
  88 class PSPromotionManager;
  89 class ParCompactionManager;
  90 
  91 class oopDesc {
  92   friend class VMStructs;
  93   friend class JVMCIVMStructs;
  94  private:
  95   volatile markOop _mark;
  96   union _metadata {
  97     Klass*      _klass;
  98     narrowKlass _compressed_klass;
  99     uintptr_t   _wide_storage_props;
 100     uint32_t   _narrow_storage_props;
 101   } _metadata;
 102 
 103  public:
 104   inline markOop  mark()          const;
 105   inline markOop  mark_raw()      const;
 106   inline markOop* mark_addr_raw() const;
 107 
 108   inline void set_mark(volatile markOop m);
 109   inline void set_mark_raw(volatile markOop m);
 110   static inline void set_mark_raw(HeapWord* mem, markOop m);
 111 
 112   inline void release_set_mark(markOop m);
 113   inline markOop cas_set_mark(markOop new_mark, markOop old_mark);
 114   inline markOop cas_set_mark_raw(markOop new_mark, markOop old_mark, atomic_memory_order order = memory_order_conservative);
 115 
 116   // Used only to re-initialize the mark word (e.g., of promoted
 117   // objects during a GC) -- requires a valid klass pointer
 118   inline void init_mark();
 119   inline void init_mark_raw();
 120 
 121   enum {
 122     storage_props_nof_bits     = LogKlassAlignmentInBytes, // This alignment gives us some "free bits"
 123     narrow_storage_props_shift = (sizeof(narrowKlass) << 3) - storage_props_nof_bits,
 124     wide_storage_props_shift   = (sizeof(Klass*) << 3) - storage_props_nof_bits,
 125   };
 126 
 127   static inline narrowKlass compressed_klass_mask();
 128   static inline narrowKlass compressed_klass_masked(narrowKlass raw);
 129   static inline uintptr_t   klass_mask();
 130   static inline Klass*      klass_masked(uintptr_t raw);
 131 
 132   inline Klass* klass() const;
 133   inline Klass* klass_or_null() const volatile;
 134   inline Klass* klass_or_null_acquire() const volatile;
 135   static inline Klass** klass_addr(HeapWord* mem);
 136   static inline narrowKlass* compressed_klass_addr(HeapWord* mem);
 137   inline Klass** klass_addr();
 138   inline narrowKlass* compressed_klass_addr();
 139 
 140   inline void set_klass(Klass* k);
 141   static inline void release_set_klass(HeapWord* mem, Klass* klass);
 142 
 143   // Extra container metadata specific to arrays (encoded into high bits of _metadata)
 144   static inline uintptr_t* wide_metadata_addr(HeapWord* mem);
 145   inline ArrayStorageProperties array_storage_properties() const;
 146   inline void set_metadata(ArrayStorageProperties storage_props, Klass* k);
 147   static inline void release_set_metadata(HeapWord* mem, ArrayStorageProperties storage_props, Klass* klass);
 148 
 149 
 150   // For klass field compression
 151   inline int klass_gap() const;
 152   inline void set_klass_gap(int z);
 153   static inline void set_klass_gap(HeapWord* mem, int z);
 154   // For when the klass pointer is being used as a linked list "next" field.
 155   inline void set_klass_to_list_ptr(oop k);
 156   inline oop list_ptr_from_klass();
 157 
 158   // size of object header, aligned to platform wordSize
 159   static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
 160 
 161   // Returns whether this is an instance of k or an instance of a subclass of k
 162   inline bool is_a(Klass* k) const;
 163 
 164   // Returns the actual oop size of the object
 165   inline int size();
 166 
 167   // Sometimes (for complicated concurrency-related reasons), it is useful
 168   // to be able to figure out the size of an object knowing its klass.
 169   inline int size_given_klass(Klass* klass);
 170 
 171   // type test operations (inlined in oop.inline.hpp)
 172   inline bool is_instance()            const;
 173   inline bool is_array()               const;
 174   inline bool is_objArray()            const;
 175   inline bool is_typeArray()           const;
 176   inline bool is_value()               const;
 177   inline bool is_valueArray()          const;
 178 
 179   // type test operations that don't require inclusion of oop.inline.hpp.
 180   bool is_instance_noinline()          const;
 181   bool is_array_noinline()             const;
 182   bool is_objArray_noinline()          const;
 183   bool is_typeArray_noinline()         const;
 184   bool is_value_noinline()             const;
 185   bool is_valueArray_noinline()        const;
 186 
 187  protected:
 188   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
 189 
 190  public:
 191   // field addresses in oop
 192   inline void* field_addr(int offset)     const;
 193   inline void* field_addr_raw(int offset) const;
 194 
 195   // Need this as public for garbage collection.
 196   template <class T> inline T* obj_field_addr_raw(int offset) const;
 197 
 198   template <typename T> inline size_t field_offset(T* p) const;
 199 
 200   // Standard compare function returns negative value if o1 < o2
 201   //                                   0              if o1 == o2
 202   //                                   positive value if o1 > o2
 203   inline static int  compare(oop o1, oop o2) {
 204     void* o1_addr = (void*)o1;
 205     void* o2_addr = (void*)o2;
 206     if (o1_addr < o2_addr) {
 207       return -1;
 208     } else if (o1_addr > o2_addr) {
 209       return 1;
 210     } else {
 211       return 0;
 212     }
 213   }
 214 
 215   inline static bool equals(oop o1, oop o2) { return Access<>::equals(o1, o2); }
 216 
 217   inline static bool equals_raw(oop o1, oop o2) { return RawAccess<>::equals(o1, o2); }
 218 
 219   // Access to fields in a instanceOop through these methods.
 220   template <DecoratorSet decorator>
 221   oop obj_field_access(int offset) const;
 222   oop obj_field(int offset) const;
 223   void obj_field_put(int offset, oop value);
 224   void obj_field_put_raw(int offset, oop value);
 225   void obj_field_put_volatile(int offset, oop value);
 226 
 227   Metadata* metadata_field(int offset) const;
 228   Metadata* metadata_field_raw(int offset) const;
 229   void metadata_field_put(int offset, Metadata* value);
 230 
 231   Metadata* metadata_field_acquire(int offset) const;
 232   void release_metadata_field_put(int offset, Metadata* value);
 233 
 234   jbyte byte_field(int offset) const;
 235   void byte_field_put(int offset, jbyte contents);
 236 
 237   jchar char_field(int offset) const;
 238   void char_field_put(int offset, jchar contents);
 239 
 240   jboolean bool_field(int offset) const;
 241   void bool_field_put(int offset, jboolean contents);
 242 
 243   jint int_field(int offset) const;
 244   jint int_field_raw(int offset) const;
 245   void int_field_put(int offset, jint contents);
 246 
 247   jshort short_field(int offset) const;
 248   void short_field_put(int offset, jshort contents);
 249 
 250   jlong long_field(int offset) const;
 251   void long_field_put(int offset, jlong contents);
 252 
 253   jfloat float_field(int offset) const;
 254   void float_field_put(int offset, jfloat contents);
 255 
 256   jdouble double_field(int offset) const;
 257   void double_field_put(int offset, jdouble contents);
 258 
 259   address address_field(int offset) const;
 260   void address_field_put(int offset, address contents);
 261 
 262   oop obj_field_acquire(int offset) const;
 263   void release_obj_field_put(int offset, oop value);
 264 
 265   jbyte byte_field_acquire(int offset) const;
 266   void release_byte_field_put(int offset, jbyte contents);
 267 
 268   jchar char_field_acquire(int offset) const;
 269   void release_char_field_put(int offset, jchar contents);
 270 
 271   jboolean bool_field_acquire(int offset) const;
 272   void release_bool_field_put(int offset, jboolean contents);
 273 
 274   jint int_field_acquire(int offset) const;
 275   void release_int_field_put(int offset, jint contents);
 276 
 277   jshort short_field_acquire(int offset) const;
 278   void release_short_field_put(int offset, jshort contents);
 279 
 280   jlong long_field_acquire(int offset) const;
 281   void release_long_field_put(int offset, jlong contents);
 282 
 283   jfloat float_field_acquire(int offset) const;
 284   void release_float_field_put(int offset, jfloat contents);
 285 
 286   jdouble double_field_acquire(int offset) const;
 287   void release_double_field_put(int offset, jdouble contents);
 288 
 289   address address_field_acquire(int offset) const;
 290   void release_address_field_put(int offset, address contents);
 291 
 292   // printing functions for VM debugging
 293   void print_on(outputStream* st) const;        // First level print
 294   void print_value_on(outputStream* st) const;  // Second level print.
 295   void print_address_on(outputStream* st) const; // Address printing
 296 
 297   // printing on default output stream
 298   void print();
 299   void print_value();
 300   void print_address();
 301 
 302   // return the print strings
 303   char* print_string();
 304   char* print_value_string();
 305 
 306   // verification operations
 307   static void verify_on(outputStream* st, oopDesc* oop_desc);
 308   static void verify(oopDesc* oopDesc);
 309 
 310   // locking operations
 311   inline bool is_locked()   const;
 312   inline bool is_unlocked() const;
 313   inline bool has_bias_pattern() const;
 314   inline bool has_bias_pattern_raw() const;
 315 
 316   // asserts and guarantees
 317   static bool is_oop(oop obj, bool ignore_mark_word = false);
 318   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
 319 #ifndef PRODUCT
 320   inline bool is_unlocked_oop() const;
 321   static bool is_archived_object(oop p) NOT_CDS_JAVA_HEAP_RETURN_(false);
 322 #endif
 323 
 324   // garbage collection
 325   inline bool is_gc_marked() const;
 326 
 327   // Forward pointer operations for scavenge
 328   inline bool is_forwarded() const;
 329 
 330   inline void forward_to(oop p);
 331   inline bool cas_forward_to(oop p, markOop compare, atomic_memory_order order = memory_order_conservative);
 332 
 333   // Like "forward_to", but inserts the forwarding pointer atomically.
 334   // Exactly one thread succeeds in inserting the forwarding pointer, and
 335   // this call returns "NULL" for that thread; any other thread has the
 336   // value of the forwarding pointer returned and does not modify "this".
 337   inline oop forward_to_atomic(oop p, markOop compare, atomic_memory_order order = memory_order_conservative);
 338 
 339   inline oop forwardee() const;
 340   inline oop forwardee_acquire() const;
 341 
 342   // Age of object during scavenge
 343   inline uint age() const;
 344   inline void incr_age();
 345 
 346   // mark-sweep support
 347   void follow_body(int begin, int end);
 348 
 349   template <typename OopClosureType>
 350   inline void oop_iterate(OopClosureType* cl);
 351 
 352   template <typename OopClosureType>
 353   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
 354 
 355   template <typename OopClosureType>
 356   inline int oop_iterate_size(OopClosureType* cl);
 357 
 358   template <typename OopClosureType>
 359   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
 360 
 361   template <typename OopClosureType>
 362   inline void oop_iterate_backwards(OopClosureType* cl);
 363 
 364   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
 365 
 366   // identity hash; returns the identity hash key (computes it if necessary)
 367   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 368   // safepoint if called on a biased object. Calling code must be aware of that.
 369   inline intptr_t identity_hash();
 370   intptr_t slow_identity_hash();
 371 
 372   // marks are forwarded to stack when object is locked
 373   inline bool    has_displaced_mark_raw() const;
 374   inline markOop displaced_mark_raw() const;
 375   inline void    set_displaced_mark_raw(markOop m);
 376 
 377   static bool has_klass_gap();
 378 
 379   // for code generation
 380   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
 381   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
 382   static int klass_gap_offset_in_bytes() {
 383     assert(has_klass_gap(), "only applicable to compressed klass pointers");
 384     return klass_offset_in_bytes() + sizeof(narrowKlass);
 385   }
 386 
 387   // for error reporting
 388   static oop   decode_oop_raw(narrowOop narrow_oop);
 389   static void* load_klass_raw(oop obj);
 390   static void* load_oop_raw(oop obj, int offset);
 391   static bool  is_valid(oop obj);
 392   static oop   oop_or_null(address addr);
 393 };
 394 
 395 #endif // SHARE_OOPS_OOP_HPP
--- EOF ---