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