1 /*
  2  * Copyright (c) 1997, 2021, 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/accessDecorators.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 FilteringClosure;
 46 
 47 class PSPromotionManager;
 48 class ParCompactionManager;
 49 
 50 class oopDesc {
 51   friend class VMStructs;
 52   friend class JVMCIVMStructs;
 53  private:
 54   volatile markWord _mark;
 55   union _metadata {
 56     Klass*      _klass;
 57     narrowKlass _compressed_klass;
 58   } _metadata;
 59 
 60  public:
 61   inline markWord  mark()          const;
 62   inline markWord  mark_acquire()  const;
 63   inline markWord* mark_addr() const;
 64 
 65   inline void set_mark(markWord m);
 66   static inline void set_mark(HeapWord* mem, markWord m);
 67 
 68   inline void release_set_mark(markWord m);
 69   inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
 70   inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);
 71 
 72   // Used only to re-initialize the mark word (e.g., of promoted
 73   // objects during a GC) -- requires a valid klass pointer
 74   inline void init_mark();
 75 
 76   inline Klass* klass() const;
 77   inline Klass* klass_or_null() const;
 78   inline Klass* klass_or_null_acquire() const;
 79 
 80   void set_narrow_klass(narrowKlass nk) NOT_CDS_JAVA_HEAP_RETURN;
 81   inline void set_klass(Klass* k);
 82   static inline void release_set_klass(HeapWord* mem, Klass* k);
 83 
 84   // For klass field compression
 85   inline int klass_gap() const;
 86   inline void set_klass_gap(int z);
 87   static inline void set_klass_gap(HeapWord* mem, int z);
 88 
 89   // size of object header, aligned to platform wordSize
 90   static int header_size() { return sizeof(oopDesc)/HeapWordSize; }
 91 
 92   // Returns whether this is an instance of k or an instance of a subclass of k
 93   inline bool is_a(Klass* k) const;
 94 
 95   // Returns the actual oop size of the object
 96   inline int size();
 97 
 98   // Sometimes (for complicated concurrency-related reasons), it is useful
 99   // to be able to figure out the size of an object knowing its klass.
100   inline int size_given_klass(Klass* klass);
101 
102   // type test operations (inlined in oop.inline.hpp)
103   inline bool is_instance()            const;
104   inline bool is_array()               const;
105   inline bool is_objArray()            const;
106   inline bool is_typeArray()           const;
107 
108   // type test operations that don't require inclusion of oop.inline.hpp.
109   bool is_instance_noinline()          const;
110   bool is_array_noinline()             const;
111   bool is_objArray_noinline()          const;
112   bool is_typeArray_noinline()         const;
113 
114  protected:
115   inline oop        as_oop() const { return const_cast<oopDesc*>(this); }
116 
117  public:
118   // field addresses in oop
119   inline void* field_addr(int offset) const;
120 
121   // Need this as public for garbage collection.
122   template <class T> inline T* obj_field_addr(int offset) const;
123 
124   template <typename T> inline size_t field_offset(T* p) const;
125 
126   // Standard compare function returns negative value if o1 < o2
127   //                                   0              if o1 == o2
128   //                                   positive value if o1 > o2
129   inline static int  compare(oop o1, oop o2) {
130     void* o1_addr = (void*)o1;
131     void* o2_addr = (void*)o2;
132     if (o1_addr < o2_addr) {
133       return -1;
134     } else if (o1_addr > o2_addr) {
135       return 1;
136     } else {
137       return 0;
138     }
139   }
140 
141   // Access to fields in a instanceOop through these methods.
142   template <DecoratorSet decorator>
143   oop obj_field_access(int offset) const;
144   oop obj_field(int offset) const;
145   void obj_field_put(int offset, oop value);
146   void obj_field_put_raw(int offset, oop value);
147   void obj_field_put_volatile(int offset, oop value);
148 
149   Metadata* metadata_field(int offset) const;
150   Metadata* metadata_field_raw(int offset) const;
151   void metadata_field_put(int offset, Metadata* value);
152 
153   Metadata* metadata_field_acquire(int offset) const;
154   void release_metadata_field_put(int offset, Metadata* value);
155 
156   jbyte byte_field(int offset) const;
157   void byte_field_put(int offset, jbyte contents);
158 
159   jchar char_field(int offset) const;
160   void char_field_put(int offset, jchar contents);
161 
162   jboolean bool_field(int offset) const;
163   void bool_field_put(int offset, jboolean contents);
164   jboolean bool_field_volatile(int offset) const;
165   void bool_field_put_volatile(int offset, jboolean contents);
166 
167   jint int_field(int offset) const;
168   jint int_field_raw(int offset) const;
169   void int_field_put(int offset, jint contents);
170 
171   jshort short_field(int offset) const;
172   void short_field_put(int offset, jshort contents);
173 
174   jlong long_field(int offset) const;
175   void long_field_put(int offset, jlong contents);
176 
177   jfloat float_field(int offset) const;
178   void float_field_put(int offset, jfloat contents);
179 
180   jdouble double_field(int offset) const;
181   void double_field_put(int offset, jdouble contents);
182 
183   address address_field(int offset) const;
184   void address_field_put(int offset, address contents);
185 
186   oop obj_field_acquire(int offset) const;
187   void release_obj_field_put(int offset, oop value);
188 
189   jbyte byte_field_acquire(int offset) const;
190   void release_byte_field_put(int offset, jbyte contents);
191 
192   jchar char_field_acquire(int offset) const;
193   void release_char_field_put(int offset, jchar contents);
194 
195   jboolean bool_field_acquire(int offset) const;
196   void release_bool_field_put(int offset, jboolean contents);
197 
198   jint int_field_acquire(int offset) const;
199   void release_int_field_put(int offset, jint contents);
200 
201   jshort short_field_acquire(int offset) const;
202   void release_short_field_put(int offset, jshort contents);
203 
204   jlong long_field_acquire(int offset) const;
205   void release_long_field_put(int offset, jlong contents);
206 
207   jfloat float_field_acquire(int offset) const;
208   void release_float_field_put(int offset, jfloat contents);
209 
210   jdouble double_field_acquire(int offset) const;
211   void release_double_field_put(int offset, jdouble contents);
212 
213   address address_field_acquire(int offset) const;
214   void release_address_field_put(int offset, address contents);
215 
216   // printing functions for VM debugging
217   void print_on(outputStream* st) const;        // First level print
218   void print_value_on(outputStream* st) const;  // Second level print.
219   void print_address_on(outputStream* st) const; // Address printing
220 
221   // printing on default output stream
222   void print();
223   void print_value();
224   void print_address();
225 
226   // return the print strings
227   char* print_string();
228   char* print_value_string();
229 
230   // verification operations
231   static void verify_on(outputStream* st, oopDesc* oop_desc);
232   static void verify(oopDesc* oopDesc);
233 
234   // locking operations
235   inline bool is_locked()   const;
236   inline bool is_unlocked() const;
237   inline bool has_bias_pattern() const;
238 
239   // asserts and guarantees
240   static bool is_oop(oop obj, bool ignore_mark_word = false);
241   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
242 
243   // garbage collection
244   inline bool is_gc_marked() const;
245 
246   // Forward pointer operations for scavenge
247   inline bool is_forwarded() const;
248 
249   void verify_forwardee(oop forwardee) NOT_DEBUG_RETURN;
250 
251   inline void forward_to(oop p);
252   inline bool cas_forward_to(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
253 
254   // Like "forward_to", but inserts the forwarding pointer atomically.
255   // Exactly one thread succeeds in inserting the forwarding pointer, and
256   // this call returns "NULL" for that thread; any other thread has the
257   // value of the forwarding pointer returned and does not modify "this".
258   inline oop forward_to_atomic(oop p, markWord compare, atomic_memory_order order = memory_order_conservative);
259 
260   inline oop forwardee() const;
261 
262   // Age of object during scavenge
263   inline uint age() const;
264   inline void incr_age();
265 
266   template <typename OopClosureType>
267   inline void oop_iterate(OopClosureType* cl);
268 
269   template <typename OopClosureType>
270   inline void oop_iterate(OopClosureType* cl, MemRegion mr);
271 
272   template <typename OopClosureType>
273   inline int oop_iterate_size(OopClosureType* cl);
274 
275   template <typename OopClosureType>
276   inline int oop_iterate_size(OopClosureType* cl, MemRegion mr);
277 
278   template <typename OopClosureType>
279   inline void oop_iterate_backwards(OopClosureType* cl);
280 
281   template <typename OopClosureType>
282   inline void oop_iterate_backwards(OopClosureType* cl, Klass* klass);
283 
284   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
285 
286   // identity hash; returns the identity hash key (computes it if necessary)
287   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
288   // safepoint if called on a biased object. Calling code must be aware of that.
289   inline intptr_t identity_hash();
290   intptr_t slow_identity_hash();
291 
292   // marks are forwarded to stack when object is locked
293   inline bool     has_displaced_mark() const;
294   inline markWord displaced_mark() const;
295   inline void     set_displaced_mark(markWord m);
296 
297   // Checks if the mark word needs to be preserved
298   inline bool mark_must_be_preserved() const;
299   inline bool mark_must_be_preserved(markWord m) const;
300   inline bool mark_must_be_preserved_for_promotion_failure(markWord m) const;
301 
302   static bool has_klass_gap();
303 
304   // for code generation
305   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
306   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
307   static int klass_gap_offset_in_bytes() {
308     assert(has_klass_gap(), "only applicable to compressed klass pointers");
309     return klass_offset_in_bytes() + sizeof(narrowKlass);
310   }
311 
312   // for error reporting
313   static void* load_klass_raw(oop obj);
314   static void* load_oop_raw(oop obj, int offset);
315 
316   // Avoid include gc_globals.hpp in oop.inline.hpp
317   DEBUG_ONLY(bool get_UseParallelGC();)
318   DEBUG_ONLY(bool get_UseG1GC();)
319 };
320 
321 #endif // SHARE_OOPS_OOP_HPP