The attributes std::experimental::issimd and std::experimental::issimdmask are detailed within the Parallelism Technical Specification Version 2 (Parallelism TS v2) and can be located in the header file. These properties are employed to determine if a certain type is an instance of particular SIMD-related class templates supplied by the C++ standard library. This guide will explore the std::experimental::issimd and std::experimental::issimdmask in C++, covering their syntax, arguments, and illustrations.
What is the std::experimental::is_simd function?
The SIMD category of T is confirmed by this attribute. SIMD types, which stand for Single Instruction, Multiple Data, are beneficial for high-performance computing tasks where a single instruction is applied to multiple data elements at the same time.
The constant member value ```
template< class T >
struct is_simd;
## Syntax:
It has the following syntax:
template< class T >
struct is_simd;
### Parameters:
- template< class T >: This template declaration indicates that the template is_simd accepts a single type parameter, T.
- struct is_simd;: A class template called is_simd is declared with the expression struct is_simd;. The structure of is_simd is declared, but its implementation is not described at this time because no definition is given. It is simply a forward declaration.
## What is the std::experimental::is_simd_mask?
A SIMD mask type validation is carried out by this functionality on T. When a comparison is executed on an element within a SIMD vector, the outcome is denoted by a bit in a SIMD mask type. This method is the conventional approach to illustrating the outcome of SIMD comparative actions.
The function is_simd_mask() provides a constant value indicating whether T is a specific instance of the simd_mask template class. It will return true only if T is a specialization of the simd_mask class template; otherwise, it will return false for all other data types.
## Syntax:
It has the following syntax:
template< class T >
struct issimdmask;
### Parameters:
- template< class T >: This template declaration indicates that the template is_simd accepts a single type parameter, T.
- struct is_simd_mask;: It declares the is_simd_mask template class or struct, which will function with type T. It would be elsewhere to define the real structure and behavior of is_simd_mask.
### Example:
Let's consider an example to demonstrate the std::experimental::is_simd and std::experimental::is_simd_mask in the C++ programming language.
include <experimental/simd>
include <iostream>
include <string_view>
include <type_traits>
namespace stdx = std::experimental;
template<typename T>
void testsimd(std::stringview type_name)
{
std::cout << std::boolalpha
<< "The type is: " << type_name << '\n'
<< " issimd: " << stdx::issimd_v<T> << '\n'
<< " isconstructible: " << std::isconstructible_v<T> << '\n'
<< " istriviallycopyable: " << std::istriviallycopyable_v<T> << '\n'
<< " alignment: " << alignof(T) << "\n\n";
}
template<typename T>
void testsimdmask(std::stringview typename)
{
std::cout << std::boolalpha
<< "The type is: " << type_name << '\n'
<< " issimdmask: " << stdx::issimdmask_v<T> << '\n'
<< " isconstructible: " << std::isconstructible_v<T> << '\n'
<< " istriviallycopyable: " << std::istriviallycopyable_v<T> << '\n'
<< " alignment: " << alignof(T) << "\n\n";
}
int main
{
test_simd<int>("int");
testsimdmask<int>("int");
test_simd<float>("float");
testsimdmask<float>("float");
// Testing std::experimental::simd with various types
test_simd<stdx::simd<float>>("simd<float>");
testsimdmask<stdx::simdmask<float>>("simdmask<float>");
test_simd<stdx::simd<double>>("simd<double>");
testsimdmask<stdx::simdmask<double>>("simdmask<double>");
test_simd<stdx::simd<int>>("simd<int>");
testsimdmask<stdx::simdmask<int>>("simdmask<int>");
// Testing with bool
test_simd<stdx::simd<bool>>("simd<bool>");
testsimdmask<stdx::simdmask<bool>>("simdmask<bool>");
// Testing with other integral types
test_simd<stdx::simd<short>>("simd<short>");
testsimdmask<stdx::simdmask<short>>("simdmask<short>");
test_simd<stdx::simd<long>>("simd<long>");
testsimdmask<stdx::simdmask<long>>("simdmask<long>");
// Testing with non-SIMD compatible types
test_simd<std::string>("std::string");
testsimdmask<std::string>("std::string");
test_simd<void>("void");
testsimdmask<void>("void");
return 0;
}
Output:
The type is: int
is_simd: false
is_constructible: true
istriviallycopyable: true
alignment: 4
The type is: int
issimdmask: false
is_constructible: true
istriviallycopyable: true
alignment: 4
The type is: float
is_simd: false
is_constructible: true
istriviallycopyable: true
alignment: 4
The type is: float
issimdmask: false
is_constructible: true
istriviallycopyable: true
alignment: 4
The type is: simd<float>
is_simd: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd_mask<float>
issimdmask: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd<double>
is_simd: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd_mask<double>
issimdmask: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd<int>
is_simd: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd_mask<int>
issimdmask: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd<bool>
is_simd: true
is_constructible: false
istriviallycopyable: true
alignment: 1
The type is: simd_mask<bool>
issimdmask: true
is_constructible: false
istriviallycopyable: true
alignment: 1
The type is: simd<short>
is_simd: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd_mask<short>
issimdmask: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd<long>
is_simd: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: simd_mask<long>
issimdmask: true
is_constructible: true
istriviallycopyable: true
alignment: 16
The type is: std::string
is_simd: false
is_constructible: true
istriviallycopyable: false
alignment: 8
The type is: std::string
issimdmask: false
is_constructible: true
istriviallycopyable: false
alignment: 8
The type is: void*
is_simd: false
is_constructible: true
istriviallycopyable: true
alignment: 8
The type is: void*
issimdmask: false
is_constructible: true
istriviallycopyable: true
alignment: 8
### Explanation:
In this instance, the code validates the compatibility of various types with SIMD (Single Instruction, Multiple Data) operations by utilizing the std::experimental::simd and std::experimental::simd_mask templates. It introduces two functions, test_simd and test_simd_mask, which ascertain and display whether a specified type qualifies as a SIMD type or a SIMD mask type, alongside assessing other characteristics such as constructibility, trivial copyability, and alignment. The primary function executes these evaluations on a range of fundamental, SIMD, and non-SIMD compatible types such as int, float, simd, and std::string, illustrating the behavior of these traits across diverse data types.
