| //===--- 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 |
| |
| #pragma once |
| |
| #include <cstddef> |
| |
| 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. |
| #ifndef _MSC_VER |
| |
| template <size_t Alignment, size_t Size> |
| struct AlignedCharArray { |
| alignas(Alignment) char buffer[Size]; |
| }; |
| |
| #else // _MSC_VER |
| |
| /// \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. |
| |
| #define AT_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \ |
| 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) |
| |
| #undef AT_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT |
| |
| #endif // _MSC_VER |
| |
| 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 { |
| 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 |