1 /*
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  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_INLINE_HPP
 26 #define SHARE_OOPS_OOP_INLINE_HPP
 27 
 28 #include "oops/oop.hpp"
 29 
 30 #include "memory/universe.hpp"
 31 #include "oops/access.inline.hpp"
 32 #include "oops/arrayKlass.hpp"
 33 #include "oops/arrayOop.hpp"
 34 #include "oops/compressedKlass.inline.hpp"
 35 #include "oops/compressedOops.inline.hpp"
 36 #include "oops/markWord.inline.hpp"
 37 #include "oops/oopsHierarchy.hpp"
 38 #include "runtime/atomic.hpp"
 39 #include "runtime/globals.hpp"
 40 #include "runtime/safepoint.hpp"
 41 #include "runtime/synchronizer.hpp"
 42 #include "utilities/align.hpp"
 43 #include "utilities/debug.hpp"
 44 #include "utilities/macros.hpp"
 45 #include "utilities/globalDefinitions.hpp"
 46 
 47 // Implementation of all inlined member functions defined in oop.hpp
 48 // We need a separate file to avoid circular references
 49 
 50 markWord oopDesc::mark() const {
 51   return Atomic::load(&_mark);
 52 }
 53 
 54 markWord oopDesc::mark_acquire() const {
 55   return Atomic::load_acquire(&_mark);
 56 }
 57 
 58 markWord* oopDesc::mark_addr() const {
 59   return (markWord*) &_mark;
 60 }
 61 
 62 void oopDesc::set_mark(markWord m) {
 63   Atomic::store(&_mark, m);
 64 }
 65 
 66 void oopDesc::set_mark(HeapWord* mem, markWord m) {
 67   *(markWord*)(((char*)mem) + mark_offset_in_bytes()) = m;
 68 }
 69 
 70 void oopDesc::release_set_mark(markWord m) {
 71   Atomic::release_store(&_mark, m);
 72 }
 73 
 74 void oopDesc::release_set_mark(HeapWord* mem, markWord m) {
 75   Atomic::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
 76 }
 77 
 78 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
 79   return Atomic::cmpxchg(&_mark, old_mark, new_mark);
 80 }
 81 
 82 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order) {
 83   return Atomic::cmpxchg(&_mark, old_mark, new_mark, order);
 84 }
 85 
 86 void oopDesc::init_mark() {
 87 #ifdef _LP64
 88   markWord header = ObjectSynchronizer::stable_mark(cast_to_oop(this));
 89   assert(UseCompressedClassPointers, "expect compressed klass pointers");
 90   header = markWord((header.value() & markWord::klass_mask_in_place) | markWord::prototype().value());
 91 #else
 92   markWord header = markWord::prototype();
 93 #endif
 94   set_mark(header);
 95 }
 96 
 97 Klass* oopDesc::klass() const {
 98 #ifdef _LP64
 99   assert(UseCompressedClassPointers, "only with compressed class pointers");
100   markWord header = mark();
101   if (!header.is_neutral()) {
102     header = ObjectSynchronizer::stable_mark(cast_to_oop(this));
103   }
104   return header.klass();
105 #else
106   return _klass;
107 #endif
108 }
109 
110 Klass* oopDesc::klass_or_null() const {
111 #ifdef _LP64
112   assert(UseCompressedClassPointers, "only with compressed class pointers");
113   markWord header = mark();
114   if (!header.is_neutral()) {
115     header = ObjectSynchronizer::stable_mark(cast_to_oop(this));
116   }
117   return header.klass_or_null();
118 #else
119   return _klass;
120 #endif
121 }
122 
123 Klass* oopDesc::klass_or_null_acquire() const {
124 #ifdef _LP64
125   assert(UseCompressedClassPointers, "only with compressed class pointers");
126   markWord header = mark_acquire();
127   if (!header.is_neutral()) {
128     header = ObjectSynchronizer::stable_mark(cast_to_oop(this));
129   }
130   return header.klass_or_null();
131 #else
132   return Atomic::load_acquire(&_klass);
133 #endif
134 }
135 
136 #ifndef _LP64
137 void oopDesc::set_klass(Klass* k) {
138   assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
139   _klass = k;
140 }
141 
142 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
143   assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
144   char* raw_mem = ((char*)mem + klass_offset_in_bytes());
145   if (UseCompressedClassPointers) {
146     Atomic::release_store((narrowKlass*)raw_mem,
147                           CompressedKlassPointers::encode_not_null(k));
148   } else {
149     Atomic::release_store((Klass**)raw_mem, k);
150   }
151 }
152 #endif
153 
154 bool oopDesc::is_a(Klass* k) const {
155   return klass()->is_subtype_of(k);
156 }
157 
158 size_t oopDesc::size()  {
159   return size_given_klass(klass());
160 }
161 
162 size_t oopDesc::size_given_klass(Klass* klass)  {
163   int lh = klass->layout_helper();
164   size_t s;
165 
166   // lh is now a value computed at class initialization that may hint
167   // at the size.  For instances, this is positive and equal to the
168   // size.  For arrays, this is negative and provides log2 of the
169   // array element size.  For other oops, it is zero and thus requires
170   // a virtual call.
171   //
172   // We go to all this trouble because the size computation is at the
173   // heart of phase 2 of mark-compaction, and called for every object,
174   // alive or dead.  So the speed here is equal in importance to the
175   // speed of allocation.
176 
177   if (lh > Klass::_lh_neutral_value) {
178     if (!Klass::layout_helper_needs_slow_path(lh)) {
179       s = lh >> LogHeapWordSize;  // deliver size scaled by wordSize
180     } else {
181       s = klass->oop_size(this);
182     }
183   } else if (lh <= Klass::_lh_neutral_value) {
184     // The most common case is instances; fall through if so.
185     if (lh < Klass::_lh_neutral_value) {
186       // Second most common case is arrays.  We have to fetch the
187       // length of the array, shift (multiply) it appropriately,
188       // up to wordSize, add the header, and align to object size.
189       size_t size_in_bytes;
190       size_t array_length = (size_t) ((arrayOop)this)->length();
191       size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
192       size_in_bytes += Klass::layout_helper_header_size(lh);
193 
194       // This code could be simplified, but by keeping array_header_in_bytes
195       // in units of bytes and doing it this way we can round up just once,
196       // skipping the intermediate round to HeapWordSize.
197       s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
198 
199       // UseParallelGC and UseG1GC can change the length field
200       // of an "old copy" of an object array in the young gen so it indicates
201       // the grey portion of an already copied array. This will cause the first
202       // disjunct below to fail if the two comparands are computed across such
203       // a concurrent change.
204       assert((s == klass->oop_size(this)) ||
205              (Universe::is_gc_active() && is_objArray() && is_forwarded() && (get_UseParallelGC() || get_UseG1GC())),
206              "wrong array object size");
207     } else {
208       // Must be zero, so bite the bullet and take the virtual call.
209       s = klass->oop_size(this);
210     }
211   }
212 
213   assert(s > 0, "Oop size must be greater than zero, not " SIZE_FORMAT, s);
214   assert(is_object_aligned(s), "Oop size is not properly aligned: " SIZE_FORMAT, s);
215   return s;
216 }
217 
218 bool oopDesc::is_instance()    const { return klass()->is_instance_klass();           }
219 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass(); }
220 bool oopDesc::is_array()       const { return klass()->is_array_klass();              }
221 bool oopDesc::is_objArray()    const { return klass()->is_objArray_klass();           }
222 bool oopDesc::is_typeArray()   const { return klass()->is_typeArray_klass();          }
223 
224 template<typename T>
225 T*       oopDesc::field_addr(int offset)     const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
226 
227 template <typename T>
228 size_t   oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
229 
230 template <DecoratorSet decorators>
231 inline oop  oopDesc::obj_field_access(int offset) const             { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
232 inline oop  oopDesc::obj_field(int offset) const                    { return HeapAccess<>::oop_load_at(as_oop(), offset);  }
233 
234 inline void oopDesc::obj_field_put(int offset, oop value)           { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
235 
236 inline jbyte oopDesc::byte_field(int offset) const                  { return *field_addr<jbyte>(offset);  }
237 inline void  oopDesc::byte_field_put(int offset, jbyte value)       { *field_addr<jbyte>(offset) = value; }
238 
239 inline jchar oopDesc::char_field(int offset) const                  { return *field_addr<jchar>(offset);  }
240 inline void  oopDesc::char_field_put(int offset, jchar value)       { *field_addr<jchar>(offset) = value; }
241 
242 inline jboolean oopDesc::bool_field(int offset) const               { return *field_addr<jboolean>(offset); }
243 inline void     oopDesc::bool_field_put(int offset, jboolean value) { *field_addr<jboolean>(offset) = jboolean(value & 1); }
244 inline jboolean oopDesc::bool_field_volatile(int offset) const      { return RawAccess<MO_SEQ_CST>::load(field_addr<jboolean>(offset)); }
245 inline void     oopDesc::bool_field_put_volatile(int offset, jboolean value) { RawAccess<MO_SEQ_CST>::store(field_addr<jboolean>(offset), jboolean(value & 1)); }
246 inline jshort oopDesc::short_field(int offset) const                { return *field_addr<jshort>(offset);   }
247 inline void   oopDesc::short_field_put(int offset, jshort value)    { *field_addr<jshort>(offset) = value;  }
248 
249 inline jint oopDesc::int_field(int offset) const                    { return *field_addr<jint>(offset);     }
250 inline void oopDesc::int_field_put(int offset, jint value)          { *field_addr<jint>(offset) = value;    }
251 
252 inline jlong oopDesc::long_field(int offset) const                  { return *field_addr<jlong>(offset);    }
253 inline void  oopDesc::long_field_put(int offset, jlong value)       { *field_addr<jlong>(offset) = value;   }
254 
255 inline jfloat oopDesc::float_field(int offset) const                { return *field_addr<jfloat>(offset);   }
256 inline void   oopDesc::float_field_put(int offset, jfloat value)    { *field_addr<jfloat>(offset) = value;  }
257 
258 inline jdouble oopDesc::double_field(int offset) const              { return *field_addr<jdouble>(offset);  }
259 inline void    oopDesc::double_field_put(int offset, jdouble value) { *field_addr<jdouble>(offset) = value; }
260 
261 bool oopDesc::is_locked() const {
262   return mark().is_locked();
263 }
264 
265 bool oopDesc::is_unlocked() const {
266   return mark().is_unlocked();
267 }
268 
269 // Used only for markSweep, scavenging
270 bool oopDesc::is_gc_marked() const {
271   return mark().is_marked();
272 }
273 
274 // Used by scavengers
275 bool oopDesc::is_forwarded() const {
276   // The extra heap check is needed since the obj might be locked, in which case the
277   // mark would point to a stack location and have the sentinel bit cleared
278   return mark().is_marked();
279 }
280 
281 // Used by scavengers
282 void oopDesc::forward_to(oop p) {
283   verify_forwardee(p);
284   markWord m = markWord::encode_pointer_as_mark(p);
285   assert(forwardee(m) == p, "encoding must be reversable");
286   set_mark(m);
287 }
288 
289 void oopDesc::forward_to_self() {
290 #ifdef _LP64
291   verify_forwardee(this);
292   markWord m = mark();
293   // If mark is displaced, we need to preserve the Klass* from real header.
294   assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
295   if (m.has_displaced_mark_helper()) {
296     m = m.displaced_mark_helper();
297   }
298   m = m.set_self_forwarded();
299   assert(forwardee(m) == cast_to_oop(this), "encoding must be reversable");
300   set_mark(m);
301 #else
302   forward_to(oop(this));
303 #endif
304 }
305 
306 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
307   verify_forwardee(p);
308   markWord m = markWord::encode_pointer_as_mark(p);
309   assert(forwardee(m) == p, "encoding must be reversable");
310   markWord old_mark = cas_set_mark(m, compare, order);
311   if (old_mark == compare) {
312     return NULL;
313   } else {
314     return forwardee(old_mark);
315   }
316 }
317 
318 oop oopDesc::forward_to_self_atomic(markWord compare, atomic_memory_order order) {
319 #ifdef _LP64
320   verify_forwardee(this);
321   markWord m = compare;
322   // If mark is displaced, we need to preserve the Klass* from real header.
323   assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
324   if (m.has_displaced_mark_helper()) {
325     m = m.displaced_mark_helper();
326   }
327   m = m.set_self_forwarded();
328   assert(forwardee(m) == cast_to_oop(this), "encoding must be reversable");
329   markWord old_mark = cas_set_mark(m, compare, order);
330   if (old_mark == compare) {
331     return NULL;
332   } else {
333     assert(old_mark.is_marked(), "must be marked here");
334     return forwardee(old_mark);
335   }
336 #else
337   return forward_to_atomic(oop(this), compare, order);
338 #endif
339 }
340 
341 // Note that the forwardee is not the same thing as the displaced_mark.
342 // The forwardee is used when copying during scavenge and mark-sweep.
343 // It does need to clear the low two locking- and GC-related bits.
344 oop oopDesc::forwardee() const {
345   return forwardee(mark());
346 }
347 
348 oop oopDesc::forwardee(markWord header) const {
349   assert(header.is_marked(), "must be forwarded");
350 #ifdef _LP64
351   if (header.self_forwarded()) {
352     return cast_to_oop(this);
353   } else
354 #endif
355   {
356     assert(header.is_marked(), "only decode when actually forwarded");
357     return cast_to_oop(header.decode_pointer());
358   }
359 }
360 
361 // The following method needs to be MT safe.
362 uint oopDesc::age() const {
363   assert(!mark().is_marked(), "Attempt to read age from forwarded mark");
364   if (has_displaced_mark()) {
365     return displaced_mark().age();
366   } else {
367     return mark().age();
368   }
369 }
370 
371 void oopDesc::incr_age() {
372   assert(!mark().is_marked(), "Attempt to increment age of forwarded mark");
373   if (has_displaced_mark()) {
374     set_displaced_mark(displaced_mark().incr_age());
375   } else {
376     set_mark(mark().incr_age());
377   }
378 }
379 
380 template <typename OopClosureType>
381 void oopDesc::oop_iterate(OopClosureType* cl) {
382   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
383 }
384 
385 template <typename OopClosureType>
386 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
387   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
388 }
389 
390 template <typename OopClosureType>
391 size_t oopDesc::oop_iterate_size(OopClosureType* cl) {
392   Klass* k = klass();
393   size_t size = size_given_klass(k);
394   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
395   return size;
396 }
397 
398 template <typename OopClosureType>
399 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
400   Klass* k = klass();
401   size_t size = size_given_klass(k);
402   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
403   return size;
404 }
405 
406 template <typename OopClosureType>
407 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
408   oop_iterate_backwards(cl, klass());
409 }
410 
411 template <typename OopClosureType>
412 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
413   OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
414 }
415 
416 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
417   return obj == NULL || obj->klass()->is_subtype_of(klass);
418 }
419 
420 intptr_t oopDesc::identity_hash() {
421   // Fast case; if the object is unlocked and the hash value is set, no locking is needed
422   // Note: The mark must be read into local variable to avoid concurrent updates.
423   markWord mrk = mark();
424   if (mrk.is_unlocked() && !mrk.has_no_hash()) {
425     return mrk.hash();
426   } else if (mrk.is_marked()) {
427     return mrk.hash();
428   } else {
429     return slow_identity_hash();
430   }
431 }
432 
433 bool oopDesc::has_displaced_mark() const {
434   return mark().has_displaced_mark_helper();
435 }
436 
437 markWord oopDesc::displaced_mark() const {
438   return mark().displaced_mark_helper();
439 }
440 
441 void oopDesc::set_displaced_mark(markWord m) {
442   mark().set_displaced_mark_helper(m);
443 }
444 
445 bool oopDesc::mark_must_be_preserved() const {
446   return mark_must_be_preserved(mark());
447 }
448 
449 bool oopDesc::mark_must_be_preserved(markWord m) const {
450   return m.must_be_preserved(this);
451 }
452 
453 #endif // SHARE_OOPS_OOP_INLINE_HPP