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/universe.hpp"
31 #include "memory/iterator.inline.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.hpp"
38 #include "oops/oopsHierarchy.hpp"
39 #include "runtime/atomic.hpp"
40 #include "runtime/globals.hpp"
41 #include "utilities/align.hpp"
42 #include "utilities/debug.hpp"
43 #include "utilities/macros.hpp"
44 #include "utilities/globalDefinitions.hpp"
45
46 // Implementation of all inlined member functions defined in oop.hpp
47 // We need a separate file to avoid circular references
48
49 markWord oopDesc::mark() const {
50 return Atomic::load(&_mark);
51 }
52
53 markWord oopDesc::mark_acquire() const {
54 return Atomic::load_acquire(&_mark);
55 }
56
57 markWord* oopDesc::mark_addr() const {
58 return (markWord*) &_mark;
59 }
60
65 void oopDesc::set_mark(HeapWord* mem, markWord m) {
66 *(markWord*)(((char*)mem) + mark_offset_in_bytes()) = m;
67 }
68
69 void oopDesc::release_set_mark(HeapWord* mem, markWord m) {
70 Atomic::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
71 }
72
73 void oopDesc::release_set_mark(markWord m) {
74 Atomic::release_store(&_mark, m);
75 }
76
77 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
78 return Atomic::cmpxchg(&_mark, old_mark, new_mark);
79 }
80
81 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order) {
82 return Atomic::cmpxchg(&_mark, old_mark, new_mark, order);
83 }
84
85 void oopDesc::init_mark() {
86 set_mark(markWord::prototype());
87 }
88
89 Klass* oopDesc::klass() const {
90 if (UseCompressedClassPointers) {
91 return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
92 } else {
93 return _metadata._klass;
94 }
95 }
96
97 Klass* oopDesc::klass_or_null() const {
98 if (UseCompressedClassPointers) {
99 return CompressedKlassPointers::decode(_metadata._compressed_klass);
100 } else {
101 return _metadata._klass;
102 }
103 }
104
105 Klass* oopDesc::klass_or_null_acquire() const {
106 if (UseCompressedClassPointers) {
107 narrowKlass nklass = Atomic::load_acquire(&_metadata._compressed_klass);
108 return CompressedKlassPointers::decode(nklass);
109 } else {
110 return Atomic::load_acquire(&_metadata._klass);
111 }
112 }
113
114 Klass* oopDesc::klass_raw() const {
115 if (UseCompressedClassPointers) {
116 return CompressedKlassPointers::decode_raw(_metadata._compressed_klass);
117 } else {
118 return _metadata._klass;
119 }
120 }
121
122 void oopDesc::set_klass(Klass* k) {
123 assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
124 if (UseCompressedClassPointers) {
125 _metadata._compressed_klass = CompressedKlassPointers::encode_not_null(k);
126 } else {
127 _metadata._klass = k;
128 }
129 }
130
131 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
132 assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
133 char* raw_mem = ((char*)mem + klass_offset_in_bytes());
134 if (UseCompressedClassPointers) {
135 Atomic::release_store((narrowKlass*)raw_mem,
136 CompressedKlassPointers::encode_not_null(k));
137 } else {
138 Atomic::release_store((Klass**)raw_mem, k);
139 }
140 }
141
142 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
143 if (UseCompressedClassPointers) {
144 *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
145 }
146 }
147
148 bool oopDesc::is_a(Klass* k) const {
149 return klass()->is_subtype_of(k);
150 }
151
152 size_t oopDesc::size() {
153 return size_given_klass(klass());
154 }
155
156 size_t oopDesc::size_given_klass(Klass* klass) {
157 int lh = klass->layout_helper();
158 size_t s;
159
160 // lh is now a value computed at class initialization that may hint
161 // at the size. For instances, this is positive and equal to the
162 // size. For arrays, this is negative and provides log2 of the
185 size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
186 size_in_bytes += Klass::layout_helper_header_size(lh);
187
188 // This code could be simplified, but by keeping array_header_in_bytes
189 // in units of bytes and doing it this way we can round up just once,
190 // skipping the intermediate round to HeapWordSize.
191 s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
192
193 assert(s == klass->oop_size(this) || size_might_change(), "wrong array object size");
194 } else {
195 // Must be zero, so bite the bullet and take the virtual call.
196 s = klass->oop_size(this);
197 }
198 }
199
200 assert(s > 0, "Oop size must be greater than zero, not " SIZE_FORMAT, s);
201 assert(is_object_aligned(s), "Oop size is not properly aligned: " SIZE_FORMAT, s);
202 return s;
203 }
204
205 bool oopDesc::is_instance() const { return klass()->is_instance_klass(); }
206 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass(); }
207 bool oopDesc::is_stackChunk() const { return klass()->is_stack_chunk_instance_klass(); }
208 bool oopDesc::is_array() const { return klass()->is_array_klass(); }
209 bool oopDesc::is_objArray() const { return klass()->is_objArray_klass(); }
210 bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }
211
212 template<typename T>
213 T* oopDesc::field_addr(int offset) const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
214
215 template <typename T>
216 size_t oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
217
218 template <DecoratorSet decorators>
219 inline oop oopDesc::obj_field_access(int offset) const { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
220 inline oop oopDesc::obj_field(int offset) const { return HeapAccess<>::oop_load_at(as_oop(), offset); }
221
222 inline void oopDesc::obj_field_put(int offset, oop value) { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
223 template <DecoratorSet decorators>
224 inline void oopDesc::obj_field_put_access(int offset, oop value) { HeapAccess<decorators>::oop_store_at(as_oop(), offset, value); }
253 }
254
255 bool oopDesc::is_unlocked() const {
256 return mark().is_unlocked();
257 }
258
259 // Used only for markSweep, scavenging
260 bool oopDesc::is_gc_marked() const {
261 return mark().is_marked();
262 }
263
264 // Used by scavengers
265 bool oopDesc::is_forwarded() const {
266 // The extra heap check is needed since the obj might be locked, in which case the
267 // mark would point to a stack location and have the sentinel bit cleared
268 return mark().is_marked();
269 }
270
271 // Used by scavengers
272 void oopDesc::forward_to(oop p) {
273 markWord m = markWord::encode_pointer_as_mark(p);
274 assert(m.decode_pointer() == p, "encoding must be reversible");
275 set_mark(m);
276 }
277
278 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
279 markWord m = markWord::encode_pointer_as_mark(p);
280 assert(m.decode_pointer() == p, "encoding must be reversible");
281 markWord old_mark = cas_set_mark(m, compare, order);
282 if (old_mark == compare) {
283 return nullptr;
284 } else {
285 return cast_to_oop(old_mark.decode_pointer());
286 }
287 }
288
289 // Note that the forwardee is not the same thing as the displaced_mark.
290 // The forwardee is used when copying during scavenge and mark-sweep.
291 // It does need to clear the low two locking- and GC-related bits.
292 oop oopDesc::forwardee() const {
293 assert(is_forwarded(), "only decode when actually forwarded");
294 return cast_to_oop(mark().decode_pointer());
295 }
296
297 // The following method needs to be MT safe.
298 uint oopDesc::age() const {
299 markWord m = mark();
300 assert(!m.is_marked(), "Attempt to read age from forwarded mark");
301 if (m.has_displaced_mark_helper()) {
302 return m.displaced_mark_helper().age();
303 } else {
304 return m.age();
305 }
306 }
307
308 void oopDesc::incr_age() {
309 markWord m = mark();
310 assert(!m.is_marked(), "Attempt to increment age of forwarded mark");
311 if (m.has_displaced_mark_helper()) {
312 m.set_displaced_mark_helper(m.displaced_mark_helper().incr_age());
313 } else {
314 set_mark(m.incr_age());
331 size_t size = size_given_klass(k);
332 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
333 return size;
334 }
335
336 template <typename OopClosureType>
337 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
338 Klass* k = klass();
339 size_t size = size_given_klass(k);
340 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
341 return size;
342 }
343
344 template <typename OopClosureType>
345 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
346 oop_iterate_backwards(cl, klass());
347 }
348
349 template <typename OopClosureType>
350 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
351 assert(k == klass(), "wrong klass");
352 OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
353 }
354
355 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
356 return obj == nullptr || obj->klass()->is_subtype_of(klass);
357 }
358
359 intptr_t oopDesc::identity_hash() {
360 // Fast case; if the object is unlocked and the hash value is set, no locking is needed
361 // Note: The mark must be read into local variable to avoid concurrent updates.
362 markWord mrk = mark();
363 if (mrk.is_unlocked() && !mrk.has_no_hash()) {
364 return mrk.hash();
365 } else if (mrk.is_marked()) {
366 return mrk.hash();
367 } else {
368 return slow_identity_hash();
369 }
370 }
371
|
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/universe.hpp"
31 #include "memory/iterator.inline.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/oopsHierarchy.hpp"
39 #include "runtime/atomic.hpp"
40 #include "runtime/globals.hpp"
41 #include "runtime/safepoint.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
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(HeapWord* mem, markWord m) {
71 Atomic::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
72 }
73
74 void oopDesc::release_set_mark(markWord m) {
75 Atomic::release_store(&_mark, 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 markWord oopDesc::resolve_mark() const {
87 assert(LockingMode != LM_LEGACY, "Not safe with legacy stack-locking");
88 markWord m = mark();
89 if (m.has_displaced_mark_helper()) {
90 m = m.displaced_mark_helper();
91 }
92 return m;
93 }
94
95 markWord oopDesc::prototype_mark() const {
96 if (UseCompactObjectHeaders) {
97 return klass()->prototype_header();
98 } else {
99 return markWord::prototype();
100 }
101 }
102
103 void oopDesc::init_mark() {
104 if (UseCompactObjectHeaders) {
105 set_mark(prototype_mark());
106 } else {
107 set_mark(markWord::prototype());
108 }
109 }
110
111 Klass* oopDesc::klass() const {
112 #ifdef _LP64
113 if (UseCompactObjectHeaders) {
114 markWord m = resolve_mark();
115 return m.klass();
116 } else if (UseCompressedClassPointers) {
117 return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
118 } else
119 #endif
120 {
121 return _metadata._klass;
122 }
123 }
124
125 Klass* oopDesc::klass_or_null() const {
126 #ifdef _LP64
127 if (UseCompactObjectHeaders) {
128 markWord m = resolve_mark();
129 return m.klass_or_null();
130 } else if (UseCompressedClassPointers) {
131 return CompressedKlassPointers::decode(_metadata._compressed_klass);
132 } else
133 #endif
134 {
135 return _metadata._klass;
136 }
137 }
138
139 Klass* oopDesc::klass_or_null_acquire() const {
140 #ifdef _LP64
141 if (UseCompactObjectHeaders) {
142 markWord m = mark_acquire();
143 if (m.has_displaced_mark_helper()) {
144 m = m.displaced_mark_helper();
145 }
146 return m.klass_or_null();
147 } else if (UseCompressedClassPointers) {
148 narrowKlass nklass = Atomic::load_acquire(&_metadata._compressed_klass);
149 return CompressedKlassPointers::decode(nklass);
150 } else
151 #endif
152 {
153 return Atomic::load_acquire(&_metadata._klass);
154 }
155 }
156
157 Klass* oopDesc::klass_raw() const {
158 if (UseCompactObjectHeaders) {
159 return klass();
160 } else if (UseCompressedClassPointers) {
161 return CompressedKlassPointers::decode_raw(_metadata._compressed_klass);
162 } else {
163 return _metadata._klass;
164 }
165 }
166
167 void oopDesc::set_klass(Klass* k) {
168 assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
169 assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
170 if (UseCompressedClassPointers) {
171 _metadata._compressed_klass = CompressedKlassPointers::encode_not_null(k);
172 } else {
173 _metadata._klass = k;
174 }
175 }
176
177 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
178 assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
179 assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
180 char* raw_mem = ((char*)mem + klass_offset_in_bytes());
181 if (UseCompressedClassPointers) {
182 Atomic::release_store((narrowKlass*)raw_mem,
183 CompressedKlassPointers::encode_not_null(k));
184 } else {
185 Atomic::release_store((Klass**)raw_mem, k);
186 }
187 }
188
189 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
190 assert(!UseCompactObjectHeaders, "don't set Klass* gap with compact headers");
191 if (UseCompressedClassPointers) {
192 *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
193 }
194 }
195
196 bool oopDesc::is_a(Klass* k) const {
197 return klass()->is_subtype_of(k);
198 }
199
200 size_t oopDesc::size() {
201 return size_given_klass(klass());
202 }
203
204 size_t oopDesc::size_given_klass(Klass* klass) {
205 int lh = klass->layout_helper();
206 size_t s;
207
208 // lh is now a value computed at class initialization that may hint
209 // at the size. For instances, this is positive and equal to the
210 // size. For arrays, this is negative and provides log2 of the
233 size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
234 size_in_bytes += Klass::layout_helper_header_size(lh);
235
236 // This code could be simplified, but by keeping array_header_in_bytes
237 // in units of bytes and doing it this way we can round up just once,
238 // skipping the intermediate round to HeapWordSize.
239 s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
240
241 assert(s == klass->oop_size(this) || size_might_change(), "wrong array object size");
242 } else {
243 // Must be zero, so bite the bullet and take the virtual call.
244 s = klass->oop_size(this);
245 }
246 }
247
248 assert(s > 0, "Oop size must be greater than zero, not " SIZE_FORMAT, s);
249 assert(is_object_aligned(s), "Oop size is not properly aligned: " SIZE_FORMAT, s);
250 return s;
251 }
252
253 #ifdef _LP64
254 Klass* oopDesc::forward_safe_klass_impl(markWord m) const {
255 assert(UseCompactObjectHeaders, "Only get here with compact headers");
256 if (m.is_marked()) {
257 oop fwd = forwardee(m);
258 markWord m2 = fwd->mark();
259 assert(!m2.is_marked() || m2.self_forwarded(), "no double forwarding: this: " PTR_FORMAT " (" INTPTR_FORMAT "), fwd: " PTR_FORMAT " (" INTPTR_FORMAT ")", p2i(this), m.value(), p2i(fwd), m2.value());
260 m = m2;
261 }
262 return m.actual_mark().klass();
263 }
264 #endif
265
266 Klass* oopDesc::forward_safe_klass(markWord m) const {
267 #ifdef _LP64
268 if (UseCompactObjectHeaders) {
269 return forward_safe_klass_impl(m);
270 } else
271 #endif
272 {
273 return klass();
274 }
275 }
276
277 Klass* oopDesc::forward_safe_klass() const {
278 #ifdef _LP64
279 if (UseCompactObjectHeaders) {
280 return forward_safe_klass_impl(mark());
281 } else
282 #endif
283 {
284 return klass();
285 }
286 }
287
288 size_t oopDesc::forward_safe_size() {
289 return size_given_klass(forward_safe_klass());
290 }
291
292 void oopDesc::forward_safe_init_mark() {
293 if (UseCompactObjectHeaders) {
294 set_mark(forward_safe_klass()->prototype_header());
295 } else {
296 set_mark(markWord::prototype());
297 }
298 }
299
300 bool oopDesc::is_instance() const { return klass()->is_instance_klass(); }
301 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass(); }
302 bool oopDesc::is_stackChunk() const { return klass()->is_stack_chunk_instance_klass(); }
303 bool oopDesc::is_array() const { return klass()->is_array_klass(); }
304 bool oopDesc::is_objArray() const { return klass()->is_objArray_klass(); }
305 bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }
306
307 template<typename T>
308 T* oopDesc::field_addr(int offset) const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
309
310 template <typename T>
311 size_t oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
312
313 template <DecoratorSet decorators>
314 inline oop oopDesc::obj_field_access(int offset) const { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
315 inline oop oopDesc::obj_field(int offset) const { return HeapAccess<>::oop_load_at(as_oop(), offset); }
316
317 inline void oopDesc::obj_field_put(int offset, oop value) { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
318 template <DecoratorSet decorators>
319 inline void oopDesc::obj_field_put_access(int offset, oop value) { HeapAccess<decorators>::oop_store_at(as_oop(), offset, value); }
348 }
349
350 bool oopDesc::is_unlocked() const {
351 return mark().is_unlocked();
352 }
353
354 // Used only for markSweep, scavenging
355 bool oopDesc::is_gc_marked() const {
356 return mark().is_marked();
357 }
358
359 // Used by scavengers
360 bool oopDesc::is_forwarded() const {
361 // The extra heap check is needed since the obj might be locked, in which case the
362 // mark would point to a stack location and have the sentinel bit cleared
363 return mark().is_marked();
364 }
365
366 // Used by scavengers
367 void oopDesc::forward_to(oop p) {
368 assert(p != cast_to_oop(this) || !UseAltGCForwarding, "Must not be called with self-forwarding");
369 markWord m = markWord::encode_pointer_as_mark(p);
370 assert(forwardee(m) == p, "encoding must be reversable");
371 set_mark(m);
372 }
373
374 void oopDesc::forward_to_self() {
375 #ifdef _LP64
376 if (UseAltGCForwarding) {
377 markWord m = mark();
378 // If mark is displaced, we need to preserve the real header during GC.
379 // It will be restored to the displaced header after GC.
380 assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
381 if (m.has_displaced_mark_helper()) {
382 m = m.displaced_mark_helper();
383 }
384 m = m.set_self_forwarded();
385 assert(forwardee(m) == cast_to_oop(this), "encoding must be reversible");
386 set_mark(m);
387 } else
388 #endif
389 {
390 forward_to(oop(this));
391 }
392 }
393
394 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
395 assert(p != cast_to_oop(this) || !UseAltGCForwarding, "Must not be called with self-forwarding");
396 markWord m = markWord::encode_pointer_as_mark(p);
397 assert(m.decode_pointer() == p, "encoding must be reversible");
398 markWord old_mark = cas_set_mark(m, compare, order);
399 if (old_mark == compare) {
400 return nullptr;
401 } else {
402 return forwardee(old_mark);
403 }
404 }
405
406 oop oopDesc::forward_to_self_atomic(markWord compare, atomic_memory_order order) {
407 #ifdef _LP64
408 if (UseAltGCForwarding) {
409 markWord m = compare;
410 // If mark is displaced, we need to preserve the real header during GC.
411 // It will be restored to the displaced header after GC.
412 assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
413 if (m.has_displaced_mark_helper()) {
414 m = m.displaced_mark_helper();
415 }
416 m = m.set_self_forwarded();
417 assert(forwardee(m) == cast_to_oop(this), "encoding must be reversible");
418 markWord old_mark = cas_set_mark(m, compare, order);
419 if (old_mark == compare) {
420 return nullptr;
421 } else {
422 assert(old_mark.is_marked(), "must be marked here");
423 return forwardee(old_mark);
424 }
425 } else
426 #endif
427 {
428 return forward_to_atomic(cast_to_oop(this), compare, order);
429 }
430 }
431
432 oop oopDesc::forwardee(markWord header) const {
433 assert(header.is_marked(), "only decode when actually forwarded");
434 #ifdef _LP64
435 if (header.self_forwarded()) {
436 return cast_to_oop(this);
437 } else
438 #endif
439 {
440 return cast_to_oop(header.decode_pointer());
441 }
442 }
443
444 // Note that the forwardee is not the same thing as the displaced_mark.
445 // The forwardee is used when copying during scavenge and mark-sweep.
446 // It does need to clear the low two locking- and GC-related bits.
447 oop oopDesc::forwardee() const {
448 return forwardee(mark());
449 }
450
451 // The following method needs to be MT safe.
452 uint oopDesc::age() const {
453 markWord m = mark();
454 assert(!m.is_marked(), "Attempt to read age from forwarded mark");
455 if (m.has_displaced_mark_helper()) {
456 return m.displaced_mark_helper().age();
457 } else {
458 return m.age();
459 }
460 }
461
462 void oopDesc::incr_age() {
463 markWord m = mark();
464 assert(!m.is_marked(), "Attempt to increment age of forwarded mark");
465 if (m.has_displaced_mark_helper()) {
466 m.set_displaced_mark_helper(m.displaced_mark_helper().incr_age());
467 } else {
468 set_mark(m.incr_age());
485 size_t size = size_given_klass(k);
486 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
487 return size;
488 }
489
490 template <typename OopClosureType>
491 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
492 Klass* k = klass();
493 size_t size = size_given_klass(k);
494 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
495 return size;
496 }
497
498 template <typename OopClosureType>
499 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
500 oop_iterate_backwards(cl, klass());
501 }
502
503 template <typename OopClosureType>
504 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
505 // In this assert, we cannot safely access the Klass* with compact headers.
506 assert(UseCompactObjectHeaders || k == klass(), "wrong klass");
507 OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
508 }
509
510 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
511 return obj == nullptr || obj->klass()->is_subtype_of(klass);
512 }
513
514 intptr_t oopDesc::identity_hash() {
515 // Fast case; if the object is unlocked and the hash value is set, no locking is needed
516 // Note: The mark must be read into local variable to avoid concurrent updates.
517 markWord mrk = mark();
518 if (mrk.is_unlocked() && !mrk.has_no_hash()) {
519 return mrk.hash();
520 } else if (mrk.is_marked()) {
521 return mrk.hash();
522 } else {
523 return slow_identity_hash();
524 }
525 }
526
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