1 /*
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  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  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.
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  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  *
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 16  * 2 along with this work; if not, write to the Free Software Foundation,
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 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 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   // Standard compare function returns negative value if o1 < o2
131   //                                   0              if o1 == o2
132   //                                   positive value if o1 > o2
133   inline static int  compare(oop o1, oop o2) {
134     void* o1_addr = (void*)o1;
135     void* o2_addr = (void*)o2;
136     if (o1_addr < o2_addr) {
137       return -1;
138     } else if (o1_addr > o2_addr) {
139       return 1;
140     } else {
141       return 0;
142     }
143   }
144 
145   inline static bool equals(oop o1, oop o2) { return Access<>::equals(o1, o2); }
146 
147   // Access to fields in a instanceOop through these methods.
148   template <DecoratorSet decorator>
149   oop obj_field_access(int offset) const;
150   oop obj_field(int offset) const;
151   void obj_field_put(int offset, oop value);
152   void obj_field_put_raw(int offset, oop value);
153   void obj_field_put_volatile(int offset, oop value);
154 
155   Metadata* metadata_field(int offset) const;
156   void metadata_field_put(int offset, Metadata* value);
157 
158   Metadata* metadata_field_acquire(int offset) const;
159   void release_metadata_field_put(int offset, Metadata* value);
160 
161   jbyte byte_field(int offset) const;
162   void byte_field_put(int offset, jbyte contents);
163 
164   jchar char_field(int offset) const;
165   void char_field_put(int offset, jchar contents);
166 
167   jboolean bool_field(int offset) const;
168   void bool_field_put(int offset, jboolean contents);
169 
170   jint int_field(int offset) const;
171   void int_field_put(int offset, jint contents);
172 
173   jshort short_field(int offset) const;
174   void short_field_put(int offset, jshort contents);
175 
176   jlong long_field(int offset) const;
177   void long_field_put(int offset, jlong contents);
178 
179   jfloat float_field(int offset) const;
180   void float_field_put(int offset, jfloat contents);
181 
182   jdouble double_field(int offset) const;
183   void double_field_put(int offset, jdouble contents);
184 
185   address address_field(int offset) const;
186   void address_field_put(int offset, address contents);
187 
188   oop obj_field_acquire(int offset) const;
189   void release_obj_field_put(int offset, oop value);
190 
191   jbyte byte_field_acquire(int offset) const;
192   void release_byte_field_put(int offset, jbyte contents);
193 
194   jchar char_field_acquire(int offset) const;
195   void release_char_field_put(int offset, jchar contents);
196 
197   jboolean bool_field_acquire(int offset) const;
198   void release_bool_field_put(int offset, jboolean contents);
199 
200   jint int_field_acquire(int offset) const;
201   void release_int_field_put(int offset, jint contents);
202 
203   jshort short_field_acquire(int offset) const;
204   void release_short_field_put(int offset, jshort contents);
205 
206   jlong long_field_acquire(int offset) const;
207   void release_long_field_put(int offset, jlong contents);
208 
209   jfloat float_field_acquire(int offset) const;
210   void release_float_field_put(int offset, jfloat contents);
211 
212   jdouble double_field_acquire(int offset) const;
213   void release_double_field_put(int offset, jdouble contents);
214 
215   address address_field_acquire(int offset) const;
216   void release_address_field_put(int offset, address contents);
217 
218   // printing functions for VM debugging
219   void print_on(outputStream* st) const;         // First level print
220   void print_value_on(outputStream* st) const;   // Second level print.
221   void print_address_on(outputStream* st) const; // Address printing
222 
223   // printing on default output stream
224   void print();
225   void print_value();
226   void print_address();
227 
228   // return the print strings
229   char* print_string();
230   char* print_value_string();
231 
232   // verification operations
233   void verify_on(outputStream* st);
234   void verify();
235 
236   // locking operations
237   inline bool is_locked()   const;
238   inline bool is_unlocked() const;
239   inline bool has_bias_pattern() const;
240 
241   // asserts and guarantees
242   static bool is_oop(oop obj, bool ignore_mark_word = false);
243   static bool is_oop_or_null(oop obj, bool ignore_mark_word = false);
244 #ifndef PRODUCT
245   inline bool is_unlocked_oop() const;
246 #endif
247 
248   // garbage collection
249   inline bool is_gc_marked() const;
250 
251   // Forward pointer operations for scavenge
252   inline bool is_forwarded() const;
253 
254   inline void forward_to(oop p);
255   inline bool cas_forward_to(oop p, markOop compare);
256 
257 #if INCLUDE_ALL_GCS
258   // Like "forward_to", but inserts the forwarding pointer atomically.
259   // Exactly one thread succeeds in inserting the forwarding pointer, and
260   // this call returns "NULL" for that thread; any other thread has the
261   // value of the forwarding pointer returned and does not modify "this".
262   inline oop forward_to_atomic(oop p);
263 #endif // INCLUDE_ALL_GCS
264 
265   inline oop forwardee() const;
266 
267   // Age of object during scavenge
268   inline uint age() const;
269   inline void incr_age();
270 
271   // mark-sweep support
272   void follow_body(int begin, int end);
273 
274   // Garbage Collection support
275 
276 #if INCLUDE_ALL_GCS
277   // Parallel Compact
278   inline void pc_follow_contents(ParCompactionManager* cm);
279   inline void pc_update_contents(ParCompactionManager* cm);
280   // Parallel Scavenge
281   inline void ps_push_contents(PSPromotionManager* pm);
282 #endif
283 
284 
285   // iterators, returns size of object
286 #define OOP_ITERATE_DECL(OopClosureType, nv_suffix)                     \
287   inline void oop_iterate(OopClosureType* blk);                         \
288   inline void oop_iterate(OopClosureType* blk, MemRegion mr);  // Only in mr.
289 
290   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_DECL)
291   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_DECL)
292 
293 #define OOP_ITERATE_SIZE_DECL(OopClosureType, nv_suffix)                \
294   inline int oop_iterate_size(OopClosureType* blk);                     \
295   inline int oop_iterate_size(OopClosureType* blk, MemRegion mr);  // Only in mr.
296 
297   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_SIZE_DECL)
298   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_SIZE_DECL)
299 
300 
301 #if INCLUDE_ALL_GCS
302 
303 #define OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)  \
304   inline void oop_iterate_backwards(OopClosureType* blk);
305 
306   ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_BACKWARDS_DECL)
307   ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_BACKWARDS_DECL)
308 
309 #endif // INCLUDE_ALL_GCS
310 
311   inline int oop_iterate_no_header(OopClosure* bk);
312   inline int oop_iterate_no_header(OopClosure* bk, MemRegion mr);
313 
314   inline static bool is_instanceof_or_null(oop obj, Klass* klass);
315 
316   // identity hash; returns the identity hash key (computes it if necessary)
317   // NOTE with the introduction of UseBiasedLocking that identity_hash() might reach a
318   // safepoint if called on a biased object. Calling code must be aware of that.
319   inline intptr_t identity_hash();
320   intptr_t slow_identity_hash();
321 
322   // Alternate hashing code if string table is rehashed
323   unsigned int new_hash(juint seed);
324 
325   // marks are forwarded to stack when object is locked
326   inline bool    has_displaced_mark() const;
327   inline markOop displaced_mark() const;
328   inline void    set_displaced_mark(markOop m);
329 
330   static bool has_klass_gap();
331 
332   // for code generation
333   static int mark_offset_in_bytes()      { return offset_of(oopDesc, _mark); }
334   static int klass_offset_in_bytes()     { return offset_of(oopDesc, _metadata._klass); }
335   static int klass_gap_offset_in_bytes() {
336     assert(has_klass_gap(), "only applicable to compressed klass pointers");
337     return klass_offset_in_bytes() + sizeof(narrowKlass);
338   }
339 
340   static bool is_archive_object(oop p) NOT_CDS_JAVA_HEAP_RETURN_(false);
341 };
342 
343 #endif // SHARE_VM_OOPS_OOP_HPP