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
61 lines
2.2 KiB
C++
61 lines
2.2 KiB
C++
//===----------------------------------------------------------------------===//
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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___RANDOM_CLAMP_TO_INTEGRAL_H
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#define _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
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#include <__config>
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#include <cmath>
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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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template <class _IntT, class _FloatT,
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bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits),
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int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)>
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_LIBCPP_INLINE_VISIBILITY
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_LIBCPP_CONSTEXPR _IntT __max_representable_int_for_float() _NOEXCEPT {
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static_assert(is_floating_point<_FloatT>::value, "must be a floating point type");
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static_assert(is_integral<_IntT>::value, "must be an integral type");
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static_assert(numeric_limits<_FloatT>::radix == 2, "FloatT has incorrect radix");
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static_assert((_IsSame<_FloatT, float>::value || _IsSame<_FloatT, double>::value
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|| _IsSame<_FloatT,long double>::value), "unsupported floating point type");
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return _FloatBigger ? numeric_limits<_IntT>::max() : (numeric_limits<_IntT>::max() >> _Bits << _Bits);
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}
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// Convert a floating point number to the specified integral type after
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// clamping to the integral type's representable range.
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//
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// The behavior is undefined if `__r` is NaN.
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template <class _IntT, class _RealT>
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_LIBCPP_INLINE_VISIBILITY
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_IntT __clamp_to_integral(_RealT __r) _NOEXCEPT {
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using _Lim = numeric_limits<_IntT>;
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const _IntT _MaxVal = __max_representable_int_for_float<_IntT, _RealT>();
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if (__r >= ::nextafter(static_cast<_RealT>(_MaxVal), INFINITY)) {
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return _Lim::max();
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} else if (__r <= _Lim::lowest()) {
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return _Lim::min();
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}
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return static_cast<_IntT>(__r);
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}
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
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