[libc++] <experimental/simd> Add swap functions of simd reference

Author: joy2myself

libcxx/include/experimental/__simd/reference.h

@@ -13,6 +13,7 @@
 #include <__type_traits/is_assignable.h>
 #include <__type_traits/is_same.h>
 #include <__utility/forward.h>
+#include <__utility/move.h>
 #include <cstddef>
 #include <experimental/__config>
 #include <experimental/__simd/utility.h>
@@ -55,6 +56,24 @@ class __simd_reference {
     __set(static_cast<value_type>(std::forward<_Up>(__v)));
     return {__s_, __idx_};
   }
+
+  friend _LIBCPP_HIDE_FROM_ABI void swap(__simd_reference&& __a, __simd_reference&& __b) noexcept {
+    value_type __tmp(std::move(__a.__get()));
+    __a.__set(std::move(__b.__get()));
+    __b.__set(std::move(__tmp));
+  }
+
+  friend _LIBCPP_HIDE_FROM_ABI void swap(value_type& __a, __simd_reference&& __b) noexcept {
+    value_type __tmp(std::move(__a));
+    __a = std::move(__b.__get());
+    __b.__set(std::move(__tmp));
+  }
+
+  friend _LIBCPP_HIDE_FROM_ABI void swap(__simd_reference&& __a, value_type& __b) noexcept {
+    value_type __tmp(std::move(__a.__get()));
+    __a.__set(std::move(__b));
+    __b = std::move(__tmp);
+  }
 };
 
 } // namespace parallelism_v2

libcxx/include/experimental/simd

@@ -78,6 +78,7 @@ inline namespace parallelism_v2 {
 #include <experimental/__config>
 #include <experimental/__simd/aligned_tag.h>
 #include <experimental/__simd/declaration.h>
+#include <experimental/__simd/reference.h>
 #include <experimental/__simd/scalar.h>
 #include <experimental/__simd/simd.h>
 #include <experimental/__simd/simd_mask.h>

libcxx/test/std/experimental/simd/simd.reference/reference_swap.pass.cpp

@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14
+
+// <experimental/simd>
+//
+// [simd.reference]
+// friend void swap(reference&& a, reference&& b) noexcept;
+// friend void swap(value_type& a, reference&& b) noexcept;
+// friend void swap(reference&& a, value_type& b) noexcept;
+
+#include "../test_utils.h"
+#include <experimental/simd>
+
+namespace ex = std::experimental::parallelism_v2;
+
+template <class T, std::size_t>
+struct CheckSimdRefSwap {
+  template <class SimdAbi>
+  void operator()() {
+    ex::simd<T, SimdAbi> origin_simd_1(1);
+    ex::simd<T, SimdAbi> origin_simd_2(2);
+    T value = 3;
+
+    static_assert(noexcept(swap(origin_simd_1[0], origin_simd_2[0])));
+    swap(origin_simd_1[0], origin_simd_2[0]);
+    assert((origin_simd_1[0] == 2) && (origin_simd_2[0] == 1));
+
+    static_assert(noexcept(swap(origin_simd_1[0], value)));
+    swap(origin_simd_1[0], value);
+    assert((origin_simd_1[0] == 3) && (value == 2));
+
+    static_assert(noexcept(swap(value, origin_simd_2[0])));
+    swap(value, origin_simd_2[0]);
+    assert((value == 1) && (origin_simd_2[0] == 2));
+  }
+};
+
+template <class T, std::size_t>
+struct CheckMaskRefSwap {
+  template <class SimdAbi>
+  void operator()() {
+    ex::simd_mask<T, SimdAbi> origin_mask_1(true);
+    ex::simd_mask<T, SimdAbi> origin_mask_2(false);
+    bool value = true;
+
+    static_assert(noexcept(swap(origin_mask_1[0], origin_mask_2[0])));
+    swap(origin_mask_1[0], origin_mask_2[0]);
+    assert((origin_mask_1[0] == false) && (origin_mask_2[0] == true));
+
+    static_assert(noexcept(swap(origin_mask_1[0], value)));
+    swap(origin_mask_1[0], value);
+    assert((origin_mask_1[0] == true) && (value == false));
+
+    static_assert(noexcept(swap(value, origin_mask_2[0])));
+    swap(value, origin_mask_2[0]);
+    assert((value == true) && (origin_mask_2[0] == false));
+  }
+};
+
+int main(int, char**) {
+  test_all_simd_abi<CheckSimdRefSwap>();
+  test_all_simd_abi<CheckMaskRefSwap>();
+  return 0;
+}