[libc++] <experimental/simd> Add operator value_type() of simd reference

Author: joy2myself

libcxx/docs/Status/ParallelismProjects.csv

@@ -14,6 +14,7 @@ Section,Description,Dependencies,Assignee,Complete
 | `[parallel.simd.traits] <https://wg21.link/N4808>`_, "simd type traits rebind_simd", None, Yin Zhang, |In Progress|
 | `[parallel.simd.traits] <https://wg21.link/N4808>`_, "simd type traits resize_simd", None, Yin Zhang, |In Progress|
 | `[parallel.simd.whereexpr] <https://wg21.link/N4808>`_, "Where expression class templates", None, Yin Zhang, |In Progress|
+| `[parallel.simd.reference] <https://wg21.link/N4808>`_, "`Element references operator value_type() <https://github.com/llvm/llvm-project/pull/68960>`_", None, Yin Zhang, |Complete|
 | `[parallel.simd.class] <https://wg21.link/N4808>`_, "`Class template simd declaration and alias <https://reviews.llvm.org/D144362>`_", [parallel.simd.abi], Yin Zhang, |Complete|
 | `[parallel.simd.class] <https://wg21.link/N4808>`_, "`simd<>::size() <https://reviews.llvm.org/D144363>`_", [parallel.simd.traits] simd_size[_v], Yin Zhang, |Complete|
 | `[parallel.simd.class] <https://wg21.link/N4808>`_, "`simd broadcast constructor <https://reviews.llvm.org/D156225>`_", None, Yin Zhang, |Complete|

libcxx/include/experimental/__simd/reference.h

@@ -26,7 +26,7 @@ class __simd_reference {
   _Storage& __s_;
   size_t __idx_;
 
-  _LIBCPP_HIDE_FROM_ABI _Vp __get() const { return __s_.__get(__idx_); }
+  _LIBCPP_HIDE_FROM_ABI _Vp __get() const noexcept { return __s_.__get(__idx_); }
 
   _LIBCPP_HIDE_FROM_ABI void __set(_Vp __v) {
     if constexpr (is_same_v<_Vp, bool>)
@@ -40,6 +40,8 @@ class __simd_reference {
 
   __simd_reference()                        = delete;
   __simd_reference(const __simd_reference&) = delete;
+
+  _LIBCPP_HIDE_FROM_ABI operator value_type() const noexcept { return __get(); }
 };
 
 } // namespace parallelism_v2

libcxx/include/experimental/__simd/simd.h

@@ -46,11 +46,11 @@ class simd {
 
   // generator constructor
   template <class _Generator, enable_if_t<__can_generate_v<value_type, _Generator, size()>, int> = 0>
-  explicit _LIBCPP_HIDE_FROM_ABI simd(_Generator&& __g) : __s_(_Impl::__generate(std::forward<_Generator>(__g))) {}
+  explicit _LIBCPP_HIDE_FROM_ABI simd(_Generator&& __g) noexcept : __s_(_Impl::__generate(std::forward<_Generator>(__g))) {}
 
   // scalar access [simd.subscr]
   // Add operator[] temporarily to test braodcast. Add test for it in later patch.
-  _LIBCPP_HIDE_FROM_ABI value_type operator[](size_t __i) const { return __s_.__get(__i); }
+  _LIBCPP_HIDE_FROM_ABI value_type operator[](size_t __i) const noexcept { return __s_.__get(__i); }
 };
 
 template <class _Tp>

libcxx/include/experimental/__simd/simd_mask.h

@@ -43,7 +43,7 @@ class simd_mask {
 
   // scalar access [simd.mask.subscr]
   // Add operator[] temporarily to test braodcast. Add test for it in later patch.
-  _LIBCPP_HIDE_FROM_ABI value_type operator[](size_t __i) const { return __s_.__get(__i); }
+  _LIBCPP_HIDE_FROM_ABI value_type operator[](size_t __i) const noexcept { return __s_.__get(__i); }
 };
 
 template <class _Tp>

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

@@ -0,0 +1,49 @@
+//===----------------------------------------------------------------------===//
+//
+// 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]
+// operator value_type() const noexcept;
+
+#include "../test_utils.h"
+#include <experimental/simd>
+
+namespace ex = std::experimental::parallelism_v2;
+
+template <class T, std::size_t>
+struct CheckSimdReferenceValueType {
+  template <class SimdAbi>
+  void operator()() {
+    ex::simd<T, SimdAbi> origin_simd([](T i) { return static_cast<T>(i); });
+    for (size_t i = 0; i < origin_simd.size(); ++i) {
+      static_assert(noexcept(T(origin_simd[i])));
+      assert(T(origin_simd[i]) == static_cast<T>(i));
+    }
+  }
+};
+
+template <class T, std::size_t>
+struct CheckMaskReferenceValueType {
+  template <class SimdAbi>
+  void operator()() {
+    ex::simd_mask<T, SimdAbi> origin_simd_mask(true);
+    for (size_t i = 0; i < origin_simd_mask.size(); ++i) {
+      static_assert(noexcept(bool(origin_simd_mask[i])));
+      assert(bool(origin_simd_mask[i]) == true);
+    }
+  }
+};
+
+int main(int, char**) {
+  test_all_simd_abi<CheckSimdReferenceValueType>();
+  test_all_simd_abi<CheckMaskReferenceValueType>();
+  return 0;
+}