117 lines
4.5 KiB
Plaintext
117 lines
4.5 KiB
Plaintext
/*===---- algorithm - CUDA wrapper for <algorithm> -------------------------===
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*
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*===-----------------------------------------------------------------------===
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*/
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#ifndef __CLANG_CUDA_WRAPPERS_ALGORITHM
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#define __CLANG_CUDA_WRAPPERS_ALGORITHM
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// This header defines __device__ overloads of std::min/max.
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//
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// Ideally we'd declare these functions only if we're <= C++11. In C++14,
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// these functions are constexpr, and so are implicitly __host__ __device__.
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//
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// However, the compiler being in C++14 mode does not imply that the standard
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// library supports C++14. There is no macro we can test to check that the
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// stdlib has constexpr std::min/max. Thus we have to unconditionally define
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// our device overloads.
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//
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// A host+device function cannot be overloaded, and a constexpr function
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// implicitly become host device if there's no explicitly host or device
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// overload preceding it. So the simple thing to do would be to declare our
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// device min/max overloads, and then #include_next <algorithm>. This way our
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// device overloads would come first, and so if we have a C++14 stdlib, its
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// min/max won't become host+device and conflict with our device overloads.
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//
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// But that also doesn't work. libstdc++ is evil and declares std::min/max in
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// an internal header that is included *before* <algorithm>. Thus by the time
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// we're inside of this file, std::min/max may already have been declared, and
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// thus we can't prevent them from becoming host+device if they're constexpr.
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//
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// Therefore we perpetrate the following hack: We mark our __device__ overloads
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// with __attribute__((enable_if(true, ""))). This causes the signature of the
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// function to change without changing anything else about it. (Except that
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// overload resolution will prefer it over the __host__ __device__ version
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// rather than considering them equally good).
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#include_next <algorithm>
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// We need to define these overloads in exactly the namespace our standard
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// library uses (including the right inline namespace), otherwise they won't be
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// picked up by other functions in the standard library (e.g. functions in
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// <complex>). Thus the ugliness below.
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#ifdef _LIBCPP_BEGIN_NAMESPACE_STD
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_LIBCPP_BEGIN_NAMESPACE_STD
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#else
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namespace std {
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#ifdef _GLIBCXX_BEGIN_NAMESPACE_VERSION
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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#endif
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#endif
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#pragma push_macro("_CPP14_CONSTEXPR")
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#if __cplusplus >= 201402L
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#define _CPP14_CONSTEXPR constexpr
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#else
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#define _CPP14_CONSTEXPR
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#endif
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template <class __T, class __Cmp>
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__attribute__((enable_if(true, "")))
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inline _CPP14_CONSTEXPR __host__ __device__ const __T &
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max(const __T &__a, const __T &__b, __Cmp __cmp) {
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return __cmp(__a, __b) ? __b : __a;
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}
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template <class __T>
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__attribute__((enable_if(true, "")))
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inline _CPP14_CONSTEXPR __host__ __device__ const __T &
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max(const __T &__a, const __T &__b) {
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return __a < __b ? __b : __a;
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}
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template <class __T, class __Cmp>
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__attribute__((enable_if(true, "")))
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inline _CPP14_CONSTEXPR __host__ __device__ const __T &
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min(const __T &__a, const __T &__b, __Cmp __cmp) {
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return __cmp(__b, __a) ? __b : __a;
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}
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template <class __T>
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__attribute__((enable_if(true, "")))
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inline _CPP14_CONSTEXPR __host__ __device__ const __T &
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min(const __T &__a, const __T &__b) {
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return __a < __b ? __a : __b;
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}
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#pragma pop_macro("_CPP14_CONSTEXPR")
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#ifdef _LIBCPP_END_NAMESPACE_STD
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_LIBCPP_END_NAMESPACE_STD
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#else
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#ifdef _GLIBCXX_BEGIN_NAMESPACE_VERSION
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_GLIBCXX_END_NAMESPACE_VERSION
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#endif
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} // namespace std
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#endif
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#endif // __CLANG_CUDA_WRAPPERS_ALGORITHM
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