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368faacac7
This commit reverts 5aaefa51 (and also partly 7f285f48e77 and b6d75682f9, which were related to the original commit). As landed, 5aaefa51 had unintended consequences on some downstream bots and didn't have proper coverage upstream due to a few subtle things. Implementing this is something we should do in libc++, however we'll first need to address a few issues listed in https://reviews.llvm.org/D106124#3349710. Differential Revision: https://reviews.llvm.org/D120683
97 lines
3.1 KiB
C++
97 lines
3.1 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___NUMERIC_GCD_LCM_H
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#define _LIBCPP___NUMERIC_GCD_LCM_H
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#include <__assert>
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#include <__config>
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#include <limits>
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#include <type_traits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER > 14
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template <typename _Result, typename _Source, bool _IsSigned = is_signed<_Source>::value> struct __ct_abs;
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template <typename _Result, typename _Source>
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struct __ct_abs<_Result, _Source, true> {
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_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
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_Result operator()(_Source __t) const noexcept
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{
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if (__t >= 0) return __t;
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if (__t == numeric_limits<_Source>::min()) return -static_cast<_Result>(__t);
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return -__t;
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}
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};
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template <typename _Result, typename _Source>
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struct __ct_abs<_Result, _Source, false> {
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_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
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_Result operator()(_Source __t) const noexcept { return __t; }
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};
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template<class _Tp>
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_LIBCPP_CONSTEXPR _LIBCPP_HIDDEN
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_Tp __gcd(_Tp __m, _Tp __n)
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{
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static_assert((!is_signed<_Tp>::value), "");
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return __n == 0 ? __m : _VSTD::__gcd<_Tp>(__n, __m % __n);
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}
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template<class _Tp, class _Up>
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_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
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common_type_t<_Tp,_Up>
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gcd(_Tp __m, _Up __n)
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{
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static_assert((is_integral<_Tp>::value && is_integral<_Up>::value), "Arguments to gcd must be integer types");
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static_assert((!is_same<typename remove_cv<_Tp>::type, bool>::value), "First argument to gcd cannot be bool" );
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static_assert((!is_same<typename remove_cv<_Up>::type, bool>::value), "Second argument to gcd cannot be bool" );
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using _Rp = common_type_t<_Tp,_Up>;
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using _Wp = make_unsigned_t<_Rp>;
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return static_cast<_Rp>(_VSTD::__gcd(
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static_cast<_Wp>(__ct_abs<_Rp, _Tp>()(__m)),
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static_cast<_Wp>(__ct_abs<_Rp, _Up>()(__n))));
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}
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template<class _Tp, class _Up>
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_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
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common_type_t<_Tp,_Up>
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lcm(_Tp __m, _Up __n)
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{
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static_assert((is_integral<_Tp>::value && is_integral<_Up>::value), "Arguments to lcm must be integer types");
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static_assert((!is_same<typename remove_cv<_Tp>::type, bool>::value), "First argument to lcm cannot be bool" );
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static_assert((!is_same<typename remove_cv<_Up>::type, bool>::value), "Second argument to lcm cannot be bool" );
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if (__m == 0 || __n == 0)
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return 0;
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using _Rp = common_type_t<_Tp,_Up>;
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_Rp __val1 = __ct_abs<_Rp, _Tp>()(__m) / _VSTD::gcd(__m, __n);
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_Rp __val2 = __ct_abs<_Rp, _Up>()(__n);
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_LIBCPP_ASSERT((numeric_limits<_Rp>::max() / __val1 > __val2), "Overflow in lcm");
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return __val1 * __val2;
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}
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#endif // _LIBCPP_STD_VER
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___NUMERIC_GCD_LCM_H
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