[libc++] <experimental/simd> Add ++/-- operators for simd reference

Author: joy2myself

libcxx/include/experimental/__simd/reference.h

@@ -12,6 +12,7 @@
 
 #include <__type_traits/is_assignable.h>
 #include <__type_traits/is_same.h>
+#include <__utility/declval.h>
 #include <__utility/forward.h>
 #include <cstddef>
 #include <experimental/__config>
@@ -55,6 +56,32 @@ class __simd_reference {
     __set(static_cast<value_type>(std::forward<_Up>(__v)));
     return {__s_, __idx_};
   }
+
+  template <class _Up = value_type, class = decltype(std::declval<_Up>() + _Up{1})>
+  __simd_reference _LIBCPP_HIDE_FROM_ABI operator++() && noexcept {
+    __set(__get() + 1);
+    return {__s_, __idx_};
+  }
+
+  template <class _Up = value_type, class = decltype(std::declval<_Up>() + _Up{1})>
+  value_type _LIBCPP_HIDE_FROM_ABI operator++(int) && noexcept {
+    auto __r = __get();
+    __set(__get() + 1);
+    return __r;
+  }
+
+  template <class _Up = value_type, class = decltype(std::declval<_Up>() - _Up{1})>
+  __simd_reference _LIBCPP_HIDE_FROM_ABI operator--() && noexcept {
+    __set(__get() - 1);
+    return {__s_, __idx_};
+  }
+
+  template <class _Up = value_type, class = decltype(std::declval<_Up>() - _Up{1})>
+  value_type _LIBCPP_HIDE_FROM_ABI operator--(int) && noexcept {
+    auto __r = __get();
+    __set(__get() - 1);
+    return __r;
+  }
 };
 
 } // namespace parallelism_v2

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

@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// 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]
+// reference operator++() && noexcept;
+// value_type operator++(int) && noexcept;
+// reference operator--() && noexcept;
+// value_type operator--(int) && noexcept;
+
+#include "../test_utils.h"
+#include <experimental/simd>
+
+namespace ex = std::experimental::parallelism_v2;
+
+template <class T, std::size_t>
+struct CheckSimdReferenceUnaryOperators {
+  template <class SimdAbi>
+  void operator()() const {
+    ex::simd<T, SimdAbi> origin_simd(static_cast<T>(3));
+    static_assert(noexcept(++origin_simd[0]));
+    assert(((T)(++origin_simd[0]) == static_cast<T>(4)) && ((T)origin_simd[0] == static_cast<T>(4)));
+    static_assert(noexcept(origin_simd[0]++));
+    assert(((T)(origin_simd[0]++) == static_cast<T>(4)) && ((T)origin_simd[0] == static_cast<T>(5)));
+    static_assert(noexcept(--origin_simd[0]));
+    assert(((T)(--origin_simd[0]) == static_cast<T>(4)) && ((T)origin_simd[0] == static_cast<T>(4)));
+    static_assert(noexcept(origin_simd[0]--));
+    assert(((T)(origin_simd[0]--) == static_cast<T>(4)) && ((T)origin_simd[0] == static_cast<T>(3)));
+  }
+};
+
+int main(int, char**) {
+  test_all_simd_abi<CheckSimdReferenceUnaryOperators>();
+  return 0;
+}