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#ifndef SHARE_OOPS_ACCESS_HPP

#define SHARE_OOPS_ACCESS_HPP

#include "memory/allocation.hpp"

#include "oops/accessBackend.hpp"

#include "oops/accessDecorators.hpp"

#include "oops/oopsHierarchy.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

// = GENERAL =

// Access is an API for performing accesses with declarative semantics. Each access can have a number of "decorators".

// A decorator is an attribute or property that affects the way a memory access is performed in some way.

// There are different groups of decorators. Some have to do with memory ordering, others to do with,

// e.g. strength of references, strength of GC barriers, or whether compression should be applied or not.

// Some decorators are set at buildtime, such as whether primitives require GC barriers or not, others

// at callsites such as whether an access is in the heap or not, and others are resolved at runtime

// such as GC-specific barriers and encoding/decoding compressed oops. For more information about what

// decorators are available, cf. oops/accessDecorators.hpp.

// By pipelining handling of these decorators, the design of the Access API allows separation of concern

// over the different orthogonal concerns of decorators, while providing a powerful way of

// expressing these orthogonal semantic properties in a unified way.

//

// == OPERATIONS ==

// * load: Load a value from an address.

// * load_at: Load a value from an internal pointer relative to a base object.

// * store: Store a value at an address.

// * store_at: Store a value in an internal pointer relative to a base object.

// * atomic_cmpxchg: Atomically compare-and-swap a new value at an address if previous value matched the compared value.

// * atomic_cmpxchg_at: Atomically compare-and-swap a new value at an internal pointer address if previous value matched the compared value.

// * atomic_xchg: Atomically swap a new value at an address if previous value matched the compared value.

// * atomic_xchg_at: Atomically swap a new value at an internal pointer address if previous value matched the compared value.

// * arraycopy: Copy data from one heap array to another heap array.

// * clone: Clone the contents of an object to a newly allocated object.

// * resolve: Resolve a stable to-space invariant oop that is guaranteed not to relocate its payload until a subsequent thread transition.

// * equals: Object equality, e.g. when different copies of the same objects are in use (from-space vs. to-space)

//

// == IMPLEMENTATION ==

// Each access goes through the following steps in a template pipeline.

// There are essentially 5 steps for each access:

// * 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.

// * Step 5.a: Barrier resolution. This step is invoked the first time a runtime-dispatch

//             happens for an access. The appropriate BarrierSet::AccessBarrier accessor

//             is resolved, then the function pointer is updated to that accessor for

//             future invocations.

// * Step 5.b: Post-runtime dispatch. This step now casts previously unknown types such

//             as the address type of an oop on the heap (is it oop* or narrowOop*) to

//             the appropriate type. It also splits sufficiently orthogonal accesses into

//             different functions, such as whether the access involves oops or primitives

//             and whether the access is performed on the heap or outside. Then the

//             appropriate BarrierSet::AccessBarrier is called to perform the access.

//

// The implementation of step 1-4 resides in in accessBackend.hpp, to allow selected

// accesses to be accessible from only access.hpp, as opposed to access.inline.hpp.

// Steps 5.a and 5.b require knowledge about the GC backends, and therefore needs to

// include the various GC backend .inline.hpp headers. Their implementation resides in

// access.inline.hpp. The accesses that are allowed through the access.hpp file

// must be instantiated in access.cpp using the INSTANTIATE_HPP_ACCESS macro.

template <DecoratorSet decorators = INTERNAL_EMPTY>

class Access: public AllStatic {

  // This function asserts that if an access gets passed in a decorator outside

  // of the expected_decorators, then something is wrong. It additionally checks

  // the consistency of the decorators so that supposedly disjoint decorators are indeed

  // disjoint. For example, an access can not be both in heap and on root at the

  // same time.

  template <DecoratorSet expected_decorators>

  static void verify_decorators();

  template <DecoratorSet expected_mo_decorators>

  static void verify_primitive_decorators() {

    const DecoratorSet primitive_decorators = (AS_DECORATOR_MASK ^ AS_NO_KEEPALIVE ^ AS_DEST_NOT_INITIALIZED) |

                                              IN_HEAP | IN_HEAP_ARRAY;

    verify_decorators<expected_mo_decorators | primitive_decorators>();

  }

  template <DecoratorSet expected_mo_decorators>

  static void verify_oop_decorators() {

    const DecoratorSet oop_decorators = AS_DECORATOR_MASK | IN_DECORATOR_MASK |

                                        (ON_DECORATOR_MASK ^ ON_UNKNOWN_OOP_REF) | // no unknown oop refs outside of the heap

                                        OOP_DECORATOR_MASK;

    verify_decorators<expected_mo_decorators | oop_decorators>();

  }

  template <DecoratorSet expected_mo_decorators>

  static void verify_heap_oop_decorators() {

    const DecoratorSet heap_oop_decorators = AS_DECORATOR_MASK | ON_DECORATOR_MASK |

                                             OOP_DECORATOR_MASK | (IN_DECORATOR_MASK ^

                                                                   (IN_ROOT | IN_CONCURRENT_ROOT)); // no root accesses in the heap

    verify_decorators<expected_mo_decorators | heap_oop_decorators>();

  }

  static const DecoratorSet load_mo_decorators = MO_UNORDERED | MO_VOLATILE | MO_RELAXED | MO_ACQUIRE | MO_SEQ_CST;

  static const DecoratorSet store_mo_decorators = MO_UNORDERED | MO_VOLATILE | MO_RELAXED | MO_RELEASE | MO_SEQ_CST;

  static const DecoratorSet atomic_xchg_mo_decorators = MO_SEQ_CST;

  static const DecoratorSet atomic_cmpxchg_mo_decorators = MO_RELAXED | MO_SEQ_CST;

public:

  // Primitive heap accesses

  static inline AccessInternal::LoadAtProxy<decorators> load_at(oop base, ptrdiff_t offset) {

    verify_primitive_decorators<load_mo_decorators>();

    return AccessInternal::LoadAtProxy<decorators>(base, offset);

  }

  template <typename T>

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

    verify_primitive_decorators<store_mo_decorators>();

    AccessInternal::store_at<decorators>(base, offset, value);

  }

  template <typename T>

  static inline T atomic_cmpxchg_at(T new_value, oop base, ptrdiff_t offset, T compare_value) {

    verify_primitive_decorators<atomic_cmpxchg_mo_decorators>();

    return AccessInternal::atomic_cmpxchg_at<decorators>(new_value, base, offset, compare_value);

  }

  template <typename T>

  static inline T atomic_xchg_at(T new_value, oop base, ptrdiff_t offset) {

    verify_primitive_decorators<atomic_xchg_mo_decorators>();

    return AccessInternal::atomic_xchg_at<decorators>(new_value, base, offset);

  }

  template <typename T>

  static inline void arraycopy(arrayOop src_obj, arrayOop dst_obj, T *src, T *dst, size_t length) {

    verify_decorators<ARRAYCOPY_DECORATOR_MASK | IN_HEAP |

                      AS_DECORATOR_MASK>();

    AccessInternal::arraycopy<decorators>(src_obj, dst_obj, src, dst, length);

  }

  // Oop heap accesses

  static inline AccessInternal::OopLoadAtProxy<decorators> oop_load_at(oop base, ptrdiff_t offset) {

    verify_heap_oop_decorators<load_mo_decorators>();

    return AccessInternal::OopLoadAtProxy<decorators>(base, offset);

  }

  template <typename T>

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

    verify_heap_oop_decorators<store_mo_decorators>();

    typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;

    OopType oop_value = value;

    AccessInternal::store_at<decorators | INTERNAL_VALUE_IS_OOP>(base, offset, oop_value);

  }

  template <typename T>

  static inline T oop_atomic_cmpxchg_at(T new_value, oop base, ptrdiff_t offset, T compare_value) {

    verify_heap_oop_decorators<atomic_cmpxchg_mo_decorators>();

    typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;

    OopType new_oop_value = new_value;

    OopType compare_oop_value = compare_value;

    return AccessInternal::atomic_cmpxchg_at<decorators | INTERNAL_VALUE_IS_OOP>(new_oop_value, base, offset, compare_oop_value);

  }

  template <typename T>

  static inline T oop_atomic_xchg_at(T new_value, oop base, ptrdiff_t offset) {

    verify_heap_oop_decorators<atomic_xchg_mo_decorators>();

    typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;

    OopType new_oop_value = new_value;

    return AccessInternal::atomic_xchg_at<decorators | INTERNAL_VALUE_IS_OOP>(new_oop_value, base, offset);

  }

  template <typename T>

  static inline bool oop_arraycopy(arrayOop src_obj, arrayOop dst_obj, T *src, T *dst, size_t length) {

    verify_decorators<ARRAYCOPY_DECORATOR_MASK | IN_HEAP | AS_DECORATOR_MASK>();

    return AccessInternal::arraycopy<decorators | INTERNAL_VALUE_IS_OOP>(src_obj, dst_obj, src, dst, length);

  }

  // Clone an object from src to dst

  static inline void clone(oop src, oop dst, size_t size) {

    verify_decorators<IN_HEAP>();

    AccessInternal::clone<decorators>(src, dst, size);

  }

  // Primitive accesses

  template <typename P>

  static inline P load(P* addr) {

    verify_primitive_decorators<load_mo_decorators>();

    return AccessInternal::load<decorators, P, P>(addr);

  }

  template <typename P, typename T>

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

    verify_primitive_decorators<store_mo_decorators>();

    AccessInternal::store<decorators>(addr, value);

  }

  template <typename P, typename T>

  static inline T atomic_cmpxchg(T new_value, P* addr, T compare_value) {

    verify_primitive_decorators<atomic_cmpxchg_mo_decorators>();

    return AccessInternal::atomic_cmpxchg<decorators>(new_value, addr, compare_value);

  }

  template <typename P, typename T>

  static inline T atomic_xchg(T new_value, P* addr) {

    verify_primitive_decorators<atomic_xchg_mo_decorators>();

    return AccessInternal::atomic_xchg<decorators>(new_value, addr);

  }

  // Oop accesses

  template <typename P>

  static inline AccessInternal::OopLoadProxy<P, decorators> oop_load(P* addr) {

    verify_oop_decorators<load_mo_decorators>();

    return AccessInternal::OopLoadProxy<P, decorators>(addr);

  }

  template <typename P, typename T>

  static inline void oop_store(P* addr, T value) {

    verify_oop_decorators<store_mo_decorators>();

    typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;

    OopType oop_value = value;

    AccessInternal::store<decorators | INTERNAL_VALUE_IS_OOP>(addr, oop_value);

  }

  template <typename P, typename T>

  static inline T oop_atomic_cmpxchg(T new_value, P* addr, T compare_value) {

    verify_oop_decorators<atomic_cmpxchg_mo_decorators>();

    typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;

    OopType new_oop_value = new_value;

    OopType compare_oop_value = compare_value;

    return AccessInternal::atomic_cmpxchg<decorators | INTERNAL_VALUE_IS_OOP>(new_oop_value, addr, compare_oop_value);

  }

  template <typename P, typename T>

  static inline T oop_atomic_xchg(T new_value, P* addr) {

    verify_oop_decorators<atomic_xchg_mo_decorators>();

    typedef typename AccessInternal::OopOrNarrowOop<T>::type OopType;

    OopType new_oop_value = new_value;

    return AccessInternal::atomic_xchg<decorators | INTERNAL_VALUE_IS_OOP>(new_oop_value, addr);

  }

  static oop resolve(oop obj) {

    verify_decorators<INTERNAL_EMPTY>();

    return AccessInternal::resolve<decorators>(obj);

  }

  static bool equals(oop o1, oop o2) {

    verify_decorators<INTERNAL_EMPTY>();

    return AccessInternal::equals<decorators>(o1, o2);

  }

};

// Helper for performing raw accesses (knows only of memory ordering

// atomicity decorators as well as compressed oops)

template <DecoratorSet decorators = INTERNAL_EMPTY>

class RawAccess: public Access<AS_RAW | decorators> {};

// Helper for performing normal accesses on the heap. These accesses

// may resolve an accessor on a GC barrier set

template <DecoratorSet decorators = INTERNAL_EMPTY>

class HeapAccess: public Access<IN_HEAP | decorators> {};

// Helper for performing normal accesses in roots. These accesses

// may resolve an accessor on a GC barrier set

template <DecoratorSet decorators = INTERNAL_EMPTY>

class RootAccess: public Access<IN_ROOT | decorators> {};

template <DecoratorSet decorators>

template <DecoratorSet expected_decorators>

void Access<decorators>::verify_decorators() {

  STATIC_ASSERT((~expected_decorators & decorators) == 0); // unexpected decorator used

  const DecoratorSet barrier_strength_decorators = decorators & AS_DECORATOR_MASK;

  STATIC_ASSERT(barrier_strength_decorators == 0 || ( // make sure barrier strength decorators are disjoint if set

    (barrier_strength_decorators ^ AS_NO_KEEPALIVE) == 0 ||

    (barrier_strength_decorators ^ AS_DEST_NOT_INITIALIZED) == 0 ||

    (barrier_strength_decorators ^ AS_RAW) == 0 ||

    (barrier_strength_decorators ^ AS_NORMAL) == 0

  ));

  const DecoratorSet ref_strength_decorators = decorators & ON_DECORATOR_MASK;

  STATIC_ASSERT(ref_strength_decorators == 0 || ( // make sure ref strength decorators are disjoint if set

    (ref_strength_decorators ^ ON_STRONG_OOP_REF) == 0 ||

    (ref_strength_decorators ^ ON_WEAK_OOP_REF) == 0 ||

    (ref_strength_decorators ^ ON_PHANTOM_OOP_REF) == 0 ||

    (ref_strength_decorators ^ ON_UNKNOWN_OOP_REF) == 0

  ));

  const DecoratorSet memory_ordering_decorators = decorators & MO_DECORATOR_MASK;

  STATIC_ASSERT(memory_ordering_decorators == 0 || ( // make sure memory ordering decorators are disjoint if set

    (memory_ordering_decorators ^ MO_UNORDERED) == 0 ||

    (memory_ordering_decorators ^ MO_VOLATILE) == 0 ||

    (memory_ordering_decorators ^ MO_RELAXED) == 0 ||

    (memory_ordering_decorators ^ MO_ACQUIRE) == 0 ||

    (memory_ordering_decorators ^ MO_RELEASE) == 0 ||

    (memory_ordering_decorators ^ MO_SEQ_CST) == 0

  ));

  const DecoratorSet location_decorators = decorators & IN_DECORATOR_MASK;

  STATIC_ASSERT(location_decorators == 0 || ( // make sure location decorators are disjoint if set

    (location_decorators ^ IN_ROOT) == 0 ||

    (location_decorators ^ IN_HEAP) == 0 ||

    (location_decorators ^ (IN_HEAP | IN_HEAP_ARRAY)) == 0 ||

    (location_decorators ^ (IN_ROOT | IN_CONCURRENT_ROOT)) == 0 ||

    (location_decorators ^ (IN_ROOT | IN_ARCHIVE_ROOT)) == 0

  ));

}

#endif // SHARE_OOPS_ACCESS_HPP