std::simd Memory permute

libcudacxx/include/cuda/std/__simd/abi.h

@@ -22,13 +22,17 @@
 #endif // no system header
 
 #include <cuda/std/__cstddef/types.h>
+#include <cuda/std/__type_traits/integral_constant.h>
 
 #include <cuda/std/__cccl/prologue.h>
 
 _CCCL_BEGIN_NAMESPACE_CUDA_STD_SIMD
 
 using __simd_size_type = ptrdiff_t;
 
+template <__simd_size_type _Np>
+using __simd_size_constant = integral_constant<__simd_size_type, _Np>;
+
 // [simd.expos.abi], simd ABI tags
 template <__simd_size_type _Np>
 struct __fixed_size; // internal ABI tag

libcudacxx/include/cuda/std/__simd/basic_mask.h

@@ -100,7 +100,7 @@ class basic_mask<_Bytes, _Abi, enable_if_t<__is_vectorizable_byte_size_v<_Bytes>
   // constexpr default_sentinel_t end() const noexcept { return {}; }
   // constexpr default_sentinel_t cend() const noexcept { return {}; }
 
-  static constexpr integral_constant<__simd_size_type, __simd_size_v<__integer_from<_Bytes>, _Abi>> size{};
+  static constexpr __simd_size_constant<__simd_size_v<__integer_from<_Bytes>, _Abi>> size{};
 
   static constexpr auto __usize = size_t{size};
   static constexpr auto __size  = __simd_size_type{size};

libcudacxx/include/cuda/std/__simd/basic_vec.h

@@ -109,7 +109,7 @@ class basic_vec<_Tp, _Abi, enable_if_t<__is_vectorizable_v<_Tp> && __is_enabled_
   // constexpr default_sentinel_t end() const noexcept { return {}; }
   // constexpr default_sentinel_t cend() const noexcept { return {}; }
 
-  static constexpr integral_constant<__simd_size_type, __simd_size_v<value_type, abi_type>> size{};
+  static constexpr __simd_size_constant<__simd_size_v<value_type, abi_type>> size{};
 
   static constexpr auto __usize = size_t{size};
   static constexpr auto __size  = __simd_size_type{size};

libcudacxx/include/cuda/std/__simd/concepts.h

@@ -44,6 +44,13 @@ _CCCL_BEGIN_NAMESPACE_CUDA_STD_SIMD
 template <typename _From, typename _To>
 _CCCL_CONCEPT __explicitly_convertible_to = _CCCL_REQUIRES_EXPR((_From, _To))((static_cast<_To>(declval<_From>())));
 
+// [simd.expos], simd-vec-type concept
+
+template <typename _Vp>
+_CCCL_CONCEPT __simd_vec_type = _CCCL_REQUIRES_EXPR(
+  (_Vp))(requires(same_as<_Vp, basic_vec<typename _Vp::value_type, typename _Vp::abi_type>>),
+         requires(is_default_constructible_v<_Vp>));
+
 // [simd.expos], constexpr-wrapper-like concept
 
 template <typename _Tp>