Spaces:
Running
Running
//===--- AlignOf.h - Portable calculation of type alignment -----*- C++ -*-===// | |
// | |
// The LLVM Compiler Infrastructure | |
// | |
// This file is distributed under the University of Illinois Open Source | |
// License. See LICENSE.TXT for details. | |
// | |
//===----------------------------------------------------------------------===// | |
// | |
// This file defines the AlignedCharArray and AlignedCharArrayUnion classes. | |
// | |
//===----------------------------------------------------------------------===// | |
// ATen: modified from llvm::AlignOf | |
// replaced LLVM_ALIGNAS with alignas | |
namespace c10 { | |
/// \struct AlignedCharArray | |
/// \brief Helper for building an aligned character array type. | |
/// | |
/// This template is used to explicitly build up a collection of aligned | |
/// character array types. We have to build these up using a macro and explicit | |
/// specialization to cope with MSVC (at least till 2015) where only an | |
/// integer literal can be used to specify an alignment constraint. Once built | |
/// up here, we can then begin to indirect between these using normal C++ | |
/// template parameters. | |
// MSVC requires special handling here. | |
template <size_t Alignment, size_t Size> | |
struct AlignedCharArray { | |
// NOLINTNEXTLINE(*c-arrays) | |
alignas(Alignment) char buffer[Size]; | |
}; | |
/// \brief Create a type with an aligned char buffer. | |
template <size_t Alignment, size_t Size> | |
struct AlignedCharArray; | |
// We provide special variations of this template for the most common | |
// alignments because __declspec(align(...)) doesn't actually work when it is | |
// a member of a by-value function argument in MSVC, even if the alignment | |
// request is something reasonably like 8-byte or 16-byte. Note that we can't | |
// even include the declspec with the union that forces the alignment because | |
// MSVC warns on the existence of the declspec despite the union member forcing | |
// proper alignment. | |
template <size_t Size> | |
struct AlignedCharArray<1, Size> { | |
union { | |
char aligned; | |
char buffer[Size]; | |
}; | |
}; | |
template <size_t Size> | |
struct AlignedCharArray<2, Size> { | |
union { | |
short aligned; | |
char buffer[Size]; | |
}; | |
}; | |
template <size_t Size> | |
struct AlignedCharArray<4, Size> { | |
union { | |
int aligned; | |
char buffer[Size]; | |
}; | |
}; | |
template <size_t Size> | |
struct AlignedCharArray<8, Size> { | |
union { | |
double aligned; | |
char buffer[Size]; | |
}; | |
}; | |
// The rest of these are provided with a __declspec(align(...)) and we simply | |
// can't pass them by-value as function arguments on MSVC. | |
template <size_t Size> \ | |
struct AlignedCharArray<x, Size> { \ | |
__declspec(align(x)) char buffer[Size]; \ | |
}; | |
AT_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(16) | |
AT_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(32) | |
AT_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(64) | |
AT_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(128) | |
namespace detail { | |
template < | |
typename T1, | |
typename T2 = char, | |
typename T3 = char, | |
typename T4 = char, | |
typename T5 = char, | |
typename T6 = char, | |
typename T7 = char, | |
typename T8 = char, | |
typename T9 = char, | |
typename T10 = char> | |
class AlignerImpl { | |
T1 t1; | |
T2 t2; | |
T3 t3; | |
T4 t4; | |
T5 t5; | |
T6 t6; | |
T7 t7; | |
T8 t8; | |
T9 t9; | |
T10 t10; | |
public: | |
AlignerImpl() = delete; | |
}; | |
template < | |
typename T1, | |
typename T2 = char, | |
typename T3 = char, | |
typename T4 = char, | |
typename T5 = char, | |
typename T6 = char, | |
typename T7 = char, | |
typename T8 = char, | |
typename T9 = char, | |
typename T10 = char> | |
union SizerImpl { | |
// NOLINTNEXTLINE(*c-arrays) | |
char arr1[sizeof(T1)], arr2[sizeof(T2)], arr3[sizeof(T3)], arr4[sizeof(T4)], | |
arr5[sizeof(T5)], arr6[sizeof(T6)], arr7[sizeof(T7)], arr8[sizeof(T8)], | |
arr9[sizeof(T9)], arr10[sizeof(T10)]; | |
}; | |
} // end namespace detail | |
/// \brief This union template exposes a suitably aligned and sized character | |
/// array member which can hold elements of any of up to ten types. | |
/// | |
/// These types may be arrays, structs, or any other types. The goal is to | |
/// expose a char array buffer member which can be used as suitable storage for | |
/// a placement new of any of these types. Support for more than ten types can | |
/// be added at the cost of more boilerplate. | |
template < | |
typename T1, | |
typename T2 = char, | |
typename T3 = char, | |
typename T4 = char, | |
typename T5 = char, | |
typename T6 = char, | |
typename T7 = char, | |
typename T8 = char, | |
typename T9 = char, | |
typename T10 = char> | |
struct AlignedCharArrayUnion | |
: AlignedCharArray< | |
alignof(detail::AlignerImpl<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>), | |
sizeof(::c10::detail:: | |
SizerImpl<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>)> {}; | |
} // end namespace c10 | |