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.
 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.
 22  *
 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/compressedOops.inline.hpp"
 36 #include "oops/instanceKlass.hpp"
 37 #include "oops/markWord.hpp"
 38 #include "oops/oopsHierarchy.hpp"
 39 #include "runtime/atomic.hpp"
 40 #include "runtime/globals.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   return Atomic::load(&_mark);
 51 }
 52 
 53 markWord oopDesc::mark_acquire() const {
 54   return Atomic::load_acquire(&_mark);
 55 }
 56 
 57 markWord* oopDesc::mark_addr() const {
 58   return (markWord*) &_mark;
 59 }
 60 
 61 void oopDesc::set_mark(markWord m) {
 62   Atomic::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(markWord m) {
 70   Atomic::release_store(&_mark, m);
 71 }
 72 
 73 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark) {
 74   return Atomic::cmpxchg(&_mark, old_mark, new_mark);
 75 }
 76 
 77 markWord oopDesc::cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order) {
 78   return Atomic::cmpxchg(&_mark, old_mark, new_mark, order);
 79 }
 80 
 81 void oopDesc::init_mark() {
 82   set_mark(markWord::prototype());
 83 }
 84 
 85 Klass* oopDesc::klass() const {
 86   if (UseCompressedClassPointers) {
 87     return CompressedKlassPointers::decode_not_null(_metadata._compressed_klass);
 88   } else {
 89     return _metadata._klass;
 90   }
 91 }
 92 
 93 Klass* oopDesc::klass_or_null() const {
 94   if (UseCompressedClassPointers) {
 95     return CompressedKlassPointers::decode(_metadata._compressed_klass);
 96   } else {
 97     return _metadata._klass;
 98   }
 99 }
100 
101 Klass* oopDesc::klass_or_null_acquire() const {
102   if (UseCompressedClassPointers) {
103     narrowKlass nklass = Atomic::load_acquire(&_metadata._compressed_klass);
104     return CompressedKlassPointers::decode(nklass);
105   } else {
106     return Atomic::load_acquire(&_metadata._klass);
107   }
108 }
109 
110 void oopDesc::set_klass(Klass* k) {
111   assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
112   if (UseCompressedClassPointers) {
113     _metadata._compressed_klass = CompressedKlassPointers::encode_not_null(k);
114   } else {
115     _metadata._klass = k;
116   }
117 }
118 
119 void oopDesc::release_set_klass(HeapWord* mem, Klass* k) {
120   assert(Universe::is_bootstrapping() || (k != NULL && k->is_klass()), "incorrect Klass");
121   char* raw_mem = ((char*)mem + klass_offset_in_bytes());
122   if (UseCompressedClassPointers) {
123     Atomic::release_store((narrowKlass*)raw_mem,
124                           CompressedKlassPointers::encode_not_null(k));
125   } else {
126     Atomic::release_store((Klass**)raw_mem, k);
127   }
128 }
129 
130 void oopDesc::set_klass_gap(HeapWord* mem, int v) {
131   if (UseCompressedClassPointers) {
132     *(int*)(((char*)mem) + klass_gap_offset_in_bytes()) = v;
133   }
134 }
135 
136 bool oopDesc::is_a(Klass* k) const {
137   return klass()->is_subtype_of(k);
138 }
139 
140 size_t oopDesc::size()  {
141   return size_given_klass(klass());
142 }
143 
144 size_t oopDesc::size_given_klass(Klass* klass)  {
145   int lh = klass->layout_helper();
146   size_t s;
147 
148   // lh is now a value computed at class initialization that may hint
149   // at the size.  For instances, this is positive and equal to the
150   // size.  For arrays, this is negative and provides log2 of the
151   // array element size.  For other oops, it is zero and thus requires
152   // a virtual call.
153   //
154   // We go to all this trouble because the size computation is at the
155   // heart of phase 2 of mark-compaction, and called for every object,
156   // alive or dead.  So the speed here is equal in importance to the
157   // speed of allocation.
158 
159   if (lh > Klass::_lh_neutral_value) {
160     if (!Klass::layout_helper_needs_slow_path(lh)) {
161       s = lh >> LogHeapWordSize;  // deliver size scaled by wordSize
162     } else {
163       s = klass->oop_size(this);
164     }
165   } else if (lh <= Klass::_lh_neutral_value) {
166     // The most common case is instances; fall through if so.
167     if (lh < Klass::_lh_neutral_value) {
168       // Second most common case is arrays.  We have to fetch the
169       // length of the array, shift (multiply) it appropriately,
170       // up to wordSize, add the header, and align to object size.
171       size_t size_in_bytes;
172       size_t array_length = (size_t) ((arrayOop)this)->length();
173       size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
174       size_in_bytes += Klass::layout_helper_header_size(lh);
175 
176       // This code could be simplified, but by keeping array_header_in_bytes
177       // in units of bytes and doing it this way we can round up just once,
178       // skipping the intermediate round to HeapWordSize.
179       s = align_up(size_in_bytes, MinObjAlignmentInBytes) / HeapWordSize;
180 
181       assert(s == klass->oop_size(this) || size_might_change(), "wrong array object size");
182     } else {
183       // Must be zero, so bite the bullet and take the virtual call.
184       s = klass->oop_size(this);
185     }
186   }
187 
188   assert(s > 0, "Oop size must be greater than zero, not " SIZE_FORMAT, s);
189   assert(is_object_aligned(s), "Oop size is not properly aligned: " SIZE_FORMAT, s);
190   return s;
191 }
192 
193 bool oopDesc::is_instance()    const { return klass()->is_instance_klass();             }
194 bool oopDesc::is_instanceRef() const { return klass()->is_reference_instance_klass();   }
195 bool oopDesc::is_stackChunk()  const { return klass()->is_stack_chunk_instance_klass(); }
196 bool oopDesc::is_array()       const { return klass()->is_array_klass();                }
197 bool oopDesc::is_objArray()    const { return klass()->is_objArray_klass();             }
198 bool oopDesc::is_typeArray()   const { return klass()->is_typeArray_klass();            }
199 
200 template<typename T>
201 T*       oopDesc::field_addr(int offset)     const { return reinterpret_cast<T*>(cast_from_oop<intptr_t>(as_oop()) + offset); }
202 
203 template <typename T>
204 size_t   oopDesc::field_offset(T* p) const { return pointer_delta((void*)p, (void*)this, 1); }
205 
206 template <DecoratorSet decorators>
207 inline oop  oopDesc::obj_field_access(int offset) const             { return HeapAccess<decorators>::oop_load_at(as_oop(), offset); }
208 inline oop  oopDesc::obj_field(int offset) const                    { return HeapAccess<>::oop_load_at(as_oop(), offset);  }
209 
210 inline void oopDesc::obj_field_put(int offset, oop value)           { HeapAccess<>::oop_store_at(as_oop(), offset, value); }
211 template <DecoratorSet decorators>
212 inline void oopDesc::obj_field_put_access(int offset, oop value)    { HeapAccess<decorators>::oop_store_at(as_oop(), offset, value); }
213 
214 inline jbyte oopDesc::byte_field(int offset) const                  { return *field_addr<jbyte>(offset);  }
215 inline void  oopDesc::byte_field_put(int offset, jbyte value)       { *field_addr<jbyte>(offset) = value; }
216 
217 inline jchar oopDesc::char_field(int offset) const                  { return *field_addr<jchar>(offset);  }
218 inline void  oopDesc::char_field_put(int offset, jchar value)       { *field_addr<jchar>(offset) = value; }
219 
220 inline jboolean oopDesc::bool_field(int offset) const               { return *field_addr<jboolean>(offset); }
221 inline void     oopDesc::bool_field_put(int offset, jboolean value) { *field_addr<jboolean>(offset) = jboolean(value & 1); }
222 inline jboolean oopDesc::bool_field_volatile(int offset) const      { return RawAccess<MO_SEQ_CST>::load(field_addr<jboolean>(offset)); }
223 inline void     oopDesc::bool_field_put_volatile(int offset, jboolean value) { RawAccess<MO_SEQ_CST>::store(field_addr<jboolean>(offset), jboolean(value & 1)); }
224 inline jshort oopDesc::short_field(int offset) const                { return *field_addr<jshort>(offset);   }
225 inline void   oopDesc::short_field_put(int offset, jshort value)    { *field_addr<jshort>(offset) = value;  }
226 
227 inline jint oopDesc::int_field(int offset) const                    { return *field_addr<jint>(offset);     }
228 inline void oopDesc::int_field_put(int offset, jint value)          { *field_addr<jint>(offset) = value;    }
229 
230 inline jlong oopDesc::long_field(int offset) const                  { return *field_addr<jlong>(offset);    }
231 inline void  oopDesc::long_field_put(int offset, jlong value)       { *field_addr<jlong>(offset) = value;   }
232 
233 inline jfloat oopDesc::float_field(int offset) const                { return *field_addr<jfloat>(offset);   }
234 inline void   oopDesc::float_field_put(int offset, jfloat value)    { *field_addr<jfloat>(offset) = value;  }
235 
236 inline jdouble oopDesc::double_field(int offset) const              { return *field_addr<jdouble>(offset);  }
237 inline void    oopDesc::double_field_put(int offset, jdouble value) { *field_addr<jdouble>(offset) = value; }
238 
239 bool oopDesc::is_locked() const {
240   return mark().is_locked();
241 }
242 
243 bool oopDesc::is_unlocked() const {
244   return mark().is_unlocked();
245 }
246 
247 // Used only for markSweep, scavenging
248 bool oopDesc::is_gc_marked() const {
249   return mark().is_marked();
250 }
251 
252 // Used by scavengers
253 bool oopDesc::is_forwarded() const {
254   // The extra heap check is needed since the obj might be locked, in which case the
255   // mark would point to a stack location and have the sentinel bit cleared
256   return mark().is_marked();
257 }
258 
259 // Used by scavengers
260 void oopDesc::forward_to(oop p) {
261   verify_forwardee(p);
262   markWord m = markWord::encode_pointer_as_mark(p);
263   assert(m.decode_pointer() == p, "encoding must be reversible");
264   set_mark(m);
265 }
266 
267 oop oopDesc::forward_to_atomic(oop p, markWord compare, atomic_memory_order order) {
268   verify_forwardee(p);
269   markWord m = markWord::encode_pointer_as_mark(p);
270   assert(m.decode_pointer() == p, "encoding must be reversible");
271   markWord old_mark = cas_set_mark(m, compare, order);
272   if (old_mark == compare) {
273     return NULL;
274   } else {
275     return cast_to_oop(old_mark.decode_pointer());
276   }
277 }
278 
279 // Note that the forwardee is not the same thing as the displaced_mark.
280 // The forwardee is used when copying during scavenge and mark-sweep.
281 // It does need to clear the low two locking- and GC-related bits.
282 oop oopDesc::forwardee() const {
283   assert(is_forwarded(), "only decode when actually forwarded");
284   return cast_to_oop(mark().decode_pointer());
285 }
286 
287 // The following method needs to be MT safe.
288 uint oopDesc::age() const {
289   assert(!mark().is_marked(), "Attempt to read age from forwarded mark");
290   if (has_displaced_mark()) {
291     return displaced_mark().age();
292   } else {
293     return mark().age();
294   }
295 }
296 
297 void oopDesc::incr_age() {
298   assert(!mark().is_marked(), "Attempt to increment age of forwarded mark");
299   if (has_displaced_mark()) {
300     set_displaced_mark(displaced_mark().incr_age());
301   } else {
302     set_mark(mark().incr_age());
303   }
304 }
305 
306 template <typename OopClosureType>
307 void oopDesc::oop_iterate(OopClosureType* cl) {
308   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass());
309 }
310 
311 template <typename OopClosureType>
312 void oopDesc::oop_iterate(OopClosureType* cl, MemRegion mr) {
313   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, klass(), mr);
314 }
315 
316 template <typename OopClosureType>
317 size_t oopDesc::oop_iterate_size(OopClosureType* cl) {
318   Klass* k = klass();
319   size_t size = size_given_klass(k);
320   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k);
321   return size;
322 }
323 
324 template <typename OopClosureType>
325 size_t oopDesc::oop_iterate_size(OopClosureType* cl, MemRegion mr) {
326   Klass* k = klass();
327   size_t size = size_given_klass(k);
328   OopIteratorClosureDispatch::oop_oop_iterate(cl, this, k, mr);
329   return size;
330 }
331 
332 template <typename OopClosureType>
333 void oopDesc::oop_iterate_backwards(OopClosureType* cl) {
334   oop_iterate_backwards(cl, klass());
335 }
336 
337 template <typename OopClosureType>
338 void oopDesc::oop_iterate_backwards(OopClosureType* cl, Klass* k) {
339   assert(k == klass(), "wrong klass");
340   OopIteratorClosureDispatch::oop_oop_iterate_backwards(cl, this, k);
341 }
342 
343 bool oopDesc::is_instanceof_or_null(oop obj, Klass* klass) {
344   return obj == NULL || obj->klass()->is_subtype_of(klass);
345 }
346 
347 intptr_t oopDesc::identity_hash() {
348   // Fast case; if the object is unlocked and the hash value is set, no locking is needed
349   // Note: The mark must be read into local variable to avoid concurrent updates.
350   markWord mrk = mark();
351   if (mrk.is_unlocked() && !mrk.has_no_hash()) {
352     return mrk.hash();
353   } else if (mrk.is_marked()) {
354     return mrk.hash();
355   } else {
356     return slow_identity_hash();
357   }
358 }
359 
360 // This checks fast simple case of whether the oop has_no_hash,
361 // to optimize JVMTI table lookup.
362 bool oopDesc::fast_no_hash_check() {
363   markWord mrk = mark_acquire();
364   assert(!mrk.is_marked(), "should never be marked");
365   return mrk.is_unlocked() && mrk.has_no_hash();
366 }
367 
368 bool oopDesc::has_displaced_mark() const {
369   return mark().has_displaced_mark_helper();
370 }
371 
372 markWord oopDesc::displaced_mark() const {
373   return mark().displaced_mark_helper();
374 }
375 
376 void oopDesc::set_displaced_mark(markWord m) {
377   mark().set_displaced_mark_helper(m);
378 }
379 
380 bool oopDesc::mark_must_be_preserved() const {
381   return mark_must_be_preserved(mark());
382 }
383 
384 bool oopDesc::mark_must_be_preserved(markWord m) const {
385   return m.must_be_preserved(this);
386 }
387 
388 #endif // SHARE_OOPS_OOP_INLINE_HPP