1 /*
2 * Copyright (c) 1997, 2023, 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.
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21 * questions.
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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/compressedOops.inline.hpp"
37 #include "oops/instanceKlass.hpp"
38 #include "oops/markWord.inline.hpp"
39 #include "oops/oopsHierarchy.hpp"
40 #include "runtime/atomic.hpp"
41 #include "runtime/globals.hpp"
42 #include "runtime/objectMonitor.inline.hpp"
43 #include "runtime/safepoint.hpp"
44 #include "runtime/synchronizer.hpp"
45 #include "utilities/align.hpp"
46 #include "utilities/debug.hpp"
47 #include "utilities/macros.hpp"
48 #include "utilities/globalDefinitions.hpp"
49
50 // Implementation of all inlined member functions defined in oop.hpp
51 // We need a separate file to avoid circular references
52
53 markWord oopDesc::mark() const {
54 return Atomic::load(&_mark);
55 }
56
57 markWord oopDesc::mark_acquire() const {
58 return Atomic::load_acquire(&_mark);
59 }
60
61 markWord* oopDesc::mark_addr() const {
62 return (markWord*) &_mark;
63 }
64
65 void oopDesc::set_mark(markWord m) {
66 Atomic::store(&_mark, m);
67 }
68
69 void oopDesc::set_mark(HeapWord* mem, markWord m) {
70 *(markWord*)(((char*)mem) + mark_offset_in_bytes()) = m;
71 }
72
73 void oopDesc::release_set_mark(markWord m) {
74 Atomic::release_store(&_mark, m);
75 }
76
77 void oopDesc::release_set_mark(HeapWord* mem, markWord m) {
78 Atomic::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
79 }
80
81 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
82 return Atomic::cmpxchg(&_mark, old_mark, new_mark);
83 }
84
85 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order) {
86 return Atomic::cmpxchg(&_mark, old_mark, new_mark, order);
87 }
88
89 markWord oopDesc::resolve_mark() const {
90 assert(LockingMode != LM_LEGACY, "Not safe with legacy stack-locking");
91 markWord hdr = mark();
92 if (hdr.has_monitor()) {
93 ObjectMonitor* monitor = hdr.monitor();
94 return monitor->header();
95 }
96 return hdr;
97 }
98
99 void oopDesc::init_mark() {
100 #ifdef _LP64
101 if (UseCompactObjectHeaders) {
102 markWord header = resolve_mark();
103 assert(CompressedKlassPointers::use_compressed_class_pointers(), "expect compressed klass pointers");
104 set_mark(markWord((header.value() & markWord::klass_mask_in_place) | markWord::prototype().value()));
105 } else
106 #endif
107 set_mark(markWord::prototype());
108 }
109
110 Klass* oopDesc::klass() const {
111 #ifdef _LP64
112 if (CompressedKlassPointers::use_compact_object_headers()) {
113 assert(CompressedKlassPointers::use_compressed_class_pointers(), "only with compressed class pointers");
114 markWord header = resolve_mark();
115 return header.klass();
116 } else if (CompressedKlassPointers::use_compressed_class_pointers()) {
117 return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
118 } else
119 #endif
120 return _metadata._klass;
121 }
122
123 Klass* oopDesc::klass_or_null() const {
124 #ifdef _LP64
125 if (CompressedKlassPointers::use_compact_object_headers()) {
126 assert(CompressedKlassPointers::use_compressed_class_pointers(), "only with compressed class pointers");
127 markWord header = resolve_mark();
128 return header.klass_or_null();
129 } else if (CompressedKlassPointers::use_compressed_class_pointers()) {
130 return CompressedKlassPointers::decode(_metadata._compressed_klass);
131 } else
132 #endif
133 return _metadata._klass;
134 }
135
136 Klass* oopDesc::klass_or_null_acquire() const {
137 #ifdef _LP64
138 if (CompressedKlassPointers::use_compact_object_headers()) {
139 assert(CompressedKlassPointers::use_compressed_class_pointers(), "only with compressed class pointers");
140 markWord header = mark_acquire();
141 if (header.has_monitor()) {
142 header = header.monitor()->header();
143 }
144 return header.klass_or_null();
145 } else if (CompressedKlassPointers::use_compressed_class_pointers()) {
146 narrowKlass nklass = Atomic::load_acquire(&_metadata._compressed_klass);
147 return CompressedKlassPointers::decode(nklass);
148 } else
149 #endif
150 return Atomic::load_acquire(&_metadata._klass);
151 }
152
153 Klass* oopDesc::klass_raw() const {
154 return klass();
155 }
156
157 void oopDesc::set_klass(Klass* k) {
158 assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
159 assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
160 if (CompressedKlassPointers::use_compressed_class_pointers()) {
161 _metadata._compressed_klass = CompressedKlassPointers::encode_not_null(k);
162 } else {
163 _metadata._klass = k;
164 }
165 }
166
167 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
168 assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
169 assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
170 char* raw_mem = ((char*)mem + klass_offset_in_bytes());
171 if (CompressedKlassPointers::use_compressed_class_pointers()) {
172 Atomic::release_store((narrowKlass*)raw_mem,
173 CompressedKlassPointers::encode_not_null(k));
174 } else {
175 Atomic::release_store((Klass**)raw_mem, k);
176 }
177 }
178
179 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
180 assert(!UseCompactObjectHeaders, "don't set Klass* gap with compact headers");
181 if (CompressedKlassPointers::use_compressed_class_pointers()) {
182 *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
183 }
184 }
185
186 bool oopDesc::is_a(Klass* k) const {
187 return klass()->is_subtype_of(k);
188 }
189
190 size_t oopDesc::size() {
191 return size_given_klass(klass());
192 }
193
194 size_t oopDesc::size_given_klass(Klass* klass) {
195 int lh = klass->layout_helper();
196 size_t s;
197
198 // lh is now a value computed at class initialization that may hint
199 // at the size. For instances, this is positive and equal to the
200 // size. For arrays, this is negative and provides log2 of the
201 // array element size. For other oops, it is zero and thus requires
202 // a virtual call.
203 //
204 // We go to all this trouble because the size computation is at the
205 // heart of phase 2 of mark-compaction, and called for every object,
206 // alive or dead. So the speed here is equal in importance to the
207 // speed of allocation.
208
209 if (lh > Klass::_lh_neutral_value) {
210 if (!Klass::layout_helper_needs_slow_path(lh)) {
211 s = lh >> LogHeapWordSize; // deliver size scaled by wordSize
212 } else {
213 s = klass->oop_size(this);
214 }
215 } else if (lh <= Klass::_lh_neutral_value) {
216 // The most common case is instances; fall through if so.
217 if (lh < Klass::_lh_neutral_value) {
218 // Second most common case is arrays. We have to fetch the
219 // length of the array, shift (multiply) it appropriately,
220 // up to wordSize, add the header, and align to object size.
221 size_t size_in_bytes;
222 size_t array_length = (size_t) ((arrayOop)this)->length();
223 size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
224 size_in_bytes += Klass::layout_helper_header_size(lh);
225
226 // This code could be simplified, but by keeping array_header_in_bytes
227 // in units of bytes and doing it this way we can round up just once,
228 // skipping the intermediate round to HeapWordSize.
229 s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
230
231 assert(s == klass->oop_size(this) || size_might_change(), "wrong array object size");
232 } else {
233 // Must be zero, so bite the bullet and take the virtual call.
234 s = klass->oop_size(this);
235 }
236 }
237
238 assert(s > 0, "Oop size must be greater than zero, not " SIZE_FORMAT, s);
239 assert(is_object_aligned(s), "Oop size is not properly aligned: " SIZE_FORMAT, s);
240 return s;
241 }
242
243 bool oopDesc::is_instance() const { return klass()->is_instance_klass(); }
244 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass(); }
245 bool oopDesc::is_stackChunk() const { return klass()->is_stack_chunk_instance_klass(); }
246 bool oopDesc::is_array() const { return klass()->is_array_klass(); }
247 bool oopDesc::is_objArray() const { return klass()->is_objArray_klass(); }
248 bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }
249
250 template<typename T>
251 T* oopDesc::field_addr(int offset) const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
252
253 template <typename T>
254 size_t oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
255
256 template <DecoratorSet decorators>
257 inline oop oopDesc::obj_field_access(int offset) const { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
258 inline oop oopDesc::obj_field(int offset) const { return HeapAccess<>::oop_load_at(as_oop(), offset); }
259
260 inline void oopDesc::obj_field_put(int offset, oop value) { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
261 template <DecoratorSet decorators>
262 inline void oopDesc::obj_field_put_access(int offset, oop value) { HeapAccess<decorators>::oop_store_at(as_oop(), offset, value); }
263
264 inline jbyte oopDesc::byte_field(int offset) const { return *field_addr<jbyte>(offset); }
265 inline void oopDesc::byte_field_put(int offset, jbyte value) { *field_addr<jbyte>(offset) = value; }
266
267 inline jchar oopDesc::char_field(int offset) const { return *field_addr<jchar>(offset); }
268 inline void oopDesc::char_field_put(int offset, jchar value) { *field_addr<jchar>(offset) = value; }
269
270 inline jboolean oopDesc::bool_field(int offset) const { return *field_addr<jboolean>(offset); }
271 inline void oopDesc::bool_field_put(int offset, jboolean value) { *field_addr<jboolean>(offset) = jboolean(value & 1); }
272 inline jboolean oopDesc::bool_field_volatile(int offset) const { return RawAccess<MO_SEQ_CST>::load(field_addr<jboolean>(offset)); }
273 inline void oopDesc::bool_field_put_volatile(int offset, jboolean value) { RawAccess<MO_SEQ_CST>::store(field_addr<jboolean>(offset), jboolean(value & 1)); }
274 inline jshort oopDesc::short_field(int offset) const { return *field_addr<jshort>(offset); }
275 inline void oopDesc::short_field_put(int offset, jshort value) { *field_addr<jshort>(offset) = value; }
276
277 inline jint oopDesc::int_field(int offset) const { return *field_addr<jint>(offset); }
278 inline void oopDesc::int_field_put(int offset, jint value) { *field_addr<jint>(offset) = value; }
279
280 inline jlong oopDesc::long_field(int offset) const { return *field_addr<jlong>(offset); }
281 inline void oopDesc::long_field_put(int offset, jlong value) { *field_addr<jlong>(offset) = value; }
282
283 inline jfloat oopDesc::float_field(int offset) const { return *field_addr<jfloat>(offset); }
284 inline void oopDesc::float_field_put(int offset, jfloat value) { *field_addr<jfloat>(offset) = value; }
285
286 inline jdouble oopDesc::double_field(int offset) const { return *field_addr<jdouble>(offset); }
287 inline void oopDesc::double_field_put(int offset, jdouble value) { *field_addr<jdouble>(offset) = value; }
288
289 bool oopDesc::is_locked() const {
290 return mark().is_locked();
291 }
292
293 bool oopDesc::is_unlocked() const {
294 return mark().is_unlocked();
295 }
296
297 // Used only for markSweep, scavenging
298 bool oopDesc::is_gc_marked() const {
299 return mark().is_marked();
300 }
301
302 // Used by scavengers
303 bool oopDesc::is_forwarded() const {
304 // The extra heap check is needed since the obj might be locked, in which case the
305 // mark would point to a stack location and have the sentinel bit cleared
306 return mark().is_marked();
307 }
308
309 // Used by scavengers
310 void oopDesc::forward_to(oop p) {
311 markWord m = markWord::encode_pointer_as_mark(p);
312 assert(forwardee(m) == p, "encoding must be reversable");
313 set_mark(m);
314 }
315
316 void oopDesc::forward_to_self() {
317 #ifdef _LP64
318 markWord m = mark();
319 // If mark is displaced, we need to preserve the Klass* from real header.
320 assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
321 if (m.has_displaced_mark_helper()) {
322 m = m.displaced_mark_helper();
323 }
324 m = m.set_self_forwarded();
325 assert(forwardee(m) == cast_to_oop(this), "encoding must be reversable");
326 set_mark(m);
327 #else
328 forward_to(oop(this));
329 #endif
330 }
331
332 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
333 markWord m = markWord::encode_pointer_as_mark(p);
334 assert(forwardee(m) == p, "encoding must be reversable");
335 markWord old_mark = cas_set_mark(m, compare, order);
336 if (old_mark == compare) {
337 return nullptr;
338 } else {
339 return forwardee(old_mark);
340 }
341 }
342
343 oop oopDesc::forward_to_self_atomic(markWord compare, atomic_memory_order order) {
344 #ifdef _LP64
345 markWord m = compare;
346 // If mark is displaced, we need to preserve the Klass* from real header.
347 assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
348 if (m.has_displaced_mark_helper()) {
349 m = m.displaced_mark_helper();
350 }
351 m = m.set_self_forwarded();
352 assert(forwardee(m) == cast_to_oop(this), "encoding must be reversable");
353 markWord old_mark = cas_set_mark(m, compare, order);
354 if (old_mark == compare) {
355 return NULL;
356 } else {
357 assert(old_mark.is_marked(), "must be marked here");
358 return forwardee(old_mark);
359 }
360 #else
361 return forward_to_atomic(oop(this), compare, order);
362 #endif
363 }
364
365 // Note that the forwardee is not the same thing as the displaced_mark.
366 // The forwardee is used when copying during scavenge and mark-sweep.
367 // It does need to clear the low two locking- and GC-related bits.
368 oop oopDesc::forwardee() const {
369 return forwardee(mark());
370 }
371
372 oop oopDesc::forwardee(markWord header) const {
373 assert(header.is_marked(), "must be forwarded");
374 #ifdef _LP64
375 if (header.self_forwarded()) {
376 return cast_to_oop(this);
377 } else
378 #endif
379 {
380 assert(header.is_marked(), "only decode when actually forwarded");
381 return cast_to_oop(header.decode_pointer());
382 }
383 }
384
385 // The following method needs to be MT safe.
386 uint oopDesc::age() const {
387 assert(!mark().is_marked(), "Attempt to read age from forwarded mark");
388 if (has_displaced_mark()) {
389 return displaced_mark().age();
390 } else {
391 return mark().age();
392 }
393 }
394
395 void oopDesc::incr_age() {
396 assert(!mark().is_marked(), "Attempt to increment age of forwarded mark");
397 if (has_displaced_mark()) {
398 set_displaced_mark(displaced_mark().incr_age());
399 } else {
400 set_mark(mark().incr_age());
401 }
402 }
403
404 template <typename OopClosureType>
405 void oopDesc::oop_iterate(OopClosureType* cl) {
406 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
407 }
408
409 template <typename OopClosureType>
410 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
411 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
412 }
413
414 template <typename OopClosureType>
415 size_t oopDesc::oop_iterate_size(OopClosureType* cl) {
416 Klass* k = klass();
417 size_t size = size_given_klass(k);
418 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
419 return size;
420 }
421
422 template <typename OopClosureType>
423 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
424 Klass* k = klass();
425 size_t size = size_given_klass(k);
426 OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
427 return size;
428 }
429
430 template <typename OopClosureType>
431 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
432 oop_iterate_backwards(cl, klass());
433 }
434
435 template <typename OopClosureType>
436 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
437 OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
438 }
439
440 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
441 return obj == nullptr || obj->klass()->is_subtype_of(klass);
442 }
443
444 intptr_t oopDesc::identity_hash() {
445 // Fast case; if the object is unlocked and the hash value is set, no locking is needed
446 // Note: The mark must be read into local variable to avoid concurrent updates.
447 markWord mrk = mark();
448 if (mrk.is_unlocked() && !mrk.has_no_hash()) {
449 return mrk.hash();
450 } else if (mrk.is_marked()) {
451 return mrk.hash();
452 } else {
453 return slow_identity_hash();
454 }
455 }
456
457 // This checks fast simple case of whether the oop has_no_hash,
458 // to optimize JVMTI table lookup.
459 bool oopDesc::fast_no_hash_check() {
460 markWord mrk = mark_acquire();
461 assert(!mrk.is_marked(), "should never be marked");
462 return mrk.is_unlocked() && mrk.has_no_hash();
463 }
464
465 bool oopDesc::has_displaced_mark() const {
466 return mark().has_displaced_mark_helper();
467 }
468
469 markWord oopDesc::displaced_mark() const {
470 return mark().displaced_mark_helper();
471 }
472
473 void oopDesc::set_displaced_mark(markWord m) {
474 mark().set_displaced_mark_helper(m);
475 }
476
477 bool oopDesc::mark_must_be_preserved() const {
478 return mark_must_be_preserved(mark());
479 }
480
481 bool oopDesc::mark_must_be_preserved(markWord m) const {
482 return m.must_be_preserved(this);
483 }
484
485 #endif // SHARE_OOPS_OOP_INLINE_HPP