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| 1 | //===-- include/flang/Common/reference-wrapper.h ----------------*- C++ -*-===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | // clang-format off |
| 9 | // |
| 10 | // Implementation of std::reference_wrapper borrowed from libcu++ |
| 11 | // https://github.com/NVIDIA/libcudacxx/blob/f7e6cd07ed5ba826aeac0b742feafddfedc1e400/include/cuda/std/detail/libcxx/include/__functional/reference_wrapper.h#L1 |
| 12 | // with modifications. |
| 13 | // |
| 14 | // The original source code is distributed under the Apache License v2.0 |
| 15 | // with LLVM Exceptions. |
| 16 | // |
| 17 | // TODO: using libcu++ is the best option for CUDA, but there is a couple |
| 18 | // of issues: |
| 19 | // * The include paths need to be set up such that all STD header files |
| 20 | // are taken from libcu++. |
| 21 | // * cuda:: namespace need to be forced for all std:: references. |
| 22 | // |
| 23 | // clang-format on |
| 24 | |
| 25 | #ifndef FORTRAN_COMMON_REFERENCE_WRAPPER_H |
| 26 | #define FORTRAN_COMMON_REFERENCE_WRAPPER_H |
| 27 | |
| 28 | #include "flang/Common/api-attrs.h" |
| 29 | #include <functional> |
| 30 | #include <type_traits> |
| 31 | |
| 32 | #if !defined(STD_REFERENCE_WRAPPER_UNSUPPORTED) && \ |
| 33 | (defined(__CUDACC__) || defined(__CUDA__)) && defined(__CUDA_ARCH__) |
| 34 | #define STD_REFERENCE_WRAPPER_UNSUPPORTED 1 |
| 35 | #endif |
| 36 | |
| 37 | namespace Fortran::common { |
| 38 | |
| 39 | template <class _Tp> |
| 40 | using __remove_cvref_t = std::remove_cv_t<std::remove_reference_t<_Tp>>; |
| 41 | template <class _Tp, class _Up> |
| 42 | struct __is_same_uncvref |
| 43 | : std::is_same<__remove_cvref_t<_Tp>, __remove_cvref_t<_Up>> {}; |
| 44 | |
| 45 | #if STD_REFERENCE_WRAPPER_UNSUPPORTED |
| 46 | template <class _Tp> class reference_wrapper { |
| 47 | public: |
| 48 | // types |
| 49 | typedef _Tp type; |
| 50 | |
| 51 | private: |
| 52 | type *__f_; |
| 53 | |
| 54 | static RT_API_ATTRS void __fun(_Tp &); |
| 55 | static void __fun(_Tp &&) = delete; |
| 56 | |
| 57 | public: |
| 58 | template <class _Up, |
| 59 | class = |
| 60 | std::enable_if_t<!__is_same_uncvref<_Up, reference_wrapper>::value, |
| 61 | decltype(__fun(std::declval<_Up>()))>> |
| 62 | constexpr RT_API_ATTRS reference_wrapper(_Up &&__u) { |
| 63 | type &__f = static_cast<_Up &&>(__u); |
| 64 | __f_ = std::addressof(__f); |
| 65 | } |
| 66 | |
| 67 | // access |
| 68 | constexpr RT_API_ATTRS operator type &() const { return *__f_; } |
| 69 | constexpr RT_API_ATTRS type &get() const { return *__f_; } |
| 70 | |
| 71 | // invoke |
| 72 | template <class... _ArgTypes> |
| 73 | constexpr RT_API_ATTRS typename std::invoke_result_t<type &, _ArgTypes...> |
| 74 | operator()(_ArgTypes &&...__args) const { |
| 75 | return std::invoke(get(), std::forward<_ArgTypes>(__args)...); |
| 76 | } |
| 77 | }; |
| 78 | |
| 79 | template <class _Tp> reference_wrapper(_Tp &) -> reference_wrapper<_Tp>; |
| 80 | |
| 81 | template <class _Tp> |
| 82 | inline constexpr RT_API_ATTRS reference_wrapper<_Tp> ref(_Tp &__t) { |
| 83 | return reference_wrapper<_Tp>(__t); |
| 84 | } |
| 85 | |
| 86 | template <class _Tp> |
| 87 | inline constexpr RT_API_ATTRS reference_wrapper<_Tp> ref( |
| 88 | reference_wrapper<_Tp> __t) { |
| 89 | return __t; |
| 90 | } |
| 91 | |
| 92 | template <class _Tp> |
| 93 | inline constexpr RT_API_ATTRS reference_wrapper<const _Tp> cref( |
| 94 | const _Tp &__t) { |
| 95 | return reference_wrapper<const _Tp>(__t); |
| 96 | } |
| 97 | |
| 98 | template <class _Tp> |
| 99 | inline constexpr RT_API_ATTRS reference_wrapper<const _Tp> cref( |
| 100 | reference_wrapper<_Tp> __t) { |
| 101 | return __t; |
| 102 | } |
| 103 | |
| 104 | template <class _Tp> void ref(const _Tp &&) = delete; |
| 105 | template <class _Tp> void cref(const _Tp &&) = delete; |
| 106 | #else // !STD_REFERENCE_WRAPPER_UNSUPPORTED |
| 107 | using std::cref; |
| 108 | using std::ref; |
| 109 | using std::reference_wrapper; |
| 110 | #endif // !STD_REFERENCE_WRAPPER_UNSUPPORTED |
| 111 | |
| 112 | } // namespace Fortran::common |
| 113 | |
| 114 | #endif // FORTRAN_COMMON_REFERENCE_WRAPPER_H |
| 115 |
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