1 /*
2 * Copyright (c) 1997, 2022, 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.
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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