/*

 * Copyright (c) 2017, 2018, 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_OOPS_ACCESSBACKEND_HPP

#define SHARE_OOPS_ACCESSBACKEND_HPP

#include "gc/shared/barrierSetConfig.hpp"

#include "memory/allocation.hpp"

#include "metaprogramming/conditional.hpp"

#include "metaprogramming/decay.hpp"

#include "metaprogramming/enableIf.hpp"

#include "metaprogramming/integralConstant.hpp"

#include "metaprogramming/isFloatingPoint.hpp"

#include "metaprogramming/isIntegral.hpp"

#include "metaprogramming/isPointer.hpp"

#include "metaprogramming/isSame.hpp"

#include "metaprogramming/isVolatile.hpp"

#include "oops/accessDecorators.hpp"

#include "oops/oopsHierarchy.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,

    BARRIER_RESOLVE,

    BARRIER_EQUALS

  };

  template <DecoratorSet decorators, typename T>

  struct MustConvertCompressedOop: public IntegralConstant<bool,

    HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value &&

    IsSame<typename HeapOopType<decorators>::type, narrowOop>::value &&

    IsSame<T, oop>::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)> {};

#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 void (*clone_func_t)(oop src, oop dst, size_t size);

    typedef oop (*resolve_func_t)(oop obj);

    typedef bool (*equals_func_t)(oop o1, oop o2);

  };

  template <DecoratorSet decorators>

  struct AccessFunctionTypes<decorators, void> {

  };

  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);

  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_RESOLVE, resolve_func_t);

  ACCESS_GENERATE_ACCESS_FUNCTION(BARRIER_EQUALS, equals_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 {

  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, T>::value,

    typename HeapOopType<idecorators>::type>::type

  encode_internal(T value);

  template <DecoratorSet idecorators, typename T>

  static inline typename EnableIf<

    !AccessInternal::MustConvertCompressedOop<idecorators, T>::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, T>::value, T>::type

  decode_internal(typename HeapOopType<idecorators>::type value);

  template <DecoratorSet idecorators, typename T>

  static inline typename EnableIf<

    !AccessInternal::MustConvertCompressedOop<idecorators, T>::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) {

  }

  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>

  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 void clone(oop src, oop dst, size_t size);

  static oop resolve(oop obj) { return obj; }

  static bool equals(oop o1, oop o2) { return o1 == o2; }

};

// Below is the implementation of the first 4 steps of the template pipeline:

// * Step 1: Set default decorators and decay types. This step gets rid of CV qualifiers

//           and sets default decorators to sensible values.

// * Step 2: Reduce types. This step makes sure there is only a single T type and not

//           multiple types. The P type of the address and T type of the value must

//           match.

// * Step 3: Pre-runtime dispatch. This step checks whether a runtime call can be

//           avoided, and in that case avoids it (calling raw accesses or

//           primitive accesses in a build that does not require primitive GC barriers)

// * Step 4: Runtime-dispatch. This step performs a runtime dispatch to the corresponding

//           BarrierSet::AccessBarrier accessor that attaches GC-required barriers

//           to the access.

namespace AccessInternal {

  template <typename T>

  struct OopOrNarrowOopInternal: AllStatic {

    typedef oop type;

  };

  template <>

  struct OopOrNarrowOopInternal<narrowOop>: AllStatic {

    typedef narrowOop type;

  };

  // This metafunction returns a canonicalized oop/narrowOop type for a passed

  // in oop-like types passed in from oop_* overloads where the user has sworn

  // that the passed in values should be oop-like (e.g. oop, oopDesc*, arrayOop,

  // narrowOoop, instanceOopDesc*, and random other things).

  // In the oop_* overloads, it must hold that if the passed in type T is not

  // narrowOop, then it by contract has to be one of many oop-like types implicitly

  // convertible to oop, and hence returns oop as the canonical oop type.

  // If it turns out it was not, then the implicit conversion to oop will fail

  // to compile, as desired.

  template <typename T>

  struct OopOrNarrowOop: AllStatic {

    typedef typename OopOrNarrowOopInternal<typename Decay<T>::type>::type type;

  };

  inline void* field_addr(oop base, ptrdiff_t byte_offset) {

    return reinterpret_cast<void*>(reinterpret_cast<intptr_t>((void*)base) + byte_offset);

  }

  // Step 4: Runtime dispatch

  // The RuntimeDispatch class is responsible for performing a runtime dispatch of the

  // accessor. This is required when the access either depends on whether compressed oops

  // is being used, or it depends on which GC implementation was chosen (e.g. requires GC

  // barriers). The way it works is that a function pointer initially pointing to an

  // accessor resolution function gets called for each access. Upon first invocation,

  // it resolves which accessor to be used in future invocations and patches the

  // function pointer to this new accessor.

  template <DecoratorSet decorators, typename T, BarrierType type>

  struct RuntimeDispatch: AllStatic {};

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_STORE>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_STORE>::type func_t;

    static func_t _store_func;

    static void store_init(void* addr, T value);

    static inline void store(void* addr, T value) {

      _store_func(addr, value);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_STORE_AT>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_STORE_AT>::type func_t;

    static func_t _store_at_func;

    static void store_at_init(oop base, ptrdiff_t offset, T value);

    static inline void store_at(oop base, ptrdiff_t offset, T value) {

      _store_at_func(base, offset, value);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_LOAD>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_LOAD>::type func_t;

    static func_t _load_func;

    static T load_init(void* addr);

    static inline T load(void* addr) {

      return _load_func(addr);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_LOAD_AT>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_LOAD_AT>::type func_t;

    static func_t _load_at_func;

    static T load_at_init(oop base, ptrdiff_t offset);

    static inline T load_at(oop base, ptrdiff_t offset) {

      return _load_at_func(base, offset);

    }

  };