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.
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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.
8 *
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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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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 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(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::prototype_mark() const {
87 if (UseCompactObjectHeaders) {
88 return klass()->prototype_header();
89 } else {
90 return markWord::prototype();
91 }
92 }
93
94 void oopDesc::init_mark() {
95 set_mark(prototype_mark());
96 }
97
98 Klass* oopDesc::klass() const {
99 switch (ObjLayout::klass_mode()) {
100 case ObjLayout::Compact:
101 return mark().klass();
102 case ObjLayout::Compressed:
103 return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
104 default:
105 return _metadata._klass;
106 }
107 }
108
109 Klass* oopDesc::klass_or_null() const {
110 switch (ObjLayout::klass_mode()) {
111 case ObjLayout::Compact:
112 return mark().klass_or_null();
113 case ObjLayout::Compressed:
114 return CompressedKlassPointers::decode(_metadata._compressed_klass);
115 default:
116 return _metadata._klass;
117 }
118 }
119
120 Klass* oopDesc::klass_or_null_acquire() const {
121 switch (ObjLayout::klass_mode()) {
122 case ObjLayout::Compact:
123 return mark_acquire().klass();
124 case ObjLayout::Compressed: {
125 narrowKlass narrow_klass = Atomic::load_acquire(&_metadata._compressed_klass);
126 return CompressedKlassPointers::decode(narrow_klass);
127 }
128 default:
129 return Atomic::load_acquire(&_metadata._klass);
130 }
131 }
132
133 Klass* oopDesc::klass_without_asserts() const {
134 switch (ObjLayout::klass_mode()) {
135 case ObjLayout::Compact:
136 return mark().klass_without_asserts();
137 case ObjLayout::Compressed:
138 return CompressedKlassPointers::decode_without_asserts(_metadata._compressed_klass);
139 default:
140 return _metadata._klass;
141 }
142 }
143
144 void oopDesc::set_klass(Klass* k) {
145 assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
146 assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
147 if (UseCompressedClassPointers) {
148 _metadata._compressed_klass = CompressedKlassPointers::encode_not_null(k);
149 } else {
150 _metadata._klass = k;
151 }
152 }
153
154 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
155 assert(Universe::is_bootstrapping() || (k != nullptr && k->is_klass()), "incorrect Klass");
156 assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
157 char* raw_mem = ((char*)mem + klass_offset_in_bytes());
158 if (UseCompressedClassPointers) {
159 Atomic::release_store((narrowKlass*)raw_mem,
160 CompressedKlassPointers::encode_not_null(k));
161 } else {
162 Atomic::release_store((Klass**)raw_mem, k);
163 }
164 }
165
166 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
167 assert(has_klass_gap(), "precondition");
168 *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
169 }
170
171 bool oopDesc::is_a(Klass* k) const {
172 return klass()->is_subtype_of(k);
173 }
174
175 size_t oopDesc::size() {
176 return size_given_klass(klass());
177 }
178
179 size_t oopDesc::size_given_klass(Klass* klass) {
180 int lh = klass->layout_helper();
181 size_t s;
182
183 // lh is now a value computed at class initialization that may hint
184 // at the size. For instances, this is positive and equal to the
185 // size. For arrays, this is negative and provides log2 of the
186 // array element size. For other oops, it is zero and thus requires
187 // a virtual call.
188 //
189 // We go to all this trouble because the size computation is at the
190 // heart of phase 2 of mark-compaction, and called for every object,
191 // alive or dead. So the speed here is equal in importance to the
192 // speed of allocation.
193
194 if (lh > Klass::_lh_neutral_value) {
195 if (!Klass::layout_helper_needs_slow_path(lh)) {
196 s = lh >> LogHeapWordSize; // deliver size scaled by wordSize
197 } else {
198 s = klass->oop_size(this);
199 }
200 } else if (lh <= Klass::_lh_neutral_value) {
201 // The most common case is instances; fall through if so.
202 if (lh < Klass::_lh_neutral_value) {
203 // Second most common case is arrays. We have to fetch the
204 // length of the array, shift (multiply) it appropriately,
205 // up to wordSize, add the header, and align to object size.
206 size_t size_in_bytes;
207 size_t array_length = (size_t) ((arrayOop)this)->length();
208 size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
209 size_in_bytes += Klass::layout_helper_header_size(lh);
210
211 // This code could be simplified, but by keeping array_header_in_bytes
212 // in units of bytes and doing it this way we can round up just once,
213 // skipping the intermediate round to HeapWordSize.
214 s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
215
216 assert(s == klass->oop_size(this), "wrong array object size");
217 } else {
218 // Must be zero, so bite the bullet and take the virtual call.
219 s = klass->oop_size(this);
220 }
221 }
222
223 assert(s > 0, "Oop size must be greater than zero, not %zu", s);
224 assert(is_object_aligned(s), "Oop size is not properly aligned: %zu", s);
225 return s;
226 }
227
228 bool oopDesc::is_instance() const { return klass()->is_instance_klass(); }
229 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass(); }
230 bool oopDesc::is_stackChunk() const { return klass()->is_stack_chunk_instance_klass(); }
231 bool oopDesc::is_array() const { return klass()->is_array_klass(); }
232 bool oopDesc::is_objArray() const { return klass()->is_objArray_klass(); }
233 bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }
234
235 template<typename T>
236 T* oopDesc::field_addr(int offset) const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
237
238 template <typename T>
239 size_t oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
240
241 template <DecoratorSet decorators>
242 inline oop oopDesc::obj_field_access(int offset) const { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
243 inline oop oopDesc::obj_field(int offset) const { return HeapAccess<>::oop_load_at(as_oop(), offset); }
244
245 inline void oopDesc::obj_field_put(int offset, oop value) { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
246 template <DecoratorSet decorators>
247 inline void oopDesc::obj_field_put_access(int offset, oop value) { HeapAccess<decorators>::oop_store_at(as_oop(), offset, value); }
248
249 inline jbyte oopDesc::byte_field(int offset) const { return *field_addr<jbyte>(offset); }
250 inline void oopDesc::byte_field_put(int offset, jbyte value) { *field_addr<jbyte>(offset) = value; }
251
252 inline jchar oopDesc::char_field(int offset) const { return *field_addr<jchar>(offset); }
253 inline void oopDesc::char_field_put(int offset, jchar value) { *field_addr<jchar>(offset) = value; }
254
255 inline jboolean oopDesc::bool_field(int offset) const { return *field_addr<jboolean>(offset); }
256 inline void oopDesc::bool_field_put(int offset, jboolean value) { *field_addr<jboolean>(offset) = jboolean(value & 1); }
257 inline jboolean oopDesc::bool_field_volatile(int offset) const { return RawAccess<MO_SEQ_CST>::load(field_addr<jboolean>(offset)); }
258 inline void oopDesc::bool_field_put_volatile(int offset, jboolean value) { RawAccess<MO_SEQ_CST>::store(field_addr<jboolean>(offset), jboolean(value & 1)); }
259 inline jshort oopDesc::short_field(int offset) const { return *field_addr<jshort>(offset); }
260 inline void oopDesc::short_field_put(int offset, jshort value) { *field_addr<jshort>(offset) = value; }
261
262 inline jint oopDesc::int_field(int offset) const { return *field_addr<jint>(offset); }
263 inline void oopDesc::int_field_put(int offset, jint value) { *field_addr<jint>(offset) = value; }
264 inline jint oopDesc::int_field_relaxed(int offset) const { return Atomic::load(field_addr<jint>(offset)); }
265 inline void oopDesc::int_field_put_relaxed(int offset, jint value) { Atomic::store(field_addr<jint>(offset), value); }
266
267 inline jlong oopDesc::long_field(int offset) const { return *field_addr<jlong>(offset); }
268 inline void oopDesc::long_field_put(int offset, jlong value) { *field_addr<jlong>(offset) = value; }
269
270 inline jfloat oopDesc::float_field(int offset) const { return *field_addr<jfloat>(offset); }
271 inline void oopDesc::float_field_put(int offset, jfloat value) { *field_addr<jfloat>(offset) = value; }
272
273 inline jdouble oopDesc::double_field(int offset) const { return *field_addr<jdouble>(offset); }
274 inline void oopDesc::double_field_put(int offset, jdouble value) { *field_addr<jdouble>(offset) = value; }
275
276 bool oopDesc::is_locked() const {
277 return mark().is_locked();
278 }
279
280 bool oopDesc::is_unlocked() const {
281 return mark().is_unlocked();
282 }
283
284 bool oopDesc::is_gc_marked() const {
285 return mark().is_marked();
286 }
287
288 // Used by scavengers
289 bool oopDesc::is_forwarded() const {
290 return mark().is_forwarded();
291 }
292
293 bool oopDesc::is_self_forwarded() const {
294 return mark().is_self_forwarded();
295 }
296
297 // Used by scavengers
298 void oopDesc::forward_to(oop p) {
299 assert(cast_from_oop<oopDesc*>(p) != this,
300 "must not be used for self-forwarding, use forward_to_self() instead");
301 markWord m = markWord::encode_pointer_as_mark(p);
302 assert(m.decode_pointer() == p, "encoding must be reversible");
303 set_mark(m);
304 }
305
306 void oopDesc::forward_to_self() {
307 set_mark(mark().set_self_forwarded());
308 }
309
310 oop oopDesc::cas_set_forwardee(markWord new_mark, markWord compare, atomic_memory_order order) {
311 markWord old_mark = cas_set_mark(new_mark, compare, order);
312 if (old_mark == compare) {
313 return nullptr;
314 } else {
315 assert(old_mark.is_forwarded(), "must be forwarded here");
316 return forwardee(old_mark);
317 }
318 }
319
320 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
321 assert(cast_from_oop<oopDesc*>(p) != this,
322 "must not be used for self-forwarding, use forward_to_self_atomic() instead");
323 markWord m = markWord::encode_pointer_as_mark(p);
324 assert(forwardee(m) == p, "encoding must be reversible");
325 return cas_set_forwardee(m, compare, order);
326 }
327
328 oop oopDesc::forward_to_self_atomic(markWord old_mark, atomic_memory_order order) {
329 markWord new_mark = old_mark.set_self_forwarded();
330 assert(forwardee(new_mark) == cast_to_oop(this), "encoding must be reversible");
331 return cas_set_forwardee(new_mark, old_mark, order);
332 }
333
334 oop oopDesc::forwardee(markWord mark) const {
335 assert(mark.is_forwarded(), "only decode when actually forwarded");
336 if (mark.is_self_forwarded()) {
337 return cast_to_oop(this);
338 } else {
339 return mark.forwardee();
340 }
341 }
342
343 // Note that the forwardee is not the same thing as the displaced_mark.
344 // The forwardee is used when copying during scavenge and mark-sweep.
345 // It does need to clear the low two locking- and GC-related bits.
346 oop oopDesc::forwardee() const {
347 return forwardee(mark());
348 }
349
350 void oopDesc::unset_self_forwarded() {
351 set_mark(mark().unset_self_forwarded());
352 }
353
354 // The following method needs to be MT safe.
355 uint oopDesc::age() const {
356 markWord m = mark();
357 assert(!m.is_marked(), "Attempt to read age from forwarded mark");
358 if (m.has_displaced_mark_helper()) {
359 return m.displaced_mark_helper().age();
360 } else {
361 return m.age();
362 }
363 }
364
365 void oopDesc::incr_age() {
366 markWord m = mark();
367 assert(!m.is_marked(), "Attempt to increment age of forwarded mark");
368 if (m.has_displaced_mark_helper()) {
369 m.set_displaced_mark_helper(m.displaced_mark_helper().incr_age());
370 } else {
371 set_mark(m.incr_age());
372 }
373 }
374
375 template <typename OopClosureType>
376 void oopDesc::oop_iterate(OopClosureType* cl) {
377 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
378 }
379
380 template <typename OopClosureType>
381 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
382 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
383 }
384
385 template <typename OopClosureType>
386 size_t oopDesc::oop_iterate_size(OopClosureType* cl) {
387 Klass* k = klass();
388 size_t size = size_given_klass(k);
389 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
390 return size;
391 }
392
393 template <typename OopClosureType>
394 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
395 Klass* k = klass();
396 size_t size = size_given_klass(k);
397 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
398 return size;
399 }
400
401 template <typename OopClosureType>
402 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
403 oop_iterate_backwards(cl, klass());
404 }
405
406 template <typename OopClosureType>
407 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
408 // In this assert, we cannot safely access the Klass* with compact headers.
409 assert(k == klass(), "wrong klass");
410 OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
411 }
412
413 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
414 return obj == nullptr || obj->klass()->is_subtype_of(klass);
415 }
416
417 intptr_t oopDesc::identity_hash() {
418 // Fast case; if the object is unlocked and the hash value is set, no locking is needed
419 // Note: The mark must be read into local variable to avoid concurrent updates.
420 markWord mrk = mark();
421 if (mrk.is_unlocked() && !mrk.has_no_hash()) {
422 return mrk.hash();
423 } else if (mrk.is_marked()) {
424 return mrk.hash();
425 } else {
426 return slow_identity_hash();
427 }
428 }
429
430 // This checks fast simple case of whether the oop has_no_hash,
431 // to optimize JVMTI table lookup.
432 bool oopDesc::fast_no_hash_check() {
433 markWord mrk = mark_acquire();
434 assert(!mrk.is_marked(), "should never be marked");
435 return mrk.is_unlocked() && mrk.has_no_hash();
436 }
437
438 bool oopDesc::has_displaced_mark() const {
439 return mark().has_displaced_mark_helper();
440 }
441
442 markWord oopDesc::displaced_mark() const {
443 return mark().displaced_mark_helper();
444 }
445
446 void oopDesc::set_displaced_mark(markWord m) {
447 mark().set_displaced_mark_helper(m);
448 }
449
450 bool oopDesc::mark_must_be_preserved() const {
451 return mark_must_be_preserved(mark());
452 }
453
454 bool oopDesc::mark_must_be_preserved(markWord m) const {
455 return m.must_be_preserved();
456 }
457
458 #endif // SHARE_OOPS_OOP_INLINE_HPP