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