std::experimental::rebind_simd, std::experimental::resize_simd

< cpp‎ | experimental‎ | simd
Technical Specification
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals TS v2)
Library fundamentals 3 (library fundamentals TS v3)
Extensions for parallelism (parallelism TS)
Extensions for parallelism 2 (parallelism TS v2)
Extensions for concurrency (concurrency TS)
Extensions for concurrency 2 (concurrency TS v2)
Concepts (concepts TS)
Ranges (ranges TS)
Reflection (reflection TS)
Mathematical special functions (special functions TR)
Experimental Non-TS
Pattern Matching
Linear Algebra
2D Graphics
Defined in header <experimental/simd>
template< class T, class V >
struct rebind_simd;
(1) (parallelism TS v2)
template< int N, class V >
struct resize_simd;
(2) (parallelism TS v2)

Creates a simd or simd_mask type with a different element type or size. The new type likely uses an ABI tag type different from V::abi_type.

1) Changes the element type to T and keeps the size unchanged.
2) Changes the size to N and keeps the element type unchanged.


[edit] Template parameters

T - the new element type; an arithmetic type other than bool
N - the new number of elements
V - a simd or simd_mask type

[edit] Member types

Name Definition
type simd or simd_mask type with a different element type (1) or size (2)

[edit] Helper types

template< class T, class V >
using rebind_simd_t = typename rebind_simd<T, V>::type;
(parallelism TS v2)
template< int N, class V >
using resize_simd_t = typename resize_simd<N, V>::type;
(parallelism TS v2)

[edit] Example

#include <experimental/simd>
#include <iostream>
namespace stdx = std::experimental;
using floatv = stdx::native_simd<float>;
// use double precision internally
floatv dp(floatv x)
    using doublev = stdx::rebind_simd_t<double, floatv>;
    return stdx::static_simd_cast<floatv>(stdx::simd_cast<doublev>(x) - 1.234);
template<class T>
stdx::resize_simd_t<T::size() / 2, T> partial_reduction(T x)
    auto [lo, hi] = stdx::split<stdx::resize_simd_t<T::size() / 2, T>>(x);
    return lo + hi;
int main() 
    floatv x([](auto i) { return 1.234f + std::numeric_limits<float>::epsilon() * i; });
    x = dp(x);
    const auto y = partial_reduction(x);
    for (unsigned i = 0; i < y.size(); ++i)
        std::cout << y[i] << ' ';
    std::cout << '\n';

Possible output:

1.73569e-07 4.11987e-07

[edit] See also

(parallelism TS v2)
obtains an ABI type for given element type and number of elements
(class template) [edit]