1 /*
2 * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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 *
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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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/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/flatArrayKlass.hpp"
37 #include "oops/instanceKlass.hpp"
38 #include "oops/markWord.inline.hpp"
39 #include "oops/objLayout.inline.hpp"
40 #include "oops/oopsHierarchy.hpp"
41 #include "runtime/arguments.hpp"
42 #include "runtime/atomicAccess.hpp"
43 #include "runtime/globals.hpp"
44 #include "utilities/align.hpp"
45 #include "utilities/debug.hpp"
46 #include "utilities/globalDefinitions.hpp"
47 #include "utilities/macros.hpp"
48
49 // Implementation of all inlined member functions defined in oop.hpp
50 // We need a separate file to avoid circular references
51
52 void* oopDesc::base_addr() { return this; }
53 const void* oopDesc::base_addr() const { return this; }
54
55 markWord oopDesc::mark() const {
56 return AtomicAccess::load(&_mark);
57 }
58
59 markWord oopDesc::mark_acquire() const {
60 return AtomicAccess::load_acquire(&_mark);
61 }
62
63 void oopDesc::set_mark(markWord m) {
64 AtomicAccess::store(&_mark, m);
65 }
66
67 void oopDesc::set_mark(HeapWord* mem, markWord m) {
68 *(markWord*)(((char*)mem) + mark_offset_in_bytes()) = m;
69 }
70
71 void oopDesc::release_set_mark(HeapWord* mem, markWord m) {
72 AtomicAccess::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
73 }
74
75 void oopDesc::release_set_mark(markWord m) {
76 AtomicAccess::release_store(&_mark, m);
77 }
78
79 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
80 return AtomicAccess::cmpxchg(&_mark, old_mark, new_mark);
81 }
82
83 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order) {
84 return AtomicAccess::cmpxchg(&_mark, old_mark, new_mark, order);
85 }
86
87 markWord oopDesc::prototype_mark() const {
88 if (UseCompactObjectHeaders || Arguments::is_valhalla_enabled()) {
89 return klass()->prototype_header();
90 } else {
91 return markWord::prototype();
92 }
93 }
94
95 void oopDesc::init_mark() {
96 set_mark(prototype_mark());
97 }
98
99 Klass* oopDesc::klass() const {
100 return CompressedKlassPointers::decode_not_null(narrow_klass());
101 }
102
103 Klass* oopDesc::klass_or_null() const {
104 return CompressedKlassPointers::decode(narrow_klass());
105 }
106
107 Klass* oopDesc::klass_or_null_acquire() const {
108 return CompressedKlassPointers::decode(narrow_klass_acquire());
109 }
110
111 Klass* oopDesc::klass_without_asserts() const {
112 return CompressedKlassPointers::decode_without_asserts(narrow_klass());
113 }
114
115 narrowKlass oopDesc::narrow_klass() const {
116 switch (ObjLayout::klass_mode()) {
117 case ObjLayout::Compact:
118 return mark().narrow_klass();
119 case ObjLayout::Compressed:
120 return _compressed_klass;
121 default:
122 ShouldNotReachHere();
123 }
124 }
125
126 narrowKlass oopDesc::narrow_klass_acquire() const {
127 switch (ObjLayout::klass_mode()) {
128 case ObjLayout::Compact:
129 return mark_acquire().narrow_klass();
130 case ObjLayout::Compressed:
131 return AtomicAccess::load_acquire(&_compressed_klass);
132 default:
133 ShouldNotReachHere();
134 }
135 }
136
137 void oopDesc::set_klass(Klass* k) {
138 assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
139 assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
140 _compressed_klass = CompressedKlassPointers::encode_not_null(k);
141 }
142
143 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
144 assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
145 assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
146 char* raw_mem = ((char*)mem + klass_offset_in_bytes());
147 AtomicAccess::release_store((narrowKlass*)raw_mem, CompressedKlassPointers::encode_not_null(k));
148 }
149
150 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
151 assert(has_klass_gap(), "precondition");
152 *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
153 }
154
155 bool oopDesc::is_a(Klass* k) const {
156 return klass()->is_subtype_of(k);
157 }
158
159 size_t oopDesc::size() {
160 return size_given_klass(klass());
161 }
162
163 size_t oopDesc::size_given_klass(Klass* klass) {
164 int lh = klass->layout_helper();
165 size_t s;
166
167 // lh is now a value computed at class initialization that may hint
168 // at the size. For instances, this is positive and equal to the
169 // size. For arrays, this is negative and provides log2 of the
170 // array element size. For other oops, it is zero and thus requires
171 // a virtual call.
172 //
173 // We go to all this trouble because the size computation is at the
174 // heart of phase 2 of mark-compaction, and called for every object,
175 // alive or dead. So the speed here is equal in importance to the
176 // speed of allocation.
177
178 if (lh > Klass::_lh_neutral_value) {
179 if (!Klass::layout_helper_needs_slow_path(lh)) {
180 s = lh >> LogHeapWordSize; // deliver size scaled by wordSize
181 } else {
182 s = klass->oop_size(this);
183 }
184 } else if (lh <= Klass::_lh_neutral_value) {
185 // The most common case is instances; fall through if so.
186 if (lh < Klass::_lh_neutral_value) {
187 // Second most common case is arrays. We have to fetch the
188 // length of the array, shift (multiply) it appropriately,
189 // up to wordSize, add the header, and align to object size.
190 size_t size_in_bytes;
191 size_t array_length = (size_t) ((arrayOop)this)->length();
192 size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
193 size_in_bytes += Klass::layout_helper_header_size(lh);
194
195 // This code could be simplified, but by keeping array_header_in_bytes
196 // in units of bytes and doing it this way we can round up just once,
197 // skipping the intermediate round to HeapWordSize.
198 s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
199
200 assert(s == klass->oop_size(this), "wrong array object size");
201 } else {
202 // Must be zero, so bite the bullet and take the virtual call.
203 s = klass->oop_size(this);
204 }
205 }
206
207 assert(s > 0, "Oop size must be greater than zero, not %zu", s);
208 assert(is_object_aligned(s), "Oop size is not properly aligned: %zu", s);
209 return s;
210 }
211
212 bool oopDesc::is_instance() const { return klass()->is_instance_klass(); }
213 bool oopDesc::is_inline() const { return klass()->is_inline_klass(); }
214 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass(); }
215 bool oopDesc::is_stackChunk() const { return klass()->is_stack_chunk_instance_klass(); }
216 bool oopDesc::is_array() const { return klass()->is_array_klass(); }
217 bool oopDesc::is_objArray() const { return klass()->is_objArray_klass(); }
218 bool oopDesc::is_refArray() const { return klass()->is_refArray_klass(); }
219 bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }
220 bool oopDesc::is_refined_objArray() const { return klass()->is_refined_objArray_klass(); }
221 bool oopDesc::is_flatArray() const { return klass()->is_flatArray_klass(); }
222
223 bool oopDesc::is_array_with_oops() const {
224 if (!is_objArray()) {
225 return false;
226 }
227
228 assert(is_refined_objArray(), "Must be");
229 return is_refArray() || FlatArrayKlass::cast(klass())->contains_oops();
230 }
231
232 bool oopDesc::is_inline_type() const { return mark().is_inline_type(); }
233
234 template<typename T>
235 T* oopDesc::field_addr(int offset) const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
236
237 template <typename T>
238 size_t oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
239
240 template <DecoratorSet decorators>
241 inline oop oopDesc::obj_field_access(int offset) const { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
242 inline oop oopDesc::obj_field(int offset) const { return HeapAccess<>::oop_load_at(as_oop(), offset); }
243
244 inline void oopDesc::obj_field_put(int offset, oop value) { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
245 template <DecoratorSet decorators>
246 inline void oopDesc::obj_field_put_access(int offset, oop value) { HeapAccess<decorators>::oop_store_at(as_oop(), offset, value); }
247
248 inline jbyte oopDesc::byte_field(int offset) const { return *field_addr<jbyte>(offset); }
249 inline void oopDesc::byte_field_put(int offset, jbyte value) { *field_addr<jbyte>(offset) = value; }
250
251 inline jchar oopDesc::char_field(int offset) const { return *field_addr<jchar>(offset); }
252 inline void oopDesc::char_field_put(int offset, jchar value) { *field_addr<jchar>(offset) = value; }
253
254 inline jboolean oopDesc::bool_field(int offset) const { return *field_addr<jboolean>(offset); }
255 inline void oopDesc::bool_field_put(int offset, jboolean value) { *field_addr<jboolean>(offset) = jboolean(value & 1); }
256 inline jboolean oopDesc::bool_field_volatile(int offset) const { return RawAccess<MO_SEQ_CST>::load(field_addr<jboolean>(offset)); }
257 inline void oopDesc::bool_field_put_volatile(int offset, jboolean value) { RawAccess<MO_SEQ_CST>::store(field_addr<jboolean>(offset), jboolean(value & 1)); }
258 inline jshort oopDesc::short_field(int offset) const { return *field_addr<jshort>(offset); }
259 inline void oopDesc::short_field_put(int offset, jshort value) { *field_addr<jshort>(offset) = value; }
260
261 inline jint oopDesc::int_field(int offset) const { return *field_addr<jint>(offset); }
262 inline void oopDesc::int_field_put(int offset, jint value) { *field_addr<jint>(offset) = value; }
263 inline jint oopDesc::int_field_relaxed(int offset) const { return AtomicAccess::load(field_addr<jint>(offset)); }
264 inline void oopDesc::int_field_put_relaxed(int offset, jint value) { AtomicAccess::store(field_addr<jint>(offset), value); }
265
266 inline jlong oopDesc::long_field(int offset) const { return *field_addr<jlong>(offset); }
267 inline void oopDesc::long_field_put(int offset, jlong value) { *field_addr<jlong>(offset) = value; }
268
269 inline jfloat oopDesc::float_field(int offset) const { return *field_addr<jfloat>(offset); }
270 inline void oopDesc::float_field_put(int offset, jfloat value) { *field_addr<jfloat>(offset) = value; }
271
272 inline jdouble oopDesc::double_field(int offset) const { return *field_addr<jdouble>(offset); }
273 inline void oopDesc::double_field_put(int offset, jdouble value) { *field_addr<jdouble>(offset) = value; }
274
275 bool oopDesc::is_locked() const {
276 return mark().is_locked();
277 }
278
279 bool oopDesc::is_unlocked() const {
280 return mark().is_unlocked();
281 }
282
283 bool oopDesc::is_gc_marked() const {
284 return mark().is_marked();
285 }
286
287 // Used by scavengers
288 bool oopDesc::is_forwarded() const {
289 return mark().is_forwarded();
290 }
291
292 bool oopDesc::is_self_forwarded() const {
293 return mark().is_self_forwarded();
294 }
295
296 // Used by scavengers
297 void oopDesc::forward_to(oop p) {
298 assert(cast_from_oop<oopDesc*>(p) != this,
299 "must not be used for self-forwarding, use forward_to_self() instead");
300 markWord m = markWord::encode_pointer_as_mark(p);
301 assert(m.decode_pointer() == p, "encoding must be reversible");
302 set_mark(m);
303 }
304
305 void oopDesc::forward_to_self() {
306 set_mark(mark().set_self_forwarded());
307 }
308
309 oop oopDesc::cas_set_forwardee(markWord new_mark, markWord compare, atomic_memory_order order) {
310 markWord old_mark = cas_set_mark(new_mark, compare, order);
311 if (old_mark == compare) {
312 return nullptr;
313 } else {
314 assert(old_mark.is_forwarded(), "must be forwarded here");
315 return forwardee(old_mark);
316 }
317 }
318
319 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
320 assert(cast_from_oop<oopDesc*>(p) != this,
321 "must not be used for self-forwarding, use forward_to_self_atomic() instead");
322 markWord m = markWord::encode_pointer_as_mark(p);
323 assert(forwardee(m) == p, "encoding must be reversible");
324 return cas_set_forwardee(m, compare, order);
325 }
326
327 oop oopDesc::forward_to_self_atomic(markWord old_mark, atomic_memory_order order) {
328 markWord new_mark = old_mark.set_self_forwarded();
329 assert(forwardee(new_mark) == cast_to_oop(this), "encoding must be reversible");
330 return cas_set_forwardee(new_mark, old_mark, order);
331 }
332
333 oop oopDesc::forwardee(markWord mark) const {
334 assert(mark.is_forwarded(), "only decode when actually forwarded");
335 if (mark.is_self_forwarded()) {
336 return cast_to_oop(this);
337 } else {
338 return mark.forwardee();
339 }
340 }
341
342 // Note that the forwardee is not the same thing as the displaced_mark.
343 // The forwardee is used when copying during scavenge and mark-sweep.
344 // It does need to clear the low two locking- and GC-related bits.
345 oop oopDesc::forwardee() const {
346 return forwardee(mark());
347 }
348
349 void oopDesc::unset_self_forwarded() {
350 set_mark(mark().unset_self_forwarded());
351 }
352
353 // The following method needs to be MT safe.
354 uint oopDesc::age() const {
355 markWord m = mark();
356 assert(!m.is_marked(), "Attempt to read age from forwarded mark");
357 if (m.has_displaced_mark_helper()) {
358 return m.displaced_mark_helper().age();
359 } else {
360 return m.age();
361 }
362 }
363
364 void oopDesc::incr_age() {
365 markWord m = mark();
366 assert(!m.is_marked(), "Attempt to increment age of forwarded mark");
367 if (m.has_displaced_mark_helper()) {
368 m.set_displaced_mark_helper(m.displaced_mark_helper().incr_age());
369 } else {
370 set_mark(m.incr_age());
371 }
372 }
373
374 template <typename OopClosureType>
375 void oopDesc::oop_iterate(OopClosureType* cl) {
376 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
377 }
378
379 template <typename OopClosureType>
380 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
381 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
382 }
383
384 template <typename OopClosureType>
385 size_t oopDesc::oop_iterate_size(OopClosureType* cl) {
386 Klass* k = klass();
387 size_t size = size_given_klass(k);
388 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
389 return size;
390 }
391
392 template <typename OopClosureType>
393 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
394 Klass* k = klass();
395 size_t size = size_given_klass(k);
396 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
397 return size;
398 }
399
400 template <typename OopClosureType>
401 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
402 oop_iterate_backwards(cl, klass());
403 }
404
405 template <typename OopClosureType>
406 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
407 // In this assert, we cannot safely access the Klass* with compact headers.
408 assert(k == klass(), "wrong klass");
409 OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
410 }
411
412 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
413 return obj == nullptr || obj->klass()->is_subtype_of(klass);
414 }
415
416 intptr_t oopDesc::identity_hash() {
417 // Fast case; if the object is unlocked and the hash value is set, no locking is needed
418 // Note: The mark must be read into local variable to avoid concurrent updates.
419 markWord mrk = mark();
420 if (mrk.is_unlocked() && !mrk.has_no_hash()) {
421 return mrk.hash();
422 } else if (mrk.is_marked()) {
423 return mrk.hash();
424 } else {
425 return slow_identity_hash();
426 }
427 }
428
429 // This checks fast simple case of whether the oop has_no_hash,
430 // to optimize JVMTI table lookup.
431 bool oopDesc::fast_no_hash_check() {
432 markWord mrk = mark_acquire();
433 assert(!mrk.is_marked(), "should never be marked");
434 return mrk.is_unlocked() && mrk.has_no_hash();
435 }
436
437 bool oopDesc::has_displaced_mark() const {
438 return mark().has_displaced_mark_helper();
439 }
440
441 markWord oopDesc::displaced_mark() const {
442 return mark().displaced_mark_helper();
443 }
444
445 void oopDesc::set_displaced_mark(markWord m) {
446 mark().set_displaced_mark_helper(m);
447 }
448
449 bool oopDesc::mark_must_be_preserved() const {
450 return mark_must_be_preserved(mark());
451 }
452
453 bool oopDesc::mark_must_be_preserved(markWord m) const {
454 return m.must_be_preserved();
455 }
456
457 #endif // SHARE_OOPS_OOP_INLINE_HPP