--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/oops/accessBackend.hpp	Mon Nov 20 13:07:44 2017 +0100
@@ -0,0 +1,383 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_RUNTIME_ACCESSBACKEND_HPP
+#define SHARE_VM_RUNTIME_ACCESSBACKEND_HPP
+
+#include "metaprogramming/conditional.hpp"
+#include "metaprogramming/enableIf.hpp"
+#include "metaprogramming/integralConstant.hpp"
+#include "utilities/debug.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+// This metafunction returns either oop or narrowOop depending on whether
+// an access needs to use compressed oops or not.
+template <DecoratorSet decorators>
+struct HeapOopType: AllStatic {
+  static const bool needs_oop_compress = HasDecorator<decorators, INTERNAL_CONVERT_COMPRESSED_OOP>::value &&
+                                         HasDecorator<decorators, INTERNAL_RT_USE_COMPRESSED_OOPS>::value;
+  typedef typename Conditional<needs_oop_compress, narrowOop, oop>::type type;
+};
+
+namespace AccessInternal {
+  enum BarrierType {
+    BARRIER_STORE,
+    BARRIER_STORE_AT,
+    BARRIER_LOAD,
+    BARRIER_LOAD_AT,
+    BARRIER_ATOMIC_CMPXCHG,
+    BARRIER_ATOMIC_CMPXCHG_AT,
+    BARRIER_ATOMIC_XCHG,
+    BARRIER_ATOMIC_XCHG_AT,
+    BARRIER_ARRAYCOPY,
+    BARRIER_CLONE
+  };
+
+  template <DecoratorSet decorators>
+  struct MustConvertCompressedOop: public IntegralConstant<bool,
+    HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value &&
+    HasDecorator<decorators, INTERNAL_CONVERT_COMPRESSED_OOP>::value &&
+    HasDecorator<decorators, INTERNAL_RT_USE_COMPRESSED_OOPS>::value> {};
+
+  // This metafunction returns an appropriate oop type if the value is oop-like
+  // and otherwise returns the same type T.
+  template <DecoratorSet decorators, typename T>
+  struct EncodedType: AllStatic {
+    typedef typename Conditional<
+      HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value,
+      typename HeapOopType<decorators>::type, T>::type type;
+  };
+
+  template <DecoratorSet decorators>
+  inline typename HeapOopType<decorators>::type*
+  oop_field_addr(oop base, ptrdiff_t byte_offset) {
+    return reinterpret_cast<typename HeapOopType<decorators>::type*>(
+             reinterpret_cast<intptr_t>((void*)base) + byte_offset);
+  }
+
+  // This metafunction returns whether it is possible for a type T to require
+  // locking to support wide atomics or not.
+  template <typename T>
+#ifdef SUPPORTS_NATIVE_CX8
+  struct PossiblyLockedAccess: public IntegralConstant<bool, false> {};
+#else
+  struct PossiblyLockedAccess: public IntegralConstant<bool, (sizeof(T) > 4)>::value> {};
+#endif
+
+  template <DecoratorSet decorators, typename T>
+  struct AccessFunctionTypes {
+    typedef T (*load_at_func_t)(oop base, ptrdiff_t offset);
+    typedef void (*store_at_func_t)(oop base, ptrdiff_t offset, T value);
+    typedef T (*atomic_cmpxchg_at_func_t)(T new_value, oop base, ptrdiff_t offset, T compare_value);
+    typedef T (*atomic_xchg_at_func_t)(T new_value, oop base, ptrdiff_t offset);
+
+    typedef T (*load_func_t)(void* addr);
+    typedef void (*store_func_t)(void* addr, T value);
+    typedef T (*atomic_cmpxchg_func_t)(T new_value, void* addr, T compare_value);
+    typedef T (*atomic_xchg_func_t)(T new_value, void* addr);
+
+    typedef bool (*arraycopy_func_t)(arrayOop src_obj, arrayOop dst_obj, T* src, T* dst, size_t length);
+    typedef void (*clone_func_t)(oop src, oop dst, size_t size);
+  };
+
+  template <DecoratorSet decorators, typename T, BarrierType barrier> struct AccessFunction {};
+
+#define ACCESS_GENERATE_ACCESS_FUNCTION(bt, func)                   \
+  template <DecoratorSet decorators, typename T>                    \
+  struct AccessFunction<decorators, T, bt>: AllStatic{              \
+    typedef typename AccessFunctionTypes<decorators, T>::func type; \
+  }
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_STORE, store_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_STORE_AT, store_at_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_LOAD, load_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_LOAD_AT, load_at_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_CMPXCHG, atomic_cmpxchg_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_CMPXCHG_AT, atomic_cmpxchg_at_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_XCHG, atomic_xchg_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ATOMIC_XCHG_AT, atomic_xchg_at_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_ARRAYCOPY, arraycopy_func_t);
+  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_CLONE, clone_func_t);
+#undef ACCESS_GENERATE_ACCESS_FUNCTION
+
+  template <DecoratorSet decorators, typename T, BarrierType barrier_type>
+  typename AccessFunction<decorators, T, barrier_type>::type resolve_barrier();
+
+  template <DecoratorSet decorators, typename T, BarrierType barrier_type>
+  typename AccessFunction<decorators, T, barrier_type>::type resolve_oop_barrier();
+
+  class AccessLocker VALUE_OBJ_CLASS_SPEC {
+  public:
+    AccessLocker();
+    ~AccessLocker();
+  };
+  bool wide_atomic_needs_locking();
+
+  void* field_addr(oop base, ptrdiff_t offset);
+
+  // Forward calls to Copy:: in the cpp file to reduce dependencies and allow
+  // faster build times, given how frequently included access is.
+  void arraycopy_arrayof_conjoint_oops(void* src, void* dst, size_t length);
+  void arraycopy_conjoint_oops(oop* src, oop* dst, size_t length);
+  void arraycopy_conjoint_oops(narrowOop* src, narrowOop* dst, size_t length);
+
+  void arraycopy_disjoint_words(void* src, void* dst, size_t length);
+  void arraycopy_disjoint_words_atomic(void* src, void* dst, size_t length);
+
+  template<typename T>
+  void arraycopy_conjoint(T* src, T* dst, size_t length);
+  template<typename T>
+  void arraycopy_arrayof_conjoint(T* src, T* dst, size_t length);
+  template<typename T>
+  void arraycopy_conjoint_atomic(T* src, T* dst, size_t length);
+}
+
+// This mask specifies what decorators are relevant for raw accesses. When passing
+// accesses to the raw layer, irrelevant decorators are removed.
+const DecoratorSet RAW_DECORATOR_MASK = INTERNAL_DECORATOR_MASK | MO_DECORATOR_MASK |
+                                        ARRAYCOPY_DECORATOR_MASK | OOP_DECORATOR_MASK;
+
+// The RawAccessBarrier performs raw accesses with additional knowledge of
+// memory ordering, so that OrderAccess/Atomic is called when necessary.
+// It additionally handles compressed oops, and hence is not completely "raw"
+// strictly speaking.
+template <DecoratorSet decorators>
+class RawAccessBarrier: public AllStatic {
+protected:
+  static inline void* field_addr(oop base, ptrdiff_t byte_offset) {
+    return AccessInternal::field_addr(base, byte_offset);
+  }
+
+protected:
+  // Only encode if INTERNAL_VALUE_IS_OOP
+  template <DecoratorSet idecorators, typename T>
+  static inline typename EnableIf<
+    AccessInternal::MustConvertCompressedOop<idecorators>::value,
+    typename HeapOopType<idecorators>::type>::type
+  encode_internal(T value);
+
+  template <DecoratorSet idecorators, typename T>
+  static inline typename EnableIf<
+    !AccessInternal::MustConvertCompressedOop<idecorators>::value, T>::type
+  encode_internal(T value) {
+    return value;
+  }
+
+  template <typename T>
+  static inline typename AccessInternal::EncodedType<decorators, T>::type
+  encode(T value) {
+    return encode_internal<decorators, T>(value);
+  }
+
+  // Only decode if INTERNAL_VALUE_IS_OOP
+  template <DecoratorSet idecorators, typename T>
+  static inline typename EnableIf<
+    AccessInternal::MustConvertCompressedOop<idecorators>::value, T>::type
+  decode_internal(typename HeapOopType<idecorators>::type value);
+
+  template <DecoratorSet idecorators, typename T>
+  static inline typename EnableIf<
+    !AccessInternal::MustConvertCompressedOop<idecorators>::value, T>::type
+  decode_internal(T value) {
+    return value;
+  }
+
+  template <typename T>
+  static inline T decode(typename AccessInternal::EncodedType<decorators, T>::type value) {
+    return decode_internal<decorators, T>(value);
+  }
+
+protected:
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_SEQ_CST>::value, T>::type
+  load_internal(void* addr);
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_ACQUIRE>::value, T>::type
+  load_internal(void* addr);
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_RELAXED>::value, T>::type
+  load_internal(void* addr);
+
+  template <DecoratorSet ds, typename T>
+  static inline typename EnableIf<
+    HasDecorator<ds, MO_VOLATILE>::value, T>::type
+  load_internal(void* addr) {
+    return *reinterpret_cast<const volatile T*>(addr);
+  }
+
+  template <DecoratorSet ds, typename T>
+  static inline typename EnableIf<
+    HasDecorator<ds, MO_UNORDERED>::value, T>::type
+  load_internal(void* addr) {
+    return *reinterpret_cast<const T*>(addr);
+  }
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_SEQ_CST>::value>::type
+  store_internal(void* addr, T value);
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_RELEASE>::value>::type
+  store_internal(void* addr, T value);
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_RELAXED>::value>::type
+  store_internal(void* addr, T value);
+
+  template <DecoratorSet ds, typename T>
+  static inline typename EnableIf<
+    HasDecorator<ds, MO_VOLATILE>::value>::type
+  store_internal(void* addr, T value) {
+    (void)const_cast<T&>(*reinterpret_cast<volatile T*>(addr) = value);
+  }
+
+  template <DecoratorSet ds, typename T>
+  static inline typename EnableIf<
+    HasDecorator<ds, MO_UNORDERED>::value>::type
+  store_internal(void* addr, T value) {
+    *reinterpret_cast<T*>(addr) = value;
+  }
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_SEQ_CST>::value, T>::type
+  atomic_cmpxchg_internal(T new_value, void* addr, T compare_value);
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_RELAXED>::value, T>::type
+  atomic_cmpxchg_internal(T new_value, void* addr, T compare_value);
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    HasDecorator<ds, MO_SEQ_CST>::value, T>::type
+  atomic_xchg_internal(T new_value, void* addr);
+
+  // The following *_locked mechanisms serve the purpose of handling atomic operations
+  // that are larger than a machine can handle, and then possibly opt for using
+  // a slower path using a mutex to perform the operation.
+
+  template <DecoratorSet ds, typename T>
+  static inline typename EnableIf<
+    !AccessInternal::PossiblyLockedAccess<T>::value, T>::type
+  atomic_cmpxchg_maybe_locked(T new_value, void* addr, T compare_value) {
+    return atomic_cmpxchg_internal<ds>(new_value, addr, compare_value);
+  }
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    AccessInternal::PossiblyLockedAccess<T>::value, T>::type
+  atomic_cmpxchg_maybe_locked(T new_value, void* addr, T compare_value);
+
+  template <DecoratorSet ds, typename T>
+  static inline typename EnableIf<
+    !AccessInternal::PossiblyLockedAccess<T>::value, T>::type
+  atomic_xchg_maybe_locked(T new_value, void* addr) {
+    return atomic_xchg_internal<ds>(new_value, addr);
+  }
+
+  template <DecoratorSet ds, typename T>
+  static typename EnableIf<
+    AccessInternal::PossiblyLockedAccess<T>::value, T>::type
+  atomic_xchg_maybe_locked(T new_value, void* addr);
+
+public:
+  template <typename T>
+  static inline void store(void* addr, T value) {
+    store_internal<decorators>(addr, value);
+  }
+
+  template <typename T>
+  static inline T load(void* addr) {
+    return load_internal<decorators, T>(addr);
+  }
+
+  template <typename T>
+  static inline T atomic_cmpxchg(T new_value, void* addr, T compare_value) {
+    return atomic_cmpxchg_maybe_locked<decorators>(new_value, addr, compare_value);
+  }
+
+  template <typename T>
+  static inline T atomic_xchg(T new_value, void* addr) {
+    return atomic_xchg_maybe_locked<decorators>(new_value, addr);
+  }
+
+  template <typename T>
+  static bool arraycopy(T* src, T* dst, size_t length);
+
+  template <typename T>
+  static void oop_store(void* addr, T value);
+  template <typename T>
+  static void oop_store_at(oop base, ptrdiff_t offset, T value);
+
+  template <typename T>
+  static T oop_load(void* addr);
+  template <typename T>
+  static T oop_load_at(oop base, ptrdiff_t offset);
+
+  template <typename T>
+  static T oop_atomic_cmpxchg(T new_value, void* addr, T compare_value);
+  template <typename T>
+  static T oop_atomic_cmpxchg_at(T new_value, oop base, ptrdiff_t offset, T compare_value);
+
+  template <typename T>
+  static T oop_atomic_xchg(T new_value, void* addr);
+  template <typename T>
+  static T oop_atomic_xchg_at(T new_value, oop base, ptrdiff_t offset);
+
+  template <typename T>
+  static void store_at(oop base, ptrdiff_t offset, T value) {
+    store(field_addr(base, offset), value);
+  }
+
+  template <typename T>
+  static T load_at(oop base, ptrdiff_t offset) {
+    return load<T>(field_addr(base, offset));
+  }
+
+  template <typename T>
+  static T atomic_cmpxchg_at(T new_value, oop base, ptrdiff_t offset, T compare_value) {
+    return atomic_cmpxchg(new_value, field_addr(base, offset), compare_value);
+  }
+
+  template <typename T>
+  static T atomic_xchg_at(T new_value, oop base, ptrdiff_t offset) {
+    return atomic_xchg(new_value, field_addr(base, offset));
+  }
+
+  template <typename T>
+  static bool oop_arraycopy(arrayOop src_obj, arrayOop dst_obj, T* src, T* dst, size_t length);
+  static bool oop_arraycopy(arrayOop src_obj, arrayOop dst_obj, HeapWord* src, HeapWord* dst, size_t length);
+
+  static void clone(oop src, oop dst, size_t size);
+};
+
+#endif // SHARE_VM_RUNTIME_ACCESSBACKEND_HPP