std::experimental::simd_abi:: deduce

Defined in header <experimental/simd>
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

This section is incomplete Reason: no example

See also

scalar (parallelism TS v2)	tag type for storing a single element (typedef)
fixed_size (parallelism TS v2)	tag type for storing specified number of elements (alias template)
compatible (parallelism TS v2)	tag type that ensures ABI compatibility (alias template)
native (parallelism TS v2)	tag type that is most efficient (alias template)