1 /*
   2  * Copyright (c) 1997, 2020, 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
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  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/markWord.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 // Forward declarations.
  44 class OopClosure;
  45 class FastScanClosure;
  46 class FilteringClosure;
  47 
  48 class PSPromotionManager;
  49 class ParCompactionManager;
  50 
  51 class oopDesc {
  52   friend class VMStructs;
  53   friend class JVMCIVMStructs;
  54  private:
  55   volatile markWord _mark;
  56   union _metadata {
  57     Klass*      _klass;
  58     narrowKlass _compressed_klass;
  59   } _metadata;
  60 
  61  public:
  62   inline markWord  mark()          const;
  63   inline markWord  mark_raw()      const;
  64   inline markWord* mark_addr_raw() const;
  65 
  66   inline void set_mark(markWord m);
  67   inline void set_mark_raw(markWord m);
  68   static inline void set_mark_raw(HeapWord* mem, markWord m);
  69 
  70   inline void release_set_mark(markWord m);
  71   inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
  72   inline markWord cas_set_mark_raw(markWord new_mark, markWord old_mark, atomic_memory_order order = memory_order_conservative);
  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   inline void init_mark_raw();
  78 
  79   inline Klass* klass() const;
  80   inline Klass* klass_or_null() const;
  81   inline Klass* klass_or_null_acquire() const;
  82   static inline Klass** klass_addr(HeapWord* mem);
  83   static inline narrowKlass* compressed_klass_addr(HeapWord* mem);
  84   inline Klass** klass_addr();
  85   inline narrowKlass* compressed_klass_addr();
  86 
  87   inline void set_klass(Klass* k);
  88   static inline void release_set_klass(HeapWord* mem, Klass* klass);
  89 
  90   // For klass field compression
  91   inline int klass_gap() const;
  92   inline void set_klass_gap(int z);
  93   static inline void set_klass_gap(HeapWord* mem, int z);
  94 
  95   // size of object header, aligned to platform wordSize
  96   static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
  97 
  98   // Returns whether this is an instance of k or an instance of a subclass of k
  99   inline bool is_a(Klass* k) const;
 100 
 101   // Returns the actual oop size of the object
 102   inline int size();
 103 
 104   // Sometimes (for complicated concurrency-related reasons), it is useful
 105   // to be able to figure out the size of an object knowing its klass.
 106   inline int size_given_klass(Klass* klass);
 107 
 108   // type test operations (inlined in oop.inline.hpp)
 109   inline bool is_instance()            const;
 110   inline bool is_array()               const;
 111   inline bool is_objArray()            const;
 112   inline bool is_typeArray()           const;
 113 
 114   // type test operations that don't require inclusion of oop.inline.hpp.
 115   bool is_instance_noinline()          const;
 116   bool is_array_noinline()             const;
 117   bool is_objArray_noinline()          const;
 118   bool is_typeArray_noinline()         const;
 119 
 120  protected:
 121   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
 122 
 123  public:
 124   // field addresses in oop
 125   inline void* field_addr(int offset)     const;
 126   inline void* field_addr_raw(int offset) const;
 127 
 128   // Need this as public for garbage collection.
 129   template <class T> inline T* obj_field_addr_raw(int offset) const;
 130 
 131   template <typename T> inline size_t field_offset(T* p) const;
 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   // Access to fields in a instanceOop through these methods.
 149   template <DecoratorSet decorator>
 150   oop obj_field_access(int offset) const;
 151   oop obj_field(int offset) const;
 152   void obj_field_put(int offset, oop value);
 153   void obj_field_put_raw(int offset, oop value);
 154   void obj_field_put_volatile(int offset, oop value);
 155 
 156   Metadata* metadata_field(int offset) const;
 157   Metadata* metadata_field_raw(int offset) const;
 158   void metadata_field_put(int offset, Metadata* value);
 159 
 160   Metadata* metadata_field_acquire(int offset) const;
 161   void release_metadata_field_put(int offset, Metadata* value);
 162 
 163   jbyte byte_field(int offset) const;
 164   void byte_field_put(int offset, jbyte contents);
 165 
 166   jchar char_field(int offset) const;
 167   void char_field_put(int offset, jchar contents);
 168 
 169   jboolean bool_field(int offset) const;
 170   void bool_field_put(int offset, jboolean contents);
 171   jboolean bool_field_volatile(int offset) const;
 172   void bool_field_put_volatile(int offset, jboolean contents);
 173 
 174   jint int_field(int offset) const;
 175   jint int_field_raw(int offset) const;
 176   void int_field_put(int offset, jint contents);
 177 
 178   jshort short_field(int offset) const;
 179   void short_field_put(int offset, jshort contents);
 180 
 181   jlong long_field(int offset) const;
 182   void long_field_put(int offset, jlong contents);
 183 
 184   jfloat float_field(int offset) const;
 185   void float_field_put(int offset, jfloat contents);
 186 
 187   jdouble double_field(int offset) const;
 188   void double_field_put(int offset, jdouble contents);
 189 
 190   address address_field(int offset) const;
 191   void address_field_put(int offset, address contents);
 192 
 193   oop obj_field_acquire(int offset) const;
 194   void release_obj_field_put(int offset, oop value);
 195 
 196   jbyte byte_field_acquire(int offset) const;
 197   void release_byte_field_put(int offset, jbyte contents);
 198 
 199   jchar char_field_acquire(int offset) const;
 200   void release_char_field_put(int offset, jchar contents);
 201 
 202   jboolean bool_field_acquire(int offset) const;
 203   void release_bool_field_put(int offset, jboolean contents);
 204 
 205   jint int_field_acquire(int offset) const;
 206   void release_int_field_put(int offset, jint contents);
 207 
 208   jshort short_field_acquire(int offset) const;
 209   void release_short_field_put(int offset, jshort contents);
 210 
 211   jlong long_field_acquire(int offset) const;
 212   void release_long_field_put(int offset, jlong contents);
 213 
 214   jfloat float_field_acquire(int offset) const;
 215   void release_float_field_put(int offset, jfloat contents);
 216 
 217   jdouble double_field_acquire(int offset) const;
 218   void release_double_field_put(int offset, jdouble contents);
 219 
 220   address address_field_acquire(int offset) const;
 221   void release_address_field_put(int offset, address contents);
 222 
 223   // printing functions for VM debugging
 224   void print_on(outputStream* st) const;        // First level print
 225   void print_value_on(outputStream* st) const;  // Second level print.
 226   void print_address_on(outputStream* st) const; // Address printing
 227 
 228   // printing on default output stream
 229   void print();
 230   void print_value();
 231   void print_address();
 232 
 233   // return the print strings
 234   char* print_string();
 235   char* print_value_string();
 236 
 237   // verification operations
 238   static void verify_on(outputStream* st, oopDesc* oop_desc);
 239   static void verify(oopDesc* oopDesc);
 240 
 241   // locking operations
 242   inline bool is_locked()   const;
 243   inline bool is_unlocked() const;
 244   inline bool has_bias_pattern() const;
 245   inline bool has_bias_pattern_raw() const;
 246 
 247   // asserts and guarantees
 248   static bool is_oop(oop obj, bool ignore_mark_word = false);
 249   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
 250 
 251   // garbage collection
 252   inline bool is_gc_marked() const;
 253 
 254   // Forward pointer operations for scavenge
 255   inline bool is_forwarded() const;
 256 
 257   void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
 258 
 259   inline void forward_to(oop p);
 260   inline bool cas_forward_to(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
 261 
 262   // Like "forward_to", but inserts the forwarding pointer atomically.
 263   // Exactly one thread succeeds in inserting the forwarding pointer, and
 264   // this call returns "NULL" for that thread; any other thread has the
 265   // value of the forwarding pointer returned and does not modify "this".
 266   inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
 267 
 268   inline oop forwardee() const;
 269   inline oop forwardee_acquire() const;
 270 
 271   // Age of object during scavenge
 272   inline uint age() const;
 273   inline void incr_age();
 274 
 275   // mark-sweep support
 276   void follow_body(int begin, int end);
 277 
 278   template <typename OopClosureType>
 279   inline void oop_iterate(OopClosureType* cl);
 280 
 281   template <typename OopClosureType>
 282   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
 283 
 284   template <typename OopClosureType>
 285   inline int oop_iterate_size(OopClosureType* cl);
 286 
 287   template <typename OopClosureType>
 288   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
 289 
 290   template <typename OopClosureType>
 291   inline void oop_iterate_backwards(OopClosureType* cl);
 292 
 293   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
 294 
 295   // identity hash; returns the identity hash key (computes it if necessary)
 296   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
 297   // safepoint if called on a biased object. Calling code must be aware of that.
 298   inline intptr_t identity_hash();
 299   intptr_t slow_identity_hash();
 300 
 301   // marks are forwarded to stack when object is locked
 302   inline bool     has_displaced_mark_raw() const;
 303   inline markWord displaced_mark_raw() const;
 304   inline void     set_displaced_mark_raw(markWord m);
 305 
 306   // Checks if the mark word needs to be preserved
 307   inline bool mark_must_be_preserved() const;
 308   inline bool mark_must_be_preserved(markWord m) const;
 309   inline bool mark_must_be_preserved_for_promotion_failure(markWord m) const;
 310 
 311   static bool has_klass_gap();
 312 
 313   // for code generation
 314   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
 315   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
 316   static int klass_gap_offset_in_bytes() {
 317     assert(has_klass_gap(), "only applicable to compressed klass pointers");
 318     return klass_offset_in_bytes() + sizeof(narrowKlass);
 319   }
 320 
 321   // for error reporting
 322   static void* load_klass_raw(oop obj);
 323   static void* load_oop_raw(oop obj, int offset);
 324 };
 325 
 326 #endif // SHARE_OOPS_OOP_HPP