a6db20f2c3
Fixes #86556 Use `__builtin_popcountg` instead of `__buildin_popcount{l|ll}` Use `__builtin_clzg instead` of `__buildin_clz{l|ll}` Use `__builtin_ctzg instead` of `__builtin_ctz{l|ll}` The generic variant of the builtins can be used to simplify some logic with >= Clang 19 or >= GCC 14, where these generic variants are available. As for backwards compatibility reasons, we can't completely remove the old logic. Therefore, I left ToDo comments to address this, as soon as support for pre Clang 19 as well as pre GCC 14 is dropped. --------- Co-authored-by: Nick Desaulniers <nickdesaulniers@users.noreply.github.com>
72 lines
2.3 KiB
C++
72 lines
2.3 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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// TODO: __builtin_popcountg is available since Clang 19 and GCC 14. When support for older versions is dropped, we can
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// refactor this code to exclusively use __builtin_popcountg.
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#ifndef _LIBCPP___BIT_POPCOUNT_H
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#define _LIBCPP___BIT_POPCOUNT_H
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#include <__bit/rotate.h>
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#include <__concepts/arithmetic.h>
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#include <__config>
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#include <limits>
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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_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_popcount(unsigned __x) _NOEXCEPT {
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return __builtin_popcount(__x);
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}
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_popcount(unsigned long __x) _NOEXCEPT {
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return __builtin_popcountl(__x);
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}
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_popcount(unsigned long long __x) _NOEXCEPT {
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return __builtin_popcountll(__x);
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}
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#if _LIBCPP_STD_VER >= 20
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template <__libcpp_unsigned_integer _Tp>
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_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept {
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# if __has_builtin(__builtin_popcountg)
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return __builtin_popcountg(__t);
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# else // __has_builtin(__builtin_popcountg)
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if (sizeof(_Tp) <= sizeof(unsigned int))
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return std::__libcpp_popcount(static_cast<unsigned int>(__t));
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else if (sizeof(_Tp) <= sizeof(unsigned long))
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return std::__libcpp_popcount(static_cast<unsigned long>(__t));
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else if (sizeof(_Tp) <= sizeof(unsigned long long))
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return std::__libcpp_popcount(static_cast<unsigned long long>(__t));
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else {
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int __ret = 0;
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while (__t != 0) {
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__ret += std::__libcpp_popcount(static_cast<unsigned long long>(__t));
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__t >>= numeric_limits<unsigned long long>::digits;
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}
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return __ret;
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}
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# endif // __has_builtin(__builtin_popcountg)
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}
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___BIT_POPCOUNT_H
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