1 /*
  2  * Copyright (c) 1997, 2021, 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.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
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 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 "oops/access.inline.hpp"
 32 #include "oops/arrayKlass.hpp"
 33 #include "oops/arrayOop.hpp"
 34 #include "oops/compressedOops.inline.hpp"
 35 #include "oops/markWord.inline.hpp"
 36 #include "oops/oopsHierarchy.hpp"
 37 #include "runtime/atomic.hpp"
 38 #include "runtime/globals.hpp"
 39 #include "runtime/safepoint.hpp"
 40 #include "runtime/objectMonitor.inline.hpp"
 41 #include "utilities/align.hpp"
 42 #include "utilities/debug.hpp"
 43 #include "utilities/macros.hpp"
 44 #include "utilities/globalDefinitions.hpp"
 45 
 46 // Implementation of all inlined member functions defined in oop.hpp
 47 // We need a separate file to avoid circular references
 48 
 49 markWord oopDesc::mark() const {
 50   uintptr_t v = HeapAccess<MO_RELAXED>::load_at(as_oop(), mark_offset_in_bytes());
 51   return markWord(v);
 52 }
 53 
 54 markWord oopDesc::mark_acquire() const {
 55   return Atomic::load_acquire(&_mark);
 56 }
 57 markWord* oopDesc::mark_addr() const {
 58   return (markWord*) &_mark;
 59 }
 60 
 61 void oopDesc::set_mark(markWord m) {
 62   HeapAccess<MO_RELAXED>::store_at(as_oop(), mark_offset_in_bytes(), m.value());
 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(markWord m) {
 70   HeapAccess<MO_RELEASE>::store_at(as_oop(), mark_offset_in_bytes(), m.value());
 71 }
 72 
 73 void oopDesc::release_set_mark(HeapWord* mem, markWord m) {
 74   Atomic::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
 75 }
 76 
 77 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
 78   uintptr_t v = HeapAccess<>::atomic_cmpxchg_at(as_oop(), mark_offset_in_bytes(), old_mark.value(), new_mark.value());
 79   return markWord(v);
 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::resolve_mark() const {
 87   assert(LockingMode != LM_LEGACY, "Not safe with legacy stack-locking");
 88   markWord hdr = mark();
 89   if (hdr.has_displaced_mark_helper()) {
 90     hdr = hdr.displaced_mark_helper();
 91   }
 92   return hdr;
 93 }
 94 
 95 markWord oopDesc::prototype_mark() const {
 96   if (UseCompactObjectHeaders) {
 97     return klass()->prototype_header();
 98   } else {
 99     return markWord::prototype();
100   }
101 }
102 
103 void oopDesc::init_mark() {
104   set_mark(markWord::prototype_for_klass(klass()));
105 }
106 
107 Klass* oopDesc::klass() const {
108 #ifdef _LP64
109   if (UseCompactObjectHeaders) {
110     assert(UseCompressedClassPointers, "only with compressed class pointers");
111     markWord header = resolve_mark();
112     return header.klass();
113   } else if (UseCompressedClassPointers) {
114     return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
115   } else
116 #endif
117   return _metadata._klass;
118 }
119 
120 Klass* oopDesc::klass_or_null() const {
121 #ifdef _LP64
122   if (UseCompactObjectHeaders) {
123     assert(UseCompressedClassPointers, "only with compressed class pointers");
124     markWord header = resolve_mark();
125     return header.klass_or_null();
126   } else if (UseCompressedClassPointers) {
127     return CompressedKlassPointers::decode(_metadata._compressed_klass);
128   } else
129 #endif
130   return _metadata._klass;
131 }
132 
133 Klass* oopDesc::klass_or_null_acquire() const {
134 #ifdef _LP64
135   if (UseCompactObjectHeaders) {
136     assert(UseCompressedClassPointers, "only with compressed class pointers");
137     markWord header = mark_acquire();
138     if (header.has_monitor()) {
139       header = header.monitor()->header();
140     }
141     return header.klass_or_null();
142   } else if (UseCompressedClassPointers) {
143      narrowKlass nklass = Atomic::load_acquire(&_metadata._compressed_klass);
144      return CompressedKlassPointers::decode(nklass);
145   } else
146 #endif
147   return Atomic::load_acquire(&_metadata._klass);
148 }
149 
150 void oopDesc::set_klass(Klass* k) {
151   assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
152   assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
153   if (UseCompressedClassPointers) {
154     _metadata._compressed_klass = CompressedKlassPointers::encode_not_null(k);
155   } else {
156     _metadata._klass = k;
157   }
158 }
159 
160 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
161   assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
162   assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
163   char* raw_mem = ((char*)mem + klass_offset_in_bytes());
164   if (UseCompressedClassPointers) {
165     Atomic::release_store((narrowKlass*)raw_mem,
166                           CompressedKlassPointers::encode_not_null(k));
167   } else {
168     Atomic::release_store((Klass**)raw_mem, k);
169   }
170 }
171 
172 int oopDesc::klass_gap() const {
173   assert(!UseCompactObjectHeaders, "don't get Klass* gap with compact headers");
174   return *(int*)(((intptr_t)this) + klass_gap_offset_in_bytes());
175 }
176 
177 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
178   assert(!UseCompactObjectHeaders, "don't set Klass* gap with compact headers");
179   if (UseCompressedClassPointers) {
180     *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
181   }
182 }
183 
184 void oopDesc::set_klass_gap(int v) {
185   assert(!UseCompactObjectHeaders, "don't set Klass* gap with compact headers");
186   set_klass_gap((HeapWord*)this, v);
187 }
188 
189 bool oopDesc::is_a(Klass* k) const {
190   return klass()->is_subtype_of(k);
191 }
192 
193 int oopDesc::size()  {
194   return size_given_klass(klass());
195 }
196 
197 int oopDesc::size_given_klass(Klass* klass)  {
198   int lh = klass->layout_helper();
199   int s;
200 
201   // lh is now a value computed at class initialization that may hint
202   // at the size.  For instances, this is positive and equal to the
203   // size.  For arrays, this is negative and provides log2 of the
204   // array element size.  For other oops, it is zero and thus requires
205   // a virtual call.
206   //
207   // We go to all this trouble because the size computation is at the
208   // heart of phase 2 of mark-compaction, and called for every object,
209   // alive or dead.  So the speed here is equal in importance to the
210   // speed of allocation.
211 
212   if (lh > Klass::_lh_neutral_value) {
213     if (!Klass::layout_helper_needs_slow_path(lh)) {
214       s = lh >> LogHeapWordSize;  // deliver size scaled by wordSize
215     } else {
216       s = klass->oop_size(this);
217     }
218   } else if (lh <= Klass::_lh_neutral_value) {
219     // The most common case is instances; fall through if so.
220     if (lh < Klass::_lh_neutral_value) {
221       // Second most common case is arrays.  We have to fetch the
222       // length of the array, shift (multiply) it appropriately,
223       // up to wordSize, add the header, and align to object size.
224       size_t size_in_bytes;
225       size_t array_length = (size_t) ((arrayOop)this)->length();
226       size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
227       size_in_bytes += Klass::layout_helper_header_size(lh);
228 
229       // This code could be simplified, but by keeping array_header_in_bytes
230       // in units of bytes and doing it this way we can round up just once,
231       // skipping the intermediate round to HeapWordSize.
232       s = (int)(align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize);
233 
234       // UseParallelGC and UseG1GC can change the length field
235       // of an "old copy" of an object array in the young gen so it indicates
236       // the grey portion of an already copied array. This will cause the first
237       // disjunct below to fail if the two comparands are computed across such
238       // a concurrent change.
239       assert((s == klass->oop_size(this)) ||
240              (Universe::is_gc_active() && is_objArray() && is_forwarded() && (get_UseParallelGC() || get_UseG1GC())),
241              "wrong array object size");
242     } else {
243       // Must be zero, so bite the bullet and take the virtual call.
244       s = klass->oop_size(this);
245     }
246   }
247 
248   assert(s > 0, "Oop size must be greater than zero, not %d", s);
249   assert(is_object_aligned(s), "Oop size is not properly aligned: %d", s);
250   return s;
251 }
252 
253 #ifdef _LP64
254 Klass* oopDesc::forward_safe_klass_impl(markWord m) const {
255   assert(UseCompactObjectHeaders, "Only get here with compact headers");
256   if (m.is_marked()) {
257     oop fwd = forwardee(m);
258     markWord m2 = fwd->mark();
259     assert(!m2.is_marked() || m2.self_forwarded(), "no double forwarding: this: " PTR_FORMAT " (" INTPTR_FORMAT "), fwd: " PTR_FORMAT " (" INTPTR_FORMAT ")", p2i(this), m.value(), p2i(fwd), m2.value());
260     m = m2;
261   }
262   return m.actual_mark().klass();
263 }
264 #endif
265 
266 Klass* oopDesc::forward_safe_klass(markWord m) const {
267 #ifdef _LP64
268   if (UseCompactObjectHeaders) {
269     return forward_safe_klass_impl(m);
270   } else
271 #endif
272   {
273     return klass();
274   }
275 }
276 
277 Klass* oopDesc::forward_safe_klass() const {
278 #ifdef _LP64
279   if (UseCompactObjectHeaders) {
280     return forward_safe_klass_impl(mark());
281   } else
282 #endif
283   {
284     return klass();
285   }
286 }
287 
288 size_t oopDesc::forward_safe_size() {
289   return size_given_klass(forward_safe_klass());
290 }
291 
292 void oopDesc::forward_safe_init_mark() {
293   if (UseCompactObjectHeaders) {
294     set_mark(forward_safe_klass()->prototype_header());
295   } else {
296     init_mark();
297   }
298 }
299 
300 bool oopDesc::is_instance()  const { return klass()->is_instance_klass();  }
301 bool oopDesc::is_array()     const { return klass()->is_array_klass();     }
302 bool oopDesc::is_objArray()  const { return klass()->is_objArray_klass();  }
303 bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }
304 
305 void*    oopDesc::field_addr(int offset)     const { return reinterpret_cast<void*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
306 
307 template <class T>
308 T*       oopDesc::obj_field_addr(int offset) const { return (T*) field_addr(offset); }
309 
310 template <typename T>
311 size_t   oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
312 
313 template <DecoratorSet decorators>
314 inline oop  oopDesc::obj_field_access(int offset) const             { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
315 inline oop  oopDesc::obj_field(int offset) const                    { return HeapAccess<>::oop_load_at(as_oop(), offset);  }
316 
317 inline void oopDesc::obj_field_put(int offset, oop value)           { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
318 
319 inline jbyte oopDesc::byte_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
320 inline void  oopDesc::byte_field_put(int offset, jbyte value)       { HeapAccess<>::store_at(as_oop(), offset, value); }
321 
322 inline jchar oopDesc::char_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
323 inline void  oopDesc::char_field_put(int offset, jchar value)       { HeapAccess<>::store_at(as_oop(), offset, value); }
324 
325 inline jboolean oopDesc::bool_field(int offset) const               { return HeapAccess<>::load_at(as_oop(), offset); }
326 inline void     oopDesc::bool_field_put(int offset, jboolean value) { HeapAccess<>::store_at(as_oop(), offset, jboolean(value & 1)); }
327 inline jboolean oopDesc::bool_field_volatile(int offset) const      { return HeapAccess<MO_SEQ_CST>::load_at(as_oop(), offset); }
328 inline void     oopDesc::bool_field_put_volatile(int offset, jboolean value) { HeapAccess<MO_SEQ_CST>::store_at(as_oop(), offset, jboolean(value & 1)); }
329 inline jshort oopDesc::short_field(int offset) const                { return HeapAccess<>::load_at(as_oop(), offset);  }
330 inline void   oopDesc::short_field_put(int offset, jshort value)    { HeapAccess<>::store_at(as_oop(), offset, value); }
331 
332 inline jint oopDesc::int_field(int offset) const                    { return HeapAccess<>::load_at(as_oop(), offset);  }
333 inline jint oopDesc::int_field_raw(int offset) const                { return RawAccess<>::load_at(as_oop(), offset);   }
334 inline void oopDesc::int_field_put(int offset, jint value)          { HeapAccess<>::store_at(as_oop(), offset, value); }
335 
336 inline jlong oopDesc::long_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
337 inline void  oopDesc::long_field_put(int offset, jlong value)       { HeapAccess<>::store_at(as_oop(), offset, value); }
338 
339 inline jfloat oopDesc::float_field(int offset) const                { return HeapAccess<>::load_at(as_oop(), offset);  }
340 inline void   oopDesc::float_field_put(int offset, jfloat value)    { HeapAccess<>::store_at(as_oop(), offset, value); }
341 
342 inline jdouble oopDesc::double_field(int offset) const              { return HeapAccess<>::load_at(as_oop(), offset);  }
343 inline void    oopDesc::double_field_put(int offset, jdouble value) { HeapAccess<>::store_at(as_oop(), offset, value); }
344 
345 bool oopDesc::is_locked() const {
346   return mark().is_locked();
347 }
348 
349 bool oopDesc::is_unlocked() const {
350   return mark().is_unlocked();
351 }
352 
353 bool oopDesc::has_bias_pattern() const {
354   return mark().has_bias_pattern();
355 }
356 
357 // Used only for markSweep, scavenging
358 bool oopDesc::is_gc_marked() const {
359   return mark().is_marked();
360 }
361 
362 // Used by scavengers
363 bool oopDesc::is_forwarded() const {
364   // The extra heap check is needed since the obj might be locked, in which case the
365   // mark would point to a stack location and have the sentinel bit cleared
366   return mark().is_marked();
367 }
368 
369 // Used by scavengers
370 void oopDesc::forward_to(oop p) {
371   assert(p != cast_to_oop(this) || !UseAltGCForwarding, "Must not be called with self-forwarding");
372   verify_forwardee(p);
373   markWord m = markWord::encode_pointer_as_mark(p);
374   assert(forwardee(m) == p, "encoding must be reversable");
375   set_mark(m);
376 }
377 
378 void oopDesc::forward_to_self() {
379 #ifdef _LP64
380   if (UseAltGCForwarding) {
381     markWord m = mark();
382     // If mark is displaced, we need to preserve the real header during GC.
383     // It will be restored to the displaced header after GC.
384     assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
385     if (m.has_displaced_mark_helper()) {
386       m = m.displaced_mark_helper();
387     }
388     m = m.set_self_forwarded();
389     assert(forwardee(m) == cast_to_oop(this), "encoding must be reversible");
390     set_mark(m);
391   } else
392 #endif
393   {
394     forward_to(oop(this));
395   }
396 }
397 
398 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
399   assert(p != cast_to_oop(this) || !UseAltGCForwarding, "Must not be called with self-forwarding");
400   verify_forwardee(p);
401   markWord m = markWord::encode_pointer_as_mark(p);
402   assert(forwardee(m) == p, "encoding must be reversable");
403   markWord old_mark = cas_set_mark(m, compare, order);
404   if (old_mark == compare) {
405     return NULL;
406   } else {
407     return forwardee(old_mark);
408   }
409 }
410 
411 oop oopDesc::forward_to_self_atomic(markWord compare, atomic_memory_order order) {
412 #ifdef _LP64
413   if (UseAltGCForwarding) {
414    markWord m = compare;
415     // If mark is displaced, we need to preserve the real header during GC.
416     // It will be restored to the displaced header after GC.
417     assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
418     if (m.has_displaced_mark_helper()) {
419       m = m.displaced_mark_helper();
420     }
421     m = m.set_self_forwarded();
422     assert(forwardee(m) == cast_to_oop(this), "encoding must be reversible");
423     markWord old_mark = cas_set_mark(m, compare, order);
424     if (old_mark == compare) {
425       return nullptr;
426     } else {
427       assert(old_mark.is_marked(), "must be marked here");
428       return forwardee(old_mark);
429     }
430   } else
431 #endif
432   {
433     return forward_to_atomic(cast_to_oop(this), compare, order);
434   }
435 }
436 
437 oop oopDesc::forwardee(markWord header) const {
438   assert(header.is_marked(), "only decode when actually forwarded");
439 #ifdef _LP64
440   if (header.self_forwarded()) {
441     return cast_to_oop(this);
442   } else
443 #endif
444   {
445     return cast_to_oop(header.decode_pointer());
446   }
447 }
448 
449 // Note that the forwardee is not the same thing as the displaced_mark.
450 // The forwardee is used when copying during scavenge and mark-sweep.
451 // It does need to clear the low two locking- and GC-related bits.
452 oop oopDesc::forwardee() const {
453   return forwardee(mark());
454 }
455 
456 // The following method needs to be MT safe.
457 uint oopDesc::age() const {
458   assert(!is_forwarded(), "Attempt to read age from forwarded mark");
459   if (has_displaced_mark()) {
460     return displaced_mark().age();
461   } else {
462     return mark().age();
463   }
464 }
465 
466 void oopDesc::incr_age() {
467   assert(!is_forwarded(), "Attempt to increment age of forwarded mark");
468   if (has_displaced_mark()) {
469     set_displaced_mark(displaced_mark().incr_age());
470   } else {
471     set_mark(mark().incr_age());
472   }
473 }
474 
475 template <typename OopClosureType>
476 void oopDesc::oop_iterate(OopClosureType* cl) {
477   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
478 }
479 
480 template <typename OopClosureType>
481 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
482   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
483 }
484 
485 template <typename OopClosureType>
486 int oopDesc::oop_iterate_size(OopClosureType* cl) {
487   Klass* k = klass();
488   int size = size_given_klass(k);
489   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
490   return size;
491 }
492 
493 template <typename OopClosureType>
494 int oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
495   Klass* k = klass();
496   int size = size_given_klass(k);
497   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
498   return size;
499 }
500 
501 template <typename OopClosureType>
502 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
503   oop_iterate_backwards(cl, klass());
504 }
505 
506 template <typename OopClosureType>
507 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
508   assert(UseCompactObjectHeaders || k == klass(), "wrong klass");
509   OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
510 }
511 
512 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
513   return obj == NULL || obj->klass()->is_subtype_of(klass);
514 }
515 
516 intptr_t oopDesc::identity_hash() {
517   // Fast case; if the object is unlocked and the hash value is set, no locking is needed
518   // Note: The mark must be read into local variable to avoid concurrent updates.
519   markWord mrk = mark();
520   if (mrk.is_unlocked() && !mrk.has_no_hash()) {
521     return mrk.hash();
522   } else if (mrk.is_marked()) {
523     return mrk.hash();
524   } else {
525     return slow_identity_hash();
526   }
527 }
528 
529 bool oopDesc::has_displaced_mark() const {
530   return mark().has_displaced_mark_helper();
531 }
532 
533 markWord oopDesc::displaced_mark() const {
534   return mark().displaced_mark_helper();
535 }
536 
537 void oopDesc::set_displaced_mark(markWord m) {
538   mark().set_displaced_mark_helper(m);
539 }
540 
541 bool oopDesc::mark_must_be_preserved() const {
542   return mark_must_be_preserved(mark());
543 }
544 
545 bool oopDesc::mark_must_be_preserved(markWord m) const {
546   return m.must_be_preserved(this);
547 }
548 
549 bool oopDesc::mark_must_be_preserved_for_promotion_failure(markWord m) const {
550   return m.must_be_preserved_for_promotion_failure(this);
551 }
552 
553 #endif // SHARE_OOPS_OOP_INLINE_HPP