std::experi...k::simd_mask(3)

💖 NAME 💖

okay bestie, welcome to the manual page for std::experi...k::simd_mask(3) from the C++ Standard Libary — yes, that's the spelling in the header, and we are not fixing it because details are sacred 😌. The name on the cover is std::experimental::simd_mask::simd_mask - std::experimental::simd_mask::simd_mask, aka the constructor of the mask type. It's giving main character energy for SIMD lanes, and honestly? iconic.

✨ Synopsis ✨

okay so here's the whole constructor lineup, copied with zero changes because code is not a vibe, it's a contract:

simd_mask() noexcept = default;                            (1)
explicit simd_mask( bool value ) noexcept;                 (2)
template< class U >
simd_mask( const simd_mask<U,
simd_abi::fixed_size<size()>>& other ) noexcept;           (3)
template< class U, class Flags >
simd_mask( const bool* mem, Flags flags );                 (4)
simd_mask( const simd_mask& other ) noexcept = default;    (5)
simd_mask( simd_mask&& other ) noexcept = default;         (6)

Every overload above is tagged (parallelism TS v2) in the page, and (5) plus (6) are also (implicitly declared). periodt 🫶

• 1) Constructs a simd_mask using default initialization (constructed without initializer) or value initialization (constructed with an empty initializer).
• 2) The broadcast constructor constructs a simd_mask with all values initialized to value.
• 3) Constructs a simd_mask where the i-th element is initialized to other[i] for all i in the range of [0, size()). This overload participates in overload resolution only if Abi is simd_abi::fixed_size<size()>.
• 4) The load constructor constructs a simd_mask where the i-th element is initialized to mem[i] for all i in the range of [0, size()).
• 5, 6) Implicitly declared copy and move constructors. Constructs a simd_mask where each element is initialized from the values of the elements in other.

🎀 Parameters 🎀

• value — the value used for initialization of all simd_mask elements.
• other — another simd_mask to copy from.
• mem — a pointer into an array where [mem, mem + size()) is a valid range.
• flags — if of type vector_aligned_tag, the load constructor may assume mem to point to storage aligned by memory_alignment_v<simd_mask>.

🦋 Type requirements 🦋

• is_simd_flag_type_v<Flags> must be true. no cap, that's the whole requirement 💅

🌸 Example 🌸

the page says // Run this code, so let's go, bestie. This is the exact example, no edits:

#include <algorithm>
#include <cstddef>
#include <experimental/simd>
#include <iostream>
namespace stdx = std::experimental;

int main()
{
    [[maybe_unused]]
    stdx::native_simd_mask<int> a;       // uninitialized
    stdx::native_simd_mask<int> b(true); // all elements initialized with true
    stdx::native_simd_mask<int> c{};     // all elements initialized with false

    alignas(stdx::memory_alignment_v<stdx::native_simd_mask<int>>)
        std::array<bool, stdx::native_simd_mask<int>::size() * 2> mem = {};
    std::ranges::generate(mem, [i{0}] mutable -> bool { return i++ & 1; });

    stdx::native_simd_mask<int> d(&mem[0], stdx::vector_aligned);  // {0, 1, 0, 1, ...}
    stdx::native_simd_mask<int> e(&mem[1], stdx::element_aligned); // {1, 0, 1, 0, ...}

    const auto xored = b ^ c ^ d ^ e;

    for (std::size_t i{}; i != xored.size(); ++i)
        std::cout << xored[i] << ' ';
    std::cout << '\n';
}

🌈 Possible output 🌈

0 0 0 0 0 0 0 0

👑 See also 👑

okay related lore, all of it:

• element_aligned_tag — flag indicating alignment of the load/store address to element alignment; also element_aligned — alignment. This pair is marked (parallelism TS v2) and (class).
• vector_aligned_tag — flag indicating alignment of the load/store address to vector alignment; also vector_aligned — alignment. This pair is marked (parallelism TS v2) and (class).
• overaligned_tag — flag indicating alignment of the load/store address to the specified alignment; also overaligned — specified alignment. This pair is marked (parallelism TS v2) and (class template).
• memory_alignment — obtains an appropriate alignment for vector_aligned. Marked (parallelism TS v2) and (class template).
• copy_from — loads simd_mask elements from contiguous memory. Marked (parallelism TS v2) and (public member function).

💌 source: http://cppreference.com · version/date: 2024.06.10 · page: std::experi...k::simd_mask(3) — byeee bestie, go construct some iconic masks 💅✨