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/* metaprogramming.h -*- C++ -*-
*
* Copyright (C) 2012-2016, Intel Corporation
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
* WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* *********************************************************************
*
* PLEASE NOTE: This file is a downstream copy of a file mainitained in
* a repository at cilkplus.org. Changes made to this file that are not
* submitted through the contribution process detailed at
* http://www.cilkplus.org/submit-cilk-contribution will be lost the next
* time that a new version is released. Changes only submitted to the
* GNU compiler collection or posted to the git repository at
* https://bitbucket.org/intelcilkruntime/intel-cilk-runtime.git are
* not tracked.
*
* We welcome your contributions to this open source project. Thank you
* for your assistance in helping us improve Cilk Plus.
*/
/** @file metaprogramming.h
*
* @brief Defines metaprogramming utility classes used in the Intel(R) Cilk(TM) Plus library.
*
* @ingroup common
*/
#ifndef METAPROGRAMMING_H_INCLUDED
#define METAPROGRAMMING_H_INCLUDED
#ifdef __cplusplus
#include <functional>
#include <new>
#include <cstdlib>
#ifdef _WIN32
#include <malloc.h>
#endif
#include <algorithm>
namespace cilk {
namespace internal {
/** Test if a class is empty.
*
* If @a Class is an empty (and therefore necessarily stateless) class, then
* the "empty base-class optimization" guarantees that
* `sizeof(check_for_empty_class<Class>) == sizeof(char)`. Conversely, if
* `sizeof(check_for_empty_class<Class>) > sizeof(char)`, then @a Class is not
* empty, and we must discriminate distinct instances of @a Class.
*
* Typical usage:
*
* // General definition of A<B> for non-empty B:
* template <typename B, bool BIsEmpty = class_is_empty<B>::value> >
* class A { ... };
*
* // Specialized definition of A<B> for empty B:
* template <typename B>
* class A<B, true> { ... };
*
* @tparam Class The class to be tested for emptiness.
*
* @result The `value` member will be `true` if @a Class is empty,
* `false` otherwise.
*
* @ingroup common
*/
template <class Class>
class class_is_empty {
class check_for_empty_class : public Class
{
char m_data;
public:
// Declared but not defined
check_for_empty_class();
check_for_empty_class(const check_for_empty_class&);
check_for_empty_class& operator=(const check_for_empty_class&);
~check_for_empty_class();
};
public:
/** Constant is true if and only if @a Class is empty.
*/
static const bool value = (sizeof(check_for_empty_class) == sizeof(char));
};
/** Get the alignment of a type.
*
* For example:
*
* align_of<double>::value == 8
*
* @tparam Tp The type whose alignment is to be computed.
*
* @result The `value` member of an instantiation of this class template
* will hold the integral alignment requirement of @a Tp.
*
* @pre @a Tp shall be a complete type.
*
* @ingroup common
*/
template <typename Tp>
struct align_of
{
private:
struct imp {
char m_padding;
Tp m_val;
// The following declarations exist to suppress compiler-generated
// definitions, in case @a Tp does not have a public default
// constructor, copy constructor, or destructor.
imp(const imp&); // Declared but not defined
~imp(); // Declared but not defined
};
public:
/// The integral alignment requirement of @a Tp.
static const std::size_t value = (sizeof(imp) - sizeof(Tp));
};
/** A class containing raw bytes with a specified alignment and size.
*
* An object of type `aligned_storage<S, A>` will have alignment `A` and
* size at least `S`. Its contents will be uninitialized bytes.
*
* @tparam Size The required minimum size of the resulting class.
* @tparam Alignment The required alignment of the resulting class.
*
* @pre @a Alignment shall be a power of 2 no greater than 64.
*
* @note This is implemented using the `CILK_ALIGNAS` macro, which uses
* the non-standard, implementation-specific features
* `__declspec(align(N))` on Windows, and
* `__attribute__((__aligned__(N)))` on Unix. The `gcc` implementation
* of `__attribute__((__aligned__(N)))` requires a numeric literal `N`
* (_not_ an arbitrary compile-time constant expression). Therefore,
* this class is implemented using specialization on the required
* alignment.
*
* @note The template class is specialized only for the supported
* alignments. An attempt to instantiate it for an unsupported
* alignment will result in a compilation error.
*/
template <std::size_t Size, std::size_t Alignment>
struct aligned_storage;
/// @cond
template<std::size_t Size> class aligned_storage<Size, 1>
{ CILK_ALIGNAS( 1) char m_bytes[Size]; };
template<std::size_t Size> class aligned_storage<Size, 2>
{ CILK_ALIGNAS( 2) char m_bytes[Size]; };
template<std::size_t Size> class aligned_storage<Size, 4>
{ CILK_ALIGNAS( 4) char m_bytes[Size]; };
template<std::size_t Size> class aligned_storage<Size, 8>
{ CILK_ALIGNAS( 8) char m_bytes[Size]; };
template<std::size_t Size> class aligned_storage<Size, 16>
{ CILK_ALIGNAS(16) char m_bytes[Size]; };
template<std::size_t Size> class aligned_storage<Size, 32>
{ CILK_ALIGNAS(32) char m_bytes[Size]; };
template<std::size_t Size> class aligned_storage<Size, 64>
{ CILK_ALIGNAS(64) char m_bytes[Size]; };
/// @endcond
/** A buffer of uninitialized bytes with the same size and alignment as a
* specified type.
*
* The class `storage_for_object<Type>` will have the same size and alignment
* properties as `Type`, but it will contain only raw (uninitialized) bytes.
* This allows the definition of a data member which can contain a `Type`
* object which is initialized explicitly under program control, rather
* than implicitly as part of the initialization of the containing class.
* For example:
*
* class C {
* storage_for_object<MemberClass> _member;
* public:
* C() ... // Does NOT initialize _member
* void initialize(args)
* { new (_member.pointer()) MemberClass(args); }
* const MemberClass& member() const { return _member.object(); }
* MemberClass& member() { return _member.object(); }
*
* @tparam Type The type whose size and alignment are to be reflected
* by this class.
*/
template <typename Type>
class storage_for_object :
aligned_storage< sizeof(Type), align_of<Type>::value >
{
public:
/// Return a typed reference to the buffer.
const Type& object() const { return *reinterpret_cast<Type*>(this); }
/// Return a typed reference to the buffer.
Type& object() { return *reinterpret_cast<Type*>(this); }
};
/** Get the functor class corresponding to a binary function type.
*
* The `binary_functor` template class can be instantiated with a binary
* functor class or with a real binary function, and will yield an equivalent
* binary functor class in either case.
*
* @tparam F A binary functor class, a binary function type, or a pointer to
* binary function type.
*
* @result `binary_functor<F>::%type` will be the same as @a F if @a F is
* a class. It will be a `std::pointer_to_binary_function` wrapper
* if @a F is a binary function or binary function pointer type.
* (It will _not_ necessarily be an `Adaptable Binary Function`
* class, since @a F might be a non-adaptable binary functor
* class.)
*
* @ingroup common
*/
template <typename F>
struct binary_functor {
/// The binary functor class equivalent to @a F.
typedef F type;
};
/// @copydoc binary_functor
/// Specialization for binary function.
template <typename R, typename A, typename B>
struct binary_functor<R(A,B)> {
/// The binary functor class equivalent to @a F.
typedef std::pointer_to_binary_function<A, B, R> type;
};
/// @copydoc binary_functor
/// Specialization for pointer to binary function.
template <typename R, typename A, typename B>
struct binary_functor<R(*)(A,B)> {
/// The binary functor class equivalent to @a F.
typedef std::pointer_to_binary_function<A, B, R> type;
};
/** Indirect binary function class with specified types.
*
* `typed_indirect_binary_function<F>` is an `Adaptable Binary Function` class
* based on an existing binary functor class or binary function type @a F. If
* @a F is a stateless class, then this class will be empty, and its
* `operator()` will invoke @a F's `operator()`. Otherwise, an object of this
* class will hold a pointer to an object of type @a F, and will refer its
* `operator()` calls to the pointed-to @a F object.
*
* That is, suppose that we have the declarations:
*
* F *p;
* typed_indirect_binary_function<F, int, int, bool> ibf(p);
*
* Then:
*
* - `ibf(x, y) == (*p)(x, y)`.
* - `ibf(x, y)` will not do a pointer dereference if `F` is an empty class.
*
* @note Just to repeat: if `F` is an empty class, then
* `typed_indirect_binary_function\<F\>' is also an empty class.
* This is critical for its use in the
* @ref cilk::cilk_lib_1_1::min_max_internal::view_base
* "min/max reducer view classes", where it allows the view to
* call a comparison functor in the monoid without actually
* having to allocate a pointer in the view class when the
* comparison class is empty.
*
* @note If you have an `Adaptable Binary Function` class or a binary
* function type, then you can use the
* @ref indirect_binary_function class, which derives the
* argument and result types parameter type instead of requiring
* you to specify them as template arguments.
*
* @tparam F A binary functor class, a binary function type, or a pointer to
* binary function type.
* @param A1 The first argument type.
* @param A2 The second argument type.
* @param R The result type.
*
* @see min_max::comparator_base
* @see indirect_binary_function
*
* @ingroup common
*/
template < typename F
, typename A1
, typename A2
, typename R
, typename Functor = typename binary_functor<F>::type
, bool FunctorIsEmpty = class_is_empty<Functor>::value
>
class typed_indirect_binary_function : std::binary_function<A1, A2, R>
{
const F* f;
public:
/// Constructor captures a pointer to the wrapped function.
typed_indirect_binary_function(const F* f) : f(f) {}
/// Return the comparator pointer, or `NULL` if the comparator is stateless.
const F* pointer() const { return f; }
/// Apply the pointed-to functor to the arguments.
R operator()(const A1& a1, const A2& a2) const { return (*f)(a1, a2); }
};
/// @copydoc typed_indirect_binary_function
/// Specialization for an empty functor class. (This is only possible if @a F
/// itself is an empty class. If @a F is a function or pointer-to-function
/// type, then the functor will contain a pointer.)
template <typename F, typename A1, typename A2, typename R, typename Functor>
class typed_indirect_binary_function<F, A1, A2, R, Functor, true> :
std::binary_function<A1, A2, R>
{
public:
/// Return `NULL` for the comparator pointer of a stateless comparator.
const F* pointer() const { return 0; }
/// Constructor discards the pointer to a stateless functor class.
typed_indirect_binary_function(const F* f) {}
/// Create an instance of the stateless functor class and apply it to the arguments.
R operator()(const A1& a1, const A2& a2) const { return F()(a1, a2); }
};
/** Indirect binary function class with inferred types.
*
* This is identical to @ref cilk::internal::typed_indirect_binary_function,
* except that it derives the binary function argument and result types from
* the parameter type @a F instead of taking them as additional template
* parameters. If @a F is a class type, then it must be an `Adaptable Binary
* Function`.
*
* @see typed_indirect_binary_function
*
* @ingroup common
*/
template <typename F, typename Functor = typename binary_functor<F>::type>
class indirect_binary_function :
typed_indirect_binary_function< F
, typename Functor::first_argument_type
, typename Functor::second_argument_type
, typename Functor::result_type
>
{
typedef typed_indirect_binary_function< F
, typename Functor::first_argument_type
, typename Functor::second_argument_type
, typename Functor::result_type
>
base;
public:
indirect_binary_function(const F* f) : base(f) {} ///< Constructor
};
/** Choose a type based on a boolean constant.
*
* This metafunction is identical to C++11's condition metafunction.
* It needs to be here until we can reasonably assume that users will be
* compiling with C++11.
*
* @tparam Cond A boolean constant.
* @tparam IfTrue A type.
* @tparam IfFalse A type.
* @result The `type` member will be a typedef of @a IfTrue if @a Cond
* is true, and a typedef of @a IfFalse if @a Cond is false.
*
* @ingroup common
*/
template <bool Cond, typename IfTrue, typename IfFalse>
struct condition
{
typedef IfTrue type; ///< The type selected by the condition.
};
/// @copydoc condition
/// Specialization for @a Cond == `false`.
template <typename IfTrue, typename IfFalse>
struct condition<false, IfTrue, IfFalse>
{
typedef IfFalse type; ///< The type selected by the condition.
};
/** @def __CILKRTS_STATIC_ASSERT
*
* @brief Compile-time assertion.
*
* Causes a compilation error if a compile-time constant expression is false.
*
* @par Usage example.
* This assertion is used in reducer_min_max.h to avoid defining
* legacy reducer classes that would not be binary-compatible with the
* same classes compiled with earlier versions of the reducer library.
*
* __CILKRTS_STATIC_ASSERT(
* internal::class_is_empty< internal::binary_functor<Compare> >::value,
* "cilk::reducer_max<Value, Compare> only works with an empty Compare class");
*
* @note In a C++11 compiler, this is just the language predefined
* `static_assert` macro.
*
* @note In a non-C++11 compiler, the @a Msg string is not directly included
* in the compiler error message, but it may appear if the compiler
* prints the source line that the error occurred on.
*
* @param Cond The expression to test.
* @param Msg A string explaining the failure.
*
* @ingroup common
*/
#if defined(__INTEL_CXX11_MODE__) || defined(__GXX_EXPERIMENTAL_CXX0X__)
# define __CILKRTS_STATIC_ASSERT(Cond, Msg) static_assert(Cond, Msg)
#else
# define __CILKRTS_STATIC_ASSERT(Cond, Msg) \
typedef int __CILKRTS_STATIC_ASSERT_DUMMY_TYPE \
[::cilk::internal::static_assert_failure<(Cond)>::Success]
/// @cond internal
template <bool> struct static_assert_failure { };
template <> struct static_assert_failure<true> { enum { Success = 1 }; };
# define __CILKRTS_STATIC_ASSERT_DUMMY_TYPE \
__CILKRTS_STATIC_ASSERT_DUMMY_TYPE1(__cilkrts_static_assert_, __LINE__)
# define __CILKRTS_STATIC_ASSERT_DUMMY_TYPE1(a, b) \
__CILKRTS_STATIC_ASSERT_DUMMY_TYPE2(a, b)
# define __CILKRTS_STATIC_ASSERT_DUMMY_TYPE2(a, b) a ## b
/// @endcond
#endif
/// @cond internal
/** @name Aligned heap management.
*/
//@{
/** Implementation-specific aligned memory allocation function.
*
* @param size The minimum number of bytes to allocate.
* @param alignment The required alignment (must be a power of 2).
* @return The address of a block of memory of at least @a size
* bytes. The address will be a multiple of @a alignment.
* `NULL` if the allocation fails.
*
* @see deallocate_aligned()
*/
inline void* allocate_aligned(std::size_t size, std::size_t alignment)
{
#ifdef _WIN32
return _aligned_malloc(size, alignment);
#else
#if defined(__ANDROID__) || defined(__VXWORKS__)
return memalign(std::max(alignment, sizeof(void*)), size);
#else
void* ptr;
return (posix_memalign(&ptr, std::max(alignment, sizeof(void*)), size) == 0) ? ptr : 0;
#endif
#endif
}
/** Implementation-specific aligned memory deallocation function.
*
* @param ptr A pointer which was returned by a call to alloc_aligned().
*/
inline void deallocate_aligned(void* ptr)
{
#ifdef _WIN32
_aligned_free(ptr);
#else
std::free(ptr);
#endif
}
/** Class to allocate and guard an aligned pointer.
*
* A new_aligned_pointer object allocates aligned heap-allocated memory when
* it is created, and automatically deallocates it when it is destroyed
* unless its `ok()` function is called.
*
* @tparam T The type of the object to allocate on the heap. The allocated
* will have the size and alignment of an object of type T.
*/
template <typename T>
class new_aligned_pointer {
void* m_ptr;
public:
/// Constructor allocates the pointer.
new_aligned_pointer() :
m_ptr(allocate_aligned(sizeof(T), internal::align_of<T>::value)) {}
/// Destructor deallocates the pointer.
~new_aligned_pointer() { if (m_ptr) deallocate_aligned(m_ptr); }
/// Get the pointer.
operator void*() { return m_ptr; }
/// Return the pointer and release the guard.
T* ok() {
T* ptr = static_cast<T*>(m_ptr);
m_ptr = 0;
return ptr;
}
};
//@}
/// @endcond
} // namespace internal
//@{
/** Allocate an aligned data structure on the heap.
*
* `cilk::aligned_new<T>([args])` is equivalent to `new T([args])`, except
* that it guarantees that the returned pointer will be at least as aligned
* as the alignment requirements of type `T`.
*
* @ingroup common
*/
template <typename T>
T* aligned_new()
{
internal::new_aligned_pointer<T> ptr;
new (ptr) T();
return ptr.ok();
}
template <typename T, typename T1>
T* aligned_new(const T1& x1)
{
internal::new_aligned_pointer<T> ptr;
new (ptr) T(x1);
return ptr.ok();
}
template <typename T, typename T1, typename T2>
T* aligned_new(const T1& x1, const T2& x2)
{
internal::new_aligned_pointer<T> ptr;
new (ptr) T(x1, x2);
return ptr.ok();
}
template <typename T, typename T1, typename T2, typename T3>
T* aligned_new(const T1& x1, const T2& x2, const T3& x3)
{
internal::new_aligned_pointer<T> ptr;
new (ptr) T(x1, x2, x3);
return ptr.ok();
}
template <typename T, typename T1, typename T2, typename T3, typename T4>
T* aligned_new(const T1& x1, const T2& x2, const T3& x3, const T4& x4)
{
internal::new_aligned_pointer<T> ptr;
new (ptr) T(x1, x2, x3, x4);
return ptr.ok();
}
template <typename T, typename T1, typename T2, typename T3, typename T4, typename T5>
T* aligned_new(const T1& x1, const T2& x2, const T3& x3, const T4& x4, const T5& x5)
{
internal::new_aligned_pointer<T> ptr;
new (ptr) T(x1, x2, x3, x4, x5);
return ptr.ok();
}
//@}
/** Deallocate an aligned data structure on the heap.
*
* `cilk::aligned_delete(ptr)` is equivalent to `delete ptr`, except that it
* operates on a pointer that was allocated by aligned_new().
*
* @ingroup common
*/
template <typename T>
void aligned_delete(const T* ptr)
{
ptr->~T();
internal::deallocate_aligned((void*)ptr);
}
} // namespace cilk
#endif // __cplusplus
#endif // METAPROGRAMMING_H_INCLUDED