diff --git a/include/llvm/Support/AlignOf.h b/include/llvm/Support/AlignOf.h index abd19afa22f..5fda901a100 100644 --- a/include/llvm/Support/AlignOf.h +++ b/include/llvm/Support/AlignOf.h @@ -102,45 +102,38 @@ LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(128) #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; +// This code implements the equivalent of std::aligned_union from C++11. +// That is supported by Visual Studio 2015 and GCC 5.1. +// Once these are the baselines for LLVM, we can use std::aligned_union instead. +namespace detail { +template <typename... Ts> class AlignerImpl; + +template <typename T1, typename... Ts> +class AlignerImpl<T1, Ts...> : AlignerImpl<Ts...> { + T1 t; 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)]; -}; +template <> class AlignerImpl<> { AlignerImpl() = delete; }; + +template <typename T1> constexpr size_t sizer() { return sizeof(T1); } + +template <typename T1, typename T2, typename... Ts> constexpr size_t sizer() { + return (sizeof(T1) > sizer<T2, Ts...>()) ? sizeof(T1) : sizer<T2, Ts...>(); +} } // 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. +/// array member which can hold elements of any of a number of 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 : llvm::AlignedCharArray< - alignof(llvm::detail::AlignerImpl<T1, T2, T3, T4, T5, - T6, T7, T8, T9, T10>), - sizeof(::llvm::detail::SizerImpl<T1, T2, T3, T4, T5, - T6, T7, T8, T9, T10>)> { -}; +/// a placement new of any of these types. +template <typename... Ts> +struct AlignedCharArrayUnion + : llvm::AlignedCharArray<alignof(llvm::detail::AlignerImpl<Ts...>), + detail::sizer<Ts...>()> {}; } // end namespace llvm #endif // LLVM_SUPPORT_ALIGNOF_H diff --git a/unittests/Support/AlignOfTest.cpp b/unittests/Support/AlignOfTest.cpp index 388ca11b776..dfcdc1484b3 100644 --- a/unittests/Support/AlignOfTest.cpp +++ b/unittests/Support/AlignOfTest.cpp @@ -91,6 +91,24 @@ V8::~V8() {} template <typename M> struct T { M m; }; +typedef uint8_t t1; +typedef uint16_t t2; +typedef uint32_t t3; +typedef uint64_t t4; +typedef int8_t t5; +typedef int16_t t6; +typedef int32_t t7; +typedef int64_t t8; +typedef struct { uint8_t bytes[16]; } t9; +typedef struct { uint16_t words[16]; } t10; +typedef struct { uint32_t words[16]; } t11; +typedef struct { uint64_t words[16]; } t12; + +typedef AlignedCharArrayUnion<t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12> U; + +static_assert(sizeof(U) == sizeof(uint64_t[16]), "Statically-computed size must be right"); +static_assert(alignof(U) == alignof(uint64_t), "Statically-computed alignment must be right"); + TEST(AlignOfTest, BasicAlignedArray) { EXPECT_LE(1u, alignof(AlignedCharArrayUnion<A1>)); EXPECT_LE(2u, alignof(AlignedCharArrayUnion<A2>));