1 /*
   2  * Copyright (c) 1997, 2016, 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_VM_OOPS_OOP_INLINE_HPP
  26 #define SHARE_VM_OOPS_OOP_INLINE_HPP
  27 
  28 #include "gc_implementation/shared/ageTable.hpp"
  29 #include "gc_implementation/shared/markSweep.inline.hpp"
  30 #include "gc_interface/collectedHeap.inline.hpp"
  31 #include "memory/barrierSet.inline.hpp"
  32 #include "memory/cardTableModRefBS.hpp"
  33 #include "memory/genCollectedHeap.hpp"
  34 #include "memory/generation.hpp"
  35 #include "memory/specialized_oop_closures.hpp"
  36 #include "oops/arrayKlass.hpp"
  37 #include "oops/arrayOop.hpp"
  38 #include "oops/klass.inline.hpp"
  39 #include "oops/markOop.inline.hpp"
  40 #include "oops/oop.hpp"
  41 #include "runtime/atomic.inline.hpp"
  42 #include "runtime/orderAccess.inline.hpp"
  43 #include "runtime/os.hpp"
  44 #include "utilities/macros.hpp"
  45 #ifdef TARGET_ARCH_x86
  46 # include "bytes_x86.hpp"
  47 #endif
  48 #ifdef TARGET_ARCH_aarch64
  49 # include "bytes_aarch64.hpp"
  50 #endif
  51 #ifdef TARGET_ARCH_sparc
  52 # include "bytes_sparc.hpp"
  53 #endif
  54 #ifdef TARGET_ARCH_zero
  55 # include "bytes_zero.hpp"
  56 #endif
  57 #ifdef TARGET_ARCH_arm
  58 # include "bytes_arm.hpp"
  59 #endif
  60 #ifdef TARGET_ARCH_ppc
  61 # include "bytes_ppc.hpp"
  62 #endif
  63 
  64 #if INCLUDE_ALL_GCS
  65 #include "gc_implementation/shenandoah/shenandoahBarrierSet.hpp"
  66 #endif
  67 
  68 // Implementation of all inlined member functions defined in oop.hpp
  69 // We need a separate file to avoid circular references
  70 
  71 inline void oopDesc::release_set_mark(markOop m) {
  72   OrderAccess::release_store_ptr(&_mark, m);
  73 }
  74 
  75 inline markOop oopDesc::cas_set_mark(markOop new_mark, markOop old_mark) {
  76   return (markOop) Atomic::cmpxchg_ptr(new_mark, &_mark, old_mark);
  77 }
  78 
  79 inline Klass* oopDesc::klass() const {
  80   if (UseCompressedClassPointers) {
  81     return Klass::decode_klass_not_null(_metadata._compressed_klass);
  82   } else {
  83     return _metadata._klass;
  84   }
  85 }
  86 
  87 inline Klass* oopDesc::klass_or_null() const volatile {
  88   if (UseCompressedClassPointers) {
  89     return Klass::decode_klass(_metadata._compressed_klass);
  90   } else {
  91     return _metadata._klass;
  92   }
  93 }
  94 
  95 inline Klass* oopDesc::klass_or_null_acquire() const volatile {
  96   if (UseCompressedClassPointers) {
  97     // Workaround for non-const load_acquire parameter.
  98     const volatile narrowKlass* addr = &_metadata._compressed_klass;
  99     volatile narrowKlass* xaddr = const_cast<volatile narrowKlass*>(addr);
 100     return Klass::decode_klass(OrderAccess::load_acquire(xaddr));
 101   } else {
 102     return (Klass*)OrderAccess::load_ptr_acquire(&_metadata._klass);
 103   }
 104 }
 105 
 106 inline int oopDesc::klass_gap_offset_in_bytes() {
 107   assert(UseCompressedClassPointers, "only applicable to compressed klass pointers");
 108   return oopDesc::klass_offset_in_bytes() + sizeof(narrowKlass);
 109 }
 110 
 111 inline Klass** oopDesc::klass_addr() {
 112   // Only used internally and with CMS and will not work with
 113   // UseCompressedOops
 114   assert(!UseCompressedClassPointers, "only supported with uncompressed klass pointers");
 115   return (Klass**) &_metadata._klass;
 116 }
 117 
 118 inline narrowKlass* oopDesc::compressed_klass_addr() {
 119   assert(UseCompressedClassPointers, "only called by compressed klass pointers");
 120   return &_metadata._compressed_klass;
 121 }
 122 
 123 #define CHECK_SET_KLASS(k)                                                \
 124   do {                                                                    \
 125     assert(Universe::is_bootstrapping() || k != NULL, "NULL Klass");      \
 126     assert(Universe::is_bootstrapping() || k->is_klass(), "not a Klass"); \
 127   } while (0)
 128 
 129 inline void oopDesc::set_klass(Klass* k) {
 130   CHECK_SET_KLASS(k);
 131   if (UseCompressedClassPointers) {
 132     *compressed_klass_addr() = Klass::encode_klass_not_null(k);
 133   } else {
 134     *klass_addr() = k;
 135   }
 136 }
 137 
 138 inline void oopDesc::release_set_klass(Klass* k) {
 139   CHECK_SET_KLASS(k);
 140   if (UseCompressedClassPointers) {
 141     OrderAccess::release_store(compressed_klass_addr(),
 142                                Klass::encode_klass_not_null(k));
 143   } else {
 144     OrderAccess::release_store_ptr(klass_addr(), k);
 145   }
 146 }
 147 
 148 #undef CHECK_SET_KLASS
 149 
 150 inline int oopDesc::klass_gap() const {
 151   return *(int*)(((intptr_t)this) + klass_gap_offset_in_bytes());
 152 }
 153 
 154 inline void oopDesc::set_klass_gap(int v) {
 155   if (UseCompressedClassPointers) {
 156     *(int*)(((intptr_t)this) + klass_gap_offset_in_bytes()) = v;
 157   }
 158 }
 159 
 160 inline void oopDesc::set_klass_to_list_ptr(oop k) {
 161   // This is only to be used during GC, for from-space objects, so no
 162   // barrier is needed.
 163   if (UseCompressedClassPointers) {
 164     _metadata._compressed_klass = (narrowKlass)encode_heap_oop(k);  // may be null (parnew overflow handling)
 165   } else {
 166     _metadata._klass = (Klass*)(address)k;
 167   }
 168 }
 169 
 170 inline oop oopDesc::list_ptr_from_klass() {
 171   // This is only to be used during GC, for from-space objects.
 172   if (UseCompressedClassPointers) {
 173     return decode_heap_oop((narrowOop)_metadata._compressed_klass);
 174   } else {
 175     // Special case for GC
 176     return (oop)(address)_metadata._klass;
 177   }
 178 }
 179 
 180 inline void   oopDesc::init_mark()                 { set_mark(markOopDesc::prototype_for_object(this)); }
 181 
 182 inline bool oopDesc::is_a(Klass* k)        const { return klass()->is_subtype_of(k); }
 183 
 184 inline bool oopDesc::is_instance()            const { return klass()->oop_is_instance(); }
 185 inline bool oopDesc::is_instanceClassLoader() const { return klass()->oop_is_instanceClassLoader(); }
 186 inline bool oopDesc::is_instanceMirror()      const { return klass()->oop_is_instanceMirror(); }
 187 inline bool oopDesc::is_instanceRef()         const { return klass()->oop_is_instanceRef(); }
 188 inline bool oopDesc::is_array()               const { return klass()->oop_is_array(); }
 189 inline bool oopDesc::is_objArray()            const { return klass()->oop_is_objArray(); }
 190 inline bool oopDesc::is_typeArray()           const { return klass()->oop_is_typeArray(); }
 191 
 192 inline void*     oopDesc::field_base(int offset)        const { return (void*)&((char*)this)[offset]; }
 193 
 194 template <class T> inline T* oopDesc::obj_field_addr(int offset) const { return (T*)field_base(offset); }
 195 inline Metadata** oopDesc::metadata_field_addr(int offset) const { return (Metadata**)field_base(offset); }
 196 inline jbyte*    oopDesc::byte_field_addr(int offset)   const { return (jbyte*)   field_base(offset); }
 197 inline jchar*    oopDesc::char_field_addr(int offset)   const { return (jchar*)   field_base(offset); }
 198 inline jboolean* oopDesc::bool_field_addr(int offset)   const { return (jboolean*)field_base(offset); }
 199 inline jint*     oopDesc::int_field_addr(int offset)    const { return (jint*)    field_base(offset); }
 200 inline jshort*   oopDesc::short_field_addr(int offset)  const { return (jshort*)  field_base(offset); }
 201 inline jlong*    oopDesc::long_field_addr(int offset)   const { return (jlong*)   field_base(offset); }
 202 inline jfloat*   oopDesc::float_field_addr(int offset)  const { return (jfloat*)  field_base(offset); }
 203 inline jdouble*  oopDesc::double_field_addr(int offset) const { return (jdouble*) field_base(offset); }
 204 inline address*  oopDesc::address_field_addr(int offset) const { return (address*) field_base(offset); }
 205 
 206 
 207 // Functions for getting and setting oops within instance objects.
 208 // If the oops are compressed, the type passed to these overloaded functions
 209 // is narrowOop.  All functions are overloaded so they can be called by
 210 // template functions without conditionals (the compiler instantiates via
 211 // the right type and inlines the appopriate code).
 212 
 213 inline bool oopDesc::is_null(oop obj)       { return obj == NULL; }
 214 inline bool oopDesc::is_null(narrowOop obj) { return obj == 0; }
 215 
 216 // Algorithm for encoding and decoding oops from 64 bit pointers to 32 bit
 217 // offset from the heap base.  Saving the check for null can save instructions
 218 // in inner GC loops so these are separated.
 219 
 220 inline bool check_obj_alignment(oop obj) {
 221   return cast_from_oop<intptr_t>(obj) % MinObjAlignmentInBytes == 0;
 222 }
 223 
 224 inline narrowOop oopDesc::encode_heap_oop_not_null(oop v) {
 225   assert(!is_null(v), "oop value can never be zero");
 226   assert(check_obj_alignment(v), "Address not aligned");
 227   assert(Universe::heap()->is_in_reserved(v), "Address not in heap");
 228   address base = Universe::narrow_oop_base();
 229   int    shift = Universe::narrow_oop_shift();
 230   uint64_t  pd = (uint64_t)(pointer_delta((void*)v, (void*)base, 1));
 231   assert(OopEncodingHeapMax > pd, "change encoding max if new encoding");
 232   uint64_t result = pd >> shift;
 233   assert((result & CONST64(0xffffffff00000000)) == 0, "narrow oop overflow");
 234   assert(decode_heap_oop(result) == v, "reversibility");
 235   return (narrowOop)result;
 236 }
 237 
 238 inline narrowOop oopDesc::encode_heap_oop(oop v) {
 239   return (is_null(v)) ? (narrowOop)0 : encode_heap_oop_not_null(v);
 240 }
 241 
 242 inline oop oopDesc::decode_heap_oop_not_null(narrowOop v) {
 243   assert(!is_null(v), "narrow oop value can never be zero");
 244   address base = Universe::narrow_oop_base();
 245   int    shift = Universe::narrow_oop_shift();
 246   oop result = (oop)(void*)((uintptr_t)base + ((uintptr_t)v << shift));
 247   assert(check_obj_alignment(result), err_msg("address not aligned: " INTPTR_FORMAT, p2i((void*) result)));
 248   return result;
 249 }
 250 
 251 inline oop oopDesc::decode_heap_oop(narrowOop v) {
 252   return is_null(v) ? (oop)NULL : decode_heap_oop_not_null(v);
 253 }
 254 
 255 inline oop oopDesc::decode_heap_oop_not_null(oop v) { return v; }
 256 inline oop oopDesc::decode_heap_oop(oop v)  { return v; }
 257 
 258 // Load an oop out of the Java heap as is without decoding.
 259 // Called by GC to check for null before decoding.
 260 inline oop       oopDesc::load_heap_oop(oop* p)          { return *p; }
 261 inline narrowOop oopDesc::load_heap_oop(narrowOop* p)    { return *p; }
 262 
 263 // Load and decode an oop out of the Java heap into a wide oop.
 264 inline oop oopDesc::load_decode_heap_oop_not_null(oop* p)       { return *p; }
 265 inline oop oopDesc::load_decode_heap_oop_not_null(narrowOop* p) {
 266   return decode_heap_oop_not_null(*p);
 267 }
 268 
 269 // Load and decode an oop out of the heap accepting null
 270 inline oop oopDesc::load_decode_heap_oop(oop* p) { return *p; }
 271 inline oop oopDesc::load_decode_heap_oop(narrowOop* p) {
 272   return decode_heap_oop(*p);
 273 }
 274 
 275 // Store already encoded heap oop into the heap.
 276 inline void oopDesc::store_heap_oop(oop* p, oop v)                 { *p = v; }
 277 inline void oopDesc::store_heap_oop(narrowOop* p, narrowOop v)     { *p = v; }
 278 
 279 // Encode and store a heap oop.
 280 inline void oopDesc::encode_store_heap_oop_not_null(narrowOop* p, oop v) {
 281   *p = encode_heap_oop_not_null(v);
 282 }
 283 inline void oopDesc::encode_store_heap_oop_not_null(oop* p, oop v) { *p = v; }
 284 
 285 // Encode and store a heap oop allowing for null.
 286 inline void oopDesc::encode_store_heap_oop(narrowOop* p, oop v) {
 287   *p = encode_heap_oop(v);
 288 }
 289 inline void oopDesc::encode_store_heap_oop(oop* p, oop v) { *p = v; }
 290 
 291 // Store heap oop as is for volatile fields.
 292 inline void oopDesc::release_store_heap_oop(volatile oop* p, oop v) {
 293   OrderAccess::release_store_ptr(p, v);
 294 }
 295 inline void oopDesc::release_store_heap_oop(volatile narrowOop* p,
 296                                             narrowOop v) {
 297   OrderAccess::release_store(p, v);
 298 }
 299 
 300 inline void oopDesc::release_encode_store_heap_oop_not_null(
 301                                                 volatile narrowOop* p, oop v) {
 302   // heap oop is not pointer sized.
 303   OrderAccess::release_store(p, encode_heap_oop_not_null(v));
 304 }
 305 
 306 inline void oopDesc::release_encode_store_heap_oop_not_null(
 307                                                       volatile oop* p, oop v) {
 308   OrderAccess::release_store_ptr(p, v);
 309 }
 310 
 311 inline void oopDesc::release_encode_store_heap_oop(volatile oop* p,
 312                                                            oop v) {
 313   OrderAccess::release_store_ptr(p, v);
 314 }
 315 inline void oopDesc::release_encode_store_heap_oop(
 316                                                 volatile narrowOop* p, oop v) {
 317   OrderAccess::release_store(p, encode_heap_oop(v));
 318 }
 319 
 320 
 321 // These functions are only used to exchange oop fields in instances,
 322 // not headers.
 323 inline oop oopDesc::atomic_exchange_oop(oop exchange_value, volatile HeapWord *dest) {
 324   oop result;
 325   if (UseCompressedOops) {
 326     // encode exchange value from oop to T
 327     narrowOop val = encode_heap_oop(exchange_value);
 328     narrowOop old = (narrowOop)Atomic::xchg(val, (narrowOop*)dest);
 329     // decode old from T to oop
 330     result = decode_heap_oop(old);
 331   } else {
 332     result = (oop)Atomic::xchg_ptr(exchange_value, (oop*)dest);
 333   }
 334 #if INCLUDE_ALL_GCS
 335   if (UseShenandoahGC) {
 336     if (exchange_value != NULL) {
 337       ShenandoahBarrierSet::barrier_set()->storeval_barrier(exchange_value);
 338     }
 339     result = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(result);
 340   }
 341 #endif
 342   return result;
 343 }
 344 
 345 // In order to put or get a field out of an instance, must first check
 346 // if the field has been compressed and uncompress it.
 347 inline oop oopDesc::obj_field(int offset) const {
 348   oop obj = UseCompressedOops ?
 349     load_decode_heap_oop(obj_field_addr<narrowOop>(offset)) :
 350     load_decode_heap_oop(obj_field_addr<oop>(offset));
 351 #if INCLUDE_ALL_GCS
 352   if (UseShenandoahGC) {
 353     obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
 354   }
 355 #endif
 356   return obj;
 357 }
 358 inline volatile oop oopDesc::obj_field_volatile(int offset) const {
 359   volatile oop value = obj_field(offset);
 360   OrderAccess::acquire();
 361   return value;
 362 }
 363 inline void oopDesc::obj_field_put(int offset, oop value) {
 364   UseCompressedOops ? oop_store(obj_field_addr<narrowOop>(offset), value) :
 365                       oop_store(obj_field_addr<oop>(offset),       value);
 366 }
 367 
 368 inline Metadata* oopDesc::metadata_field(int offset) const {
 369   return *metadata_field_addr(offset);
 370 }
 371 
 372 inline void oopDesc::metadata_field_put(int offset, Metadata* value) {
 373   *metadata_field_addr(offset) = value;
 374 }
 375 
 376 inline void oopDesc::obj_field_put_raw(int offset, oop value) {
 377   UseCompressedOops ?
 378     encode_store_heap_oop(obj_field_addr<narrowOop>(offset), value) :
 379     encode_store_heap_oop(obj_field_addr<oop>(offset),       value);
 380 }
 381 inline void oopDesc::obj_field_put_volatile(int offset, oop value) {
 382   OrderAccess::release();
 383   obj_field_put(offset, value);
 384   OrderAccess::fence();
 385 }
 386 
 387 inline jbyte oopDesc::byte_field(int offset) const                  { return (jbyte) *byte_field_addr(offset);    }
 388 inline void oopDesc::byte_field_put(int offset, jbyte contents)     { *byte_field_addr(offset) = (jint) contents; }
 389 
 390 inline jboolean oopDesc::bool_field(int offset) const               { return (jboolean) *bool_field_addr(offset); }
 391 inline void oopDesc::bool_field_put(int offset, jboolean contents)  { *bool_field_addr(offset) = (( (jint) contents) & 1); }
 392 
 393 inline jchar oopDesc::char_field(int offset) const                  { return (jchar) *char_field_addr(offset);    }
 394 inline void oopDesc::char_field_put(int offset, jchar contents)     { *char_field_addr(offset) = (jint) contents; }
 395 
 396 inline jint oopDesc::int_field(int offset) const                    { return *int_field_addr(offset);        }
 397 inline void oopDesc::int_field_put(int offset, jint contents)       { *int_field_addr(offset) = contents;    }
 398 
 399 inline jshort oopDesc::short_field(int offset) const                { return (jshort) *short_field_addr(offset);  }
 400 inline void oopDesc::short_field_put(int offset, jshort contents)   { *short_field_addr(offset) = (jint) contents;}
 401 
 402 inline jlong oopDesc::long_field(int offset) const                  { return *long_field_addr(offset);       }
 403 inline void oopDesc::long_field_put(int offset, jlong contents)     { *long_field_addr(offset) = contents;   }
 404 
 405 inline jfloat oopDesc::float_field(int offset) const                { return *float_field_addr(offset);      }
 406 inline void oopDesc::float_field_put(int offset, jfloat contents)   { *float_field_addr(offset) = contents;  }
 407 
 408 inline jdouble oopDesc::double_field(int offset) const              { return *double_field_addr(offset);     }
 409 inline void oopDesc::double_field_put(int offset, jdouble contents) { *double_field_addr(offset) = contents; }
 410 
 411 inline address oopDesc::address_field(int offset) const              { return *address_field_addr(offset);     }
 412 inline void oopDesc::address_field_put(int offset, address contents) { *address_field_addr(offset) = contents; }
 413 
 414 inline oop oopDesc::obj_field_acquire(int offset) const {
 415   oop obj = UseCompressedOops ?
 416              decode_heap_oop((narrowOop)
 417                OrderAccess::load_acquire(obj_field_addr<narrowOop>(offset)))
 418            : decode_heap_oop((oop)
 419                OrderAccess::load_ptr_acquire(obj_field_addr<oop>(offset)));
 420 #if INCLUDE_ALL_GCS
 421   if (UseShenandoahGC) {
 422     obj = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(obj);
 423   }
 424 #endif
 425   return obj;
 426 }
 427 inline void oopDesc::release_obj_field_put(int offset, oop value) {
 428   UseCompressedOops ?
 429     oop_store((volatile narrowOop*)obj_field_addr<narrowOop>(offset), value) :
 430     oop_store((volatile oop*)      obj_field_addr<oop>(offset),       value);
 431 }
 432 
 433 inline jbyte oopDesc::byte_field_acquire(int offset) const                  { return OrderAccess::load_acquire(byte_field_addr(offset));     }
 434 inline void oopDesc::release_byte_field_put(int offset, jbyte contents)     { OrderAccess::release_store(byte_field_addr(offset), contents); }
 435 
 436 inline jboolean oopDesc::bool_field_acquire(int offset) const               { return OrderAccess::load_acquire(bool_field_addr(offset));     }
 437 inline void oopDesc::release_bool_field_put(int offset, jboolean contents)  { OrderAccess::release_store(bool_field_addr(offset), (contents & 1)); }
 438 
 439 inline jchar oopDesc::char_field_acquire(int offset) const                  { return OrderAccess::load_acquire(char_field_addr(offset));     }
 440 inline void oopDesc::release_char_field_put(int offset, jchar contents)     { OrderAccess::release_store(char_field_addr(offset), contents); }
 441 
 442 inline jint oopDesc::int_field_acquire(int offset) const                    { return OrderAccess::load_acquire(int_field_addr(offset));      }
 443 inline void oopDesc::release_int_field_put(int offset, jint contents)       { OrderAccess::release_store(int_field_addr(offset), contents);  }
 444 
 445 inline jshort oopDesc::short_field_acquire(int offset) const                { return (jshort)OrderAccess::load_acquire(short_field_addr(offset)); }
 446 inline void oopDesc::release_short_field_put(int offset, jshort contents)   { OrderAccess::release_store(short_field_addr(offset), contents);     }
 447 
 448 inline jlong oopDesc::long_field_acquire(int offset) const                  { return OrderAccess::load_acquire(long_field_addr(offset));       }
 449 inline void oopDesc::release_long_field_put(int offset, jlong contents)     { OrderAccess::release_store(long_field_addr(offset), contents);   }
 450 
 451 inline jfloat oopDesc::float_field_acquire(int offset) const                { return OrderAccess::load_acquire(float_field_addr(offset));      }
 452 inline void oopDesc::release_float_field_put(int offset, jfloat contents)   { OrderAccess::release_store(float_field_addr(offset), contents);  }
 453 
 454 inline jdouble oopDesc::double_field_acquire(int offset) const              { return OrderAccess::load_acquire(double_field_addr(offset));     }
 455 inline void oopDesc::release_double_field_put(int offset, jdouble contents) { OrderAccess::release_store(double_field_addr(offset), contents); }
 456 
 457 inline address oopDesc::address_field_acquire(int offset) const             { return (address) OrderAccess::load_ptr_acquire(address_field_addr(offset)); }
 458 inline void oopDesc::release_address_field_put(int offset, address contents) { OrderAccess::release_store_ptr(address_field_addr(offset), contents); }
 459 
 460 inline int oopDesc::size_given_klass(Klass* klass)  {
 461   int lh = klass->layout_helper();
 462   int s;
 463 
 464   // lh is now a value computed at class initialization that may hint
 465   // at the size.  For instances, this is positive and equal to the
 466   // size.  For arrays, this is negative and provides log2 of the
 467   // array element size.  For other oops, it is zero and thus requires
 468   // a virtual call.
 469   //
 470   // We go to all this trouble because the size computation is at the
 471   // heart of phase 2 of mark-compaction, and called for every object,
 472   // alive or dead.  So the speed here is equal in importance to the
 473   // speed of allocation.
 474 
 475   if (lh > Klass::_lh_neutral_value) {
 476     if (!Klass::layout_helper_needs_slow_path(lh)) {
 477       s = lh >> LogHeapWordSize;  // deliver size scaled by wordSize
 478     } else {
 479       s = klass->oop_size(this);
 480     }
 481   } else if (lh <= Klass::_lh_neutral_value) {
 482     // The most common case is instances; fall through if so.
 483     if (lh < Klass::_lh_neutral_value) {
 484       // Second most common case is arrays.  We have to fetch the
 485       // length of the array, shift (multiply) it appropriately,
 486       // up to wordSize, add the header, and align to object size.
 487       size_t size_in_bytes;
 488 #ifdef _M_IA64
 489       // The Windows Itanium Aug 2002 SDK hoists this load above
 490       // the check for s < 0.  An oop at the end of the heap will
 491       // cause an access violation if this load is performed on a non
 492       // array oop.  Making the reference volatile prohibits this.
 493       // (%%% please explain by what magic the length is actually fetched!)
 494       volatile int *array_length;
 495       array_length = (volatile int *)( (intptr_t)this +
 496                           arrayOopDesc::length_offset_in_bytes() );
 497       assert(array_length > 0, "Integer arithmetic problem somewhere");
 498       // Put into size_t to avoid overflow.
 499       size_in_bytes = (size_t) array_length;
 500       size_in_bytes = size_in_bytes << Klass::layout_helper_log2_element_size(lh);
 501 #else
 502       size_t array_length = (size_t) ((arrayOop)this)->length();
 503       size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
 504 #endif
 505       size_in_bytes += Klass::layout_helper_header_size(lh);
 506 
 507       // This code could be simplified, but by keeping array_header_in_bytes
 508       // in units of bytes and doing it this way we can round up just once,
 509       // skipping the intermediate round to HeapWordSize.  Cast the result
 510       // of round_to to size_t to guarantee unsigned division == right shift.
 511       s = (int)((size_t)round_to(size_in_bytes, MinObjAlignmentInBytes) /
 512         HeapWordSize);
 513 
 514       // UseParNewGC, UseParallelGC and UseG1GC can change the length field
 515       // of an "old copy" of an object array in the young gen so it indicates
 516       // the grey portion of an already copied array. This will cause the first
 517       // disjunct below to fail if the two comparands are computed across such
 518       // a concurrent change.
 519       // UseParNewGC also runs with promotion labs (which look like int
 520       // filler arrays) which are subject to changing their declared size
 521       // when finally retiring a PLAB; this also can cause the first disjunct
 522       // to fail for another worker thread that is concurrently walking the block
 523       // offset table. Both these invariant failures are benign for their
 524       // current uses; we relax the assertion checking to cover these two cases below:
 525       //     is_objArray() && is_forwarded()   // covers first scenario above
 526       //  || is_typeArray()                    // covers second scenario above
 527       // If and when UseParallelGC uses the same obj array oop stealing/chunking
 528       // technique, we will need to suitably modify the assertion.
 529       assert((s == klass->oop_size(this)) ||
 530              (Universe::heap()->is_gc_active() &&
 531               ((is_typeArray() && UseParNewGC) ||
 532                (is_objArray()  && is_forwarded() && (UseParNewGC || UseParallelGC || UseG1GC)))),
 533              "wrong array object size");
 534     } else {
 535       // Must be zero, so bite the bullet and take the virtual call.
 536       s = klass->oop_size(this);
 537     }
 538   }
 539 
 540   assert(s % MinObjAlignment == 0, "alignment check");
 541   assert(s > 0, "Bad size calculated");
 542   return s;
 543 }
 544 
 545 
 546 inline int oopDesc::size()  {
 547   return size_given_klass(klass());
 548 }
 549 
 550 inline void update_barrier_set(void* p, oop v, bool release = false) {
 551   assert(oopDesc::bs() != NULL, "Uninitialized bs in oop!");
 552   oopDesc::bs()->write_ref_field(p, v, release);
 553 }
 554 
 555 template <class T> inline void update_barrier_set_pre(T* p, oop v) {
 556   oopDesc::bs()->write_ref_field_pre(p, v);
 557 }
 558 
 559 template <class T> inline void oop_store(T* p, oop v) {
 560   if (always_do_update_barrier) {
 561     oop_store((volatile T*)p, v);
 562   } else {
 563     update_barrier_set_pre(p, v);
 564     oopDesc::encode_store_heap_oop(p, v);
 565     // always_do_update_barrier == false =>
 566     // Either we are at a safepoint (in GC) or CMS is not used. In both
 567     // cases it's unnecessary to mark the card as dirty with release sematics.
 568     update_barrier_set((void*)p, v, false /* release */);  // cast away type
 569   }
 570 }
 571 
 572 template <class T> inline void oop_store(volatile T* p, oop v) {
 573   update_barrier_set_pre((T*)p, v);   // cast away volatile
 574   // Used by release_obj_field_put, so use release_store_ptr.
 575   oopDesc::release_encode_store_heap_oop(p, v);
 576   // When using CMS we must mark the card corresponding to p as dirty
 577   // with release sematics to prevent that CMS sees the dirty card but
 578   // not the new value v at p due to reordering of the two
 579   // stores. Note that CMS has a concurrent precleaning phase, where
 580   // it reads the card table while the Java threads are running.
 581   update_barrier_set((void*)p, v, true /* release */);    // cast away type
 582 }
 583 
 584 // Should replace *addr = oop assignments where addr type depends on UseCompressedOops
 585 // (without having to remember the function name this calls).
 586 inline void oop_store_raw(HeapWord* addr, oop value) {
 587   if (UseCompressedOops) {
 588     oopDesc::encode_store_heap_oop((narrowOop*)addr, value);
 589   } else {
 590     oopDesc::encode_store_heap_oop((oop*)addr, value);
 591   }
 592 }
 593 
 594 inline oop oopDesc::atomic_compare_exchange_oop(oop exchange_value,
 595                                                 volatile HeapWord *dest,
 596                                                 oop compare_value,
 597                                                 bool prebarrier) {
 598 #if INCLUDE_ALL_GCS
 599   if (UseShenandoahGC && ShenandoahCASBarrier) {
 600     return ShenandoahBarrierSet::barrier_set()->oop_atomic_cmpxchg_in_heap(exchange_value, dest, compare_value);
 601   }
 602 #endif
 603   if (UseCompressedOops) {
 604     if (prebarrier) {
 605       update_barrier_set_pre((narrowOop*)dest, exchange_value);
 606     }
 607     // encode exchange and compare value from oop to T
 608     narrowOop val = encode_heap_oop(exchange_value);
 609     narrowOop cmp = encode_heap_oop(compare_value);
 610 
 611     narrowOop old = (narrowOop) Atomic::cmpxchg(val, (narrowOop*)dest, cmp);
 612     // decode old from T to oop
 613     return decode_heap_oop(old);
 614   } else {
 615     if (prebarrier) {
 616       update_barrier_set_pre((oop*)dest, exchange_value);
 617     }
 618     return (oop)Atomic::cmpxchg_ptr(exchange_value, (oop*)dest, compare_value);
 619   }
 620 }
 621 
 622 // Used only for markSweep, scavenging
 623 inline bool oopDesc::is_gc_marked() const {
 624   return mark()->is_marked();
 625 }
 626 
 627 inline bool oopDesc::is_locked() const {
 628   return mark()->is_locked();
 629 }
 630 
 631 inline bool oopDesc::is_unlocked() const {
 632   return mark()->is_unlocked();
 633 }
 634 
 635 inline bool oopDesc::has_bias_pattern() const {
 636   return mark()->has_bias_pattern();
 637 }
 638 
 639 
 640 // used only for asserts
 641 inline bool oopDesc::is_oop(bool ignore_mark_word) const {
 642   oop obj = (oop) this;
 643   if (!check_obj_alignment(obj)) return false;
 644   if (!Universe::heap()->is_in_reserved(obj)) return false;
 645   // obj is aligned and accessible in heap
 646   if (Universe::heap()->is_in_reserved(obj->klass_or_null())) return false;
 647 
 648   // Header verification: the mark is typically non-NULL. If we're
 649   // at a safepoint, it must not be null.
 650   // Outside of a safepoint, the header could be changing (for example,
 651   // another thread could be inflating a lock on this object).
 652   if (ignore_mark_word) {
 653     return true;
 654   }
 655   if (mark() != NULL) {
 656     return true;
 657   }
 658   return !SafepointSynchronize::is_at_safepoint();
 659 }
 660 
 661 
 662 // used only for asserts
 663 inline bool oopDesc::is_oop_or_null(bool ignore_mark_word) const {
 664   return this == NULL ? true : is_oop(ignore_mark_word);
 665 }
 666 
 667 #ifndef PRODUCT
 668 // used only for asserts
 669 inline bool oopDesc::is_unlocked_oop() const {
 670   if (!Universe::heap()->is_in_reserved(this)) return false;
 671   return mark()->is_unlocked();
 672 }
 673 #endif // PRODUCT
 674 
 675 inline void oopDesc::follow_contents(void) {
 676   assert (is_gc_marked(), "should be marked");
 677   klass()->oop_follow_contents(this);
 678 }
 679 
 680 // Used by scavengers
 681 
 682 inline bool oopDesc::is_forwarded() const {
 683   // The extra heap check is needed since the obj might be locked, in which case the
 684   // mark would point to a stack location and have the sentinel bit cleared
 685   return mark()->is_marked();
 686 }
 687 
 688 // Used by scavengers
 689 inline void oopDesc::forward_to(oop p) {
 690   assert(check_obj_alignment(p),
 691          "forwarding to something not aligned");
 692   assert(Universe::heap()->is_in_reserved(p),
 693          "forwarding to something not in heap");
 694   markOop m = markOopDesc::encode_pointer_as_mark(p);
 695   assert(m->decode_pointer() == p, "encoding must be reversable");
 696   set_mark(m);
 697 }
 698 
 699 // Used by parallel scavengers
 700 inline bool oopDesc::cas_forward_to(oop p, markOop compare) {
 701   assert(check_obj_alignment(p),
 702          "forwarding to something not aligned");
 703   assert(Universe::heap()->is_in_reserved(p),
 704          "forwarding to something not in heap");
 705   markOop m = markOopDesc::encode_pointer_as_mark(p);
 706   assert(m->decode_pointer() == p, "encoding must be reversable");
 707   return cas_set_mark(m, compare) == compare;
 708 }
 709 
 710 // Note that the forwardee is not the same thing as the displaced_mark.
 711 // The forwardee is used when copying during scavenge and mark-sweep.
 712 // It does need to clear the low two locking- and GC-related bits.
 713 inline oop oopDesc::forwardee() const {
 714   return (oop) mark()->decode_pointer();
 715 }
 716 
 717 inline bool oopDesc::has_displaced_mark() const {
 718   return mark()->has_displaced_mark_helper();
 719 }
 720 
 721 inline markOop oopDesc::displaced_mark() const {
 722   return mark()->displaced_mark_helper();
 723 }
 724 
 725 inline void oopDesc::set_displaced_mark(markOop m) {
 726   mark()->set_displaced_mark_helper(m);
 727 }
 728 
 729 // The following method needs to be MT safe.
 730 inline uint oopDesc::age() const {
 731   assert(!is_forwarded(), "Attempt to read age from forwarded mark");
 732   if (has_displaced_mark()) {
 733     return displaced_mark()->age();
 734   } else {
 735     return mark()->age();
 736   }
 737 }
 738 
 739 inline void oopDesc::incr_age() {
 740   assert(!is_forwarded(), "Attempt to increment age of forwarded mark");
 741   if (has_displaced_mark()) {
 742     set_displaced_mark(displaced_mark()->incr_age());
 743   } else {
 744     set_mark(mark()->incr_age());
 745   }
 746 }
 747 
 748 
 749 inline intptr_t oopDesc::identity_hash() {
 750   // Fast case; if the object is unlocked and the hash value is set, no locking is needed
 751   // Note: The mark must be read into local variable to avoid concurrent updates.
 752   markOop mrk = mark();
 753   if (mrk->is_unlocked() && !mrk->has_no_hash()) {
 754     return mrk->hash();
 755   } else if (mrk->is_marked()) {
 756     return mrk->hash();
 757   } else {
 758     return slow_identity_hash();
 759   }
 760 }
 761 
 762 inline int oopDesc::adjust_pointers() {
 763   debug_only(int check_size = size());
 764   int s = klass()->oop_adjust_pointers(this);
 765   assert(s == check_size, "should be the same");
 766   return s;
 767 }
 768 
 769 #define OOP_ITERATE_DEFN(OopClosureType, nv_suffix)                        \
 770                                                                            \
 771 inline int oopDesc::oop_iterate(OopClosureType* blk) {                     \
 772   SpecializationStats::record_call();                                      \
 773   return klass()->oop_oop_iterate##nv_suffix(this, blk);               \
 774 }                                                                          \
 775                                                                            \
 776 inline int oopDesc::oop_iterate(OopClosureType* blk, MemRegion mr) {       \
 777   SpecializationStats::record_call();                                      \
 778   return klass()->oop_oop_iterate##nv_suffix##_m(this, blk, mr);       \
 779 }
 780 
 781 
 782 inline int oopDesc::oop_iterate_no_header(OopClosure* blk) {
 783   // The NoHeaderExtendedOopClosure wraps the OopClosure and proxies all
 784   // the do_oop calls, but turns off all other features in ExtendedOopClosure.
 785   NoHeaderExtendedOopClosure cl(blk);
 786   return oop_iterate(&cl);
 787 }
 788 
 789 inline int oopDesc::oop_iterate_no_header(OopClosure* blk, MemRegion mr) {
 790   NoHeaderExtendedOopClosure cl(blk);
 791   return oop_iterate(&cl, mr);
 792 }
 793 
 794 ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_DEFN)
 795 ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_DEFN)
 796 
 797 #if INCLUDE_ALL_GCS
 798 #define OOP_ITERATE_BACKWARDS_DEFN(OopClosureType, nv_suffix)              \
 799                                                                            \
 800 inline int oopDesc::oop_iterate_backwards(OopClosureType* blk) {           \
 801   SpecializationStats::record_call();                                      \
 802   return klass()->oop_oop_iterate_backwards##nv_suffix(this, blk);     \
 803 }
 804 
 805 ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_BACKWARDS_DEFN)
 806 ALL_OOP_OOP_ITERATE_CLOSURES_2(OOP_ITERATE_BACKWARDS_DEFN)
 807 #endif // INCLUDE_ALL_GCS
 808 
 809 #endif // SHARE_VM_OOPS_OOP_INLINE_HPP