1 /*
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   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.
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   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).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  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_ACCESSBACKEND_HPP
  26 #define SHARE_OOPS_ACCESSBACKEND_HPP
  27 
  28 #include "cppstdlib/type_traits.hpp"
  29 #include "gc/shared/barrierSetConfig.hpp"
  30 #include "memory/allocation.hpp"
  31 #include "metaprogramming/enableIf.hpp"
  32 #include "oops/accessDecorators.hpp"
  33 #include "oops/oopsHierarchy.hpp"
  34 #include "runtime/globals.hpp"
  35 #include "utilities/debug.hpp"
  36 #include "utilities/globalDefinitions.hpp"
  37 
  38 // This metafunction returns either oop or narrowOop depending on whether
  39 // an access needs to use compressed oops or not.
  40 template <DecoratorSet decorators>
  41 struct HeapOopType: AllStatic {
  42   static const bool needs_oop_compress = HasDecorator<decorators, INTERNAL_CONVERT_COMPRESSED_OOP>::value &&
  43                                          HasDecorator<decorators, INTERNAL_RT_USE_COMPRESSED_OOPS>::value;
  44   using type = std::conditional_t<needs_oop_compress, narrowOop, oop>;
  45 };
  46 
  47 namespace AccessInternal {
  48   enum BarrierType {
  49     BARRIER_STORE,
  50     BARRIER_STORE_AT,
  51     BARRIER_LOAD,
  52     BARRIER_LOAD_AT,
  53     BARRIER_ATOMIC_CMPXCHG,
  54     BARRIER_ATOMIC_CMPXCHG_AT,
  55     BARRIER_ATOMIC_XCHG,
  56     BARRIER_ATOMIC_XCHG_AT,
  57     BARRIER_ARRAYCOPY,
  58     BARRIER_CLONE
  59   };
  60 
  61   template <DecoratorSet decorators, typename T>
  62   struct MustConvertCompressedOop: public std::integral_constant<bool,
  63     HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value &&
  64     std::is_same<typename HeapOopType<decorators>::type, narrowOop>::value &&
  65     std::is_same<T, oop>::value> {};
  66 
  67   // This metafunction returns an appropriate oop type if the value is oop-like
  68   // and otherwise returns the same type T.
  69   template <DecoratorSet decorators, typename T>
  70   struct EncodedType: AllStatic {
  71     using type = std::conditional_t<HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value,
  72                                     typename HeapOopType<decorators>::type,
  73                                     T>;
  74   };
  75 
  76   template <DecoratorSet decorators>
  77   inline typename HeapOopType<decorators>::type*
  78   oop_field_addr(oop base, ptrdiff_t byte_offset) {
  79     return reinterpret_cast<typename HeapOopType<decorators>::type*>(
  80              reinterpret_cast<intptr_t>((void*)base) + byte_offset);
  81   }
  82 
  83   template <DecoratorSet decorators, typename T>
  84   struct AccessFunctionTypes {
  85     typedef T (*load_at_func_t)(oop base, ptrdiff_t offset);
  86     typedef void (*store_at_func_t)(oop base, ptrdiff_t offset, T value);
  87     typedef T (*atomic_cmpxchg_at_func_t)(oop base, ptrdiff_t offset, T compare_value, T new_value);
  88     typedef T (*atomic_xchg_at_func_t)(oop base, ptrdiff_t offset, T new_value);
  89 
  90     typedef T (*load_func_t)(void* addr);
  91     typedef void (*store_func_t)(void* addr, T value);
  92     typedef T (*atomic_cmpxchg_func_t)(void* addr, T compare_value, T new_value);
  93     typedef T (*atomic_xchg_func_t)(void* addr, T new_value);
  94 
  95     typedef bool (*arraycopy_func_t)(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
  96                                      arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
  97                                      size_t length);
  98     typedef void (*clone_func_t)(oop src, oop dst, size_t size);
  99   };
 100 
 101   template <DecoratorSet decorators>
 102   struct AccessFunctionTypes<decorators, void> {
 103     typedef bool (*arraycopy_func_t)(arrayOop src_obj, size_t src_offset_in_bytes, void* src,
 104                                      arrayOop dst_obj, size_t dst_offset_in_bytes, void* dst,
 105                                      size_t length);
 106   };
 107 
 108   template <DecoratorSet decorators, typename T, BarrierType barrier> struct AccessFunction {};
 109 
 110 #define ACCESS_GENERATE_ACCESS_FUNCTION(bt, func)                   \
 111   template <DecoratorSet decorators, typename T>                    \
 112   struct AccessFunction<decorators, T, bt>: AllStatic{              \
 113     typedef typename AccessFunctionTypes<decorators, T>::func type; \
 114   }
 115   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_STORE, store_func_t);
 116   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_STORE_AT, store_at_func_t);
 117   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_LOAD, load_func_t);
 118   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_LOAD_AT, load_at_func_t);
 119   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_CMPXCHG, atomic_cmpxchg_func_t);
 120   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_CMPXCHG_AT, atomic_cmpxchg_at_func_t);
 121   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_XCHG, atomic_xchg_func_t);
 122   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_XCHG_AT, atomic_xchg_at_func_t);
 123   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ARRAYCOPY, arraycopy_func_t);
 124   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_CLONE, clone_func_t);
 125 #undef ACCESS_GENERATE_ACCESS_FUNCTION
 126 
 127   template <DecoratorSet decorators, typename T, BarrierType barrier_type>
 128   typename AccessFunction<decorators, T, barrier_type>::type resolve_barrier();
 129 
 130   template <DecoratorSet decorators, typename T, BarrierType barrier_type>
 131   typename AccessFunction<decorators, T, barrier_type>::type resolve_oop_barrier();
 132 
 133   void* field_addr(oop base, ptrdiff_t offset);
 134 
 135   // Forward calls to Copy:: in the cpp file to reduce dependencies and allow
 136   // faster build times, given how frequently included access is.
 137   void arraycopy_arrayof_conjoint_oops(void* src, void* dst, size_t length);
 138   void arraycopy_conjoint_oops(oop* src, oop* dst, size_t length);
 139   void arraycopy_conjoint_oops(narrowOop* src, narrowOop* dst, size_t length);
 140 
 141   void arraycopy_disjoint_words(void* src, void* dst, size_t length);
 142   void arraycopy_disjoint_words_atomic(void* src, void* dst, size_t length);
 143 
 144   template<typename T>
 145   void arraycopy_conjoint(T* src, T* dst, size_t length);
 146   template<typename T>
 147   void arraycopy_arrayof_conjoint(T* src, T* dst, size_t length);
 148   template<typename T>
 149   void arraycopy_conjoint_atomic(T* src, T* dst, size_t length);
 150 }
 151 
 152 // This mask specifies what decorators are relevant for raw accesses. When passing
 153 // accesses to the raw layer, irrelevant decorators are removed.
 154 const DecoratorSet RAW_DECORATOR_MASK = INTERNAL_DECORATOR_MASK | MO_DECORATOR_MASK |
 155                                         ARRAYCOPY_DECORATOR_MASK | IS_NOT_NULL;
 156 
 157 // The RawAccessBarrier performs raw accesses with additional knowledge of
 158 // memory ordering, so that OrderAccess/Atomic is called when necessary.
 159 // It additionally handles compressed oops, and hence is not completely "raw"
 160 // strictly speaking.
 161 template <DecoratorSet decorators>
 162 class RawAccessBarrier: public AllStatic {
 163 protected:
 164   static inline void* field_addr(oop base, ptrdiff_t byte_offset) {
 165     return AccessInternal::field_addr(base, byte_offset);
 166   }
 167 
 168 protected:
 169   // Only encode if INTERNAL_VALUE_IS_OOP
 170   template <DecoratorSet idecorators, typename T>
 171   static inline typename EnableIf<
 172     AccessInternal::MustConvertCompressedOop<idecorators, T>::value,
 173     typename HeapOopType<idecorators>::type>::type
 174   encode_internal(T value);
 175 
 176   template <DecoratorSet idecorators, typename T>
 177   static inline typename EnableIf<
 178     !AccessInternal::MustConvertCompressedOop<idecorators, T>::value, T>::type
 179   encode_internal(T value) {
 180     return value;
 181   }
 182 
 183   template <typename T>
 184   static inline typename AccessInternal::EncodedType<decorators, T>::type
 185   encode(T value) {
 186     return encode_internal<decorators, T>(value);
 187   }
 188 
 189   // Only decode if INTERNAL_VALUE_IS_OOP
 190   template <DecoratorSet idecorators, typename T>
 191   static inline typename EnableIf<
 192     AccessInternal::MustConvertCompressedOop<idecorators, T>::value, T>::type
 193   decode_internal(typename HeapOopType<idecorators>::type value);
 194 
 195   template <DecoratorSet idecorators, typename T>
 196   static inline typename EnableIf<
 197     !AccessInternal::MustConvertCompressedOop<idecorators, T>::value, T>::type
 198   decode_internal(T value) {
 199     return value;
 200   }
 201 
 202   template <typename T>
 203   static inline T decode(typename AccessInternal::EncodedType<decorators, T>::type value) {
 204     return decode_internal<decorators, T>(value);
 205   }
 206 
 207 protected:
 208   template <DecoratorSet ds, typename T>
 209   static typename EnableIf<
 210     HasDecorator<ds, MO_SEQ_CST>::value, T>::type
 211   load_internal(void* addr);
 212 
 213   template <DecoratorSet ds, typename T>
 214   static typename EnableIf<
 215     HasDecorator<ds, MO_ACQUIRE>::value, T>::type
 216   load_internal(void* addr);
 217 
 218   template <DecoratorSet ds, typename T>
 219   static typename EnableIf<
 220     HasDecorator<ds, MO_RELAXED>::value, T>::type
 221   load_internal(void* addr);
 222 
 223   template <DecoratorSet ds, typename T>
 224   static inline typename EnableIf<
 225     HasDecorator<ds, MO_UNORDERED>::value, T>::type
 226   load_internal(void* addr) {
 227     return *reinterpret_cast<T*>(addr);
 228   }
 229 
 230   template <DecoratorSet ds, typename T>
 231   static typename EnableIf<
 232     HasDecorator<ds, MO_SEQ_CST>::value>::type
 233   store_internal(void* addr, T value);
 234 
 235   template <DecoratorSet ds, typename T>
 236   static typename EnableIf<
 237     HasDecorator<ds, MO_RELEASE>::value>::type
 238   store_internal(void* addr, T value);
 239 
 240   template <DecoratorSet ds, typename T>
 241   static typename EnableIf<
 242     HasDecorator<ds, MO_RELAXED>::value>::type
 243   store_internal(void* addr, T value);
 244 
 245   template <DecoratorSet ds, typename T>
 246   static inline typename EnableIf<
 247     HasDecorator<ds, MO_UNORDERED>::value>::type
 248   store_internal(void* addr, T value) {
 249     *reinterpret_cast<T*>(addr) = value;
 250   }
 251 
 252   template <DecoratorSet ds, typename T>
 253   static typename EnableIf<
 254     HasDecorator<ds, MO_SEQ_CST>::value, T>::type
 255   atomic_cmpxchg_internal(void* addr, T compare_value, T new_value);
 256 
 257   template <DecoratorSet ds, typename T>
 258   static typename EnableIf<
 259     HasDecorator<ds, MO_RELAXED>::value, T>::type
 260   atomic_cmpxchg_internal(void* addr, T compare_value, T new_value);
 261 
 262   template <DecoratorSet ds, typename T>
 263   static typename EnableIf<
 264     HasDecorator<ds, MO_SEQ_CST>::value, T>::type
 265   atomic_xchg_internal(void* addr, T new_value);
 266 
 267 public:
 268   template <typename T>
 269   static inline void store(void* addr, T value) {
 270     store_internal<decorators>(addr, value);
 271   }
 272 
 273   template <typename T>
 274   static inline T load(void* addr) {
 275     return load_internal<decorators, T>(addr);
 276   }
 277 
 278   template <typename T>
 279   static inline T atomic_cmpxchg(void* addr, T compare_value, T new_value) {
 280     return atomic_cmpxchg_internal<decorators>(addr, compare_value, new_value);
 281   }
 282 
 283   template <typename T>
 284   static inline T atomic_xchg(void* addr, T new_value) {
 285     return atomic_xchg_internal<decorators>(addr, new_value);
 286   }
 287 
 288   template <typename T>
 289   static bool arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 290                         arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 291                         size_t length);
 292 
 293   template <typename T>
 294   static void oop_store(void* addr, T value);
 295   template <typename T>
 296   static void oop_store_at(oop base, ptrdiff_t offset, T value);
 297 
 298   template <typename T>
 299   static T oop_load(void* addr);
 300   template <typename T>
 301   static T oop_load_at(oop base, ptrdiff_t offset);
 302 
 303   template <typename T>
 304   static T oop_atomic_cmpxchg(void* addr, T compare_value, T new_value);
 305   template <typename T>
 306   static T oop_atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value);
 307 
 308   template <typename T>
 309   static T oop_atomic_xchg(void* addr, T new_value);
 310   template <typename T>
 311   static T oop_atomic_xchg_at(oop base, ptrdiff_t offset, T new_value);
 312 
 313   template <typename T>
 314   static void store_at(oop base, ptrdiff_t offset, T value) {
 315     store(field_addr(base, offset), value);
 316   }
 317 
 318   template <typename T>
 319   static T load_at(oop base, ptrdiff_t offset) {
 320     return load<T>(field_addr(base, offset));
 321   }
 322 
 323   template <typename T>
 324   static T atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value) {
 325     return atomic_cmpxchg(field_addr(base, offset), compare_value, new_value);
 326   }
 327 
 328   template <typename T>
 329   static T atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
 330     return atomic_xchg(field_addr(base, offset), new_value);
 331   }
 332 
 333   template <typename T>
 334   static bool oop_arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 335                             arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 336                             size_t length);
 337 
 338   static void clone(oop src, oop dst, size_t size);
 339 };
 340 
 341 namespace AccessInternal {
 342   DEBUG_ONLY(void check_access_thread_state());
 343 #define assert_access_thread_state() DEBUG_ONLY(check_access_thread_state())
 344 }
 345 
 346 // Below is the implementation of the first 4 steps of the template pipeline:
 347 // * Step 1: Set default decorators and decay types. This step gets rid of CV qualifiers
 348 //           and sets default decorators to sensible values.
 349 // * Step 2: Reduce types. This step makes sure there is only a single T type and not
 350 //           multiple types. The P type of the address and T type of the value must
 351 //           match.
 352 // * Step 3: Pre-runtime dispatch. This step checks whether a runtime call can be
 353 //           avoided, and in that case avoids it (calling raw accesses or
 354 //           primitive accesses in a build that does not require primitive GC barriers)
 355 // * Step 4: Runtime-dispatch. This step performs a runtime dispatch to the corresponding
 356 //           BarrierSet::AccessBarrier accessor that attaches GC-required barriers
 357 //           to the access.
 358 
 359 namespace AccessInternal {
 360   template <typename T>
 361   struct OopOrNarrowOopInternal: AllStatic {
 362     typedef oop type;
 363   };
 364 
 365   template <>
 366   struct OopOrNarrowOopInternal<narrowOop>: AllStatic {
 367     typedef narrowOop type;
 368   };
 369 
 370   // This metafunction returns a canonicalized oop/narrowOop type for a passed
 371   // in oop-like types passed in from oop_* overloads where the user has sworn
 372   // that the passed in values should be oop-like (e.g. oop, oopDesc*, arrayOop,
 373   // narrowOoop, instanceOopDesc*, and random other things).
 374   // In the oop_* overloads, it must hold that if the passed in type T is not
 375   // narrowOop, then it by contract has to be one of many oop-like types implicitly
 376   // convertible to oop, and hence returns oop as the canonical oop type.
 377   // If it turns out it was not, then the implicit conversion to oop will fail
 378   // to compile, as desired.
 379   template <typename T>
 380   struct OopOrNarrowOop: AllStatic {
 381     typedef typename OopOrNarrowOopInternal<std::decay_t<T>>::type type;
 382   };
 383 
 384   inline void* field_addr(oop base, ptrdiff_t byte_offset) {
 385     return reinterpret_cast<void*>(reinterpret_cast<intptr_t>((void*)base) + byte_offset);
 386   }
 387   // Step 4: Runtime dispatch
 388   // The RuntimeDispatch class is responsible for performing a runtime dispatch of the
 389   // accessor. This is required when the access either depends on whether compressed oops
 390   // is being used, or it depends on which GC implementation was chosen (e.g. requires GC
 391   // barriers). The way it works is that a function pointer initially pointing to an
 392   // accessor resolution function gets called for each access. Upon first invocation,
 393   // it resolves which accessor to be used in future invocations and patches the
 394   // function pointer to this new accessor.
 395 
 396   template <DecoratorSet decorators, typename T, BarrierType type>
 397   struct RuntimeDispatch: AllStatic {};
 398 
 399   template <DecoratorSet decorators, typename T>
 400   struct RuntimeDispatch<decorators, T, BARRIER_STORE>: AllStatic {
 401     typedef typename AccessFunction<decorators, T, BARRIER_STORE>::type func_t;
 402     static func_t _store_func;
 403 
 404     static void store_init(void* addr, T value);
 405 
 406     static inline void store(void* addr, T value) {
 407       assert_access_thread_state();
 408       _store_func(addr, value);
 409     }
 410   };
 411 
 412   template <DecoratorSet decorators, typename T>
 413   struct RuntimeDispatch<decorators, T, BARRIER_STORE_AT>: AllStatic {
 414     typedef typename AccessFunction<decorators, T, BARRIER_STORE_AT>::type func_t;
 415     static func_t _store_at_func;
 416 
 417     static void store_at_init(oop base, ptrdiff_t offset, T value);
 418 
 419     static inline void store_at(oop base, ptrdiff_t offset, T value) {
 420       assert_access_thread_state();
 421       _store_at_func(base, offset, value);
 422     }
 423   };
 424 
 425   template <DecoratorSet decorators, typename T>
 426   struct RuntimeDispatch<decorators, T, BARRIER_LOAD>: AllStatic {
 427     typedef typename AccessFunction<decorators, T, BARRIER_LOAD>::type func_t;
 428     static func_t _load_func;
 429 
 430     static T load_init(void* addr);
 431 
 432     static inline T load(void* addr) {
 433       assert_access_thread_state();
 434       return _load_func(addr);
 435     }
 436   };
 437 
 438   template <DecoratorSet decorators, typename T>
 439   struct RuntimeDispatch<decorators, T, BARRIER_LOAD_AT>: AllStatic {
 440     typedef typename AccessFunction<decorators, T, BARRIER_LOAD_AT>::type func_t;
 441     static func_t _load_at_func;
 442 
 443     static T load_at_init(oop base, ptrdiff_t offset);
 444 
 445     static inline T load_at(oop base, ptrdiff_t offset) {
 446       assert_access_thread_state();
 447       return _load_at_func(base, offset);
 448     }
 449   };
 450 
 451   template <DecoratorSet decorators, typename T>
 452   struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG>: AllStatic {
 453     typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG>::type func_t;
 454     static func_t _atomic_cmpxchg_func;
 455 
 456     static T atomic_cmpxchg_init(void* addr, T compare_value, T new_value);
 457 
 458     static inline T atomic_cmpxchg(void* addr, T compare_value, T new_value) {
 459       assert_access_thread_state();
 460       return _atomic_cmpxchg_func(addr, compare_value, new_value);
 461     }
 462   };
 463 
 464   template <DecoratorSet decorators, typename T>
 465   struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>: AllStatic {
 466     typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::type func_t;
 467     static func_t _atomic_cmpxchg_at_func;
 468 
 469     static T atomic_cmpxchg_at_init(oop base, ptrdiff_t offset, T compare_value, T new_value);
 470 
 471     static inline T atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value) {
 472       assert_access_thread_state();
 473       return _atomic_cmpxchg_at_func(base, offset, compare_value, new_value);
 474     }
 475   };
 476 
 477   template <DecoratorSet decorators, typename T>
 478   struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG>: AllStatic {
 479     typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG>::type func_t;
 480     static func_t _atomic_xchg_func;
 481 
 482     static T atomic_xchg_init(void* addr, T new_value);
 483 
 484     static inline T atomic_xchg(void* addr, T new_value) {
 485       assert_access_thread_state();
 486       return _atomic_xchg_func(addr, new_value);
 487     }
 488   };
 489 
 490   template <DecoratorSet decorators, typename T>
 491   struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG_AT>: AllStatic {
 492     typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG_AT>::type func_t;
 493     static func_t _atomic_xchg_at_func;
 494 
 495     static T atomic_xchg_at_init(oop base, ptrdiff_t offset, T new_value);
 496 
 497     static inline T atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
 498       assert_access_thread_state();
 499       return _atomic_xchg_at_func(base, offset, new_value);
 500     }
 501   };
 502 
 503   template <DecoratorSet decorators, typename T>
 504   struct RuntimeDispatch<decorators, T, BARRIER_ARRAYCOPY>: AllStatic {
 505     typedef typename AccessFunction<decorators, T, BARRIER_ARRAYCOPY>::type func_t;
 506     static func_t _arraycopy_func;
 507 
 508     static bool arraycopy_init(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 509                                arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 510                                size_t length);
 511 
 512     static inline bool arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 513                                  arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 514                                  size_t length) {
 515       assert_access_thread_state();
 516       return _arraycopy_func(src_obj, src_offset_in_bytes, src_raw,
 517                              dst_obj, dst_offset_in_bytes, dst_raw,
 518                              length);
 519     }
 520   };
 521 
 522   template <DecoratorSet decorators, typename T>
 523   struct RuntimeDispatch<decorators, T, BARRIER_CLONE>: AllStatic {
 524     typedef typename AccessFunction<decorators, T, BARRIER_CLONE>::type func_t;
 525     static func_t _clone_func;
 526 
 527     static void clone_init(oop src, oop dst, size_t size);
 528 
 529     static inline void clone(oop src, oop dst, size_t size) {
 530       assert_access_thread_state();
 531       _clone_func(src, dst, size);
 532     }
 533   };
 534 
 535   // Initialize the function pointers to point to the resolving function.
 536   template <DecoratorSet decorators, typename T>
 537   typename AccessFunction<decorators, T, BARRIER_STORE>::type
 538   RuntimeDispatch<decorators, T, BARRIER_STORE>::_store_func = &store_init;
 539 
 540   template <DecoratorSet decorators, typename T>
 541   typename AccessFunction<decorators, T, BARRIER_STORE_AT>::type
 542   RuntimeDispatch<decorators, T, BARRIER_STORE_AT>::_store_at_func = &store_at_init;
 543 
 544   template <DecoratorSet decorators, typename T>
 545   typename AccessFunction<decorators, T, BARRIER_LOAD>::type
 546   RuntimeDispatch<decorators, T, BARRIER_LOAD>::_load_func = &load_init;
 547 
 548   template <DecoratorSet decorators, typename T>
 549   typename AccessFunction<decorators, T, BARRIER_LOAD_AT>::type
 550   RuntimeDispatch<decorators, T, BARRIER_LOAD_AT>::_load_at_func = &load_at_init;
 551 
 552   template <DecoratorSet decorators, typename T>
 553   typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG>::type
 554   RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG>::_atomic_cmpxchg_func = &atomic_cmpxchg_init;
 555 
 556   template <DecoratorSet decorators, typename T>
 557   typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::type
 558   RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::_atomic_cmpxchg_at_func = &atomic_cmpxchg_at_init;
 559 
 560   template <DecoratorSet decorators, typename T>
 561   typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG>::type
 562   RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG>::_atomic_xchg_func = &atomic_xchg_init;
 563 
 564   template <DecoratorSet decorators, typename T>
 565   typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG_AT>::type
 566   RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG_AT>::_atomic_xchg_at_func = &atomic_xchg_at_init;
 567 
 568   template <DecoratorSet decorators, typename T>
 569   typename AccessFunction<decorators, T, BARRIER_ARRAYCOPY>::type
 570   RuntimeDispatch<decorators, T, BARRIER_ARRAYCOPY>::_arraycopy_func = &arraycopy_init;
 571 
 572   template <DecoratorSet decorators, typename T>
 573   typename AccessFunction<decorators, T, BARRIER_CLONE>::type
 574   RuntimeDispatch<decorators, T, BARRIER_CLONE>::_clone_func = &clone_init;
 575 
 576   // Step 3: Pre-runtime dispatching.
 577   // The PreRuntimeDispatch class is responsible for filtering the barrier strength
 578   // decorators. That is, for AS_RAW, it hardwires the accesses without a runtime
 579   // dispatch point. Otherwise it goes through a runtime check if hardwiring was
 580   // not possible.
 581   struct PreRuntimeDispatch: AllStatic {
 582     template<DecoratorSet decorators>
 583     struct CanHardwireRaw: public std::integral_constant<
 584       bool,
 585       !HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value || // primitive access
 586       !HasDecorator<decorators, INTERNAL_CONVERT_COMPRESSED_OOP>::value || // don't care about compressed oops (oop* address)
 587       HasDecorator<decorators, INTERNAL_RT_USE_COMPRESSED_OOPS>::value> // we can infer we use compressed oops (narrowOop* address)
 588     {};
 589 
 590     static const DecoratorSet convert_compressed_oops = INTERNAL_RT_USE_COMPRESSED_OOPS | INTERNAL_CONVERT_COMPRESSED_OOP;
 591 
 592     template<DecoratorSet decorators>
 593     static bool is_hardwired_primitive() {
 594       return !HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value;
 595     }
 596 
 597     template <DecoratorSet decorators, typename T>
 598     inline static typename EnableIf<
 599       HasDecorator<decorators, AS_RAW>::value && CanHardwireRaw<decorators>::value>::type
 600     store(void* addr, T value) {
 601       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 602       if (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value) {
 603         Raw::oop_store(addr, value);
 604       } else {
 605         Raw::store(addr, value);
 606       }
 607     }
 608 
 609     template <DecoratorSet decorators, typename T>
 610     inline static typename EnableIf<
 611       HasDecorator<decorators, AS_RAW>::value && !CanHardwireRaw<decorators>::value>::type
 612     store(void* addr, T value) {
 613       if (UseCompressedOops) {
 614         const DecoratorSet expanded_decorators = decorators | convert_compressed_oops;
 615         PreRuntimeDispatch::store<expanded_decorators>(addr, value);
 616       } else {
 617         const DecoratorSet expanded_decorators = decorators & ~convert_compressed_oops;
 618         PreRuntimeDispatch::store<expanded_decorators>(addr, value);
 619       }
 620     }
 621 
 622     template <DecoratorSet decorators, typename T>
 623     inline static typename EnableIf<
 624       !HasDecorator<decorators, AS_RAW>::value>::type
 625     store(void* addr, T value) {
 626       if (is_hardwired_primitive<decorators>()) {
 627         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 628         PreRuntimeDispatch::store<expanded_decorators>(addr, value);
 629       } else {
 630         RuntimeDispatch<decorators, T, BARRIER_STORE>::store(addr, value);
 631       }
 632     }
 633 
 634     template <DecoratorSet decorators, typename T>
 635     inline static typename EnableIf<
 636       HasDecorator<decorators, AS_RAW>::value>::type
 637     store_at(oop base, ptrdiff_t offset, T value) {
 638       store<decorators>(field_addr(base, offset), value);
 639     }
 640 
 641     template <DecoratorSet decorators, typename T>
 642     inline static typename EnableIf<
 643       !HasDecorator<decorators, AS_RAW>::value>::type
 644     store_at(oop base, ptrdiff_t offset, T value) {
 645       if (is_hardwired_primitive<decorators>()) {
 646         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 647         PreRuntimeDispatch::store_at<expanded_decorators>(base, offset, value);
 648       } else {
 649         RuntimeDispatch<decorators, T, BARRIER_STORE_AT>::store_at(base, offset, value);
 650       }
 651     }
 652 
 653     template <DecoratorSet decorators, typename T>
 654     inline static typename EnableIf<
 655       HasDecorator<decorators, AS_RAW>::value && CanHardwireRaw<decorators>::value, T>::type
 656     load(void* addr) {
 657       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 658       if (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value) {
 659         return Raw::template oop_load<T>(addr);
 660       } else {
 661         return Raw::template load<T>(addr);
 662       }
 663     }
 664 
 665     template <DecoratorSet decorators, typename T>
 666     inline static typename EnableIf<
 667       HasDecorator<decorators, AS_RAW>::value && !CanHardwireRaw<decorators>::value, T>::type
 668     load(void* addr) {
 669       if (UseCompressedOops) {
 670         const DecoratorSet expanded_decorators = decorators | convert_compressed_oops;
 671         return PreRuntimeDispatch::load<expanded_decorators, T>(addr);
 672       } else {
 673         const DecoratorSet expanded_decorators = decorators & ~convert_compressed_oops;
 674         return PreRuntimeDispatch::load<expanded_decorators, T>(addr);
 675       }
 676     }
 677 
 678     template <DecoratorSet decorators, typename T>
 679     inline static typename EnableIf<
 680       !HasDecorator<decorators, AS_RAW>::value, T>::type
 681     load(void* addr) {
 682       if (is_hardwired_primitive<decorators>()) {
 683         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 684         return PreRuntimeDispatch::load<expanded_decorators, T>(addr);
 685       } else {
 686         return RuntimeDispatch<decorators, T, BARRIER_LOAD>::load(addr);
 687       }
 688     }
 689 
 690     template <DecoratorSet decorators, typename T>
 691     inline static typename EnableIf<
 692       HasDecorator<decorators, AS_RAW>::value, T>::type
 693     load_at(oop base, ptrdiff_t offset) {
 694       return load<decorators, T>(field_addr(base, offset));
 695     }
 696 
 697     template <DecoratorSet decorators, typename T>
 698     inline static typename EnableIf<
 699       !HasDecorator<decorators, AS_RAW>::value, T>::type
 700     load_at(oop base, ptrdiff_t offset) {
 701       if (is_hardwired_primitive<decorators>()) {
 702         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 703         return PreRuntimeDispatch::load_at<expanded_decorators, T>(base, offset);
 704       } else {
 705         return RuntimeDispatch<decorators, T, BARRIER_LOAD_AT>::load_at(base, offset);
 706       }
 707     }
 708 
 709     template <DecoratorSet decorators, typename T>
 710     inline static typename EnableIf<
 711       HasDecorator<decorators, AS_RAW>::value && CanHardwireRaw<decorators>::value, T>::type
 712     atomic_cmpxchg(void* addr, T compare_value, T new_value) {
 713       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 714       if (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value) {
 715         return Raw::oop_atomic_cmpxchg(addr, compare_value, new_value);
 716       } else {
 717         return Raw::atomic_cmpxchg(addr, compare_value, new_value);
 718       }
 719     }
 720 
 721     template <DecoratorSet decorators, typename T>
 722     inline static typename EnableIf<
 723       HasDecorator<decorators, AS_RAW>::value && !CanHardwireRaw<decorators>::value, T>::type
 724     atomic_cmpxchg(void* addr, T compare_value, T new_value) {
 725       if (UseCompressedOops) {
 726         const DecoratorSet expanded_decorators = decorators | convert_compressed_oops;
 727         return PreRuntimeDispatch::atomic_cmpxchg<expanded_decorators>(addr, compare_value, new_value);
 728       } else {
 729         const DecoratorSet expanded_decorators = decorators & ~convert_compressed_oops;
 730         return PreRuntimeDispatch::atomic_cmpxchg<expanded_decorators>(addr, compare_value, new_value);
 731       }
 732     }
 733 
 734     template <DecoratorSet decorators, typename T>
 735     inline static typename EnableIf<
 736       !HasDecorator<decorators, AS_RAW>::value, T>::type
 737     atomic_cmpxchg(void* addr, T compare_value, T new_value) {
 738       if (is_hardwired_primitive<decorators>()) {
 739         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 740         return PreRuntimeDispatch::atomic_cmpxchg<expanded_decorators>(addr, compare_value, new_value);
 741       } else {
 742         return RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG>::atomic_cmpxchg(addr, compare_value, new_value);
 743       }
 744     }
 745 
 746     template <DecoratorSet decorators, typename T>
 747     inline static typename EnableIf<
 748       HasDecorator<decorators, AS_RAW>::value, T>::type
 749     atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value) {
 750       return atomic_cmpxchg<decorators>(field_addr(base, offset), compare_value, new_value);
 751     }
 752 
 753     template <DecoratorSet decorators, typename T>
 754     inline static typename EnableIf<
 755       !HasDecorator<decorators, AS_RAW>::value, T>::type
 756     atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value) {
 757       if (is_hardwired_primitive<decorators>()) {
 758         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 759         return PreRuntimeDispatch::atomic_cmpxchg_at<expanded_decorators>(base, offset, compare_value, new_value);
 760       } else {
 761         return RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::atomic_cmpxchg_at(base, offset, compare_value, new_value);
 762       }
 763     }
 764 
 765     template <DecoratorSet decorators, typename T>
 766     inline static typename EnableIf<
 767       HasDecorator<decorators, AS_RAW>::value && CanHardwireRaw<decorators>::value, T>::type
 768     atomic_xchg(void* addr, T new_value) {
 769       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 770       if (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value) {
 771         return Raw::oop_atomic_xchg(addr, new_value);
 772       } else {
 773         return Raw::atomic_xchg(addr, new_value);
 774       }
 775     }
 776 
 777     template <DecoratorSet decorators, typename T>
 778     inline static typename EnableIf<
 779       HasDecorator<decorators, AS_RAW>::value && !CanHardwireRaw<decorators>::value, T>::type
 780     atomic_xchg(void* addr, T new_value) {
 781       if (UseCompressedOops) {
 782         const DecoratorSet expanded_decorators = decorators | convert_compressed_oops;
 783         return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(addr, new_value);
 784       } else {
 785         const DecoratorSet expanded_decorators = decorators & ~convert_compressed_oops;
 786         return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(addr, new_value);
 787       }
 788     }
 789 
 790     template <DecoratorSet decorators, typename T>
 791     inline static typename EnableIf<
 792       !HasDecorator<decorators, AS_RAW>::value, T>::type
 793     atomic_xchg(void* addr, T new_value) {
 794       if (is_hardwired_primitive<decorators>()) {
 795         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 796         return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(addr, new_value);
 797       } else {
 798         return RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG>::atomic_xchg(addr, new_value);
 799       }
 800     }
 801 
 802     template <DecoratorSet decorators, typename T>
 803     inline static typename EnableIf<
 804       HasDecorator<decorators, AS_RAW>::value, T>::type
 805     atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
 806       return atomic_xchg<decorators>(field_addr(base, offset), new_value);
 807     }
 808 
 809     template <DecoratorSet decorators, typename T>
 810     inline static typename EnableIf<
 811       !HasDecorator<decorators, AS_RAW>::value, T>::type
 812     atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
 813       if (is_hardwired_primitive<decorators>()) {
 814         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 815         return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(base, offset, new_value);
 816       } else {
 817         return RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG_AT>::atomic_xchg_at(base, offset, new_value);
 818       }
 819     }
 820 
 821     template <DecoratorSet decorators, typename T>
 822     inline static typename EnableIf<
 823       HasDecorator<decorators, AS_RAW>::value && CanHardwireRaw<decorators>::value, bool>::type
 824     arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 825               arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 826               size_t length) {
 827       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 828       if (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value) {
 829         return Raw::oop_arraycopy(src_obj, src_offset_in_bytes, src_raw,
 830                                   dst_obj, dst_offset_in_bytes, dst_raw,
 831                                   length);
 832       } else {
 833         return Raw::arraycopy(src_obj, src_offset_in_bytes, src_raw,
 834                               dst_obj, dst_offset_in_bytes, dst_raw,
 835                               length);
 836       }
 837     }
 838 
 839     template <DecoratorSet decorators, typename T>
 840     inline static typename EnableIf<
 841       HasDecorator<decorators, AS_RAW>::value && !CanHardwireRaw<decorators>::value, bool>::type
 842     arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 843               arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 844               size_t length) {
 845       if (UseCompressedOops) {
 846         const DecoratorSet expanded_decorators = decorators | convert_compressed_oops;
 847         return PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
 848                                                                   dst_obj, dst_offset_in_bytes, dst_raw,
 849                                                                   length);
 850       } else {
 851         const DecoratorSet expanded_decorators = decorators & ~convert_compressed_oops;
 852         return PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
 853                                                                   dst_obj, dst_offset_in_bytes, dst_raw,
 854                                                                   length);
 855       }
 856     }
 857 
 858     template <DecoratorSet decorators, typename T>
 859     inline static typename EnableIf<
 860       !HasDecorator<decorators, AS_RAW>::value, bool>::type
 861     arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 862               arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 863               size_t length) {
 864       if (is_hardwired_primitive<decorators>()) {
 865         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 866         return PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
 867                                                                   dst_obj, dst_offset_in_bytes, dst_raw,
 868                                                                   length);
 869       } else {
 870         return RuntimeDispatch<decorators, T, BARRIER_ARRAYCOPY>::arraycopy(src_obj, src_offset_in_bytes, src_raw,
 871                                                                             dst_obj, dst_offset_in_bytes, dst_raw,
 872                                                                             length);
 873       }
 874     }
 875 
 876     template <DecoratorSet decorators>
 877     inline static typename EnableIf<
 878       HasDecorator<decorators, AS_RAW>::value>::type
 879     clone(oop src, oop dst, size_t size) {
 880       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 881       Raw::clone(src, dst, size);
 882     }
 883 
 884     template <DecoratorSet decorators>
 885     inline static typename EnableIf<
 886       !HasDecorator<decorators, AS_RAW>::value>::type
 887     clone(oop src, oop dst, size_t size) {
 888       RuntimeDispatch<decorators, oop, BARRIER_CLONE>::clone(src, dst, size);
 889     }
 890   };
 891 
 892   // Step 2: Reduce types.
 893   // Enforce that for non-oop types, T and P have to be strictly the same.
 894   // P is the type of the address and T is the type of the values.
 895   // As for oop types, it is allow to send T in {narrowOop, oop} and
 896   // P in {narrowOop, oop, HeapWord*}. The following rules apply according to
 897   // the subsequent table. (columns are P, rows are T)
 898   // |           | HeapWord  |   oop   | narrowOop |
 899   // |   oop     |  rt-comp  | hw-none |  hw-comp  |
 900   // | narrowOop |     x     |    x    |  hw-none  |
 901   //
 902   // x means not allowed
 903   // rt-comp means it must be checked at runtime whether the oop is compressed.
 904   // hw-none means it is statically known the oop will not be compressed.
 905   // hw-comp means it is statically known the oop will be compressed.
 906 
 907   template <DecoratorSet decorators, typename T>
 908   inline void store_reduce_types(T* addr, T value) {
 909     PreRuntimeDispatch::store<decorators>(addr, value);
 910   }
 911 
 912   template <DecoratorSet decorators>
 913   inline void store_reduce_types(narrowOop* addr, oop value) {
 914     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
 915                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
 916     PreRuntimeDispatch::store<expanded_decorators>(addr, value);
 917   }
 918 
 919   template <DecoratorSet decorators>
 920   inline void store_reduce_types(narrowOop* addr, narrowOop value) {
 921     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
 922                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
 923     PreRuntimeDispatch::store<expanded_decorators>(addr, value);
 924   }
 925 
 926   template <DecoratorSet decorators>
 927   inline void store_reduce_types(HeapWord* addr, oop value) {
 928     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP;
 929     PreRuntimeDispatch::store<expanded_decorators>(addr, value);
 930   }
 931 
 932   template <DecoratorSet decorators, typename T>
 933   inline T atomic_cmpxchg_reduce_types(T* addr, T compare_value, T new_value) {
 934     return PreRuntimeDispatch::atomic_cmpxchg<decorators>(addr, compare_value, new_value);
 935   }
 936 
 937   template <DecoratorSet decorators>
 938   inline oop atomic_cmpxchg_reduce_types(narrowOop* addr, oop compare_value, oop new_value) {
 939     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
 940                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
 941     return PreRuntimeDispatch::atomic_cmpxchg<expanded_decorators>(addr, compare_value, new_value);
 942   }
 943 
 944   template <DecoratorSet decorators>
 945   inline narrowOop atomic_cmpxchg_reduce_types(narrowOop* addr, narrowOop compare_value, narrowOop new_value) {
 946     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
 947                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
 948     return PreRuntimeDispatch::atomic_cmpxchg<expanded_decorators>(addr, compare_value, new_value);
 949   }
 950 
 951   template <DecoratorSet decorators>
 952   inline oop atomic_cmpxchg_reduce_types(HeapWord* addr,
 953                                          oop compare_value,
 954                                          oop new_value) {
 955     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP;
 956     return PreRuntimeDispatch::atomic_cmpxchg<expanded_decorators>(addr, compare_value, new_value);
 957   }
 958 
 959   template <DecoratorSet decorators, typename T>
 960   inline T atomic_xchg_reduce_types(T* addr, T new_value) {
 961     const DecoratorSet expanded_decorators = decorators;
 962     return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(addr, new_value);
 963   }
 964 
 965   template <DecoratorSet decorators>
 966   inline oop atomic_xchg_reduce_types(narrowOop* addr, oop new_value) {
 967     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
 968                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
 969     return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(addr, new_value);
 970   }
 971 
 972   template <DecoratorSet decorators>
 973   inline narrowOop atomic_xchg_reduce_types(narrowOop* addr, narrowOop new_value) {
 974     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
 975                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
 976     return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(addr, new_value);
 977   }
 978 
 979   template <DecoratorSet decorators>
 980   inline oop atomic_xchg_reduce_types(HeapWord* addr, oop new_value) {
 981     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP;
 982     return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(addr, new_value);
 983   }
 984 
 985   template <DecoratorSet decorators, typename T>
 986   inline T load_reduce_types(T* addr) {
 987     return PreRuntimeDispatch::load<decorators, T>(addr);
 988   }
 989 
 990   template <DecoratorSet decorators, typename T>
 991   inline typename OopOrNarrowOop<T>::type load_reduce_types(narrowOop* addr) {
 992     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
 993                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
 994     return PreRuntimeDispatch::load<expanded_decorators, typename OopOrNarrowOop<T>::type>(addr);
 995   }
 996 
 997   template <DecoratorSet decorators, typename T>
 998   inline oop load_reduce_types(HeapWord* addr) {
 999     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP;
1000     return PreRuntimeDispatch::load<expanded_decorators, oop>(addr);
1001   }
1002 
1003   template <DecoratorSet decorators, typename T>
1004   inline bool arraycopy_reduce_types(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
1005                                      arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
1006                                      size_t length) {
1007     return PreRuntimeDispatch::arraycopy<decorators>(src_obj, src_offset_in_bytes, src_raw,
1008                                                      dst_obj, dst_offset_in_bytes, dst_raw,
1009                                                      length);
1010   }
1011 
1012   template <DecoratorSet decorators>
1013   inline bool arraycopy_reduce_types(arrayOop src_obj, size_t src_offset_in_bytes, HeapWord* src_raw,
1014                                      arrayOop dst_obj, size_t dst_offset_in_bytes, HeapWord* dst_raw,
1015                                      size_t length) {
1016     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP;
1017     return PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
1018                                                               dst_obj, dst_offset_in_bytes, dst_raw,
1019                                                               length);
1020   }
1021 
1022   template <DecoratorSet decorators>
1023   inline bool arraycopy_reduce_types(arrayOop src_obj, size_t src_offset_in_bytes, narrowOop* src_raw,
1024                                      arrayOop dst_obj, size_t dst_offset_in_bytes, narrowOop* dst_raw,
1025                                      size_t length) {
1026     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
1027                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
1028     return PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
1029                                                               dst_obj, dst_offset_in_bytes, dst_raw,
1030                                                               length);
1031   }
1032 
1033   // Step 1: Set default decorators. This step remembers if a type was volatile
1034   // and then sets the MO_RELAXED decorator by default. Otherwise, a default
1035   // memory ordering is set for the access, and the implied decorator rules
1036   // are applied to select sensible defaults for decorators that have not been
1037   // explicitly set. For example, default object referent strength is set to strong.
1038   // This step also decays the types passed in (e.g. getting rid of CV qualifiers
1039   // and references from the types). This step also perform some type verification
1040   // that the passed in types make sense.
1041 
1042   template <DecoratorSet decorators, typename T>
1043   static void verify_types(){
1044     // If this fails to compile, then you have sent in something that is
1045     // not recognized as a valid primitive type to a primitive Access function.
1046     STATIC_ASSERT((HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value || // oops have already been validated
1047                    (std::is_pointer<T>::value || std::is_integral<T>::value) ||
1048                     std::is_floating_point<T>::value)); // not allowed primitive type
1049   }
1050 
1051   template <DecoratorSet decorators, typename P, typename T>
1052   inline void store(P* addr, T value) {
1053     verify_types<decorators, T>();
1054     using DecayedP = std::decay_t<P>;
1055     using DecayedT = std::decay_t<T>;
1056     DecayedT decayed_value = value;
1057     // If a volatile address is passed in but no memory ordering decorator,
1058     // set the memory ordering to MO_RELAXED by default.
1059     const DecoratorSet expanded_decorators = DecoratorFixup<
1060       (std::is_volatile<P>::value && !HasDecorator<decorators, MO_DECORATOR_MASK>::value) ?
1061       (MO_RELAXED | decorators) : decorators>::value;
1062     store_reduce_types<expanded_decorators>(const_cast<DecayedP*>(addr), decayed_value);
1063   }
1064 
1065   template <DecoratorSet decorators, typename T>
1066   inline void store_at(oop base, ptrdiff_t offset, T value) {
1067     verify_types<decorators, T>();
1068     using DecayedT = std::decay_t<T>;
1069     DecayedT decayed_value = value;
1070     const DecoratorSet expanded_decorators = DecoratorFixup<decorators |
1071                                              (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value ?
1072                                               INTERNAL_CONVERT_COMPRESSED_OOP : DECORATORS_NONE)>::value;
1073     PreRuntimeDispatch::store_at<expanded_decorators>(base, offset, decayed_value);
1074   }
1075 
1076   template <DecoratorSet decorators, typename P, typename T>
1077   inline T load(P* addr) {
1078     verify_types<decorators, T>();
1079     using DecayedP = std::decay_t<P>;
1080     using DecayedT = std::conditional_t<HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value,
1081                                         typename OopOrNarrowOop<T>::type,
1082                                         std::decay_t<T>>;
1083     // If a volatile address is passed in but no memory ordering decorator,
1084     // set the memory ordering to MO_RELAXED by default.
1085     const DecoratorSet expanded_decorators = DecoratorFixup<
1086       (std::is_volatile<P>::value && !HasDecorator<decorators, MO_DECORATOR_MASK>::value) ?
1087       (MO_RELAXED | decorators) : decorators>::value;
1088     return load_reduce_types<expanded_decorators, DecayedT>(const_cast<DecayedP*>(addr));
1089   }
1090 
1091   template <DecoratorSet decorators, typename T>
1092   inline T load_at(oop base, ptrdiff_t offset) {
1093     verify_types<decorators, T>();
1094     using DecayedT = std::conditional_t<HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value,
1095                                         typename OopOrNarrowOop<T>::type,
1096                                         std::decay_t<T>>;
1097     // Expand the decorators (figure out sensible defaults)
1098     // Potentially remember if we need compressed oop awareness
1099     const DecoratorSet expanded_decorators = DecoratorFixup<decorators |
1100                                              (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value ?
1101                                               INTERNAL_CONVERT_COMPRESSED_OOP : DECORATORS_NONE)>::value;
1102     return PreRuntimeDispatch::load_at<expanded_decorators, DecayedT>(base, offset);
1103   }
1104 
1105   template <DecoratorSet decorators, typename P, typename T>
1106   inline T atomic_cmpxchg(P* addr, T compare_value, T new_value) {
1107     verify_types<decorators, T>();
1108     using DecayedP = std::decay_t<P>;
1109     using DecayedT = std::decay_t<T>;
1110     DecayedT new_decayed_value = new_value;
1111     DecayedT compare_decayed_value = compare_value;
1112     const DecoratorSet expanded_decorators = DecoratorFixup<
1113       (!HasDecorator<decorators, MO_DECORATOR_MASK>::value) ?
1114       (MO_SEQ_CST | decorators) : decorators>::value;
1115     return atomic_cmpxchg_reduce_types<expanded_decorators>(const_cast<DecayedP*>(addr),
1116                                                             compare_decayed_value,
1117                                                             new_decayed_value);
1118   }
1119 
1120   template <DecoratorSet decorators, typename T>
1121   inline T atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value) {
1122     verify_types<decorators, T>();
1123     using DecayedT = std::decay_t<T>;
1124     DecayedT new_decayed_value = new_value;
1125     DecayedT compare_decayed_value = compare_value;
1126     // Determine default memory ordering
1127     const DecoratorSet expanded_decorators = DecoratorFixup<
1128       (!HasDecorator<decorators, MO_DECORATOR_MASK>::value) ?
1129       (MO_SEQ_CST | decorators) : decorators>::value;
1130     // Potentially remember that we need compressed oop awareness
1131     const DecoratorSet final_decorators = expanded_decorators |
1132                                           (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value ?
1133                                            INTERNAL_CONVERT_COMPRESSED_OOP : DECORATORS_NONE);
1134     return PreRuntimeDispatch::atomic_cmpxchg_at<final_decorators>(base, offset, compare_decayed_value,
1135                                                                    new_decayed_value);
1136   }
1137 
1138   template <DecoratorSet decorators, typename P, typename T>
1139   inline T atomic_xchg(P* addr, T new_value) {
1140     verify_types<decorators, T>();
1141     using DecayedP = std::decay_t<P>;
1142     using DecayedT = std::decay_t<T>;
1143     DecayedT new_decayed_value = new_value;
1144     // atomic_xchg is only available in SEQ_CST flavour.
1145     const DecoratorSet expanded_decorators = DecoratorFixup<decorators | MO_SEQ_CST>::value;
1146     return atomic_xchg_reduce_types<expanded_decorators>(const_cast<DecayedP*>(addr),
1147                                                          new_decayed_value);
1148   }
1149 
1150   template <DecoratorSet decorators, typename T>
1151   inline T atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
1152     verify_types<decorators, T>();
1153     using DecayedT = std::decay_t<T>;
1154     DecayedT new_decayed_value = new_value;
1155     // atomic_xchg is only available in SEQ_CST flavour.
1156     const DecoratorSet expanded_decorators = DecoratorFixup<decorators | MO_SEQ_CST |
1157                                              (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value ?
1158                                               INTERNAL_CONVERT_COMPRESSED_OOP : DECORATORS_NONE)>::value;
1159     return PreRuntimeDispatch::atomic_xchg_at<expanded_decorators>(base, offset, new_decayed_value);
1160   }
1161 
1162   template <DecoratorSet decorators, typename T>
1163   inline bool arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, const T* src_raw,
1164                         arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
1165                         size_t length) {
1166     STATIC_ASSERT((HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value ||
1167                    (std::is_same<T, void>::value || std::is_integral<T>::value) ||
1168                     std::is_floating_point<T>::value)); // arraycopy allows type erased void elements
1169     using DecayedT = std::decay_t<T>;
1170     const DecoratorSet expanded_decorators = DecoratorFixup<decorators | IS_ARRAY | IN_HEAP>::value;
1171     return arraycopy_reduce_types<expanded_decorators>(src_obj, src_offset_in_bytes, const_cast<DecayedT*>(src_raw),
1172                                                        dst_obj, dst_offset_in_bytes, const_cast<DecayedT*>(dst_raw),
1173                                                        length);
1174   }
1175 
1176   template <DecoratorSet decorators>
1177   inline void clone(oop src, oop dst, size_t size) {
1178     const DecoratorSet expanded_decorators = DecoratorFixup<decorators>::value;
1179     PreRuntimeDispatch::clone<expanded_decorators>(src, dst, size);
1180   }
1181 
1182   // Infer the type that should be returned from an Access::oop_load.
1183   template <typename P, DecoratorSet decorators>
1184   class OopLoadProxy: public StackObj {
1185   private:
1186     P *const _addr;
1187   public:
1188     explicit OopLoadProxy(P* addr) : _addr(addr) {}
1189 
1190     inline operator oop() {
1191       return load<decorators | INTERNAL_VALUE_IS_OOP, P, oop>(_addr);
1192     }
1193 
1194     inline operator narrowOop() {
1195       return load<decorators | INTERNAL_VALUE_IS_OOP, P, narrowOop>(_addr);
1196     }
1197 
1198     template <typename T>
1199     inline bool operator ==(const T& other) const {
1200       return load<decorators | INTERNAL_VALUE_IS_OOP, P, T>(_addr) == other;
1201     }
1202 
1203     template <typename T>
1204     inline bool operator !=(const T& other) const {
1205       return load<decorators | INTERNAL_VALUE_IS_OOP, P, T>(_addr) != other;
1206     }
1207 
1208     inline bool operator ==(std::nullptr_t) const {
1209       return load<decorators | INTERNAL_VALUE_IS_OOP, P, oop>(_addr) == nullptr;
1210     }
1211 
1212     inline bool operator !=(std::nullptr_t) const {
1213       return load<decorators | INTERNAL_VALUE_IS_OOP, P, oop>(_addr) != nullptr;
1214     }
1215   };
1216 
1217   // Infer the type that should be returned from an Access::load_at.
1218   template <DecoratorSet decorators>
1219   class LoadAtProxy: public StackObj {
1220   private:
1221     const oop _base;
1222     const ptrdiff_t _offset;
1223   public:
1224     LoadAtProxy(oop base, ptrdiff_t offset) : _base(base), _offset(offset) {}
1225 
1226     template <typename T>
1227     inline operator T() const {
1228       return load_at<decorators, T>(_base, _offset);
1229     }
1230 
1231     template <typename T>
1232     inline bool operator ==(const T& other) const { return load_at<decorators, T>(_base, _offset) == other; }
1233 
1234     template <typename T>
1235     inline bool operator !=(const T& other) const { return load_at<decorators, T>(_base, _offset) != other; }
1236   };
1237 
1238   // Infer the type that should be returned from an Access::oop_load_at.
1239   template <DecoratorSet decorators>
1240   class OopLoadAtProxy: public StackObj {
1241   private:
1242     const oop _base;
1243     const ptrdiff_t _offset;
1244   public:
1245     OopLoadAtProxy(oop base, ptrdiff_t offset) : _base(base), _offset(offset) {}
1246 
1247     inline operator oop() const {
1248       return load_at<decorators | INTERNAL_VALUE_IS_OOP, oop>(_base, _offset);
1249     }
1250 
1251     inline operator narrowOop() const {
1252       return load_at<decorators | INTERNAL_VALUE_IS_OOP, narrowOop>(_base, _offset);
1253     }
1254 
1255     template <typename T>
1256     inline bool operator ==(const T& other) const {
1257       return load_at<decorators | INTERNAL_VALUE_IS_OOP, T>(_base, _offset) == other;
1258     }
1259 
1260     template <typename T>
1261     inline bool operator !=(const T& other) const {
1262       return load_at<decorators | INTERNAL_VALUE_IS_OOP, T>(_base, _offset) != other;
1263     }
1264   };
1265 }
1266 
1267 #endif // SHARE_OOPS_ACCESSBACKEND_HPP