[libcxx-commits] [libcxx] [libc++] Start implementing std::datapar::simd (PR #139919)

[Louis Dionne via libcxx-commits]

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@@ -0,0 +1,350 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___SIMD_BASIC_SIMD_H
+#define _LIBCPP___SIMD_BASIC_SIMD_H
+
+#include <__assert>
+#include <__concepts/convertible_to.h>
+#include <__config>
+#include <__memory/assume_aligned.h>
+#include <__ranges/concepts.h>
+#include <__simd/abi.h>
+#include <__simd/basic_simd_mask.h>
+#include <__simd/simd_flags.h>
+#include <__type_traits/is_arithmetic.h>
+#include <__type_traits/pack_utils.h>
+#include <__type_traits/remove_const.h>
+#include <__type_traits/remove_cvref.h>
+#include <__utility/integer_sequence.h>
+
+#if _LIBCPP_STD_VER >= 26
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace datapar {
+
+_LIBCPP_DIAGNOSTIC_PUSH
+_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wpsabi")
+template <class _Tp, class _Abi = __native_abi<_Tp>>
+class basic_simd {
+public:
+  using value_type = _Tp;
+  using mask_type  = basic_simd_mask<sizeof(_Tp), _Abi>;
+  using abi_type   = _Abi;
+
+private:
+  using __data_t = abi_type::_SimdT;
+
+  __data_t __data_;
+
+  _LIBCPP_ALWAYS_INLINE static constexpr __data_t __broadcast(value_type __value) {
+    return [&]<size_t... _Indices>(index_sequence<_Indices...>) _LIBCPP_ALWAYS_INLINE noexcept {
+      return __data_t{((void)_Indices, __value)...};
+    }(make_index_sequence<size()>{});
+  }
+
+  template <class _Up>
+  _LIBCPP_ALWAYS_INLINE static constexpr __data_t __load_from_pointer(const _Up* __ptr) {
+    return [&]<size_t... _Indices>(index_sequence<_Indices...>) _LIBCPP_ALWAYS_INLINE noexcept {
+      return __data_t{__ptr[_Indices]...};
+    }(make_index_sequence<size()>{});
+  }
+
+public:
+  static constexpr integral_constant<__simd_size_type, __simd_size_v<value_type, abi_type>> size{};
+
+  constexpr basic_simd() noexcept = default;
+
+  // [simd.ctor]
+  template <convertible_to<value_type> _Up, class _From = remove_cvref_t<_Up>>
+    requires(__value_preserving_convertible<_From, value_type> ||
+             (!is_arithmetic_v<_From> && !__constexpr_wrapper_like<_From>) ||
+             (__constexpr_wrapper_like<_From> && is_arithmetic_v<remove_const_t<decltype(_From::value)>> &&
+              bool_constant<(static_cast<value_type>(_From::value) == _From::value)>::value))
+  _LIBCPP_HIDE_FROM_ABI constexpr basic_simd(_Up&& __value) noexcept : __data_{__broadcast(__value)} {}
----------------
ldionne wrote:

https://eel.is/c++draft/simd#ctor-4 says there's a conditional `explicit` here. Can you double-check all the other constructors for this mistake, and also ensure that we've got tests for those?

Actually, it looks like you got your constraints wrong. You seem to have taken the `explicit(see-below)` for the `Constraints` clauses.

https://github.com/llvm/llvm-project/pull/139919