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copied!<p><strong>Edit:</strong> I removed the inheritance of <code>std::allocator</code> as suggested by GManNickG and made the alignment parameter a compile time thing.</p> <p>I recently wrote this piece of code. It's not tested as much as I would like it so go on and report errors. :-)</p> <pre><code>enum class Alignment : size_t { Normal = sizeof(void*), SSE = 16, AVX = 32, }; namespace detail { void* allocate_aligned_memory(size_t align, size_t size); void deallocate_aligned_memory(void* ptr) noexcept; } template <typename T, Alignment Align = Alignment::AVX> class AlignedAllocator; template <Alignment Align> class AlignedAllocator<void, Align> { public: typedef void* pointer; typedef const void* const_pointer; typedef void value_type; template <class U> struct rebind { typedef AlignedAllocator<U, Align> other; }; }; template <typename T, Alignment Align> class AlignedAllocator { public: typedef T value_type; typedef T* pointer; typedef const T* const_pointer; typedef T& reference; typedef const T& const_reference; typedef size_t size_type; typedef ptrdiff_t difference_type; typedef std::true_type propagate_on_container_move_assignment; template <class U> struct rebind { typedef AlignedAllocator<U, Align> other; }; public: AlignedAllocator() noexcept {} template <class U> AlignedAllocator(const AlignedAllocator<U, Align>&) noexcept {} size_type max_size() const noexcept { return (size_type(~0) - size_type(Align)) / sizeof(T); } pointer address(reference x) const noexcept { return std::addressof(x); } const_pointer address(const_reference x) const noexcept { return std::addressof(x); } pointer allocate(size_type n, typename AlignedAllocator<void, Align>::const_pointer = 0) { const size_type alignment = static_cast<size_type>( Align ); void* ptr = detail::allocate_aligned_memory(alignment , n * sizeof(T)); if (ptr == nullptr) { throw std::bad_alloc(); } return reinterpret_cast<pointer>(ptr); } void deallocate(pointer p, size_type) noexcept { return detail::deallocate_aligned_memory(p); } template <class U, class ...Args> void construct(U* p, Args&&... args) { ::new(reinterpret_cast<void*>(p)) U(std::forward<Args>(args)...); } void destroy(pointer p) { p->~T(); } }; template <typename T, Alignment Align> class AlignedAllocator<const T, Align> { public: typedef T value_type; typedef const T* pointer; typedef const T* const_pointer; typedef const T& reference; typedef const T& const_reference; typedef size_t size_type; typedef ptrdiff_t difference_type; typedef std::true_type propagate_on_container_move_assignment; template <class U> struct rebind { typedef AlignedAllocator<U, Align> other; }; public: AlignedAllocator() noexcept {} template <class U> AlignedAllocator(const AlignedAllocator<U, Align>&) noexcept {} size_type max_size() const noexcept { return (size_type(~0) - size_type(Align)) / sizeof(T); } const_pointer address(const_reference x) const noexcept { return std::addressof(x); } pointer allocate(size_type n, typename AlignedAllocator<void, Align>::const_pointer = 0) { const size_type alignment = static_cast<size_type>( Align ); void* ptr = detail::allocate_aligned_memory(alignment , n * sizeof(T)); if (ptr == nullptr) { throw std::bad_alloc(); } return reinterpret_cast<pointer>(ptr); } void deallocate(pointer p, size_type) noexcept { return detail::deallocate_aligned_memory(p); } template <class U, class ...Args> void construct(U* p, Args&&... args) { ::new(reinterpret_cast<void*>(p)) U(std::forward<Args>(args)...); } void destroy(pointer p) { p->~T(); } }; template <typename T, Alignment TAlign, typename U, Alignment UAlign> inline bool operator== (const AlignedAllocator<T,TAlign>&, const AlignedAllocator<U, UAlign>&) noexcept { return TAlign == UAlign; } template <typename T, Alignment TAlign, typename U, Alignment UAlign> inline bool operator!= (const AlignedAllocator<T,TAlign>&, const AlignedAllocator<U, UAlign>&) noexcept { return TAlign != UAlign; } </code></pre> <p>The implementation for the actual allocate calls is posix only but you can extent that easily.</p> <pre><code>void* detail::allocate_aligned_memory(size_t align, size_t size) { assert(align >= sizeof(void*)); assert(nail::is_power_of_two(align)); if (size == 0) { return nullptr; } void* ptr = nullptr; int rc = posix_memalign(&ptr, align, size); if (rc != 0) { return nullptr; } return ptr; } void detail::deallocate_aligned_memory(void *ptr) noexcept { return free(ptr); } </code></pre> <p>Needs C++11, btw.</p>

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