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Merge 2025-02 LWG Motion 13
P2933R4 Extend <bit> header function with overloads for std::simd
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‎source/numerics.tex

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@@ -16125,6 +16125,11 @@
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template<class V, class T> using @\exposidnc{make-compatible-simd-t} = \seebelownc@; // \expos
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template<class V>
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concept @\defexposconceptnc{simd-type}@ = // \expos
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@\libconcept{same_as}@<V, basic_simd<typename V::value_type, typename V::abi_type>> &&
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is_default_constructible_v<V>;
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template<class V>
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concept @\defexposconceptnc{simd-floating-point}@ = // \expos
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@\libconcept{same_as}@<V, basic_simd<typename V::value_type, typename V::abi_type>> &&
@@ -16743,6 +16748,43 @@
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template<@\exposconcept{math-floating-point}@ V>
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@\exposid{deduced-simd-t}@<V>
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sph_neumann(const rebind_simd_t<unsigned, @\exposid{deduced-simd-t}@<V>>& n, const V& x);
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// \ref{simd.bit}, Bit manipulation
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template<@\exposconcept{simd-type}@ V> constexpr V byteswap(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V> constexpr V bit_ceil(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V> constexpr V bit_floor(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr typename V::mask_type has_single_bit(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V0, @\exposconcept{simd-type}@ V1>
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constexpr V0 rotl(const V0& v, const V1& s) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr V rotl(const V& v, int s) noexcept;
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template<@\exposconcept{simd-type}@ V0, @\exposconcept{simd-type}@ V1>
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constexpr V0 rotr(const V0& v, const V1& s) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr V rotr(const V& v, int s) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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bit_width(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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countl_zero(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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countl_one(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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countr_zero(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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countr_one(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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popcount(const V& v) noexcept;
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}
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\end{codeblock}
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@@ -18471,6 +18513,165 @@
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\tcode{ret.first}.
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\end{itemdescr}
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\rSec3[simd.bit]{\tcode{basic_simd} bit library}
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\begin{itemdecl}
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template<@\exposconcept{simd-type}@ V> constexpr V byteswap(const V& v) noexcept;
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\end{itemdecl}
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\begin{itemdescr}
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\pnum
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\constraints
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The type \tcode{V::value_type} models \tcode{integral}.
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\pnum
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\returns
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A \tcode{basic_simd} object where the $i^\text{th}$ element is initialized to
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the result of \tcode{std::byteswap(v[$i$])} for all $i$ in the range
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\range{0}{V::size()}.
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\end{itemdescr}
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\begin{itemdecl}
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template<@\exposconcept{simd-type}@ V> constexpr V bit_ceil(const V& v) noexcept;
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\end{itemdecl}
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\begin{itemdescr}
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\pnum
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\constraints
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The type \tcode{V::value_type} is an unsigned integer type\iref{basic.fundamental}.
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\pnum
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\expects
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For every $i$ in the range \range{0}{V::size()}, the smallest power of 2
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greater than or equal to \tcode{v[$i$]} is representable as a value of type
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\tcode{V::value_type}.
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\pnum
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\returns
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A \tcode{basic_simd} object where the $i^\text{th}$ element is initialized to
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the result of \tcode{std::bit_ceil(v[$i$])} for all $i$ in the range
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\range{0}{V::size()}.
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\pnum
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\remarks
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A function call expression that violates the precondition in the \expects
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element is not a core constant expression\iref{expr.const}.
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\end{itemdescr}
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\begin{itemdecl}
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template<@\exposconcept{simd-type}@ V> constexpr V bit_floor(const V& v) noexcept;
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\end{itemdecl}
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\begin{itemdescr}
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\pnum
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\constraints
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The type \tcode{V::value_type} is an unsigned integer type\iref{basic.fundamental}.
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\pnum
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\returns
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A \tcode{basic_simd} object where the $i^\text{th}$ element is initialized to
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the result of \tcode{std::bit_floor(v[$i$])} for all $i$ in the range
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\range{0}{V::size()}.
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\end{itemdescr}
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\begin{itemdecl}
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template<@\exposconcept{simd-type}@ V>
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constexpr typename V::mask_type has_single_bit(const V& v) noexcept;
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\end{itemdecl}
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\begin{itemdescr}
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\pnum
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\constraints
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The type \tcode{V::value_type} is an unsigned integer type\iref{basic.fundamental}.
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\pnum
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\returns
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A \tcode{basic_simd_mask} object where the $i^\text{th}$ element is initialized
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to the result of \tcode{std::has_single_bit(v[$i$])} for all $i$ in the range
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\range{0}{V::size()}.
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\end{itemdescr}
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\begin{itemdecl}
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template<@\exposconcept{simd-type}@ V0, @\exposconcept{simd-type}@ V1>
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constexpr V0 rotl(const V0& v0, const V1& v1) noexcept;
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template<@\exposconcept{simd-type}@ V0, @\exposconcept{simd-type}@ V1>
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constexpr V0 rotr(const V0& v0, const V1& v1) noexcept;
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\end{itemdecl}
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\begin{itemdescr}
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\pnum
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\constraints
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\begin{itemize}
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\item
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The type \tcode{V0::value_type} is an unsigned integer type\iref{basic.fundamental},
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\item
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the type \tcode{V1::value_type} models \tcode{integral},
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\item
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\tcode{V0::size() == V1::size()} is \tcode{true}, and
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\item
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\tcode{sizeof(typename V0::value_type) == sizeof(typename V1::value_type)} is \tcode{true}.
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\end{itemize}
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\pnum
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\returns
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A \tcode{basic_simd} object where the $i^\text{th}$ element is initialized to
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the result of \tcode{\placeholder{bit-func}(v0[$i$],
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static_cast<int>(v1[$i$]))} for all $i$ in the range \range{0}{V0::size()},
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where \placeholder{bit-func} is the corresponding scalar function from \libheader{bit}.
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\end{itemdescr}
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\begin{itemdecl}
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template<@\exposconcept{simd-type}@ V> constexpr V rotl(const V& v, int s) noexcept;
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template<@\exposconcept{simd-type}@ V> constexpr V rotr(const V& v, int s) noexcept;
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\end{itemdecl}
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\begin{itemdescr}
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\pnum
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\constraints
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The type \tcode{V::value_type} is an unsigned integer type\iref{basic.fundamental}
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\pnum
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\returns
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A \tcode{basic_simd} object where the $i^\text{th}$ element is initialized to
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the result of \tcode{\placeholder{bit-func}(v[$i$], s)} for all $i$ in the
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range \range{0}{V::size()}, where \placeholder{bit-func} is the corresponding
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scalar function from \libheader{bit}.
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\end{itemdescr}
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\begin{itemdecl}
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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bit_width(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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countl_zero(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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countl_one(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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countr_zero(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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countr_one(const V& v) noexcept;
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template<@\exposconcept{simd-type}@ V>
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constexpr rebind_simd_t<make_signed_t<typename V::value_type>, V>
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popcount(const V& v) noexcept;
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\end{itemdecl}
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\begin{itemdescr}
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\pnum
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\constraints
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The type \tcode{V::value_type} is an unsigned integer type\iref{basic.fundamental}
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\pnum
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\returns
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A \tcode{basic_simd} object where the $i^\text{th}$ element is initialized to
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the result of \tcode{\placeholder{bit-func}(v[$i$])} for all $i$ in the range
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\range{0}{V::size()}, where \placeholder{bit-func} is the corresponding scalar
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function from \libheader{bit}.
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\end{itemdescr}
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\rSec2[simd.mask.class]{Class template \tcode{basic_simd_mask}}
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\rSec3[simd.mask.overview]{Class template \tcode{basic_simd_mask} overview}

‎source/support.tex

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@@ -799,7 +799,7 @@
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#define @\defnlibxname{cpp_lib_shared_ptr_weak_type}@ 201606L // also in \libheader{memory}
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#define @\defnlibxname{cpp_lib_shared_timed_mutex}@ 201402L // also in \libheader{shared_mutex}
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#define @\defnlibxname{cpp_lib_shift}@ 202202L // also in \libheader{algorithm}
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#define @\defnlibxname{cpp_lib_simd}@ 202411L // also in \libheader{simd}
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#define @\defnlibxname{cpp_lib_simd}@ 202502L // also in \libheader{simd}
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#define @\defnlibxname{cpp_lib_smart_ptr_for_overwrite}@ 202002L // also in \libheader{memory}
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#define @\defnlibxname{cpp_lib_smart_ptr_owner_equality}@ 202306L // also in \libheader{memory}
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#define @\defnlibxname{cpp_lib_source_location}@ 201907L // freestanding, also in \libheader{source_location}

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