std::experi..._abi::deduce(3)

💖 NAME 💖

okay so bestie, welcome to the std::experi..._abi::deduce(3) page from the C++ Standard Libary manual 💅 this whole page is literally about std::experimental::simd_abi::deduce — and the NAME line is std::experimental::simd_abi::deduce followed by another std::experimental::simd_abi::deduce, because why not 😭.

🌸 Synopsis 🌸

here’s the header + template situation, exact:

Defined in header <experimental/simd>
template< class T, std::size_t N, class ...Abis >  (parallelism TS v2)
struct deduce;

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 — yes, “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 🎀

one-row table realness:

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

🦋 Helper types 🦋

the helper alias, exactly as promised:

template< class T, std::size_t N, class ...Abis >       (parallelism TS v2)
using deduce_t = typename deduce<T, N, Abis...>::type;

💜 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

not me arriving with no example 😭💀.

🌈 See also 🌈

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

🍓 Category 🍓

• Todo no example

byeee bestie, this page is from http://cppreference.com, date/version 2024.06.10, and it’s the std::experi..._abi::deduce(3) page — mwah 💋💖