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Add [parallel.simd.traits]
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‎data_parallel_types.html

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@@ -375,6 +375,176 @@ <h1><ins><code>simd</code> ABI tags</ins></h1>
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</p>
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</cxx-section>
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<cxx-section id="parallel.simd.traits">
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<h1><ins><code>simd</code> type traits</ins></h1>
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<ins>
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<code>template&lt;class&gt; struct is_abi_tag { <em>see-below</em> };</code>
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</ins>
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<p>
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<ins>
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The type <code>is_abi_tag&lt;T&gt;</code> is a <code>UnaryTypeTrait</code> with a <code>BaseCharacteristic</code> of <code>true_type</code> if <code>T</code> is a standard or extended ABI tag, and <code>false_type</code> otherwise.
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</ins>
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</p>
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<p>
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<ins>
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The behavior of a program that adds specializations for <code>is_abi_tag</code> is undefined.
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</ins>
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</p>
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<ins>
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<code>template&lt;class&gt; struct is_simd { <em>see-below</em> };</code>
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</ins>
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<p>
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<ins>
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The type <code>is_simd&lt;T&gt;</code> is a <code>UnaryTypeTrait</code> with a <code>BaseCharacteristic</code> of <code>true_type</code> if <code>T</code> is a specialization of the <code>simd</code> class template, and <code>false_type</code> otherwise.
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</ins>
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</p>
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<p>
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<ins>
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The behavior of a program that adds specializations for <code>is_simd</code> is undefined.
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</ins>
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</p>
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<p>
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<ins>
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The type <code>is_simd_mask&lt;T&gt;</code> is a <code>UnaryTypeTrait</code> with a <code>BaseCharacteristic</code> of <code>true_type</code> if <code>T</code> is a specialization of the <code>simd_mask</code> class template, and <code>false_type</code> otherwise.
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</ins>
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</p>
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<p>
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<ins>
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The behavior of a program that adds specializations for <code>is_simd_mask</code> is undefined.
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</ins>
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</p>
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<ins>
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<code>template&lt;class T&gt; struct is_simd_flag_type { <em>see-below</em> };</code>
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</ins>
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<p>
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<ins>
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The type <code>is_simd_flag_type&lt;class T&gt;</code> is a <code>UnaryTypeTrait</code> with a <code>BaseCharacteristic</code> of <code>true_type</code> if <code>T</code> is one of
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<bl>
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<li>
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<ins>
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<code>element_aligned_tag</code>, or
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</ins>
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</li>
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<li>
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<ins>
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<code>vector_aligned_tag</code>, or
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</ins>
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</li>
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<li>
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<ins>
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<code>overaligned_tag&lt;N&gt;</code> with <code>N &gt; 0</code> and <code>N</code> an integral power of two,
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</ins>
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</li>
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</bl>
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<br>
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<ins>
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and <code>false_type</code> otherwise.
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</ins>
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</ins>
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</p>
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<p>
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<ins>
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The behavior of a program that adds specializations for <code>is_simd_flag_type</code> is undefined.
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</ins>
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</p>
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<ins>
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<code>template&lt;class T, class Abi = simd_abi::compatible&lt;T&gt;&gt; struct simd_size { <em>see-below</em> };</code>
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</ins>
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<p>
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<ins>
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<code>simd_size&lt;T, Abi&gt;</code> has a member <code>value</code> if and only if
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<bl>
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<li>
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<ins>
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<code>T</code> is a vectorizable type, and
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</ins>
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</li>
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<li>
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<ins>
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<code>is_abi_tag_v&lt;Abi&gt;</code> is <code>true</code>.
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</ins>
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</li>
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</bl>
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<br>
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<ins>
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<cxx-note>
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The rules are different from <cxx-ref to="parallel.simd.overview"></cxx-ref>.
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</cxx-note>
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</ins>
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</ins>
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</p>
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<p>
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<ins>
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If <code>value</code> is present, the type <code>simd_size&lt;T, Abi&gt;</code> is a <code>BinaryTypeTrait</code> with a <code>BaseCharacteristic</code> of <code>integral_constant&lt;size_t, N&gt;</code> with <code>N</code> equal to the number of elements in a <code>simd&lt;T, Abi&gt;</code> object. <cxx-note>If <code>simd&lt;T, Abi&gt;</code> is not supported for the currently targeted system, <code>simd_size&lt;T, Abi&gt;::value</code> produces the value <code>simd&lt;T, Abi&gt;::size()</code> would return if it were supported.</cxx-note>
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</ins>
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</p>
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<p>
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<ins>
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The behavior of a program that adds specializations for <code>simd_size</code> is undefined.
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</ins>
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</p>
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<ins>
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<code>template&lt;class T, class U = typename T::value_type&gt; struct memory_alignment { <em>see-below</em> };</code>
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</ins>
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<p>
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<ins>
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<code>memory_alignment&lt;T, U&gt;</code> has a member <code>value</code> if and only if
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</ins>
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<bl>
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<li>
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<ins>
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<code>is_simd_mask_v&lt;T&gt;</code> is <code>true</code> and <code>U</code> is <code>bool</code>, or
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</ins>
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</li>
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<li>
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<ins>
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<code>is_simd_v&lt;T&gt;</code> is <code>true</code> and <code>U</code> is a vectorizable type.
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</ins>
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</li>
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</bl>
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</p>
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<p>
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<ins>
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If <code>value</code> is present, the type <code>memory_alignment&lt;T, U&gt;</code> is a <code>BinaryTypeTrait</code> with a <code>BaseCharacteristic</code> of <code>integral_constant&lt;size_t, N&gt;</code> for some implementation-defined <code>N</code> (see <cxx-ref to="parallel.simd.copy"></cxx-ref> and <cxx-ref to="parallel.simd.mask.copy"></cxx-ref>). <cxx-note><code>value</code> identifies the alignment restrictions on pointers used for (converting) loads and stores for the give type <code>T</code> on arrays of type <code>U</code>.</cxx-note>
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</ins>
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</p>
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<p>
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<ins>
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The behavior of a program that adds specializations for <code>memory_alignment</code> is undefined.
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</ins>
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</p>
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</cxx-section>
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<cxx-section id="parallel.simd.overview">
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</cxx-section>
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</cxx-clause>

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