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[support] Add a macro wrapper for alignas and simplify some code. 

We wrap __attribute((aligned)) for GCC 4.7 and __declspec(align) for
MSVC. The latter behaves weird in some contexts so this should be used
carefully.

llvm-svn: 233910
This commit is contained in:
Benjamin Kramer 2015-04-02 11:32:48 +00:00
parent 580f067f72
commit 165307184a
3 changed files with 19 additions and 46 deletions
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29
llvm/include/llvm/Support/AlignOf.h
View File

@ -70,38 +70,11 @@ inline unsigned alignOf() { return AlignOf<T>::Alignment; }
// MSVC requires special handling here.
#ifndef _MSC_VER
#if __has_feature(cxx_alignas)
template<std::size_t Alignment, std::size_t Size>
struct AlignedCharArray {
alignas(Alignment) char buffer[Size];
LLVM_ALIGNAS(Alignment) char buffer[Size];
};
#elif defined(__GNUC__) || defined(__IBM_ATTRIBUTES)
/// \brief Create a type with an aligned char buffer.
template<std::size_t Alignment, std::size_t Size>
struct AlignedCharArray;
#define LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(x) \
template<std::size_t Size> \
struct AlignedCharArray<x, Size> { \
__attribute__((aligned(x))) char buffer[Size]; \
};
LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(1)
LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(2)
LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(4)
LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(8)
LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(16)
LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(32)
LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(64)
LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(128)
#undef LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT
#else
# error No supported align as directive.
#endif
#else // _MSC_VER
/// \brief Create a type with an aligned char buffer.

14
llvm/include/llvm/Support/Compiler.h
View File

@ -281,6 +281,20 @@
# define LLVM_ASSUME_ALIGNED(p, a) (p)
#endif
/// \macro LLVM_ALIGNAS
/// \brief Used to specify a minimum alignment for a structure or variable. The
/// alignment must be a constant integer.
///
/// Note that __declspec(align) has special quirks, it's not legal to pass a
/// structure with __declspec(align) as a formal parameter.
#ifdef _MSC_VER
# define LLVM_ALIGNAS(x) __declspec(align(x))
#elif __GNUC__ && !__has_feature(cxx_alignas) && !LLVM_GNUC_PREREQ(4, 8, 0)
# define LLVM_ALIGNAS(x) __attribute__((aligned(x)))
#else
# define LLVM_ALIGNAS(x) alignas(x)
#endif
/// \macro LLVM_FUNCTION_NAME
/// \brief Expands to __func__ on compilers which support it. Otherwise,
/// expands to a compiler-dependent replacement.

22
llvm/unittests/Support/AlignOfTest.cpp
View File

@ -39,24 +39,10 @@ namespace {
#endif
// Define some fixed alignment types to use in these tests.
#if __has_feature(cxx_alignas)
struct alignas(1) A1 { };
struct alignas(2) A2 { };
struct alignas(4) A4 { };
struct alignas(8) A8 { };
#elif defined(__GNUC__)
struct A1 { } __attribute__((aligned(1)));
struct A2 { } __attribute__((aligned(2)));
struct A4 { } __attribute__((aligned(4)));
struct A8 { } __attribute__((aligned(8)));
#elif defined(_MSC_VER)
__declspec(align(1)) struct A1 { };
__declspec(align(2)) struct A2 { };
__declspec(align(4)) struct A4 { };
__declspec(align(8)) struct A8 { };
#else
# error No supported align as directive.
#endif
struct LLVM_ALIGNAS(1) A1 {};
struct LLVM_ALIGNAS(2) A2 {};
struct LLVM_ALIGNAS(4) A4 {};
struct LLVM_ALIGNAS(8) A8 {};
struct S1 {};
struct S2 { char a; };