forked from OSchip/llvm-project
76 lines
2.6 KiB
C++
76 lines
2.6 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___BITS
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#define _LIBCPP___BITS
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#include <__config>
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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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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned __x) _NOEXCEPT { return __builtin_ctz(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned long __x) _NOEXCEPT { return __builtin_ctzl(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_clz(unsigned __x) _NOEXCEPT { return __builtin_clz(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_clz(unsigned long __x) _NOEXCEPT { return __builtin_clzl(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_clz(unsigned long long __x) _NOEXCEPT { return __builtin_clzll(__x); }
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# ifndef _LIBCPP_HAS_NO_INT128
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_clz(__uint128_t __x) _NOEXCEPT {
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// The function is written in this form due to C++ constexpr limitations.
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// The algorithm:
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// - Test whether any bit in the high 64-bits is set
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// - No bits set:
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// - The high 64-bits contain 64 leading zeros,
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// - Add the result of the low 64-bits.
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// - Any bits set:
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// - The number of leading zeros of the input is the number of leading
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// zeros in the high 64-bits.
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return ((__x >> 64) == 0)
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? (64 + __builtin_clzll(static_cast<unsigned long long>(__x)))
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: __builtin_clzll(static_cast<unsigned long long>(__x >> 64));
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}
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# endif
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_popcount(unsigned __x) _NOEXCEPT { return __builtin_popcount(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_popcount(unsigned long __x) _NOEXCEPT { return __builtin_popcountl(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); }
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___BITS
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