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1//===----------------------------------------------------------------------===//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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___BIT_BIT_LOG2_H10#define _LIBCPP___BIT_BIT_LOG2_H11 12#include <__assert>13#include <__bit/countl.h>14#include <__config>15#include <__type_traits/integer_traits.h>16#include <limits>17 18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)19# pragma GCC system_header20#endif21 22_LIBCPP_BEGIN_NAMESPACE_STD23 24template <class _Tp>25_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp __bit_log2(_Tp __t) _NOEXCEPT {26 static_assert(__is_unsigned_integer_v<_Tp>, "__bit_log2 requires an unsigned integer type");27 _LIBCPP_ASSERT_INTERNAL(__t != 0, "logarithm of 0 is undefined");28 return numeric_limits<_Tp>::digits - 1 - std::__countl_zero(__t);29}30 31_LIBCPP_END_NAMESPACE_STD32 33#endif // _LIBCPP___BIT_BIT_LOG2_H34