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src/hotspot/share/oops/accessBackend.hpp

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  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_OOPS_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

 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);

 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 

 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;

 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     }

 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);

 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 

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     }

  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_OOPS_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/inlineKlass.hpp"
  34 #include "oops/oopsHierarchy.hpp"
  35 #include "runtime/globals.hpp"
  36 #include "utilities/debug.hpp"
  37 #include "utilities/globalDefinitions.hpp"
  38 
  39 // This metafunction returns either oop or narrowOop depending on whether
  40 // an access needs to use compressed oops or not.
  41 template <DecoratorSet decorators>
  42 struct HeapOopType: AllStatic {
  43   static const bool needs_oop_compress = HasDecorator<decorators, INTERNAL_CONVERT_COMPRESSED_OOP>::value &&
  44                                          HasDecorator<decorators, INTERNAL_RT_USE_COMPRESSED_OOPS>::value;
  45   using type = std::conditional_t<needs_oop_compress, narrowOop, oop>;
  46 };
  47 
  48 // This meta-function returns either oop or narrowOop depending on whether
  49 // a back-end needs to consider compressed oops types or not.
  50 template <DecoratorSet decorators>
  51 struct ValueOopType: AllStatic {
  52   static const bool needs_oop_compress = HasDecorator<decorators, INTERNAL_RT_USE_COMPRESSED_OOPS>::value;
  53   using type = std::conditional_t<needs_oop_compress, narrowOop, oop>;
  54 };
  55 
  56 namespace AccessInternal {
  57   enum BarrierType {
  58     BARRIER_STORE,
  59     BARRIER_STORE_AT,
  60     BARRIER_LOAD,
  61     BARRIER_LOAD_AT,
  62     BARRIER_ATOMIC_CMPXCHG,
  63     BARRIER_ATOMIC_CMPXCHG_AT,
  64     BARRIER_ATOMIC_XCHG,
  65     BARRIER_ATOMIC_XCHG_AT,
  66     BARRIER_ARRAYCOPY,
  67     BARRIER_CLONE,
  68     BARRIER_VALUE_COPY
  69   };
  70 
  71   template <DecoratorSet decorators, typename T>
  72   struct MustConvertCompressedOop: public std::integral_constant<bool,
  73     HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value &&
  74     std::is_same<typename HeapOopType<decorators>::type, narrowOop>::value &&
  75     std::is_same<T, oop>::value> {};
  76 
  77   // This metafunction returns an appropriate oop type if the value is oop-like
  78   // and otherwise returns the same type T.
  79   template <DecoratorSet decorators, typename T>
  80   struct EncodedType: AllStatic {
  81     using type = std::conditional_t<HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value,
  82                                     typename HeapOopType<decorators>::type,
  83                                     T>;
  84   };
  85 
  86   template <DecoratorSet decorators>
  87   inline typename HeapOopType<decorators>::type*
  88   oop_field_addr(oop base, ptrdiff_t byte_offset) {
  89     return reinterpret_cast<typename HeapOopType<decorators>::type*>(
  90              reinterpret_cast<intptr_t>((void*)base) + byte_offset);
  91   }
  92 
  93   template <DecoratorSet decorators, typename T>
  94   struct AccessFunctionTypes {
  95     typedef T (*load_at_func_t)(oop base, ptrdiff_t offset);
  96     typedef void (*store_at_func_t)(oop base, ptrdiff_t offset, T value);
  97     typedef T (*atomic_cmpxchg_at_func_t)(oop base, ptrdiff_t offset, T compare_value, T new_value);
  98     typedef T (*atomic_xchg_at_func_t)(oop base, ptrdiff_t offset, T new_value);
  99 
 100     typedef T (*load_func_t)(void* addr);
 101     typedef void (*store_func_t)(void* addr, T value);
 102     typedef T (*atomic_cmpxchg_func_t)(void* addr, T compare_value, T new_value);
 103     typedef T (*atomic_xchg_func_t)(void* addr, T new_value);
 104 
 105     typedef void (*arraycopy_func_t)(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 106                                      arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 107                                      size_t length);
 108     typedef void (*clone_func_t)(oop src, oop dst, size_t size);
 109     typedef void (*value_copy_func_t)(void* src, void* dst, InlineKlass* md, LayoutKind lk);
 110   };
 111 
 112   template <DecoratorSet decorators>
 113   struct AccessFunctionTypes<decorators, void> {
 114     typedef void (*arraycopy_func_t)(arrayOop src_obj, size_t src_offset_in_bytes, void* src,
 115                                      arrayOop dst_obj, size_t dst_offset_in_bytes, void* dst,
 116                                      size_t length);
 117   };
 118 
 119   template <DecoratorSet decorators, typename T, BarrierType barrier> struct AccessFunction {};
 120 
 121 #define ACCESS_GENERATE_ACCESS_FUNCTION(bt, func)                   \
 122   template <DecoratorSet decorators, typename T>                    \
 123   struct AccessFunction<decorators, T, bt>: AllStatic{              \
 124     typedef typename AccessFunctionTypes<decorators, T>::func type; \
 125   }
 126   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_STORE, store_func_t);
 127   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_STORE_AT, store_at_func_t);
 128   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_LOAD, load_func_t);
 129   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_LOAD_AT, load_at_func_t);
 130   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_CMPXCHG, atomic_cmpxchg_func_t);
 131   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_CMPXCHG_AT, atomic_cmpxchg_at_func_t);
 132   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_XCHG, atomic_xchg_func_t);
 133   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_XCHG_AT, atomic_xchg_at_func_t);
 134   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ARRAYCOPY, arraycopy_func_t);
 135   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_CLONE, clone_func_t);
 136   ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_VALUE_COPY, value_copy_func_t);
 137 #undef ACCESS_GENERATE_ACCESS_FUNCTION
 138 
 139   template <DecoratorSet decorators, typename T, BarrierType barrier_type>
 140   typename AccessFunction<decorators, T, barrier_type>::type resolve_barrier();
 141 
 142   template <DecoratorSet decorators, typename T, BarrierType barrier_type>
 143   typename AccessFunction<decorators, T, barrier_type>::type resolve_oop_barrier();
 144 
 145   void* field_addr(oop base, ptrdiff_t offset);
 146 
 147   // Forward calls to Copy:: in the cpp file to reduce dependencies and allow
 148   // faster build times, given how frequently included access is.
 149   void arraycopy_arrayof_conjoint_oops(void* src, void* dst, size_t length);
 150   void arraycopy_conjoint_oops(oop* src, oop* dst, size_t length);
 151   void arraycopy_conjoint_oops(narrowOop* src, narrowOop* dst, size_t length);
 152 
 153   void arraycopy_disjoint_words(void* src, void* dst, size_t length);
 154   void arraycopy_disjoint_words_atomic(void* src, void* dst, size_t length);
 155 
 156   template<typename T>
 157   void arraycopy_conjoint(T* src, T* dst, size_t length);
 158   template<typename T>
 159   void arraycopy_arrayof_conjoint(T* src, T* dst, size_t length);
 160   template<typename T>
 161   void arraycopy_conjoint_atomic(T* src, T* dst, size_t length);
 162 
 163   void value_copy_internal(void* src, void* dst, size_t length);
 164 }
 165 
 166 // This mask specifies what decorators are relevant for raw accesses. When passing
 167 // accesses to the raw layer, irrelevant decorators are removed.
 168 const DecoratorSet RAW_DECORATOR_MASK = INTERNAL_DECORATOR_MASK | MO_DECORATOR_MASK |
 169                                         ARRAYCOPY_DECORATOR_MASK | IS_NOT_NULL;
 170 
 171 // The RawAccessBarrier performs raw accesses with additional knowledge of
 172 // memory ordering, so that OrderAccess/Atomic is called when necessary.
 173 // It additionally handles compressed oops, and hence is not completely "raw"
 174 // strictly speaking.
 175 template <DecoratorSet decorators>
 176 class RawAccessBarrier: public AllStatic {
 177 protected:
 178   static inline void* field_addr(oop base, ptrdiff_t byte_offset) {
 179     return AccessInternal::field_addr(base, byte_offset);
 180   }
 181 
 182 protected:
 183   // Only encode if INTERNAL_VALUE_IS_OOP

 283   static inline void store(void* addr, T value) {
 284     store_internal<decorators>(addr, value);
 285   }
 286 
 287   template <typename T>
 288   static inline T load(void* addr) {
 289     return load_internal<decorators, T>(addr);
 290   }
 291 
 292   template <typename T>
 293   static inline T atomic_cmpxchg(void* addr, T compare_value, T new_value) {
 294     return atomic_cmpxchg_internal<decorators>(addr, compare_value, new_value);
 295   }
 296 
 297   template <typename T>
 298   static inline T atomic_xchg(void* addr, T new_value) {
 299     return atomic_xchg_internal<decorators>(addr, new_value);
 300   }
 301 
 302   template <typename T>
 303   static void arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 304                         arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 305                         size_t length);
 306 
 307   template <typename T>
 308   static void oop_store(void* addr, T value);
 309   template <typename T>
 310   static void oop_store_at(oop base, ptrdiff_t offset, T value);
 311 
 312   template <typename T>
 313   static T oop_load(void* addr);
 314   template <typename T>
 315   static T oop_load_at(oop base, ptrdiff_t offset);
 316 
 317   template <typename T>
 318   static T oop_atomic_cmpxchg(void* addr, T compare_value, T new_value);
 319   template <typename T>
 320   static T oop_atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value);
 321 
 322   template <typename T>
 323   static T oop_atomic_xchg(void* addr, T new_value);

 328   static void store_at(oop base, ptrdiff_t offset, T value) {
 329     store(field_addr(base, offset), value);
 330   }
 331 
 332   template <typename T>
 333   static T load_at(oop base, ptrdiff_t offset) {
 334     return load<T>(field_addr(base, offset));
 335   }
 336 
 337   template <typename T>
 338   static T atomic_cmpxchg_at(oop base, ptrdiff_t offset, T compare_value, T new_value) {
 339     return atomic_cmpxchg(field_addr(base, offset), compare_value, new_value);
 340   }
 341 
 342   template <typename T>
 343   static T atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
 344     return atomic_xchg(field_addr(base, offset), new_value);
 345   }
 346 
 347   template <typename T>
 348   static void oop_arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 349                             arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 350                             size_t length);
 351 
 352   static void clone(oop src, oop dst, size_t size);
 353   static void value_copy(void* src, void* dst, InlineKlass* md, LayoutKind lk);
 354 
 355 };
 356 
 357 namespace AccessInternal {
 358   DEBUG_ONLY(void check_access_thread_state());
 359 #define assert_access_thread_state() DEBUG_ONLY(check_access_thread_state())
 360 }
 361 
 362 // Below is the implementation of the first 4 steps of the template pipeline:
 363 // * Step 1: Set default decorators and decay types. This step gets rid of CV qualifiers
 364 //           and sets default decorators to sensible values.
 365 // * Step 2: Reduce types. This step makes sure there is only a single T type and not
 366 //           multiple types. The P type of the address and T type of the value must
 367 //           match.
 368 // * Step 3: Pre-runtime dispatch. This step checks whether a runtime call can be
 369 //           avoided, and in that case avoids it (calling raw accesses or
 370 //           primitive accesses in a build that does not require primitive GC barriers)
 371 // * Step 4: Runtime-dispatch. This step performs a runtime dispatch to the corresponding
 372 //           BarrierSet::AccessBarrier accessor that attaches GC-required barriers
 373 //           to the access.
 374 

 504   };
 505 
 506   template <DecoratorSet decorators, typename T>
 507   struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG_AT>: AllStatic {
 508     typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG_AT>::type func_t;
 509     static func_t _atomic_xchg_at_func;
 510 
 511     static T atomic_xchg_at_init(oop base, ptrdiff_t offset, T new_value);
 512 
 513     static inline T atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
 514       assert_access_thread_state();
 515       return _atomic_xchg_at_func(base, offset, new_value);
 516     }
 517   };
 518 
 519   template <DecoratorSet decorators, typename T>
 520   struct RuntimeDispatch<decorators, T, BARRIER_ARRAYCOPY>: AllStatic {
 521     typedef typename AccessFunction<decorators, T, BARRIER_ARRAYCOPY>::type func_t;
 522     static func_t _arraycopy_func;
 523 
 524     static void arraycopy_init(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 525                                arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 526                                size_t length);
 527 
 528     static inline void arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 529                                  arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 530                                  size_t length) {
 531       assert_access_thread_state();
 532       return _arraycopy_func(src_obj, src_offset_in_bytes, src_raw,
 533                              dst_obj, dst_offset_in_bytes, dst_raw,
 534                              length);
 535     }
 536   };
 537 
 538   template <DecoratorSet decorators, typename T>
 539   struct RuntimeDispatch<decorators, T, BARRIER_CLONE>: AllStatic {
 540     typedef typename AccessFunction<decorators, T, BARRIER_CLONE>::type func_t;
 541     static func_t _clone_func;
 542 
 543     static void clone_init(oop src, oop dst, size_t size);
 544 
 545     static inline void clone(oop src, oop dst, size_t size) {
 546       assert_access_thread_state();
 547       _clone_func(src, dst, size);
 548     }
 549   };
 550 
 551   template <DecoratorSet decorators, typename T>
 552   struct RuntimeDispatch<decorators, T, BARRIER_VALUE_COPY>: AllStatic {
 553     typedef typename AccessFunction<decorators, T, BARRIER_VALUE_COPY>::type func_t;
 554     static func_t _value_copy_func;
 555 
 556     static void value_copy_init(void* src, void* dst, InlineKlass* md, LayoutKind lk);
 557 
 558     static inline void value_copy(void* src, void* dst, InlineKlass* md, LayoutKind lk) {
 559       _value_copy_func(src, dst, md, lk);
 560     }
 561   };
 562 
 563   // Initialize the function pointers to point to the resolving function.
 564   template <DecoratorSet decorators, typename T>
 565   typename AccessFunction<decorators, T, BARRIER_STORE>::type
 566   RuntimeDispatch<decorators, T, BARRIER_STORE>::_store_func = &store_init;
 567 
 568   template <DecoratorSet decorators, typename T>
 569   typename AccessFunction<decorators, T, BARRIER_STORE_AT>::type
 570   RuntimeDispatch<decorators, T, BARRIER_STORE_AT>::_store_at_func = &store_at_init;
 571 
 572   template <DecoratorSet decorators, typename T>
 573   typename AccessFunction<decorators, T, BARRIER_LOAD>::type
 574   RuntimeDispatch<decorators, T, BARRIER_LOAD>::_load_func = &load_init;
 575 
 576   template <DecoratorSet decorators, typename T>
 577   typename AccessFunction<decorators, T, BARRIER_LOAD_AT>::type
 578   RuntimeDispatch<decorators, T, BARRIER_LOAD_AT>::_load_at_func = &load_at_init;
 579 
 580   template <DecoratorSet decorators, typename T>
 581   typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG>::type
 582   RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG>::_atomic_cmpxchg_func = &atomic_cmpxchg_init;

 584   template <DecoratorSet decorators, typename T>
 585   typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::type
 586   RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::_atomic_cmpxchg_at_func = &atomic_cmpxchg_at_init;
 587 
 588   template <DecoratorSet decorators, typename T>
 589   typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG>::type
 590   RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG>::_atomic_xchg_func = &atomic_xchg_init;
 591 
 592   template <DecoratorSet decorators, typename T>
 593   typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG_AT>::type
 594   RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG_AT>::_atomic_xchg_at_func = &atomic_xchg_at_init;
 595 
 596   template <DecoratorSet decorators, typename T>
 597   typename AccessFunction<decorators, T, BARRIER_ARRAYCOPY>::type
 598   RuntimeDispatch<decorators, T, BARRIER_ARRAYCOPY>::_arraycopy_func = &arraycopy_init;
 599 
 600   template <DecoratorSet decorators, typename T>
 601   typename AccessFunction<decorators, T, BARRIER_CLONE>::type
 602   RuntimeDispatch<decorators, T, BARRIER_CLONE>::_clone_func = &clone_init;
 603 
 604   template <DecoratorSet decorators, typename T>
 605   typename AccessFunction<decorators, T, BARRIER_VALUE_COPY>::type
 606   RuntimeDispatch<decorators, T, BARRIER_VALUE_COPY>::_value_copy_func = &value_copy_init;
 607 
 608   // Step 3: Pre-runtime dispatching.
 609   // The PreRuntimeDispatch class is responsible for filtering the barrier strength
 610   // decorators. That is, for AS_RAW, it hardwires the accesses without a runtime
 611   // dispatch point. Otherwise it goes through a runtime check if hardwiring was
 612   // not possible.
 613   struct PreRuntimeDispatch: AllStatic {
 614     template<DecoratorSet decorators>
 615     struct CanHardwireRaw: public std::integral_constant<
 616       bool,
 617       !HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value || // primitive access
 618       !HasDecorator<decorators, INTERNAL_CONVERT_COMPRESSED_OOP>::value || // don't care about compressed oops (oop* address)
 619       HasDecorator<decorators, INTERNAL_RT_USE_COMPRESSED_OOPS>::value> // we can infer we use compressed oops (narrowOop* address)
 620     {};
 621 
 622     static const DecoratorSet convert_compressed_oops = INTERNAL_RT_USE_COMPRESSED_OOPS | INTERNAL_CONVERT_COMPRESSED_OOP;
 623 
 624     template<DecoratorSet decorators>
 625     static bool is_hardwired_primitive() {
 626       return !HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value;
 627     }

 835     inline static typename EnableIf<
 836       HasDecorator<decorators, AS_RAW>::value, T>::type
 837     atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
 838       return atomic_xchg<decorators>(field_addr(base, offset), new_value);
 839     }
 840 
 841     template <DecoratorSet decorators, typename T>
 842     inline static typename EnableIf<
 843       !HasDecorator<decorators, AS_RAW>::value, T>::type
 844     atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
 845       if (is_hardwired_primitive<decorators>()) {
 846         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 847         return PreRuntimeDispatch::atomic_xchg<expanded_decorators>(base, offset, new_value);
 848       } else {
 849         return RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG_AT>::atomic_xchg_at(base, offset, new_value);
 850       }
 851     }
 852 
 853     template <DecoratorSet decorators, typename T>
 854     inline static typename EnableIf<
 855       HasDecorator<decorators, AS_RAW>::value && CanHardwireRaw<decorators>::value, void>::type
 856     arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 857               arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 858               size_t length) {
 859       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 860       if (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value) {
 861         Raw::oop_arraycopy(src_obj, src_offset_in_bytes, src_raw,
 862                            dst_obj, dst_offset_in_bytes, dst_raw,
 863                            length);
 864       } else {
 865         Raw::arraycopy(src_obj, src_offset_in_bytes, src_raw,
 866                        dst_obj, dst_offset_in_bytes, dst_raw,
 867                        length);
 868       }
 869     }
 870 
 871     template <DecoratorSet decorators, typename T>
 872     inline static typename EnableIf<
 873       HasDecorator<decorators, AS_RAW>::value && !CanHardwireRaw<decorators>::value, void>::type
 874     arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 875               arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 876               size_t length) {
 877       if (UseCompressedOops) {
 878         const DecoratorSet expanded_decorators = decorators | convert_compressed_oops;
 879         PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
 880                                                            dst_obj, dst_offset_in_bytes, dst_raw,
 881                                                            length);
 882       } else {
 883         const DecoratorSet expanded_decorators = decorators & ~convert_compressed_oops;
 884         PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
 885                                                            dst_obj, dst_offset_in_bytes, dst_raw,
 886                                                            length);
 887       }
 888     }
 889 
 890     template <DecoratorSet decorators, typename T>
 891     inline static typename EnableIf<
 892       !HasDecorator<decorators, AS_RAW>::value, void>::type
 893     arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
 894               arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
 895               size_t length) {
 896       if (is_hardwired_primitive<decorators>()) {
 897         const DecoratorSet expanded_decorators = decorators | AS_RAW;
 898         PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
 899                                                            dst_obj, dst_offset_in_bytes, dst_raw,
 900                                                            length);
 901       } else {
 902         RuntimeDispatch<decorators, T, BARRIER_ARRAYCOPY>::arraycopy(src_obj, src_offset_in_bytes, src_raw,
 903                                                                      dst_obj, dst_offset_in_bytes, dst_raw,
 904                                                                      length);
 905       }
 906     }
 907 
 908     template <DecoratorSet decorators>
 909     inline static typename EnableIf<
 910       HasDecorator<decorators, AS_RAW>::value>::type
 911     clone(oop src, oop dst, size_t size) {
 912       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 913       Raw::clone(src, dst, size);
 914     }
 915 
 916     template <DecoratorSet decorators>
 917     inline static typename EnableIf<
 918       !HasDecorator<decorators, AS_RAW>::value>::type
 919     clone(oop src, oop dst, size_t size) {
 920       RuntimeDispatch<decorators, oop, BARRIER_CLONE>::clone(src, dst, size);
 921     }
 922 
 923     template <DecoratorSet decorators>
 924     inline static typename EnableIf<
 925       HasDecorator<decorators, AS_RAW>::value>::type
 926     value_copy(void* src, void* dst, InlineKlass* md, LayoutKind lk) {
 927       typedef RawAccessBarrier<decorators & RAW_DECORATOR_MASK> Raw;
 928       Raw::value_copy(src, dst, md, lk);
 929     }
 930 
 931     template <DecoratorSet decorators>
 932     inline static typename EnableIf<
 933       !HasDecorator<decorators, AS_RAW>::value>::type
 934       value_copy(void* src, void* dst, InlineKlass* md, LayoutKind lk) {
 935       const DecoratorSet expanded_decorators = decorators;
 936       RuntimeDispatch<expanded_decorators, void*, BARRIER_VALUE_COPY>::value_copy(src, dst, md, lk);
 937     }
 938   };
 939 
 940   // Step 2: Reduce types.
 941   // Enforce that for non-oop types, T and P have to be strictly the same.
 942   // P is the type of the address and T is the type of the values.
 943   // As for oop types, it is allow to send T in {narrowOop, oop} and
 944   // P in {narrowOop, oop, HeapWord*}. The following rules apply according to
 945   // the subsequent table. (columns are P, rows are T)
 946   // |           | HeapWord  |   oop   | narrowOop |
 947   // |   oop     |  rt-comp  | hw-none |  hw-comp  |
 948   // | narrowOop |     x     |    x    |  hw-none  |
 949   //
 950   // x means not allowed
 951   // rt-comp means it must be checked at runtime whether the oop is compressed.
 952   // hw-none means it is statically known the oop will not be compressed.
 953   // hw-comp means it is statically known the oop will be compressed.
 954 
 955   template <DecoratorSet decorators, typename T>
 956   inline void store_reduce_types(T* addr, T value) {
 957     PreRuntimeDispatch::store<decorators>(addr, value);

1032 
1033   template <DecoratorSet decorators, typename T>
1034   inline T load_reduce_types(T* addr) {
1035     return PreRuntimeDispatch::load<decorators, T>(addr);
1036   }
1037 
1038   template <DecoratorSet decorators, typename T>
1039   inline typename OopOrNarrowOop<T>::type load_reduce_types(narrowOop* addr) {
1040     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
1041                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
1042     return PreRuntimeDispatch::load<expanded_decorators, typename OopOrNarrowOop<T>::type>(addr);
1043   }
1044 
1045   template <DecoratorSet decorators, typename T>
1046   inline oop load_reduce_types(HeapWord* addr) {
1047     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP;
1048     return PreRuntimeDispatch::load<expanded_decorators, oop>(addr);
1049   }
1050 
1051   template <DecoratorSet decorators, typename T>
1052   inline void arraycopy_reduce_types(arrayOop src_obj, size_t src_offset_in_bytes, T* src_raw,
1053                                      arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
1054                                      size_t length) {
1055     PreRuntimeDispatch::arraycopy<decorators>(src_obj, src_offset_in_bytes, src_raw,
1056                                               dst_obj, dst_offset_in_bytes, dst_raw,
1057                                               length);
1058   }
1059 
1060   template <DecoratorSet decorators>
1061   inline void arraycopy_reduce_types(arrayOop src_obj, size_t src_offset_in_bytes, HeapWord* src_raw,
1062                                      arrayOop dst_obj, size_t dst_offset_in_bytes, HeapWord* dst_raw,
1063                                      size_t length) {
1064     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP;
1065     PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
1066                                                        dst_obj, dst_offset_in_bytes, dst_raw,
1067                                                        length);
1068   }
1069 
1070   template <DecoratorSet decorators>
1071   inline void arraycopy_reduce_types(arrayOop src_obj, size_t src_offset_in_bytes, narrowOop* src_raw,
1072                                      arrayOop dst_obj, size_t dst_offset_in_bytes, narrowOop* dst_raw,
1073                                      size_t length) {
1074     const DecoratorSet expanded_decorators = decorators | INTERNAL_CONVERT_COMPRESSED_OOP |
1075                                              INTERNAL_RT_USE_COMPRESSED_OOPS;
1076     PreRuntimeDispatch::arraycopy<expanded_decorators>(src_obj, src_offset_in_bytes, src_raw,
1077                                                        dst_obj, dst_offset_in_bytes, dst_raw,
1078                                                        length);
1079   }
1080 
1081   // Step 1: Set default decorators. This step remembers if a type was volatile
1082   // and then sets the MO_RELAXED decorator by default. Otherwise, a default
1083   // memory ordering is set for the access, and the implied decorator rules
1084   // are applied to select sensible defaults for decorators that have not been
1085   // explicitly set. For example, default object referent strength is set to strong.
1086   // This step also decays the types passed in (e.g. getting rid of CV qualifiers
1087   // and references from the types). This step also perform some type verification
1088   // that the passed in types make sense.
1089 
1090   template <DecoratorSet decorators, typename T>
1091   static void verify_types(){
1092     // If this fails to compile, then you have sent in something that is
1093     // not recognized as a valid primitive type to a primitive Access function.
1094     STATIC_ASSERT((HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value || // oops have already been validated
1095                    (std::is_pointer<T>::value || std::is_integral<T>::value) ||
1096                     std::is_floating_point<T>::value)); // not allowed primitive type
1097   }
1098 

1191     DecayedT new_decayed_value = new_value;
1192     // atomic_xchg is only available in SEQ_CST flavour.
1193     const DecoratorSet expanded_decorators = DecoratorFixup<decorators | MO_SEQ_CST>::value;
1194     return atomic_xchg_reduce_types<expanded_decorators>(const_cast<DecayedP*>(addr),
1195                                                          new_decayed_value);
1196   }
1197 
1198   template <DecoratorSet decorators, typename T>
1199   inline T atomic_xchg_at(oop base, ptrdiff_t offset, T new_value) {
1200     verify_types<decorators, T>();
1201     using DecayedT = std::decay_t<T>;
1202     DecayedT new_decayed_value = new_value;
1203     // atomic_xchg is only available in SEQ_CST flavour.
1204     const DecoratorSet expanded_decorators = DecoratorFixup<decorators | MO_SEQ_CST |
1205                                              (HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value ?
1206                                               INTERNAL_CONVERT_COMPRESSED_OOP : DECORATORS_NONE)>::value;
1207     return PreRuntimeDispatch::atomic_xchg_at<expanded_decorators>(base, offset, new_decayed_value);
1208   }
1209 
1210   template <DecoratorSet decorators, typename T>
1211   inline void arraycopy(arrayOop src_obj, size_t src_offset_in_bytes, const T* src_raw,
1212                         arrayOop dst_obj, size_t dst_offset_in_bytes, T* dst_raw,
1213                         size_t length) {
1214     STATIC_ASSERT((HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value ||
1215                    (std::is_same<T, void>::value || std::is_integral<T>::value) ||
1216                     std::is_floating_point<T>::value)); // arraycopy allows type erased void elements
1217     using DecayedT = std::decay_t<T>;
1218     const DecoratorSet expanded_decorators = DecoratorFixup<decorators | IS_ARRAY | IN_HEAP>::value;
1219     arraycopy_reduce_types<expanded_decorators>(src_obj, src_offset_in_bytes, const_cast<DecayedT*>(src_raw),
1220                                                 dst_obj, dst_offset_in_bytes, const_cast<DecayedT*>(dst_raw),
1221                                                 length);
1222   }
1223 
1224   template <DecoratorSet decorators>
1225   inline void clone(oop src, oop dst, size_t size) {
1226     const DecoratorSet expanded_decorators = DecoratorFixup<decorators>::value;
1227     PreRuntimeDispatch::clone<expanded_decorators>(src, dst, size);
1228   }
1229 
1230   template <DecoratorSet decorators>
1231   inline void value_copy(void* src, void* dst, InlineKlass* md, LayoutKind lk) {
1232     const DecoratorSet expanded_decorators = DecoratorFixup<decorators>::value;
1233     PreRuntimeDispatch::value_copy<expanded_decorators>(src, dst, md, lk);
1234   }
1235 
1236   // Infer the type that should be returned from an Access::oop_load.
1237   template <typename P, DecoratorSet decorators>
1238   class OopLoadProxy: public StackObj {
1239   private:
1240     P *const _addr;
1241   public:
1242     explicit OopLoadProxy(P* addr) : _addr(addr) {}
1243 
1244     inline operator oop() {
1245       return load<decorators | INTERNAL_VALUE_IS_OOP, P, oop>(_addr);
1246     }
1247 
1248     inline operator narrowOop() {
1249       return load<decorators | INTERNAL_VALUE_IS_OOP, P, narrowOop>(_addr);
1250     }
1251 
1252     template <typename T>
1253     inline bool operator ==(const T& other) const {
1254       return load<decorators | INTERNAL_VALUE_IS_OOP, P, T>(_addr) == other;
1255     }
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