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
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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/objectMonitor.inline.hpp"
 40 #include "utilities/align.hpp"
 41 #include "utilities/debug.hpp"
 42 #include "utilities/macros.hpp"
 43 #include "utilities/globalDefinitions.hpp"
 44 
 45 // Implementation of all inlined member functions defined in oop.hpp
 46 // We need a separate file to avoid circular references
 47 
 48 markWord oopDesc::mark() const {
 49   uintptr_t v = HeapAccess<MO_RELAXED>::load_at(as_oop(), mark_offset_in_bytes());
 50   return markWord(v);
 51 }
 52 
 53 markWord oopDesc::mark_acquire() const {
 54   return Atomic::load_acquire(&_mark);
 55 }
 56 markWord* oopDesc::mark_addr() const {
 57   return (markWord*) &_mark;
 58 }
 59 
 60 void oopDesc::set_mark(markWord m) {
 61   HeapAccess<MO_RELAXED>::store_at(as_oop(), mark_offset_in_bytes(), m.value());
 62 }
 63 
 64 void oopDesc::set_mark(HeapWord* mem, markWord m) {
 65   *(markWord*)(((char*)mem) + mark_offset_in_bytes()) = m;
 66 }
 67 
 68 void oopDesc::release_set_mark(markWord m) {
 69   HeapAccess<MO_RELEASE>::store_at(as_oop(), mark_offset_in_bytes(), m.value());
 70 }
 71 
 72 void oopDesc::release_set_mark(HeapWord* mem, markWord m) {
 73   Atomic::release_store((markWord*)(((char*)mem) + mark_offset_in_bytes()), m);
 74 }
 75 
 76 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
 77   uintptr_t v = HeapAccess<>::atomic_cmpxchg_at(as_oop(), mark_offset_in_bytes(), old_mark.value(), new_mark.value());
 78   return markWord(v);
 79 }
 80 
 81 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order) {
 82   return Atomic::cmpxchg(&_mark, old_mark, new_mark, order);
 83 }
 84 
 85 markWord oopDesc::resolve_mark() const {
 86   assert(UseFastLocking, "Only safe with fast-locking");
 87   markWord hdr = mark();
 88   if (hdr.has_displaced_mark_helper()) {
 89     hdr = hdr.displaced_mark_helper();
 90   }
 91   return hdr;
 92 }
 93 
 94 void oopDesc::init_mark() {
 95 #ifdef _LP64
 96   if (UseCompactObjectHeaders) {
 97     markWord header = resolve_mark();
 98     assert(UseCompressedClassPointers, "expect compressed klass pointers");
 99     set_mark(markWord((header.value() & markWord::klass_mask_in_place) | markWord::prototype().value()));
100   } else
101 #endif
102   set_mark(markWord::prototype());
103 }
104 
105 Klass* oopDesc::klass() const {
106 #ifdef _LP64
107   if (UseCompactObjectHeaders) {
108     assert(UseCompressedClassPointers, "only with compressed class pointers");
109     markWord header = resolve_mark();
110     return header.klass();
111   } else if (UseCompressedClassPointers) {
112     return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
113   } else
114 #endif
115   return _metadata._klass;
116 }
117 
118 Klass* oopDesc::klass_or_null() const {
119 #ifdef _LP64
120   if (UseCompactObjectHeaders) {
121     assert(UseCompressedClassPointers, "only with compressed class pointers");
122     markWord header = resolve_mark();
123     return header.klass_or_null();
124   } else if (UseCompressedClassPointers) {
125     return CompressedKlassPointers::decode(_metadata._compressed_klass);
126   } else
127 #endif
128   return _metadata._klass;
129 }
130 
131 Klass* oopDesc::klass_or_null_acquire() const {
132 #ifdef _LP64
133   if (UseCompactObjectHeaders) {
134     assert(UseCompressedClassPointers, "only with compressed class pointers");
135     markWord header = mark_acquire();
136     if (header.has_monitor()) {
137       header = header.monitor()->header();
138     }
139     return header.klass_or_null();
140   } else if (UseCompressedClassPointers) {
141      narrowKlass nklass = Atomic::load_acquire(&_metadata._compressed_klass);
142      return CompressedKlassPointers::decode(nklass);
143   } else
144 #endif
145   return Atomic::load_acquire(&_metadata._klass);
146 }
147 
148 void oopDesc::set_klass(Klass* k) {
149   assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
150   assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
151   if (UseCompressedClassPointers) {
152     _metadata._compressed_klass = CompressedKlassPointers::encode_not_null(k);
153   } else {
154     _metadata._klass = k;
155   }
156 }
157 
158 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
159   assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
160   assert(!UseCompactObjectHeaders, "don't set Klass* with compact headers");
161   char* raw_mem = ((char*)mem + klass_offset_in_bytes());
162   if (UseCompressedClassPointers) {
163     Atomic::release_store((narrowKlass*)raw_mem,
164                           CompressedKlassPointers::encode_not_null(k));
165   } else {
166     Atomic::release_store((Klass**)raw_mem, k);
167   }
168 }
169 
170 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
171   assert(!UseCompactObjectHeaders, "don't set Klass* gap with compact headers");
172   if (UseCompressedClassPointers) {
173     *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
174   }
175 }
176 
177 bool oopDesc::is_a(Klass* k) const {
178   return klass()->is_subtype_of(k);
179 }
180 
181 int oopDesc::size()  {
182   return size_given_klass(klass());
183 }
184 
185 int oopDesc::size_given_klass(Klass* klass)  {
186   int lh = klass->layout_helper();
187   int s;
188 
189   // lh is now a value computed at class initialization that may hint
190   // at the size.  For instances, this is positive and equal to the
191   // size.  For arrays, this is negative and provides log2 of the
192   // array element size.  For other oops, it is zero and thus requires
193   // a virtual call.
194   //
195   // We go to all this trouble because the size computation is at the
196   // heart of phase 2 of mark-compaction, and called for every object,
197   // alive or dead.  So the speed here is equal in importance to the
198   // speed of allocation.
199 
200   if (lh > Klass::_lh_neutral_value) {
201     if (!Klass::layout_helper_needs_slow_path(lh)) {
202       s = lh >> LogHeapWordSize;  // deliver size scaled by wordSize
203     } else {
204       s = klass->oop_size(this);
205     }
206   } else if (lh <= Klass::_lh_neutral_value) {
207     // The most common case is instances; fall through if so.
208     if (lh < Klass::_lh_neutral_value) {
209       // Second most common case is arrays.  We have to fetch the
210       // length of the array, shift (multiply) it appropriately,
211       // up to wordSize, add the header, and align to object size.
212       size_t size_in_bytes;
213       size_t array_length = (size_t) ((arrayOop)this)->length();
214       size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
215       size_in_bytes += Klass::layout_helper_header_size(lh);
216 
217       // This code could be simplified, but by keeping array_header_in_bytes
218       // in units of bytes and doing it this way we can round up just once,
219       // skipping the intermediate round to HeapWordSize.
220       s = (int)(align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize);
221 
222       // UseParallelGC and UseG1GC can change the length field
223       // of an "old copy" of an object array in the young gen so it indicates
224       // the grey portion of an already copied array. This will cause the first
225       // disjunct below to fail if the two comparands are computed across such
226       // a concurrent change.
227       assert((s == klass->oop_size(this)) ||
228              (Universe::is_gc_active() && is_objArray() && is_forwarded() && (get_UseParallelGC() || get_UseG1GC())),
229              "wrong array object size");
230     } else {
231       // Must be zero, so bite the bullet and take the virtual call.
232       s = klass->oop_size(this);
233     }
234   }
235 
236   assert(s > 0, "Oop size must be greater than zero, not %d", s);
237   assert(is_object_aligned(s), "Oop size is not properly aligned: %d", s);
238   return s;
239 }
240 
241 bool oopDesc::is_instance()  const { return klass()->is_instance_klass();  }
242 bool oopDesc::is_array()     const { return klass()->is_array_klass();     }
243 bool oopDesc::is_objArray()  const { return klass()->is_objArray_klass();  }
244 bool oopDesc::is_typeArray() const { return klass()->is_typeArray_klass(); }
245 
246 void*    oopDesc::field_addr(int offset)     const { return reinterpret_cast<void*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
247 
248 template <class T>
249 T*       oopDesc::obj_field_addr(int offset) const { return (T*) field_addr(offset); }
250 
251 template <typename T>
252 size_t   oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
253 
254 template <DecoratorSet decorators>
255 inline oop  oopDesc::obj_field_access(int offset) const             { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
256 inline oop  oopDesc::obj_field(int offset) const                    { return HeapAccess<>::oop_load_at(as_oop(), offset);  }
257 
258 inline void oopDesc::obj_field_put(int offset, oop value)           { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
259 
260 inline jbyte oopDesc::byte_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
261 inline void  oopDesc::byte_field_put(int offset, jbyte value)       { HeapAccess<>::store_at(as_oop(), offset, value); }
262 
263 inline jchar oopDesc::char_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
264 inline void  oopDesc::char_field_put(int offset, jchar value)       { HeapAccess<>::store_at(as_oop(), offset, value); }
265 
266 inline jboolean oopDesc::bool_field(int offset) const               { return HeapAccess<>::load_at(as_oop(), offset); }
267 inline void     oopDesc::bool_field_put(int offset, jboolean value) { HeapAccess<>::store_at(as_oop(), offset, jboolean(value & 1)); }
268 inline jboolean oopDesc::bool_field_volatile(int offset) const      { return HeapAccess<MO_SEQ_CST>::load_at(as_oop(), offset); }
269 inline void     oopDesc::bool_field_put_volatile(int offset, jboolean value) { HeapAccess<MO_SEQ_CST>::store_at(as_oop(), offset, jboolean(value & 1)); }
270 inline jshort oopDesc::short_field(int offset) const                { return HeapAccess<>::load_at(as_oop(), offset);  }
271 inline void   oopDesc::short_field_put(int offset, jshort value)    { HeapAccess<>::store_at(as_oop(), offset, value); }
272 
273 inline jint oopDesc::int_field(int offset) const                    { return HeapAccess<>::load_at(as_oop(), offset);  }
274 inline jint oopDesc::int_field_raw(int offset) const                { return RawAccess<>::load_at(as_oop(), offset);   }
275 inline void oopDesc::int_field_put(int offset, jint value)          { HeapAccess<>::store_at(as_oop(), offset, value); }
276 
277 inline jlong oopDesc::long_field(int offset) const                  { return HeapAccess<>::load_at(as_oop(), offset);  }
278 inline void  oopDesc::long_field_put(int offset, jlong value)       { HeapAccess<>::store_at(as_oop(), offset, value); }
279 
280 inline jfloat oopDesc::float_field(int offset) const                { return HeapAccess<>::load_at(as_oop(), offset);  }
281 inline void   oopDesc::float_field_put(int offset, jfloat value)    { HeapAccess<>::store_at(as_oop(), offset, value); }
282 
283 inline jdouble oopDesc::double_field(int offset) const              { return HeapAccess<>::load_at(as_oop(), offset);  }
284 inline void    oopDesc::double_field_put(int offset, jdouble value) { HeapAccess<>::store_at(as_oop(), offset, value); }
285 
286 bool oopDesc::is_locked() const {
287   return mark().is_locked();
288 }
289 
290 bool oopDesc::is_unlocked() const {
291   return mark().is_unlocked();
292 }
293 
294 bool oopDesc::has_bias_pattern() const {
295   return mark().has_bias_pattern();
296 }
297 
298 // Used only for markSweep, scavenging
299 bool oopDesc::is_gc_marked() const {
300   return mark().is_marked();
301 }
302 
303 // Used by scavengers
304 bool oopDesc::is_forwarded() const {
305   // The extra heap check is needed since the obj might be locked, in which case the
306   // mark would point to a stack location and have the sentinel bit cleared
307   return mark().is_marked();
308 }
309 
310 // Used by scavengers
311 void oopDesc::forward_to(oop p) {
312   verify_forwardee(p);
313   markWord m = markWord::encode_pointer_as_mark(p);
314   assert(forwardee(m) == p, "encoding must be reversable");
315   set_mark(m);
316 }
317 
318 // Used by parallel scavengers
319 bool oopDesc::cas_forward_to(oop p, markWord compare, atomic_memory_order order) {
320   verify_forwardee(p);
321   markWord m = markWord::encode_pointer_as_mark(p);
322   assert(m.decode_pointer() == p, "encoding must be reversable");
323   return cas_set_mark(m, compare, order) == compare;
324 }
325 
326 void oopDesc::forward_to_self() {
327 #ifdef _LP64
328   verify_forwardee(this);
329   markWord m = mark();
330   // If mark is displaced, we need to preserve the Klass* from real header.
331   assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
332   if (m.has_displaced_mark_helper()) {
333     m = m.displaced_mark_helper();
334   }
335   m = m.set_self_forwarded();
336   assert(forwardee(m) == cast_to_oop(this), "encoding must be reversable");
337   set_mark(m);
338 #else
339   forward_to(oop(this));
340 #endif
341 }
342 
343 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
344   verify_forwardee(p);
345   markWord m = markWord::encode_pointer_as_mark(p);
346   assert(forwardee(m) == p, "encoding must be reversable");
347   markWord old_mark = cas_set_mark(m, compare, order);
348   if (old_mark == compare) {
349     return NULL;
350   } else {
351     return forwardee(old_mark);
352   }
353 }
354 
355 oop oopDesc::forward_to_self_atomic(markWord compare, atomic_memory_order order) {
356 #ifdef _LP64
357   verify_forwardee(this);
358   markWord m = compare;
359   // If mark is displaced, we need to preserve the Klass* from real header.
360   assert(SafepointSynchronize::is_at_safepoint(), "we can only safely fetch the displaced header at safepoint");
361   if (m.has_displaced_mark_helper()) {
362     m = m.displaced_mark_helper();
363   }
364   m = m.set_self_forwarded();
365   assert(forwardee(m) == cast_to_oop(this), "encoding must be reversable");
366   markWord old_mark = cas_set_mark(m, compare, order);
367   if (old_mark == compare) {
368     return NULL;
369   } else {
370     assert(old_mark.is_marked(), "must be marked here");
371     return forwardee(old_mark);
372   }
373 #else
374   return forward_to_atomic(oop(this), compare, order);
375 #endif
376 }
377 
378 // Note that the forwardee is not the same thing as the displaced_mark.
379 // The forwardee is used when copying during scavenge and mark-sweep.
380 // It does need to clear the low two locking- and GC-related bits.
381 oop oopDesc::forwardee() const {
382   return forwardee(mark());
383 }
384 
385 oop oopDesc::forwardee(markWord header) const {
386   assert(header.is_marked(), "must be forwarded");
387 #ifdef _LP64
388   if (header.self_forwarded()) {
389     return cast_to_oop(this);
390   } else
391 #endif
392   {
393     assert(header.is_marked(), "only decode when actually forwarded");
394     return cast_to_oop(header.decode_pointer());
395   }
396 }
397 
398 // The following method needs to be MT safe.
399 uint oopDesc::age() const {
400   assert(!is_forwarded(), "Attempt to read age from forwarded mark");
401   if (has_displaced_mark()) {
402     return displaced_mark().age();
403   } else {
404     return mark().age();
405   }
406 }
407 
408 void oopDesc::incr_age() {
409   assert(!is_forwarded(), "Attempt to increment age of forwarded mark");
410   if (has_displaced_mark()) {
411     set_displaced_mark(displaced_mark().incr_age());
412   } else {
413     set_mark(mark().incr_age());
414   }
415 }
416 
417 template <typename OopClosureType>
418 void oopDesc::oop_iterate(OopClosureType* cl) {
419   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
420 }
421 
422 template <typename OopClosureType>
423 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
424   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
425 }
426 
427 template <typename OopClosureType>
428 int oopDesc::oop_iterate_size(OopClosureType* cl) {
429   Klass* k = klass();
430   int size = size_given_klass(k);
431   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
432   return size;
433 }
434 
435 template <typename OopClosureType>
436 int oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
437   Klass* k = klass();
438   int size = size_given_klass(k);
439   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
440   return size;
441 }
442 
443 template <typename OopClosureType>
444 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
445   oop_iterate_backwards(cl, klass());
446 }
447 
448 template <typename OopClosureType>
449 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
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 == NULL || 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 bool oopDesc::has_displaced_mark() const {
471   return mark().has_displaced_mark_helper();
472 }
473 
474 markWord oopDesc::displaced_mark() const {
475   return mark().displaced_mark_helper();
476 }
477 
478 void oopDesc::set_displaced_mark(markWord m) {
479   mark().set_displaced_mark_helper(m);
480 }
481 
482 bool oopDesc::mark_must_be_preserved() const {
483   return mark_must_be_preserved(mark());
484 }
485 
486 bool oopDesc::mark_must_be_preserved(markWord m) const {
487   return m.must_be_preserved(this);
488 }
489 
490 bool oopDesc::mark_must_be_preserved_for_promotion_failure(markWord m) const {
491   return m.must_be_preserved_for_promotion_failure(this);
492 }
493 
494 #endif // SHARE_OOPS_OOP_INLINE_HPP