1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  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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  24 
  25 #ifndef SHARE_VM_RUNTIME_ACCESS_HPP
  26 #define SHARE_VM_RUNTIME_ACCESS_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "metaprogramming/decay.hpp"
  30 #include "metaprogramming/integralConstant.hpp"
  31 #include "oops/oopsHierarchy.hpp"
  32 #include "utilities/debug.hpp"
  33 #include "utilities/globalDefinitions.hpp"
  34 
  35 // = GENERAL =
  36 // Access is an API for performing accesses with declarative semantics. Each access can have a number of "decorators".
  37 // A decorator is an attribute or property that affects the way a memory access is performed in some way.
  38 // There are different groups of decorators. Some have to do with memory ordering, others to do with,
  39 // e.g. strength of references, strength of GC barriers, or whether compression should be applied or not.
  40 // Some decorators are set at buildtime, such as whether primitives require GC barriers or not, others
  41 // at callsites such as whether an access is in the heap or not, and others are resolved at runtime
  42 // such as GC-specific barriers and encoding/decoding compressed oops.
  43 // By pipelining handling of these decorators, the design of the Access API allows separation of concern
  44 // over the different orthogonal concerns of decorators, while providing a powerful way of
  45 // expressing these orthogonal semantic properties in a unified way.
  46 
  47 // == OPERATIONS ==
  48 // * load: Load a value from an address.
  49 // * load_at: Load a value from an internal pointer relative to a base object.
  50 // * store: Store a value at an address.
  51 // * store_at: Store a value in an internal pointer relative to a base object.
  52 // * atomic_cmpxchg: Atomically compare-and-swap a new value at an address if previous value matched the compared value.
  53 // * atomic_cmpxchg_at: Atomically compare-and-swap a new value at an internal pointer address if previous value matched the compared value.
  54 // * atomic_xchg: Atomically swap a new value at an address if previous value matched the compared value.
  55 // * atomic_xchg_at: Atomically swap a new value at an internal pointer address if previous value matched the compared value.
  56 // * arraycopy: Copy data from one heap array to another heap array.
  57 // * clone: Clone the contents of an object to a newly allocated object.
  58 
  59 typedef uint64_t DecoratorSet;
  60 
  61 // == Internal Decorators - do not use ==
  62 // * INTERNAL_EMPTY: This is the name for the empty decorator set (in absence of other decorators).
  63 // * INTERNAL_CONVERT_COMPRESSED_OOPS: This is an oop access that will require converting an oop
  64 //   to a narrowOop or vice versa, if UseCompressedOops is known to be set.
  65 // * INTERNAL_VALUE_IS_OOP: Remember that the involved access is on oop rather than primitive.
  66 const DecoratorSet INTERNAL_EMPTY                    = UCONST64(0);
  67 const DecoratorSet INTERNAL_CONVERT_COMPRESSED_OOP   = UCONST64(1) << 1;
  68 const DecoratorSet INTERNAL_VALUE_IS_OOP             = UCONST64(1) << 2;
  69 
  70 // == Internal build-time Decorators ==
  71 // * INTERNAL_BT_BARRIER_ON_PRIMITIVES: This is set in the barrierSetConfig.hpp file.
  72 const DecoratorSet INTERNAL_BT_BARRIER_ON_PRIMITIVES = UCONST64(1) << 3;
  73 
  74 // == Internal run-time Decorators ==
  75 // * INTERNAL_RT_USE_COMPRESSED_OOPS: This decorator will be set in runtime resolved
  76 //   access backends iff UseCompressedOops is true.
  77 const DecoratorSet INTERNAL_RT_USE_COMPRESSED_OOPS   = UCONST64(1) << 4;
  78 
  79 const DecoratorSet INTERNAL_DECORATOR_MASK           = INTERNAL_CONVERT_COMPRESSED_OOP | INTERNAL_VALUE_IS_OOP |
  80                                                        INTERNAL_BT_BARRIER_ON_PRIMITIVES | INTERNAL_RT_USE_COMPRESSED_OOPS;
  81 
  82 // == Memory Ordering Decorators ==
  83 // The memory ordering decorators can be described in the following way:
  84 // === Decorator Rules ===
  85 // The different types of memory ordering guarantees have a strict order of strength.
  86 // Explicitly specifying the stronger ordering implies that the guarantees of the weaker
  87 // property holds too. The names come from the C++11 atomic operations, and typically
  88 // have a JMM equivalent property.
  89 // The equivalence may be viewed like this:
  90 // MO_UNORDERED is equivalent to JMM plain.
  91 // MO_VOLATILE has no equivalence in JMM, because it's a C++ thing.
  92 // MO_RELAXED is equivalent to JMM opaque.
  93 // MO_ACQUIRE is equivalent to JMM acquire.
  94 // MO_RELEASE is equivalent to JMM release.
  95 // MO_SEQ_CST is equivalent to JMM volatile.
  96 //
  97 // === Stores ===
  98 //  * MO_UNORDERED (Default): No guarantees.
  99 //    - The compiler and hardware are free to reorder aggressively. And they will.
 100 //  * MO_VOLATILE: Volatile stores (in the C++ sense).
 101 //    - The stores are not reordered by the compiler (but possibly the HW) w.r.t. other
 102 //      volatile accesses in program order (but possibly non-volatile accesses).
 103 //  * MO_RELAXED: Relaxed atomic stores.
 104 //    - The stores are atomic.
 105 //    - Guarantees from volatile stores hold.
 106 //  * MO_RELEASE: Releasing stores.
 107 //    - The releasing store will make its preceding memory accesses observable to memory accesses
 108 //      subsequent to an acquiring load observing this releasing store.
 109 //    - Guarantees from relaxed stores hold.
 110 //  * MO_SEQ_CST: Sequentially consistent stores.
 111 //    - The stores are observed in the same order by MO_SEQ_CST loads on other processors
 112 //    - Preceding loads and stores in program order are not reordered with subsequent loads and stores in program order.
 113 //    - Guarantees from releasing stores hold.
 114 // === Loads ===
 115 //  * MO_UNORDERED (Default): No guarantees
 116 //    - The compiler and hardware are free to reorder aggressively. And they will.
 117 //  * MO_VOLATILE: Volatile loads (in the C++ sense).
 118 //    - The loads are not reordered by the compiler (but possibly the HW) w.r.t. other
 119 //      volatile accesses in program order (but possibly non-volatile accesses).
 120 //  * MO_RELAXED: Relaxed atomic loads.
 121 //    - The stores are atomic.
 122 //    - Guarantees from volatile loads hold.
 123 //  * MO_ACQUIRE: Acquiring loads.
 124 //    - An acquiring load will make subsequent memory accesses observe the memory accesses
 125 //      preceding the releasing store that the acquiring load observed.
 126 //    - Guarantees from relaxed loads hold.
 127 //  * MO_SEQ_CST: Sequentially consistent loads.
 128 //    - These loads observe MO_SEQ_CST stores in the same order on other processors
 129 //    - Preceding loads and stores in program order are not reordered with subsequent loads and stores in program order.
 130 //    - Guarantees from acquiring loads hold.
 131 // === Atomic Cmpxchg ===
 132 //  * MO_RELAXED: Atomic but relaxed cmpxchg.
 133 //    - Guarantees from MO_RELAXED loads and MO_RELAXED stores hold unconditionally.
 134 //  * MO_SEQ_CST: Sequentially consistent cmpxchg.
 135 //    - Guarantees from MO_SEQ_CST loads and MO_SEQ_CST stores hold unconditionally.
 136 // === Atomic Xchg ===
 137 //  * MO_RELAXED: Atomic but relaxed atomic xchg.
 138 //    - Guarantees from MO_RELAXED loads and MO_RELAXED stores hold.
 139 //  * MO_SEQ_CST: Sequentially consistent xchg.
 140 //    - Guarantees from MO_SEQ_CST loads and MO_SEQ_CST stores hold.
 141 const DecoratorSet MO_UNORDERED      = UCONST64(1) << 5;
 142 const DecoratorSet MO_VOLATILE       = UCONST64(1) << 6;
 143 const DecoratorSet MO_RELAXED        = UCONST64(1) << 7;
 144 const DecoratorSet MO_ACQUIRE        = UCONST64(1) << 8;
 145 const DecoratorSet MO_RELEASE        = UCONST64(1) << 9;
 146 const DecoratorSet MO_SEQ_CST        = UCONST64(1) << 10;
 147 const DecoratorSet MO_DECORATOR_MASK = MO_UNORDERED | MO_VOLATILE | MO_RELAXED |
 148                                        MO_ACQUIRE | MO_RELEASE | MO_SEQ_CST;
 149 
 150 // === Barrier Strength Decorators ===
 151 // * AS_RAW: The access will translate into a raw memory access, hence ignoring all semantic concerns
 152 //   except memory ordering and compressed oops. This will bypass runtime function pointer dispatching
 153 //   in the pipeline and hardwire to raw accesses without going trough the GC access barriers.
 154 //  - Accesses on oop* translate to raw memory accesses without runtime checks
 155 //  - Accesses on narrowOop* translate to encoded/decoded memory accesses without runtime checks
 156 //  - Accesses on HeapWord* translate to a runtime check choosing one of the above
 157 //  - Accesses on other types translate to raw memory accesses without runtime checks
 158 // * AS_NO_KEEPALIVE: The barrier is used only on oop references and will not keep any involved objects
 159 //   alive, regardless of the type of reference being accessed. It will however perform the memory access
 160 //   in a consistent way w.r.t. e.g. concurrent compaction, so that the right field is being accessed,
 161 //   or maintain, e.g. intergenerational or interregional pointers if applicable. This should be used with
 162 //   extreme caution in isolated scopes.
 163 // * AS_NORMAL: The accesses will be resolved to an accessor on the BarrierSet class, giving the
 164 //   responsibility of performing the access and what barriers to be performed to the GC. This is the default.
 165 //   Note that primitive accesses will only be resolved on the barrier set if the appropriate build-time
 166 //   decorator for enabling primitive barriers is enabled for the build.
 167 const DecoratorSet AS_RAW            = UCONST64(1) << 11;
 168 const DecoratorSet AS_NO_KEEPALIVE   = UCONST64(1) << 12;
 169 const DecoratorSet AS_NORMAL         = UCONST64(1) << 13;
 170 const DecoratorSet AS_DECORATOR_MASK = AS_RAW | AS_NO_KEEPALIVE | AS_NORMAL;
 171 
 172 // === Reference Strength Decorators ===
 173 // These decorators only apply to accesses on oop-like types (oop/narrowOop).
 174 // * ON_STRONG_OOP_REF: Memory access is performed on a strongly reachable reference.
 175 // * ON_WEAK_OOP_REF: The memory access is performed on a weakly reachable reference.
 176 // * ON_PHANTOM_OOP_REF: The memory access is performed on a phantomly reachable reference.
 177 //   This is the same ring of strength as jweak and weak oops in the VM.
 178 // * ON_UNKNOWN_OOP_REF: The memory access is performed on a reference of unknown strength.
 179 //   This could for example come from the unsafe API.
 180 // * Default (no explicit reference strength specified): ON_STRONG_OOP_REF
 181 const DecoratorSet ON_STRONG_OOP_REF  = UCONST64(1) << 14;
 182 const DecoratorSet ON_WEAK_OOP_REF    = UCONST64(1) << 15;
 183 const DecoratorSet ON_PHANTOM_OOP_REF = UCONST64(1) << 16;
 184 const DecoratorSet ON_UNKNOWN_OOP_REF = UCONST64(1) << 17;
 185 const DecoratorSet ON_DECORATOR_MASK  = ON_STRONG_OOP_REF | ON_WEAK_OOP_REF |
 186                                         ON_PHANTOM_OOP_REF | ON_UNKNOWN_OOP_REF;
 187 
 188 // === Access Location ===
 189 // Accesses can take place in, e.g. the heap, old or young generation and different native roots.
 190 // The location is important to the GC as it may imply different actions. The following decorators are used:
 191 // * IN_HEAP: The access is performed in the heap. Many barriers such as card marking will
 192 //   be omitted if this decorator is not set.
 193 // * IN_HEAP_ARRAY: The access is performed on a heap allocated array. This is sometimes a special case
 194 //   for some GCs, and implies that it is an IN_HEAP.
 195 // * IN_ROOT: The access is performed in an off-heap data structure pointing into the Java heap.
 196 // * IN_CONCURRENT_ROOT: The access is performed in an off-heap data structure pointing into the Java heap,
 197 //   but is notably not scanned during safepoints. This is sometimes a special case for some GCs and
 198 //   implies that it is also an IN_ROOT.
 199 const DecoratorSet IN_HEAP            = UCONST64(1) << 18;
 200 const DecoratorSet IN_HEAP_ARRAY      = UCONST64(1) << 19;
 201 const DecoratorSet IN_ROOT            = UCONST64(1) << 20;
 202 const DecoratorSet IN_CONCURRENT_ROOT = UCONST64(1) << 21;
 203 const DecoratorSet IN_ARCHIVE_ROOT    = UCONST64(1) << 22;
 204 const DecoratorSet IN_DECORATOR_MASK  = IN_HEAP | IN_HEAP_ARRAY |
 205                                         IN_ROOT | IN_CONCURRENT_ROOT |
 206                                         IN_ARCHIVE_ROOT;
 207 
 208 // == Value Decorators ==
 209 // * OOP_NOT_NULL: This property can make certain barriers faster such as compressing oops.
 210 const DecoratorSet OOP_NOT_NULL       = UCONST64(1) << 23;
 211 const DecoratorSet OOP_DECORATOR_MASK = OOP_NOT_NULL;
 212 
 213 // == Arraycopy Decorators ==
 214 // * ARRAYCOPY_DEST_NOT_INITIALIZED: This property can be important to e.g. SATB barriers by
 215 //   marking that the previous value uninitialized nonsense rather than a real value.
 216 // * ARRAYCOPY_CHECKCAST: This property means that the class of the objects in source
 217 //   are not guaranteed to be subclasses of the class of the destination array. This requires
 218 //   a check-cast barrier during the copying operation. If this is not set, it is assumed
 219 //   that the array is covariant: (the source array type is-a destination array type)
 220 // * ARRAYCOPY_DISJOINT: This property means that it is known that the two array ranges
 221 //   are disjoint.
 222 // * ARRAYCOPY_ARRAYOF: The copy is in the arrayof form.
 223 // * ARRAYCOPY_ATOMIC: The accesses have to be atomic over the size of its elements.
 224 // * ARRAYCOPY_ALIGNED: The accesses have to be aligned on a HeapWord.
 225 const DecoratorSet ARRAYCOPY_DEST_NOT_INITIALIZED = UCONST64(1) << 24;
 226 const DecoratorSet ARRAYCOPY_CHECKCAST            = UCONST64(1) << 25;
 227 const DecoratorSet ARRAYCOPY_DISJOINT             = UCONST64(1) << 26;
 228 const DecoratorSet ARRAYCOPY_ARRAYOF              = UCONST64(1) << 27;
 229 const DecoratorSet ARRAYCOPY_ATOMIC               = UCONST64(1) << 28;
 230 const DecoratorSet ARRAYCOPY_ALIGNED              = UCONST64(1) << 29;
 231 const DecoratorSet ARRAYCOPY_DECORATOR_MASK       = ARRAYCOPY_DEST_NOT_INITIALIZED |
 232                                                     ARRAYCOPY_CHECKCAST | ARRAYCOPY_DISJOINT |
 233                                                     ARRAYCOPY_DISJOINT | ARRAYCOPY_ARRAYOF |
 234                                                     ARRAYCOPY_ATOMIC | ARRAYCOPY_ALIGNED;
 235 
 236 // The HasDecorator trait can help at compile-time determining whether a decorator set
 237 // has an intersection with a certain other decorator set
 238 template <DecoratorSet decorators, DecoratorSet decorator>
 239 struct HasDecorator: public IntegralConstant<bool, (decorators & decorator) != 0> {};
 240 
 241 namespace AccessInternal {
 242   template <typename T>
 243   struct OopOrNarrowOopInternal: AllStatic {
 244     typedef oop type;
 245   };
 246 
 247   template <>
 248   struct OopOrNarrowOopInternal<narrowOop>: AllStatic {
 249     typedef narrowOop type;
 250   };
 251 
 252   // This metafunction returns a canonicalized oop/narrowOop type for a passed
 253   // in oop-like types passed in from oop_* overloads where the user has sworn
 254   // that the passed in values should be oop-like (e.g. oop, oopDesc*, arrayOop,
 255   // narrowOoop, instanceOopDesc*, and random other things).
 256   // In the oop_* overloads, it must hold that if the passed in type T is not
 257   // narrowOop, then it by contract has to be one of many oop-like types implicitly
 258   // convertible to oop, and hence returns oop as the canonical oop type.
 259   // If it turns out it was not, then the implicit conversion to oop will fail
 260   // to compile, as desired.
 261   template <typename T>
 262   struct OopOrNarrowOop: AllStatic {
 263     typedef typename OopOrNarrowOopInternal<typename Decay<T>::type>::type type;
 264   };
 265 
 266   inline void* field_addr(oop base, ptrdiff_t byte_offset) {
 267     return reinterpret_cast<void*>(reinterpret_cast<intptr_t>((void*)base) + byte_offset);
 268   }
 269 
 270   template <DecoratorSet decorators, typename T>
 271   void store_at(oop base, ptrdiff_t offset, T value);
 272 
 273   template <DecoratorSet decorators, typename T>
 274   T load_at(oop base, ptrdiff_t offset);
 275 
 276   template <DecoratorSet decorators, typename T>
 277   T atomic_cmpxchg_at(T new_value, oop base, ptrdiff_t offset, T compare_value);
 278 
 279   template <DecoratorSet decorators, typename T>
 280   T atomic_xchg_at(T new_value, oop base, ptrdiff_t offset);
 281 
 282   template <DecoratorSet decorators, typename P, typename T>
 283   void store(P* addr, T value);
 284 
 285   template <DecoratorSet decorators, typename P, typename T>
 286   T load(P* addr);
 287 
 288   template <DecoratorSet decorators, typename P, typename T>
 289   T atomic_cmpxchg(T new_value, P* addr, T compare_value);
 290 
 291   template <DecoratorSet decorators, typename P, typename T>
 292   T atomic_xchg(T new_value, P* addr);
 293 
 294   template <DecoratorSet decorators, typename T>
 295   bool arraycopy(arrayOop src_obj, arrayOop dst_obj, T *src, T *dst, size_t length);
 296 
 297   template <DecoratorSet decorators>
 298   void clone(oop src, oop dst, size_t size);
 299 
 300   // Infer the type that should be returned from a load.
 301   template <typename P, DecoratorSet decorators>
 302   class LoadProxy: public StackObj {
 303   private:
 304     P *const _addr;
 305   public:
 306     LoadProxy(P* addr) : _addr(addr) {}
 307 
 308     template <typename T>
 309     inline operator T() {
 310       return load<decorators, P, T>(_addr);
 311     }
 312 
 313     inline operator P() {
 314       return load<decorators, P, P>(_addr);
 315     }
 316   };
 317 
 318   // Infer the type that should be returned from a load_at.
 319   template <DecoratorSet decorators>
 320   class LoadAtProxy: public StackObj {
 321   private:
 322     const oop _base;
 323     const ptrdiff_t _offset;
 324   public:
 325     LoadAtProxy(oop base, ptrdiff_t offset) : _base(base), _offset(offset) {}
 326 
 327     template <typename T>
 328     inline operator T() const {
 329       return load_at<decorators, T>(_base, _offset);
 330     }
 331   };
 332 }
 333 
 334 template <DecoratorSet decorators = INTERNAL_EMPTY>
 335 class Access: public AllStatic {
 336   // This function asserts that if an access gets passed in a decorator outside
 337   // of the expected_decorators, then something is wrong. It additionally checks
 338   // the consistency of the decorators so that supposedly disjoint decorators are indeed
 339   // disjoint. For example, an access can not be both in heap and on root at the
 340   // same time.
 341   template <DecoratorSet expected_decorators>
 342   static void verify_decorators();
 343 
 344   template <DecoratorSet expected_mo_decorators>
 345   static void verify_primitive_decorators() {
 346     const DecoratorSet primitive_decorators = (AS_DECORATOR_MASK ^ AS_NO_KEEPALIVE) | IN_HEAP |
 347                                                IN_HEAP_ARRAY | MO_DECORATOR_MASK;
 348     verify_decorators<expected_mo_decorators | primitive_decorators>();
 349   }
 350 
 351   template <DecoratorSet expected_mo_decorators>
 352   static void verify_oop_decorators() {
 353     const DecoratorSet oop_decorators = AS_DECORATOR_MASK | IN_DECORATOR_MASK |
 354                                         (ON_DECORATOR_MASK ^ ON_UNKNOWN_OOP_REF) | // no unknown oop refs outside of the heap
 355                                         OOP_DECORATOR_MASK | MO_DECORATOR_MASK;
 356     verify_decorators<expected_mo_decorators | oop_decorators>();
 357   }
 358 
 359   template <DecoratorSet expected_mo_decorators>
 360   static void verify_heap_oop_decorators() {
 361     const DecoratorSet heap_oop_decorators = AS_DECORATOR_MASK | ON_DECORATOR_MASK |
 362                                              OOP_DECORATOR_MASK | (IN_DECORATOR_MASK ^
 363                                                                   (IN_ROOT ^ IN_CONCURRENT_ROOT)) | // no root accesses in the heap
 364                                              MO_DECORATOR_MASK;
 365     verify_decorators<expected_mo_decorators | heap_oop_decorators>();
 366   }
 367 
 368   static const DecoratorSet load_mo_decorators = MO_UNORDERED | MO_VOLATILE | MO_RELAXED | MO_ACQUIRE | MO_SEQ_CST;
 369   static const DecoratorSet store_mo_decorators = MO_UNORDERED | MO_VOLATILE | MO_RELAXED | MO_RELEASE | MO_SEQ_CST;
 370   static const DecoratorSet atomic_xchg_mo_decorators = MO_SEQ_CST;
 371   static const DecoratorSet atomic_cmpxchg_mo_decorators = MO_RELAXED | MO_SEQ_CST;
 372 
 373 public:
 374   // Primitive heap accesses
 375   static inline AccessInternal::LoadAtProxy<decorators> load_at(oop base, ptrdiff_t offset) {
 376     verify_primitive_decorators<load_mo_decorators>();
 377     return AccessInternal::LoadAtProxy<decorators>(base, offset);
 378   }
 379 
 380   template <typename T>
 381   static inline void store_at(oop base, ptrdiff_t offset, T value) {
 382     verify_primitive_decorators<store_mo_decorators>();
 383     AccessInternal::store_at<decorators>(base, offset, value);
 384   }
 385 
 386   template <typename T>
 387   static inline T atomic_cmpxchg_at(T new_value, oop base, ptrdiff_t offset, T compare_value) {
 388     verify_primitive_decorators<atomic_cmpxchg_mo_decorators>();
 389     return AccessInternal::atomic_cmpxchg_at<decorators>(new_value, base, offset, compare_value);
 390   }
 391 
 392   template <typename T>
 393   static inline T atomic_xchg_at(T new_value, oop base, ptrdiff_t offset) {
 394     verify_primitive_decorators<atomic_xchg_mo_decorators>();
 395     return AccessInternal::atomic_xchg_at<decorators>(new_value, base, offset);
 396   }
 397 
 398   template <typename T>
 399   static inline bool arraycopy(arrayOop src_obj, arrayOop dst_obj, T *src, T *dst, size_t length) {
 400     verify_decorators<ARRAYCOPY_DECORATOR_MASK | IN_HEAP |
 401                       AS_DECORATOR_MASK>();
 402     return AccessInternal::arraycopy<decorators>(src_obj, dst_obj, src, dst, length);
 403   }
 404 
 405   // Oop heap accesses
 406   static inline AccessInternal::LoadAtProxy<decorators | INTERNAL_VALUE_IS_OOP> oop_load_at(oop base, ptrdiff_t offset) {
 407     verify_heap_oop_decorators<load_mo_decorators>();
 408     return AccessInternal::LoadAtProxy<decorators | INTERNAL_VALUE_IS_OOP>(base, offset);
 409   }
 410 
 411   template <typename T>
 412   static inline void oop_store_at(oop base, ptrdiff_t offset, T value) {
 413     verify_heap_oop_decorators<store_mo_decorators>();
 414     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
 415     OopType oop_value = value;
 416     AccessInternal::store_at<decorators | INTERNAL_VALUE_IS_OOP>(base, offset, oop_value);
 417   }
 418 
 419   template <typename T>
 420   static inline T oop_atomic_cmpxchg_at(T new_value, oop base, ptrdiff_t offset, T compare_value) {
 421     verify_heap_oop_decorators<atomic_cmpxchg_mo_decorators>();
 422     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
 423     OopType new_oop_value = new_value;
 424     OopType compare_oop_value = compare_value;
 425     return AccessInternal::atomic_cmpxchg_at<decorators | INTERNAL_VALUE_IS_OOP>(new_oop_value, base, offset, compare_oop_value);
 426   }
 427 
 428   template <typename T>
 429   static inline T oop_atomic_xchg_at(T new_value, oop base, ptrdiff_t offset) {
 430     verify_heap_oop_decorators<atomic_xchg_mo_decorators>();
 431     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
 432     OopType new_oop_value = new_value;
 433     return AccessInternal::atomic_xchg_at<decorators | INTERNAL_VALUE_IS_OOP>(new_oop_value, base, offset);
 434   }
 435 
 436   template <typename T>
 437   static inline bool oop_arraycopy(arrayOop src_obj, arrayOop dst_obj, T *src, T *dst, size_t length) {
 438     verify_decorators<ARRAYCOPY_DECORATOR_MASK | IN_HEAP | AS_DECORATOR_MASK>();
 439     return AccessInternal::arraycopy<decorators | INTERNAL_VALUE_IS_OOP>(src_obj, dst_obj, src, dst, length);
 440   }
 441 
 442   // Clone an object from src to dst
 443   static inline void clone(oop src, oop dst, size_t size) {
 444     verify_decorators<IN_HEAP>();
 445     AccessInternal::clone<decorators>(src, dst, size);
 446   }
 447 
 448   // Primitive accesses
 449   template <typename P>
 450   static inline P load(P* addr) {
 451     verify_primitive_decorators<load_mo_decorators>();
 452     return AccessInternal::load<decorators, P, P>(addr);
 453   }
 454 
 455   template <typename P, typename T>
 456   static inline void store(P* addr, T value) {
 457     verify_primitive_decorators<store_mo_decorators>();
 458     AccessInternal::store<decorators>(addr, value);
 459   }
 460 
 461   template <typename P, typename T>
 462   static inline T atomic_cmpxchg(T new_value, P* addr, T compare_value) {
 463     verify_primitive_decorators<atomic_cmpxchg_mo_decorators>();
 464     return AccessInternal::atomic_cmpxchg<decorators>(new_value, addr, compare_value);
 465   }
 466 
 467   template <typename P, typename T>
 468   static inline T atomic_xchg(T new_value, P* addr) {
 469     verify_primitive_decorators<atomic_xchg_mo_decorators>();
 470     return AccessInternal::atomic_xchg<decorators>(new_value, addr);
 471   }
 472 
 473   // Oop accesses
 474   template <typename P>
 475   static inline AccessInternal::LoadProxy<P, decorators | INTERNAL_VALUE_IS_OOP> oop_load(P* addr) {
 476     verify_oop_decorators<load_mo_decorators>();
 477     return AccessInternal::LoadProxy<P, decorators | INTERNAL_VALUE_IS_OOP>(addr);
 478   }
 479 
 480   template <typename P, typename T>
 481   static inline void oop_store(P* addr, T value) {
 482     verify_oop_decorators<store_mo_decorators>();
 483     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
 484     OopType oop_value = value;
 485     AccessInternal::store<decorators | INTERNAL_VALUE_IS_OOP>(addr, oop_value);
 486   }
 487 
 488   template <typename P, typename T>
 489   static inline T oop_atomic_cmpxchg(T new_value, P* addr, T compare_value) {
 490     verify_oop_decorators<atomic_cmpxchg_mo_decorators>();
 491     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
 492     OopType new_oop_value = new_value;
 493     OopType compare_oop_value = compare_value;
 494     return AccessInternal::atomic_cmpxchg<decorators | INTERNAL_VALUE_IS_OOP>(new_oop_value, addr, compare_oop_value);
 495   }
 496 
 497   template <typename P, typename T>
 498   static inline T oop_atomic_xchg(T new_value, P* addr) {
 499     verify_oop_decorators<atomic_xchg_mo_decorators>();
 500     typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;
 501     OopType new_oop_value = new_value;
 502     return AccessInternal::atomic_xchg<decorators | INTERNAL_VALUE_IS_OOP>(new_oop_value, addr);
 503   }
 504 };
 505 
 506 // Helper for performing raw accesses (knows only of memory ordering
 507 // atomicity decorators as well as compressed oops)
 508 template <DecoratorSet decorators = INTERNAL_EMPTY>
 509 class RawAccess: public Access<AS_RAW | decorators> {};
 510 
 511 // Helper for performing normal accesses on the heap. These accesses
 512 // may resolve an accessor on a GC barrier set
 513 template <DecoratorSet decorators = INTERNAL_EMPTY>
 514 class HeapAccess: public Access<IN_HEAP | decorators> {};
 515 
 516 // Helper for performing normal accesses in roots. These accesses
 517 // may resolve an accessor on a GC barrier set
 518 template <DecoratorSet decorators = INTERNAL_EMPTY>
 519 class RootAccess: public Access<IN_ROOT | decorators> {};
 520 
 521 #endif // SHARE_VM_RUNTIME_ACCESS_HPP