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https://github.com/capstone-engine/llvm-capstone.git
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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
103 lines
3.1 KiB
C++
103 lines
3.1 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___ALGORITHM_SHIFT_RIGHT_H
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#define _LIBCPP___ALGORITHM_SHIFT_RIGHT_H
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#include <__algorithm/move.h>
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#include <__algorithm/move_backward.h>
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#include <__algorithm/swap_ranges.h>
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#include <__config>
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#include <__iterator/iterator_traits.h>
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#include <__utility/swap.h>
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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_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER > 17
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template <class _ForwardIterator>
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inline _LIBCPP_INLINE_VISIBILITY constexpr
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_ForwardIterator
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shift_right(_ForwardIterator __first, _ForwardIterator __last,
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typename iterator_traits<_ForwardIterator>::difference_type __n)
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{
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if (__n == 0) {
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return __first;
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}
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if constexpr (__is_cpp17_random_access_iterator<_ForwardIterator>::value) {
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decltype(__n) __d = __last - __first;
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if (__n >= __d) {
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return __last;
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}
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_ForwardIterator __m = __first + (__d - __n);
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return _VSTD::move_backward(__first, __m, __last);
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} else if constexpr (__is_cpp17_bidirectional_iterator<_ForwardIterator>::value) {
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_ForwardIterator __m = __last;
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for (; __n > 0; --__n) {
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if (__m == __first) {
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return __last;
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}
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--__m;
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}
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return _VSTD::move_backward(__first, __m, __last);
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} else {
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_ForwardIterator __ret = __first;
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for (; __n > 0; --__n) {
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if (__ret == __last) {
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return __last;
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}
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++__ret;
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}
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// We have an __n-element scratch space from __first to __ret.
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// Slide an __n-element window [__trail, __lead) from left to right.
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// We're essentially doing swap_ranges(__first, __ret, __trail, __lead)
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// over and over; but once __lead reaches __last we needn't bother
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// to save the values of elements [__trail, __last).
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auto __trail = __first;
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auto __lead = __ret;
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while (__trail != __ret) {
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if (__lead == __last) {
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_VSTD::move(__first, __trail, __ret);
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return __ret;
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}
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++__trail;
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++__lead;
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}
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_ForwardIterator __mid = __first;
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while (true) {
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if (__lead == __last) {
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__trail = _VSTD::move(__mid, __ret, __trail);
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_VSTD::move(__first, __mid, __trail);
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return __ret;
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}
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swap(*__mid, *__trail);
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++__mid;
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++__trail;
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++__lead;
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if (__mid == __ret) {
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__mid = __first;
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}
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}
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}
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}
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#endif // _LIBCPP_STD_VER > 17
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ALGORITHM_SHIFT_RIGHT_H
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