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std::experimental::simd_abi::deduce - cppreference.com

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template< class T, std::size_t N, class ...Abis > struct deduce;

 (parallelism TS v2)

The type deduce<T, N, Abis...>::type is present if and only if:

  • T is a vectorizable type,
  • simd_abi::fixed_size<N> is supported, and
  • every type in Abis... is an ABI tag.

Let DA denote deduce<T, N, Abis...>::type when it presents, then

  • simd_size_v<T, DA> == N,
  • simd<T, DA> is default constructible, i.e. it is supported,
  • DA is simd_abi::scalar if N == 1, otherwise it is implementation-defined.

Member types

Name Definition
type an ABI tag type suitable for specified element type T and size N

Helper types

template< class T, std::size_t N, class ...Abis > using deduce_t = typename deduce<T, N, Abis...>::type;

 (parallelism TS v2)

Notes

simd_abi::deduce is SFINAE-friendly.

The ABI tag deduced via this facility is a Quality-of-Implementation feature. Implementations can base the choice on Abis..., but can also ignore the Abis... arguments. A simple implementation might simply return fixed_size<N> unconditionally. An optimized implementation might return an implementation-defined extended ABI tag for most inputs. Consequently, if you need an ABI tag for a certain number of elements, use fixed_size if ABI stability is of concern, and prefer deduce_t otherwise.

Example

See also

tag type for storing a single element
(typedef) [edit]
tag type for storing specified number of elements
(alias template)[edit]
tag type that ensures ABI compatibility
(alias template)[edit]
tag type that is most efficient
(alias template)[edit]