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