Add proposed alignment specifier

experimental/bits/simd.h

@@ -185,6 +185,53 @@ struct vector_aligned_tag
     }
 };
 
+namespace __proposed
+{
+namespace {
+	enum _AlignmentType{
+		_Unaligned,
+		_Vector,
+		_Element
+	};
+
+	template<_AlignmentType at>
+	struct _alignment_tag_selector{
+		static_assert(at!=_Unaligned,"Unaligned reads are undefined behavior.");
+	};
+	template<>
+	struct _alignment_tag_selector<_Element>{
+		using type=element_aligned_tag;
+	};
+	template<>
+	struct _alignment_tag_selector<_Vector>{
+		using type=vector_aligned_tag;
+	};
+}
+
+template<size_t _Np>
+struct aligned_tag
+{
+	template <typename _Tp, typename _Up = typename _Tp::value_type>
+	static constexpr size_t _S_alignment = _Np;
+
+	template <typename _Tp, typename _Up>
+	_GLIBCXX_SIMD_INTRINSIC static constexpr _Up*
+	_S_apply(_Up* __ptr){
+		constexpr size_t _expected_vector_alignment=vector_aligned_tag::_S_alignment<_Tp,_Up>;
+		constexpr size_t _expected_element_alignment=element_aligned_tag::_S_alignment<_Tp,_Up>;
+		constexpr _AlignmentType _computed_at=
+			((_Np % _expected_vector_alignment)==0) ? _Vector :
+			((_Np % _expected_element_alignment)==0) ? _Element : _Unaligned;
+		using _result_tag=typename _alignment_tag_selector<_computed_at>::type;
+		return _result_tag::template _S_apply<_Tp,_Up>(__ptr);
+	}
+};
+
+template<size_t _Np>
+  inline constexpr aligned_tag<_Np> aligned = {};
+
+}
+
 template <size_t _Np> struct overaligned_tag
 {
   template <typename _Tp, typename _Up = typename _Tp::value_type>
@@ -193,7 +240,7 @@ template <size_t _Np> struct overaligned_tag
   template <typename _Tp, typename _Up>
     _GLIBCXX_SIMD_INTRINSIC static constexpr _Up*
     _S_apply(_Up* __ptr)
-    { return static_cast<_Up*>(__builtin_assume_aligned(__ptr, _Np)); }
+	{ return __proposed::aligned_tag<_Np>::_S_apply(__ptr); }
 };
 
 inline constexpr element_aligned_tag element_aligned = {};
@@ -203,6 +250,8 @@ inline constexpr vector_aligned_tag vector_aligned = {};
 template <size_t _Np>
   inline constexpr overaligned_tag<_Np> overaligned = {};
 
+
+
 // }}}
 template <size_t _X>
   using _SizeConstant = integral_constant<size_t, _X>;

tests/simple_tests/CMakeLists.txt

@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.14)
+
+add_executable(alignment_compute alignment_compute.cpp)
+target_compile_options(alignment_compute PUBLIC 
+	"$<$<CONFIG:Release>:-march=native>"
+	"$<$<CONFIG:Debug>:-march=native>"
+	"$<$<CONFIG:RelWithDebInfo>:-march=native>"
+	"$<$<CONFIG:MinSizeRel>:-march=native>"
+)
+set_target_properties(alignment_compute PROPERTIES
+            CXX_STANDARD 20
+            CXX_STANDARD_REQUIRED ON)
+
+		message(WARNING "${CMAKE_CURRENT_SOURCE_DIR}/../..")
+target_include_directories(alignment_compute PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/../..")

tests/simple_tests/alignment_compute.cpp

@@ -0,0 +1,28 @@
+#include<experimental/simd>
+
+#include<array>
+#include<vector>
+#include<cstdint>
+#include<cstdlib>
+#include<type_traits>
+
+#include<experimental/simd>
+namespace stdx = std::experimental;
+
+
+using uint8v_t = stdx::native_simd<uint8_t>;
+using uint8v_mask_t = stdx::native_simd_mask<uint8_t>;
+//using mask_cpu_t = min_uint_t<stdx::native_simd_mask<uint8_t>::size()>;
+
+
+
+int main()
+{
+	std::array<uint8_t,128> data;
+	uint8v_t hi(&data[0],stdx::__proposed::aligned<3>);
+
+	std::array<float,128> dataf;
+	stdx::native_simd<float> vf(&dataf[0],stdx::__proposed::aligned<3>);
+	return 0;
+}
+