diff options
Diffstat (limited to 'include/llvm/Support/AlignOf.h')
| -rw-r--r-- | include/llvm/Support/AlignOf.h | 65 |
1 files changed, 42 insertions, 23 deletions
diff --git a/include/llvm/Support/AlignOf.h b/include/llvm/Support/AlignOf.h index cf71251..d6b0ab8 100644 --- a/include/llvm/Support/AlignOf.h +++ b/include/llvm/Support/AlignOf.h @@ -68,24 +68,20 @@ inline unsigned alignOf() { return AlignOf<T>::Alignment; } /// 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. -template <size_t Alignment> struct AlignedCharArrayImpl {}; -template <> struct AlignedCharArrayImpl<0> { - typedef char type; -}; +template <size_t Alignment> struct AlignedCharArrayImpl; + +// MSVC requires special handling here. +#ifndef _MSC_VER + #if __has_feature(cxx_alignas) #define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \ template <> struct AlignedCharArrayImpl<x> { \ - typedef char alignas(x) type; \ + char alignas(x) aligned; \ } -#elif defined(__clang__) || defined(__GNUC__) +#elif defined(__GNUC__) || defined(__IBM_ATTRIBUTES) #define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \ template <> struct AlignedCharArrayImpl<x> { \ - typedef char type __attribute__((aligned(x))); \ - } -#elif defined(_MSC_VER) -#define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \ - template <> struct AlignedCharArrayImpl<x> { \ - typedef __declspec(align(x)) char type; \ + char aligned __attribute__((aligned(x))); \ } #else # error No supported align as directive. @@ -104,9 +100,38 @@ LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(1024); LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(2048); LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(4096); LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(8192); + +#undef LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT + +#else // _MSC_VER + +// 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. +template <> struct AlignedCharArrayImpl<1> { char aligned; }; +template <> struct AlignedCharArrayImpl<2> { short aligned; }; +template <> struct AlignedCharArrayImpl<4> { int aligned; }; +template <> struct AlignedCharArrayImpl<8> { double aligned; }; + +#define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \ + template <> struct AlignedCharArrayImpl<x> { \ + __declspec(align(x)) char aligned; \ + } +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(16); +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(32); +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(64); +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(128); +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(512); +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(1024); +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(2048); +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(4096); +LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(8192); // Any larger and MSVC complains. #undef LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT +#endif // _MSC_VER + /// \brief This union template exposes a suitably aligned and sized character /// array member which can hold elements of any of up to four types. /// @@ -134,17 +159,11 @@ public: /// constrain the layout of this character array. char buffer[sizeof(SizerImpl)]; - // Sadly, Clang and GCC both fail to align a character array properly even - // with an explicit alignment attribute. To work around this, we union - // the character array that will actually be used with a struct that contains - // a single aligned character member. Tests seem to indicate that both Clang - // and GCC will properly register the alignment of a struct containing an - // aligned member, and this alignment should carry over to the character - // array in the union. - struct { - typename llvm::AlignedCharArrayImpl<AlignOf<AlignerImpl>::Alignment>::type - nonce_inner_member; - } nonce_member; +private: + // Tests seem to indicate that both Clang and GCC will properly register the + // alignment of a struct containing an aligned member, and this alignment + // should carry over to the character array in the union. + llvm::AlignedCharArrayImpl<AlignOf<AlignerImpl>::Alignment> nonce_member; }; } // end namespace llvm |
