1 /*
  2  * Copyright (c) 1997, 2025, 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.
 22  *
 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/iterator.inline.hpp"
 31 #include "memory/universe.hpp"
 32 #include "oops/access.inline.hpp"
 33 #include "oops/arrayKlass.hpp"
 34 #include "oops/arrayOop.hpp"
 35 #include "oops/compressedKlass.inline.hpp"
 36 #include "oops/instanceKlass.hpp"
 37 #include "oops/markWord.inline.hpp"
 38 #include "oops/objLayout.inline.hpp"
 39 #include "oops/oopsHierarchy.hpp"
 40 #include "runtime/atomicAccess.hpp"
 41 #include "runtime/globals.hpp"
 42 #include "utilities/align.hpp"
 43 #include "utilities/debug.hpp"
 44 #include "utilities/globalDefinitions.hpp"
 45 #include "utilities/macros.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 void* oopDesc::base_addr() { return this; }
 51 const void* oopDesc::base_addr() const { return this; }
 52 
 53 markWord oopDesc::mark() const {
 54   return AtomicAccess::load(&_mark);
 55 }
 56 
 57 markWord oopDesc::mark_acquire() const {
 58   return AtomicAccess::load_acquire(&_mark);
 59 }
 60 
 61 void oopDesc::set_mark(markWord m) {
 62   if (UseCompactObjectHeaders) {
 63     AtomicAccess::store(reinterpret_cast<uint32_t volatile*>(&_mark), m.value32());
 64   } else {
 65     AtomicAccess::store(&_mark, m);
 66   }
 67 }
 68 
 69 void oopDesc::set_mark_full(markWord m) {
 70   AtomicAccess::store(&_mark, m);
 71 }
 72 
 73 void oopDesc::set_mark(HeapWord* mem, markWord m) {
 74   if (UseCompactObjectHeaders) {
 75     *(uint32_t*)(((char*)mem) + mark_offset_in_bytes()) = m.value32();
 76   } else {
 77     *(markWord*)(((char*)mem) + mark_offset_in_bytes()) = m;
 78   }
 79 }
 80 
 81 void oopDesc::release_set_mark(HeapWord* mem, markWord m) {
 82   if (UseCompactObjectHeaders) {
 83     AtomicAccess::release_store((uint32_t*)(((char*)mem) + mark_offset_in_bytes()), m.value32());
 84   } else {
 85     AtomicAccess::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
 86   }
 87 }
 88 
 89 void oopDesc::release_set_mark(markWord m) {
 90   if (UseCompactObjectHeaders) {
 91     AtomicAccess::release_store(reinterpret_cast<uint32_t volatile*>(&_mark), m.value32());
 92   } else {
 93     AtomicAccess::release_store(&_mark, m);
 94   }
 95 }
 96 
 97 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
 98   return AtomicAccess::cmpxchg(&_mark, old_mark, new_mark);
 99 }
100 
101 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order) {
102   return AtomicAccess::cmpxchg(&_mark, old_mark, new_mark, order);
103 }
104 
105 markWord oopDesc::prototype_mark() const {
106   if (UseCompactObjectHeaders) {
107     return klass()->prototype_header();
108   } else {
109     return markWord::prototype();
110   }
111 }
112 
113 void oopDesc::init_mark() {
114   set_mark(prototype_mark());
115 }
116 
117 void oopDesc::reinit_mark() {
118   if (UseCompactObjectHeaders) {
119     markWord m = prototype_mark().copy_hashctrl_from(mark());
120     assert(m.is_neutral(), "must be neutral");
121     set_mark(m);
122   } else {
123     set_mark(prototype_mark());
124   }
125 }
126 
127 Klass* oopDesc::klass() const {
128   switch (ObjLayout::klass_mode()) {
129     case ObjLayout::Compact:
130       return mark().klass();
131     case ObjLayout::Compressed:
132       return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
133     default:
134       return _metadata._klass;
135   }
136 }
137 
138 Klass* oopDesc::klass_or_null() const {
139   switch (ObjLayout::klass_mode()) {
140     case ObjLayout::Compact:
141       return mark().klass_or_null();
142     case ObjLayout::Compressed:
143       return CompressedKlassPointers::decode(_metadata._compressed_klass);
144     default:
145       return _metadata._klass;
146   }
147 }
148 
149 Klass* oopDesc::klass_or_null_acquire() const {
150   switch (ObjLayout::klass_mode()) {
151     case ObjLayout::Compact:
152       return mark_acquire().klass();
153     case ObjLayout::Compressed: {
154       narrowKlass narrow_klass = AtomicAccess::load_acquire(&_metadata._compressed_klass);
155       return CompressedKlassPointers::decode(narrow_klass);
156     }
157     default:
158       return AtomicAccess::load_acquire(&_metadata._klass);
159   }
160 }
161 
162 Klass* oopDesc::klass_without_asserts() const {
163   switch (ObjLayout::klass_mode()) {
164     case ObjLayout::Compact:
165       return mark().klass_without_asserts();
166     case ObjLayout::Compressed:
167       return CompressedKlassPointers::decode_without_asserts(_metadata._compressed_klass);
168     default:
169       return _metadata._klass;
170   }
171 }
172 
173 narrowKlass oopDesc::narrow_klass() const {
174   switch (ObjLayout::klass_mode()) {
175     case ObjLayout::Compact:
176       return mark().narrow_klass();
177     case ObjLayout::Compressed:
178       return _metadata._compressed_klass;
179     default:
180       ShouldNotReachHere();
181   }
182 }
183 
184 void oopDesc::set_klass(Klass* k) {
185   assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
186   assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
187   if (UseCompressedClassPointers) {
188     _metadata._compressed_klass = CompressedKlassPointers::encode_not_null(k);
189   } else {
190     _metadata._klass = k;
191   }
192 }
193 
194 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
195   assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
196   assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
197   char* raw_mem = ((char*)mem + klass_offset_in_bytes());
198   if (UseCompressedClassPointers) {
199     AtomicAccess::release_store((narrowKlass*)raw_mem,
200                           CompressedKlassPointers::encode_not_null(k));
201   } else {
202     AtomicAccess::release_store((Klass**)raw_mem, k);
203   }
204 }
205 
206 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
207   assert(has_klass_gap(), "precondition");
208   *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
209 }
210 
211 bool oopDesc::is_a(Klass* k) const {
212   return klass()->is_subtype_of(k);
213 }
214 
215 size_t oopDesc::size_given_mark_and_klass(markWord mrk, const Klass* kls) {
216   size_t sz = base_size_given_klass(mrk, kls);
217   if (UseCompactObjectHeaders) {
218     assert(!mrk.has_displaced_mark_helper(), "must not be displaced");
219     if (mrk.is_expanded() && kls->expand_for_hash(cast_to_oop(this), mrk)) {
220       sz = align_object_size(sz + 1);
221     }
222   }
223   return sz;
224 }
225 
226 size_t oopDesc::size_forwarded() {
227   assert(is_forwarded(), "must be forwarded");
228   markWord m = mark();
229   oop fwd = forwardee(m);
230   if (!UseCompactObjectHeaders) {
231     return fwd->size();
232   }
233   markWord fm = fwd->mark();
234   Klass* klass = fm.klass();
235   if (m.is_forward_expanded()) {
236     // Forwardee was expanded during copy but the original was not.
237     // Original must have base size.
238     return fwd->base_size_given_klass(fm, klass);
239   }
240   // Original and copy have same size (whether expanded or not).
241   return fwd->size_given_mark_and_klass(fm, klass);
242 }
243 
244 size_t oopDesc::copy_size(size_t size, markWord mark) const {
245   if (UseCompactObjectHeaders) {
246     assert(!mark.has_displaced_mark_helper(), "must not be displaced");
247     Klass* klass = mark.klass();
248     if (mark.is_hashed_not_expanded() && klass->expand_for_hash(cast_to_oop(this), mark)) {
249       size = align_object_size(size + 1);
250     }
251   }
252   assert(is_object_aligned(size), "Oop size is not properly aligned: %zu", size);
253   return size;
254 }
255 
256 size_t oopDesc::copy_size_cds(size_t size, markWord mark) const {
257   if (UseCompactObjectHeaders) {
258     assert(!mark.has_displaced_mark_helper(), "must not be displaced");
259     Klass* klass = mark.klass();
260     if (mark.is_not_hashed_expanded()) {
261       assert(klass->expand_for_hash(cast_to_oop(this), mark), "must be?");
262     }
263     if (mark.is_hashed_not_expanded() && klass->expand_for_hash(cast_to_oop(this), mark)) {
264       size = align_object_size(size + 1);
265     }
266     if (mark.is_not_hashed_expanded() && klass->expand_for_hash(cast_to_oop(this), mark)) {
267       size = align_object_size(size - ObjectAlignmentInBytes / HeapWordSize);
268     }
269   }
270   assert(is_object_aligned(size), "Oop size is not properly aligned: %zu", size);
271   return size;
272 }
273 
274 size_t oopDesc::size()  {
275   return size_given_mark_and_klass(mark(), klass());
276 }
277 
278 size_t oopDesc::base_size_given_klass(markWord mrk, const Klass* klass)  {
279   int lh = klass->layout_helper();
280   size_t s;
281 
282   // lh is now a value computed at class initialization that may hint
283   // at the size.  For instances, this is positive and equal to the
284   // size.  For arrays, this is negative and provides log2 of the
285   // array element size.  For other oops, it is zero and thus requires
286   // a virtual call.
287   //
288   // We go to all this trouble because the size computation is at the
289   // heart of phase 2 of mark-compaction, and called for every object,
290   // alive or dead.  So the speed here is equal in importance to the
291   // speed of allocation.
292 
293   if (lh > Klass::_lh_neutral_value) {
294     if (!Klass::layout_helper_needs_slow_path(lh)) {
295       s = lh >> LogHeapWordSize;  // deliver size scaled by wordSize
296     } else {
297       s = klass->oop_size(this, mrk);
298     }
299   } else if (lh <= Klass::_lh_neutral_value) {
300     // The most common case is instances; fall through if so.
301     if (lh < Klass::_lh_neutral_value) {
302       // Second most common case is arrays.  We have to fetch the
303       // length of the array, shift (multiply) it appropriately,
304       // up to wordSize, add the header, and align to object size.
305       size_t size_in_bytes;
306       size_t array_length;
307 #ifdef _LP64
308       if (UseCompactObjectHeaders) {
309         array_length = (size_t) mrk.array_length();
310       } else
311 #endif
312         array_length = (size_t)((arrayOop)this)->length();
313 
314       size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
315       size_in_bytes += Klass::layout_helper_header_size(lh);
316 
317       // This code could be simplified, but by keeping array_header_in_bytes
318       // in units of bytes and doing it this way we can round up just once,
319       // skipping the intermediate round to HeapWordSize.
320       s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
321       if (s != klass->oop_size(this, mrk)) {
322         tty->print_cr("length: %zu", array_length);
323         tty->print_cr("log element size: %d", Klass::layout_helper_log2_element_size(lh));
324         tty->print_cr("is_objArray: %s", BOOL_TO_STR(klass->is_objArray_klass()));
325       }
326       assert(s == klass->oop_size(this, mrk), "wrong array object size, s: %zu, oop_size: %zu", s, klass->oop_size(this, mrk));
327     } else {
328       // Must be zero, so bite the bullet and take the virtual call.
329       s = klass->oop_size(this, mrk);
330     }
331   }
332 
333   assert(s > 0, "Oop size must be greater than zero, not %zu", s);
334   assert(is_object_aligned(s), "Oop size is not properly aligned: %zu", s);
335   return s;
336 }
337 
338 bool oopDesc::is_instance()    const { return klass()->is_instance_klass();             }
339 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass();   }
340 bool oopDesc::is_stackChunk()  const { return klass()->is_stack_chunk_instance_klass(); }
341 bool oopDesc::is_array()       const { return klass()->is_array_klass();                }
342 bool oopDesc::is_objArray()    const { return klass()->is_objArray_klass();             }
343 bool oopDesc::is_typeArray()   const { return klass()->is_typeArray_klass();            }
344 
345 template<typename T>
346 T*       oopDesc::field_addr(int offset)     const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
347 
348 template <typename T>
349 size_t   oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
350 
351 template <DecoratorSet decorators>
352 inline oop  oopDesc::obj_field_access(int offset) const             { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
353 inline oop  oopDesc::obj_field(int offset) const                    { return HeapAccess<>::oop_load_at(as_oop(), offset);  }
354 
355 inline void oopDesc::obj_field_put(int offset, oop value)           { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
356 template <DecoratorSet decorators>
357 inline void oopDesc::obj_field_put_access(int offset, oop value)    { HeapAccess<decorators>::oop_store_at(as_oop(), offset, value); }
358 
359 inline jbyte oopDesc::byte_field(int offset) const                  { return *field_addr<jbyte>(offset);  }
360 inline void  oopDesc::byte_field_put(int offset, jbyte value)       { *field_addr<jbyte>(offset) = value; }
361 
362 inline jchar oopDesc::char_field(int offset) const                  { return *field_addr<jchar>(offset);  }
363 inline void  oopDesc::char_field_put(int offset, jchar value)       { *field_addr<jchar>(offset) = value; }
364 
365 inline jboolean oopDesc::bool_field(int offset) const               { return *field_addr<jboolean>(offset); }
366 inline void     oopDesc::bool_field_put(int offset, jboolean value) { *field_addr<jboolean>(offset) = jboolean(value & 1); }
367 inline jboolean oopDesc::bool_field_volatile(int offset) const      { return RawAccess<MO_SEQ_CST>::load(field_addr<jboolean>(offset)); }
368 inline void     oopDesc::bool_field_put_volatile(int offset, jboolean value) { RawAccess<MO_SEQ_CST>::store(field_addr<jboolean>(offset), jboolean(value & 1)); }
369 inline jshort oopDesc::short_field(int offset) const                { return *field_addr<jshort>(offset);   }
370 inline void   oopDesc::short_field_put(int offset, jshort value)    { *field_addr<jshort>(offset) = value;  }
371 
372 inline jint oopDesc::int_field(int offset) const                    { return *field_addr<jint>(offset);     }
373 inline void oopDesc::int_field_put(int offset, jint value)          { *field_addr<jint>(offset) = value;    }
374 inline jint oopDesc::int_field_relaxed(int offset) const            { return AtomicAccess::load(field_addr<jint>(offset)); }
375 inline void oopDesc::int_field_put_relaxed(int offset, jint value)  { AtomicAccess::store(field_addr<jint>(offset), value); }
376 
377 inline jlong oopDesc::long_field(int offset) const                  { return *field_addr<jlong>(offset);    }
378 inline void  oopDesc::long_field_put(int offset, jlong value)       { *field_addr<jlong>(offset) = value;   }
379 
380 inline jfloat oopDesc::float_field(int offset) const                { return *field_addr<jfloat>(offset);   }
381 inline void   oopDesc::float_field_put(int offset, jfloat value)    { *field_addr<jfloat>(offset) = value;  }
382 
383 inline jdouble oopDesc::double_field(int offset) const              { return *field_addr<jdouble>(offset);  }
384 inline void    oopDesc::double_field_put(int offset, jdouble value) { *field_addr<jdouble>(offset) = value; }
385 
386 bool oopDesc::is_locked() const {
387   return mark().is_locked();
388 }
389 
390 bool oopDesc::is_unlocked() const {
391   return mark().is_unlocked();
392 }
393 
394 bool oopDesc::is_gc_marked() const {
395   return mark().is_marked();
396 }
397 
398 // Used by scavengers
399 bool oopDesc::is_forwarded() const {
400   return mark().is_forwarded();
401 }
402 
403 bool oopDesc::is_self_forwarded() const {
404   return mark().is_self_forwarded();
405 }
406 
407 // Used by scavengers
408 void oopDesc::forward_to(oop p) {
409   assert(cast_from_oop<oopDesc*>(p) != this,
410          "must not be used for self-forwarding, use forward_to_self() instead");
411   markWord m = markWord::encode_pointer_as_mark(p);
412   if (UseCompactObjectHeaders && p->mark().is_expanded() && !mark().is_expanded()) {
413     m = m.set_forward_expanded();
414   }
415   assert(m.decode_pointer() == p, "encoding must be reversible");
416   set_mark_full(m);
417 }
418 
419 void oopDesc::forward_to_self() {
420   set_mark(mark().set_self_forwarded());
421 }
422 
423 void oopDesc::reset_forwarded() {
424   markWord m = mark();
425   if (m.is_self_forwarded()) {
426     unset_self_forwarded();
427   } else if (m.is_forwarded()) {
428     // Restore Klass* and hash-bits in the header,
429     // for correct iteration.
430     markWord fwd_mark = forwardee()->mark();
431     if (m.is_forward_expanded()) {
432       // Un-expand original object.
433       fwd_mark = fwd_mark.set_hashed_not_expanded();
434     }
435     set_mark_full(fwd_mark);
436   }
437 }
438 
439 oop oopDesc::cas_set_forwardee(markWord new_mark, markWord compare, atomic_memory_order order) {
440   markWord old_mark = cas_set_mark(new_mark, compare, order);
441   if (old_mark == compare) {
442     return nullptr;
443   } else {
444     assert(old_mark.is_forwarded(), "must be forwarded here");
445     return forwardee(old_mark);
446   }
447 }
448 
449 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
450   assert(cast_from_oop<oopDesc*>(p) != this,
451          "must not be used for self-forwarding, use forward_to_self_atomic() instead");
452   markWord m = markWord::encode_pointer_as_mark(p);
453   if (UseCompactObjectHeaders && compare.is_hashed_not_expanded()) {
454     m = m.set_forward_expanded();
455   }
456   assert(forwardee(m) == p, "encoding must be reversible");
457   return cas_set_forwardee(m, compare, order);
458 }
459 
460 oop oopDesc::forward_to_self_atomic(markWord old_mark, atomic_memory_order order) {
461   markWord new_mark = old_mark.set_self_forwarded();
462   assert(forwardee(new_mark) == cast_to_oop(this), "encoding must be reversible");
463   return cas_set_forwardee(new_mark, old_mark, order);
464 }
465 
466 oop oopDesc::forwardee(markWord mark) const {
467   assert(mark.is_forwarded(), "only decode when actually forwarded");
468   if (mark.is_self_forwarded()) {
469     return cast_to_oop(this);
470   } else {
471     return mark.forwardee();
472   }
473 }
474 
475 // Note that the forwardee is not the same thing as the displaced_mark.
476 // The forwardee is used when copying during scavenge and mark-sweep.
477 // It does need to clear the low two locking- and GC-related bits.
478 oop oopDesc::forwardee() const {
479   return forwardee(mark());
480 }
481 
482 void oopDesc::unset_self_forwarded() {
483   set_mark(mark().unset_self_forwarded());
484 }
485 
486 // The following method needs to be MT safe.
487 uint oopDesc::age() const {
488   markWord m = mark();
489   assert(!m.is_marked(), "Attempt to read age from forwarded mark");
490   if (m.has_displaced_mark_helper()) {
491     return m.displaced_mark_helper().age();
492   } else {
493     return m.age();
494   }
495 }
496 
497 void oopDesc::incr_age() {
498   markWord m = mark();
499   assert(!m.is_marked(), "Attempt to increment age of forwarded mark");
500   if (m.has_displaced_mark_helper()) {
501     m.set_displaced_mark_helper(m.displaced_mark_helper().incr_age());
502   } else {
503     set_mark(m.incr_age());
504   }
505 }
506 
507 template <typename OopClosureType>
508 void oopDesc::oop_iterate(OopClosureType* cl) {
509   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
510 }
511 
512 template <typename OopClosureType>
513 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
514   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
515 }
516 
517 template <typename OopClosureType>
518 size_t oopDesc::oop_iterate_size(OopClosureType* cl) {
519   Klass* k = klass();
520   size_t size = size_given_mark_and_klass(mark(), k);
521   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
522   return size;
523 }
524 
525 template <typename OopClosureType>
526 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
527   Klass* k = klass();
528   size_t size = size_given_mark_and_klass(mark(), k);
529   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
530   return size;
531 }
532 
533 template <typename OopClosureType>
534 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
535   oop_iterate_backwards(cl, klass());
536 }
537 
538 template <typename OopClosureType>
539 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
540   // In this assert, we cannot safely access the Klass* with compact headers.
541   assert(k == klass(), "wrong klass");
542   OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
543 }
544 
545 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
546   return obj == nullptr || obj->klass()->is_subtype_of(klass);
547 }
548 
549 intptr_t oopDesc::identity_hash() {
550   // Fast case; if the object is unlocked and the hash value is set, no locking is needed
551   // Note: The mark must be read into local variable to avoid concurrent updates.
552   if (UseCompactObjectHeaders) {
553     markWord mrk = mark();
554     if (mrk.is_hashed_expanded()) {
555       Klass* klass = mrk.klass();
556       return int_field(klass->hash_offset_in_bytes(cast_to_oop(this), mrk));
557     }
558     // Fall-through to slow-case.
559   } else {
560     markWord mrk = mark();
561     if (mrk.is_unlocked() && !mrk.has_no_hash()) {
562       return mrk.hash();
563     } else if (mrk.is_marked()) {
564       return mrk.hash();
565     }
566     // Fall-through to slow-case.
567   }
568   return slow_identity_hash();
569 }
570 
571 // This checks fast simple case of whether the oop has_no_hash,
572 // to optimize JVMTI table lookup.
573 bool oopDesc::fast_no_hash_check() {
574   markWord mrk = mark_acquire();
575   assert(!mrk.is_marked(), "should never be marked");
576   return (UseCompactObjectHeaders || mrk.is_unlocked()) && mrk.has_no_hash();
577 }
578 
579 bool oopDesc::has_displaced_mark() const {
580   return mark().has_displaced_mark_helper();
581 }
582 
583 markWord oopDesc::displaced_mark() const {
584   return mark().displaced_mark_helper();
585 }
586 
587 void oopDesc::set_displaced_mark(markWord m) {
588   mark().set_displaced_mark_helper(m);
589 }
590 
591 bool oopDesc::mark_must_be_preserved() const {
592   return mark_must_be_preserved(mark());
593 }
594 
595 bool oopDesc::mark_must_be_preserved(markWord m) const {
596   return m.must_be_preserved();
597 }
598 
599 inline void oopDesc::initialize_hash_if_necessary(oop obj) {
600   if (!UseCompactObjectHeaders) {
601     return;
602   }
603   markWord m = mark();
604   assert(!m.has_displaced_mark_helper(), "must not be displaced header");
605   if (m.is_hashed_not_expanded()) {
606     set_mark(initialize_hash_if_necessary(obj, m.klass(), m));
607   }
608 }
609 
610 
611 #endif // SHARE_OOPS_OOP_INLINE_HPP