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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13 * accompanied this code).
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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/instanceKlass.hpp"
37 #include "oops/markWord.inline.hpp"
38 #include "oops/objLayout.inline.hpp"
39 #include "oops/oopsHierarchy.hpp"
40 #include "runtime/atomicAccess.hpp"
41 #include "runtime/globals.hpp"
42 #include "utilities/align.hpp"
43 #include "utilities/debug.hpp"
44 #include "utilities/globalDefinitions.hpp"
45 #include "utilities/macros.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 void* oopDesc::base_addr() { return this; }
51 const void* oopDesc::base_addr() const { return this; }
52
53 markWord oopDesc::mark() const {
54 return AtomicAccess::load(&_mark);
55 }
56
57 markWord oopDesc::mark_acquire() const {
58 return AtomicAccess::load_acquire(&_mark);
59 }
60
61 void oopDesc::set_mark(markWord m) {
62 AtomicAccess::store(&_mark, m);
63 }
64
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 AtomicAccess::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
71 }
72
73 void oopDesc::release_set_mark(markWord m) {
74 AtomicAccess::release_store(&_mark, m);
75 }
76
77 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
78 return AtomicAccess::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 AtomicAccess::cmpxchg(&_mark, old_mark, new_mark, order);
83 }
84
85 markWord oopDesc::prototype_mark() const {
86 if (UseCompactObjectHeaders || EnableValhalla) {
87 return klass()->prototype_header();
88 } else {
89 return markWord::prototype();
90 }
91 }
92
93 void oopDesc::init_mark() {
94 set_mark(prototype_mark());
95 }
96
97 // This is specifically for Parallel GC. The other collectors need klass()->prototype_header()
98 // even without using Compact Object Headers. The issue is that this operation is unsafe
99 // using Parallel, as there are multiple concurrent GC workers that could access it.
100 // In practice, this has lead to relatively frequent crashes.
101 // More work needs to be done in the future to consolidate reinit_mark with init_mark.
102 void oopDesc::reinit_mark() {
103 if (UseCompactObjectHeaders) {
104 set_mark(klass()->prototype_header());
105 } else {
106 set_mark(markWord::prototype());
107 }
108 }
109
110 Klass* oopDesc::klass() const {
111 switch (ObjLayout::klass_mode()) {
112 case ObjLayout::Compact:
113 return mark().klass();
114 case ObjLayout::Compressed:
115 return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
116 default:
117 return _metadata._klass;
118 }
119 }
120
121 Klass* oopDesc::klass_or_null() const {
122 switch (ObjLayout::klass_mode()) {
123 case ObjLayout::Compact:
124 return mark().klass_or_null();
125 case ObjLayout::Compressed:
126 return CompressedKlassPointers::decode(_metadata._compressed_klass);
127 default:
128 return _metadata._klass;
129 }
130 }
131
132 Klass* oopDesc::klass_or_null_acquire() const {
133 switch (ObjLayout::klass_mode()) {
134 case ObjLayout::Compact:
135 return mark_acquire().klass();
136 case ObjLayout::Compressed: {
137 narrowKlass narrow_klass = AtomicAccess::load_acquire(&_metadata._compressed_klass);
138 return CompressedKlassPointers::decode(narrow_klass);
139 }
140 default:
141 return AtomicAccess::load_acquire(&_metadata._klass);
142 }
143 }
144
145 Klass* oopDesc::klass_without_asserts() const {
146 switch (ObjLayout::klass_mode()) {
147 case ObjLayout::Compact:
148 return mark().klass_without_asserts();
149 case ObjLayout::Compressed:
150 return CompressedKlassPointers::decode_without_asserts(_metadata._compressed_klass);
151 default:
152 return _metadata._klass;
153 }
154 }
155
156 narrowKlass oopDesc::narrow_klass() const {
157 switch (ObjLayout::klass_mode()) {
158 case ObjLayout::Compact:
159 return mark().narrow_klass();
160 case ObjLayout::Compressed:
161 return _metadata._compressed_klass;
162 default:
163 ShouldNotReachHere();
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 AtomicAccess::release_store((narrowKlass*)raw_mem,
183 CompressedKlassPointers::encode_not_null(k));
184 } else {
185 AtomicAccess::release_store((Klass**)raw_mem, k);
186 }
187 }
188
189 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
190 assert(has_klass_gap(), "precondition");
191 *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
192 }
193
194 bool oopDesc::is_a(Klass* k) const {
195 return klass()->is_subtype_of(k);
196 }
197
198 size_t oopDesc::size() {
199 return size_given_klass(klass());
200 }
201
202 size_t oopDesc::size_given_klass(Klass* klass) {
203 int lh = klass->layout_helper();
204 size_t s;
205
206 // lh is now a value computed at class initialization that may hint
207 // at the size. For instances, this is positive and equal to the
208 // size. For arrays, this is negative and provides log2 of the
209 // array element size. For other oops, it is zero and thus requires
210 // a virtual call.
211 //
212 // We go to all this trouble because the size computation is at the
213 // heart of phase 2 of mark-compaction, and called for every object,
214 // alive or dead. So the speed here is equal in importance to the
215 // speed of allocation.
216
217 if (lh > Klass::_lh_neutral_value) {
218 if (!Klass::layout_helper_needs_slow_path(lh)) {
219 s = lh >> LogHeapWordSize; // deliver size scaled by wordSize
220 } else {
221 s = klass->oop_size(this);
222 }
223 } else if (lh <= Klass::_lh_neutral_value) {
224 // The most common case is instances; fall through if so.
225 if (lh < Klass::_lh_neutral_value) {
226 // Second most common case is arrays. We have to fetch the
227 // length of the array, shift (multiply) it appropriately,
228 // up to wordSize, add the header, and align to object size.
229 size_t size_in_bytes;
230 size_t array_length = (size_t) ((arrayOop)this)->length();
231 size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
232 size_in_bytes += Klass::layout_helper_header_size(lh);
233
234 // This code could be simplified, but by keeping array_header_in_bytes
235 // in units of bytes and doing it this way we can round up just once,
236 // skipping the intermediate round to HeapWordSize.
237 s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
238
239 assert(s == klass->oop_size(this), "wrong array object size");
240 } else {
241 // Must be zero, so bite the bullet and take the virtual call.
242 s = klass->oop_size(this);
243 }
244 }
245
246 assert(s > 0, "Oop size must be greater than zero, not %zu", s);
247 assert(is_object_aligned(s), "Oop size is not properly aligned: %zu", s);
248 return s;
249 }
250
251 bool oopDesc::is_instance() const { return klass()->is_instance_klass(); }
252 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass(); }
253 bool oopDesc::is_stackChunk() const { return klass()->is_stack_chunk_instance_klass(); }
254 bool oopDesc::is_array() const { return klass()->is_array_klass(); }
255 bool oopDesc::is_objArray() const { return klass()->is_objArray_klass(); }
256 bool oopDesc::is_refArray() const { return klass()->is_refArray_klass(); }
257 bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }
258 bool oopDesc::is_refined_objArray() const { return klass()->is_refined_objArray_klass(); }
259
260 bool oopDesc::is_inline_type() const { return mark().is_inline_type(); }
261 #ifdef _LP64
262 bool oopDesc::is_flatArray() const {
263 markWord mrk = mark();
264 return (mrk.is_unlocked()) ? mrk.is_flat_array() : klass()->is_flatArray_klass();
265 }
266 bool oopDesc::is_null_free_array() const {
267 markWord mrk = mark();
268 return (mrk.is_unlocked()) ? mrk.is_null_free_array() : klass()->is_null_free_array_klass();
269 }
270 #else
271 bool oopDesc::is_flatArray() const { return klass()->is_flatArray_klass(); }
272 bool oopDesc::is_null_free_array() const { return klass()->is_null_free_array_klass(); }
273 #endif
274
275 template<typename T>
276 T* oopDesc::field_addr(int offset) const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
277
278 template <typename T>
279 size_t oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
280
281 template <DecoratorSet decorators>
282 inline oop oopDesc::obj_field_access(int offset) const { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
283 inline oop oopDesc::obj_field(int offset) const { return HeapAccess<>::oop_load_at(as_oop(), offset); }
284
285 inline void oopDesc::obj_field_put(int offset, oop value) { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
286 template <DecoratorSet decorators>
287 inline void oopDesc::obj_field_put_access(int offset, oop value) { HeapAccess<decorators>::oop_store_at(as_oop(), offset, value); }
288
289 inline jbyte oopDesc::byte_field(int offset) const { return *field_addr<jbyte>(offset); }
290 inline void oopDesc::byte_field_put(int offset, jbyte value) { *field_addr<jbyte>(offset) = value; }
291
292 inline jchar oopDesc::char_field(int offset) const { return *field_addr<jchar>(offset); }
293 inline void oopDesc::char_field_put(int offset, jchar value) { *field_addr<jchar>(offset) = value; }
294
295 inline jboolean oopDesc::bool_field(int offset) const { return *field_addr<jboolean>(offset); }
296 inline void oopDesc::bool_field_put(int offset, jboolean value) { *field_addr<jboolean>(offset) = jboolean(value & 1); }
297 inline jboolean oopDesc::bool_field_volatile(int offset) const { return RawAccess<MO_SEQ_CST>::load(field_addr<jboolean>(offset)); }
298 inline void oopDesc::bool_field_put_volatile(int offset, jboolean value) { RawAccess<MO_SEQ_CST>::store(field_addr<jboolean>(offset), jboolean(value & 1)); }
299 inline jshort oopDesc::short_field(int offset) const { return *field_addr<jshort>(offset); }
300 inline void oopDesc::short_field_put(int offset, jshort value) { *field_addr<jshort>(offset) = value; }
301
302 inline jint oopDesc::int_field(int offset) const { return *field_addr<jint>(offset); }
303 inline void oopDesc::int_field_put(int offset, jint value) { *field_addr<jint>(offset) = value; }
304 inline jint oopDesc::int_field_relaxed(int offset) const { return AtomicAccess::load(field_addr<jint>(offset)); }
305 inline void oopDesc::int_field_put_relaxed(int offset, jint value) { AtomicAccess::store(field_addr<jint>(offset), value); }
306
307 inline jlong oopDesc::long_field(int offset) const { return *field_addr<jlong>(offset); }
308 inline void oopDesc::long_field_put(int offset, jlong value) { *field_addr<jlong>(offset) = value; }
309
310 inline jfloat oopDesc::float_field(int offset) const { return *field_addr<jfloat>(offset); }
311 inline void oopDesc::float_field_put(int offset, jfloat value) { *field_addr<jfloat>(offset) = value; }
312
313 inline jdouble oopDesc::double_field(int offset) const { return *field_addr<jdouble>(offset); }
314 inline void oopDesc::double_field_put(int offset, jdouble value) { *field_addr<jdouble>(offset) = value; }
315
316 bool oopDesc::is_locked() const {
317 return mark().is_locked();
318 }
319
320 bool oopDesc::is_unlocked() const {
321 return mark().is_unlocked();
322 }
323
324 bool oopDesc::is_gc_marked() const {
325 return mark().is_marked();
326 }
327
328 // Used by scavengers
329 bool oopDesc::is_forwarded() const {
330 return mark().is_forwarded();
331 }
332
333 bool oopDesc::is_self_forwarded() const {
334 return mark().is_self_forwarded();
335 }
336
337 // Used by scavengers
338 void oopDesc::forward_to(oop p) {
339 assert(cast_from_oop<oopDesc*>(p) != this,
340 "must not be used for self-forwarding, use forward_to_self() instead");
341 markWord m = markWord::encode_pointer_as_mark(p);
342 assert(m.decode_pointer() == p, "encoding must be reversible");
343 set_mark(m);
344 }
345
346 void oopDesc::forward_to_self() {
347 set_mark(mark().set_self_forwarded());
348 }
349
350 oop oopDesc::cas_set_forwardee(markWord new_mark, markWord compare, atomic_memory_order order) {
351 markWord old_mark = cas_set_mark(new_mark, compare, order);
352 if (old_mark == compare) {
353 return nullptr;
354 } else {
355 assert(old_mark.is_forwarded(), "must be forwarded here");
356 return forwardee(old_mark);
357 }
358 }
359
360 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
361 assert(cast_from_oop<oopDesc*>(p) != this,
362 "must not be used for self-forwarding, use forward_to_self_atomic() instead");
363 markWord m = markWord::encode_pointer_as_mark(p);
364 assert(forwardee(m) == p, "encoding must be reversible");
365 return cas_set_forwardee(m, compare, order);
366 }
367
368 oop oopDesc::forward_to_self_atomic(markWord old_mark, atomic_memory_order order) {
369 markWord new_mark = old_mark.set_self_forwarded();
370 assert(forwardee(new_mark) == cast_to_oop(this), "encoding must be reversible");
371 return cas_set_forwardee(new_mark, old_mark, order);
372 }
373
374 oop oopDesc::forwardee(markWord mark) const {
375 assert(mark.is_forwarded(), "only decode when actually forwarded");
376 if (mark.is_self_forwarded()) {
377 return cast_to_oop(this);
378 } else {
379 return mark.forwardee();
380 }
381 }
382
383 // Note that the forwardee is not the same thing as the displaced_mark.
384 // The forwardee is used when copying during scavenge and mark-sweep.
385 // It does need to clear the low two locking- and GC-related bits.
386 oop oopDesc::forwardee() const {
387 return forwardee(mark());
388 }
389
390 void oopDesc::unset_self_forwarded() {
391 set_mark(mark().unset_self_forwarded());
392 }
393
394 // The following method needs to be MT safe.
395 uint oopDesc::age() const {
396 markWord m = mark();
397 assert(!m.is_marked(), "Attempt to read age from forwarded mark");
398 if (m.has_displaced_mark_helper()) {
399 return m.displaced_mark_helper().age();
400 } else {
401 return m.age();
402 }
403 }
404
405 void oopDesc::incr_age() {
406 markWord m = mark();
407 assert(!m.is_marked(), "Attempt to increment age of forwarded mark");
408 if (m.has_displaced_mark_helper()) {
409 m.set_displaced_mark_helper(m.displaced_mark_helper().incr_age());
410 } else {
411 set_mark(m.incr_age());
412 }
413 }
414
415 template <typename OopClosureType>
416 void oopDesc::oop_iterate(OopClosureType* cl) {
417 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
418 }
419
420 template <typename OopClosureType>
421 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
422 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
423 }
424
425 template <typename OopClosureType>
426 size_t oopDesc::oop_iterate_size(OopClosureType* cl) {
427 Klass* k = klass();
428 size_t size = size_given_klass(k);
429 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
430 return size;
431 }
432
433 template <typename OopClosureType>
434 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
435 Klass* k = klass();
436 size_t size = size_given_klass(k);
437 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
438 return size;
439 }
440
441 template <typename OopClosureType>
442 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
443 oop_iterate_backwards(cl, klass());
444 }
445
446 template <typename OopClosureType>
447 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
448 // In this assert, we cannot safely access the Klass* with compact headers.
449 assert(k == klass(), "wrong klass");
450 OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
451 }
452
453 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
454 return obj == nullptr || obj->klass()->is_subtype_of(klass);
455 }
456
457 intptr_t oopDesc::identity_hash() {
458 // Fast case; if the object is unlocked and the hash value is set, no locking is needed
459 // Note: The mark must be read into local variable to avoid concurrent updates.
460 markWord mrk = mark();
461 if (mrk.is_unlocked() && !mrk.has_no_hash()) {
462 return mrk.hash();
463 } else if (mrk.is_marked()) {
464 return mrk.hash();
465 } else {
466 return slow_identity_hash();
467 }
468 }
469
470 // This checks fast simple case of whether the oop has_no_hash,
471 // to optimize JVMTI table lookup.
472 bool oopDesc::fast_no_hash_check() {
473 markWord mrk = mark_acquire();
474 assert(!mrk.is_marked(), "should never be marked");
475 return mrk.is_unlocked() && mrk.has_no_hash();
476 }
477
478 bool oopDesc::has_displaced_mark() const {
479 return mark().has_displaced_mark_helper();
480 }
481
482 markWord oopDesc::displaced_mark() const {
483 return mark().displaced_mark_helper();
484 }
485
486 void oopDesc::set_displaced_mark(markWord m) {
487 mark().set_displaced_mark_helper(m);
488 }
489
490 bool oopDesc::mark_must_be_preserved() const {
491 return mark_must_be_preserved(mark());
492 }
493
494 bool oopDesc::mark_must_be_preserved(markWord m) const {
495 return m.must_be_preserved();
496 }
497
498 #endif // SHARE_OOPS_OOP_INLINE_HPP