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| 14 | pmbaty | 1 | /*===---- algorithm - CUDA wrapper for <algorithm> -------------------------=== |
| 2 | * |
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| 3 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
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| 4 | * of this software and associated documentation files (the "Software"), to deal |
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| 5 | * in the Software without restriction, including without limitation the rights |
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| 6 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
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| 7 | * copies of the Software, and to permit persons to whom the Software is |
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| 8 | * furnished to do so, subject to the following conditions: |
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| 9 | * |
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| 10 | * The above copyright notice and this permission notice shall be included in |
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| 11 | * all copies or substantial portions of the Software. |
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| 12 | * |
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| 13 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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| 14 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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| 15 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
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| 16 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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| 17 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
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| 18 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
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| 19 | * THE SOFTWARE. |
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| 20 | * |
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| 21 | *===-----------------------------------------------------------------------=== |
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| 22 | */ |
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| 23 | |||
| 24 | #ifndef __CLANG_CUDA_WRAPPERS_ALGORITHM |
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| 25 | #define __CLANG_CUDA_WRAPPERS_ALGORITHM |
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| 26 | |||
| 27 | // This header defines __device__ overloads of std::min/max. |
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| 28 | // |
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| 29 | // Ideally we'd declare these functions only if we're <= C++11. In C++14, |
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| 30 | // these functions are constexpr, and so are implicitly __host__ __device__. |
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| 31 | // |
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| 32 | // However, the compiler being in C++14 mode does not imply that the standard |
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| 33 | // library supports C++14. There is no macro we can test to check that the |
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| 34 | // stdlib has constexpr std::min/max. Thus we have to unconditionally define |
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| 35 | // our device overloads. |
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| 36 | // |
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| 37 | // A host+device function cannot be overloaded, and a constexpr function |
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| 38 | // implicitly become host device if there's no explicitly host or device |
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| 39 | // overload preceding it. So the simple thing to do would be to declare our |
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| 40 | // device min/max overloads, and then #include_next <algorithm>. This way our |
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| 41 | // device overloads would come first, and so if we have a C++14 stdlib, its |
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| 42 | // min/max won't become host+device and conflict with our device overloads. |
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| 43 | // |
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| 44 | // But that also doesn't work. libstdc++ is evil and declares std::min/max in |
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| 45 | // an internal header that is included *before* <algorithm>. Thus by the time |
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| 46 | // we're inside of this file, std::min/max may already have been declared, and |
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| 47 | // thus we can't prevent them from becoming host+device if they're constexpr. |
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| 48 | // |
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| 49 | // Therefore we perpetrate the following hack: We mark our __device__ overloads |
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| 50 | // with __attribute__((enable_if(true, ""))). This causes the signature of the |
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| 51 | // function to change without changing anything else about it. (Except that |
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| 52 | // overload resolution will prefer it over the __host__ __device__ version |
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| 53 | // rather than considering them equally good). |
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| 54 | |||
| 55 | #include_next <algorithm> |
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| 56 | |||
| 57 | // We need to define these overloads in exactly the namespace our standard |
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| 58 | // library uses (including the right inline namespace), otherwise they won't be |
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| 59 | // picked up by other functions in the standard library (e.g. functions in |
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| 60 | // <complex>). Thus the ugliness below. |
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| 61 | #ifdef _LIBCPP_BEGIN_NAMESPACE_STD |
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| 62 | _LIBCPP_BEGIN_NAMESPACE_STD |
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| 63 | #else |
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| 64 | namespace std { |
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| 65 | #ifdef _GLIBCXX_BEGIN_NAMESPACE_VERSION |
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| 66 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
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| 67 | #endif |
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| 68 | #endif |
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| 69 | |||
| 70 | #pragma push_macro("_CPP14_CONSTEXPR") |
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| 71 | #if __cplusplus >= 201402L |
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| 72 | #define _CPP14_CONSTEXPR constexpr |
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| 73 | #else |
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| 74 | #define _CPP14_CONSTEXPR |
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| 75 | #endif |
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| 76 | |||
| 77 | template <class __T, class __Cmp> |
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| 78 | __attribute__((enable_if(true, ""))) |
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| 79 | inline _CPP14_CONSTEXPR __host__ __device__ const __T & |
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| 80 | max(const __T &__a, const __T &__b, __Cmp __cmp) { |
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| 81 | return __cmp(__a, __b) ? __b : __a; |
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| 82 | } |
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| 83 | |||
| 84 | template <class __T> |
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| 85 | __attribute__((enable_if(true, ""))) |
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| 86 | inline _CPP14_CONSTEXPR __host__ __device__ const __T & |
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| 87 | max(const __T &__a, const __T &__b) { |
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| 88 | return __a < __b ? __b : __a; |
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| 89 | } |
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| 90 | |||
| 91 | template <class __T, class __Cmp> |
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| 92 | __attribute__((enable_if(true, ""))) |
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| 93 | inline _CPP14_CONSTEXPR __host__ __device__ const __T & |
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| 94 | min(const __T &__a, const __T &__b, __Cmp __cmp) { |
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| 95 | return __cmp(__b, __a) ? __b : __a; |
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| 96 | } |
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| 97 | |||
| 98 | template <class __T> |
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| 99 | __attribute__((enable_if(true, ""))) |
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| 100 | inline _CPP14_CONSTEXPR __host__ __device__ const __T & |
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| 101 | min(const __T &__a, const __T &__b) { |
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| 102 | return __a < __b ? __a : __b; |
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| 103 | } |
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| 104 | |||
| 105 | #pragma pop_macro("_CPP14_CONSTEXPR") |
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| 106 | |||
| 107 | #ifdef _LIBCPP_END_NAMESPACE_STD |
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| 108 | _LIBCPP_END_NAMESPACE_STD |
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| 109 | #else |
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| 110 | #ifdef _GLIBCXX_BEGIN_NAMESPACE_VERSION |
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| 111 | _GLIBCXX_END_NAMESPACE_VERSION |
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| 112 | #endif |
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| 113 | } // namespace std |
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| 114 | #endif |
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| 115 | |||
| 116 | #endif // __CLANG_CUDA_WRAPPERS_ALGORITHM |