368faacac7
This commit reverts5aaefa51(and also partly7f285f48e7andb6d75682f9, which were related to the original commit). As landed,5aaefa51had 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
146 lines
4.6 KiB
C++
146 lines
4.6 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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#ifndef _LIBCPP_COMPILER_MSVC
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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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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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#else // _LIBCPP_COMPILER_MSVC
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// Precondition: __x != 0
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_ctz(unsigned __x) {
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static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
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static_assert(sizeof(unsigned long) == 4, "");
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unsigned long __where;
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if (_BitScanForward(&__where, __x))
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return static_cast<int>(__where);
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return 32;
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}
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_ctz(unsigned long __x) {
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static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
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return __ctz(static_cast<unsigned>(__x));
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}
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_ctz(unsigned long long __x) {
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unsigned long __where;
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#if defined(_LIBCPP_HAS_BITSCAN64)
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if (_BitScanForward64(&__where, __x))
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return static_cast<int>(__where);
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#else
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// Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
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if (_BitScanForward(&__where, static_cast<unsigned long>(__x)))
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return static_cast<int>(__where);
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if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32)))
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return static_cast<int>(__where + 32);
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#endif
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return 64;
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}
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// Precondition: __x != 0
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_clz(unsigned __x) {
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static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
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static_assert(sizeof(unsigned long) == 4, "");
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unsigned long __where;
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if (_BitScanReverse(&__where, __x))
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return static_cast<int>(31 - __where);
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return 32; // Undefined Behavior.
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}
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_clz(unsigned long __x) {
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static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
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return __libcpp_clz(static_cast<unsigned>(__x));
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}
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_clz(unsigned long long __x) {
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unsigned long __where;
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#if defined(_LIBCPP_HAS_BITSCAN64)
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if (_BitScanReverse64(&__where, __x))
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return static_cast<int>(63 - __where);
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#else
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// Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls.
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if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32)))
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return static_cast<int>(63 - (__where + 32));
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if (_BitScanReverse(&__where, static_cast<unsigned long>(__x)))
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return static_cast<int>(63 - __where);
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#endif
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return 64; // Undefined Behavior.
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}
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inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned __x) {
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static_assert(sizeof(unsigned) == 4, "");
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return __popcnt(__x);
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}
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inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long __x) {
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static_assert(sizeof(unsigned long) == 4, "");
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return __popcnt(__x);
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}
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inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long long __x) {
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static_assert(sizeof(unsigned long long) == 8, "");
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return __popcnt64(__x);
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}
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#endif // _LIBCPP_COMPILER_MSVC
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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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