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llvm-project/libcxx/include/__algorithm/sort.h
Louis Dionne 368faacac7 [libc++] Revert "Protect users from relying on detail headers" & related changes 
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
2022-03-01 08:20:24 -05:00

557 lines
22 KiB
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Raw Blame History

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___ALGORITHM_SORT_H
#define _LIBCPP___ALGORITHM_SORT_H
#include <__algorithm/comp.h>
#include <__algorithm/comp_ref_type.h>
#include <__algorithm/min_element.h>
#include <__algorithm/partial_sort.h>
#include <__algorithm/unwrap_iter.h>
#include <__config>
#include <__utility/swap.h>
#include <memory>
#if defined(_LIBCPP_DEBUG_RANDOMIZE_UNSPECIFIED_STABILITY)
# include <__algorithm/shuffle.h>
#endif
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
// stable, 2-3 compares, 0-2 swaps
template <class _Compare, class _ForwardIterator>
_LIBCPP_CONSTEXPR_AFTER_CXX11 unsigned
__sort3(_ForwardIterator __x, _ForwardIterator __y, _ForwardIterator __z, _Compare __c)
{
unsigned __r = 0;
if (!__c(*__y, *__x)) // if x <= y
{
if (!__c(*__z, *__y)) // if y <= z
return __r; // x <= y && y <= z
// x <= y && y > z
swap(*__y, *__z); // x <= z && y < z
__r = 1;
if (__c(*__y, *__x)) // if x > y
{
swap(*__x, *__y); // x < y && y <= z
__r = 2;
}
return __r; // x <= y && y < z
}
if (__c(*__z, *__y)) // x > y, if y > z
{
swap(*__x, *__z); // x < y && y < z
__r = 1;
return __r;
}
swap(*__x, *__y); // x > y && y <= z
__r = 1; // x < y && x <= z
if (__c(*__z, *__y)) // if y > z
{
swap(*__y, *__z); // x <= y && y < z
__r = 2;
}
return __r;
} // x <= y && y <= z
// stable, 3-6 compares, 0-5 swaps
template <class _Compare, class _ForwardIterator>
unsigned
__sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
_ForwardIterator __x4, _Compare __c)
{
unsigned __r = _VSTD::__sort3<_Compare>(__x1, __x2, __x3, __c);
if (__c(*__x4, *__x3))
{
swap(*__x3, *__x4);
++__r;
if (__c(*__x3, *__x2))
{
swap(*__x2, *__x3);
++__r;
if (__c(*__x2, *__x1))
{
swap(*__x1, *__x2);
++__r;
}
}
}
return __r;
}
// stable, 4-10 compares, 0-9 swaps
template <class _Compare, class _ForwardIterator>
_LIBCPP_HIDDEN
unsigned
__sort5(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
_ForwardIterator __x4, _ForwardIterator __x5, _Compare __c)
{
unsigned __r = _VSTD::__sort4<_Compare>(__x1, __x2, __x3, __x4, __c);
if (__c(*__x5, *__x4))
{
swap(*__x4, *__x5);
++__r;
if (__c(*__x4, *__x3))
{
swap(*__x3, *__x4);
++__r;
if (__c(*__x3, *__x2))
{
swap(*__x2, *__x3);
++__r;
if (__c(*__x2, *__x1))
{
swap(*__x1, *__x2);
++__r;
}
}
}
}
return __r;
}
// Assumes size > 0
template <class _Compare, class _BidirectionalIterator>
_LIBCPP_CONSTEXPR_AFTER_CXX11 void
__selection_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
{
_BidirectionalIterator __lm1 = __last;
for (--__lm1; __first != __lm1; ++__first)
{
_BidirectionalIterator __i = _VSTD::min_element(__first, __last, __comp);
if (__i != __first)
swap(*__first, *__i);
}
}
template <class _Compare, class _BidirectionalIterator>
void
__insertion_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
{
typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
if (__first != __last)
{
_BidirectionalIterator __i = __first;
for (++__i; __i != __last; ++__i)
{
_BidirectionalIterator __j = __i;
value_type __t(_VSTD::move(*__j));
for (_BidirectionalIterator __k = __i; __k != __first && __comp(__t, *--__k); --__j)
*__j = _VSTD::move(*__k);
*__j = _VSTD::move(__t);
}
}
}
template <class _Compare, class _RandomAccessIterator>
void
__insertion_sort_3(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
_RandomAccessIterator __j = __first+difference_type(2);
_VSTD::__sort3<_Compare>(__first, __first+difference_type(1), __j, __comp);
for (_RandomAccessIterator __i = __j+difference_type(1); __i != __last; ++__i)
{
if (__comp(*__i, *__j))
{
value_type __t(_VSTD::move(*__i));
_RandomAccessIterator __k = __j;
__j = __i;
do
{
*__j = _VSTD::move(*__k);
__j = __k;
} while (__j != __first && __comp(__t, *--__k));
*__j = _VSTD::move(__t);
}
__j = __i;
}
}
template <class _Compare, class _RandomAccessIterator>
bool
__insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
switch (__last - __first)
{
case 0:
case 1:
return true;
case 2:
if (__comp(*--__last, *__first))
swap(*__first, *__last);
return true;
case 3:
_VSTD::__sort3<_Compare>(__first, __first+difference_type(1), --__last, __comp);
return true;
case 4:
_VSTD::__sort4<_Compare>(__first, __first+difference_type(1), __first+difference_type(2), --__last, __comp);
return true;
case 5:
_VSTD::__sort5<_Compare>(__first, __first+difference_type(1), __first+difference_type(2), __first+difference_type(3), --__last, __comp);
return true;
}
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
_RandomAccessIterator __j = __first+difference_type(2);
_VSTD::__sort3<_Compare>(__first, __first+difference_type(1), __j, __comp);
const unsigned __limit = 8;
unsigned __count = 0;
for (_RandomAccessIterator __i = __j+difference_type(1); __i != __last; ++__i)
{
if (__comp(*__i, *__j))
{
value_type __t(_VSTD::move(*__i));
_RandomAccessIterator __k = __j;
__j = __i;
do
{
*__j = _VSTD::move(*__k);
__j = __k;
} while (__j != __first && __comp(__t, *--__k));
*__j = _VSTD::move(__t);
if (++__count == __limit)
return ++__i == __last;
}
__j = __i;
}
return true;
}
template <class _Compare, class _BidirectionalIterator>
void
__insertion_sort_move(_BidirectionalIterator __first1, _BidirectionalIterator __last1,
typename iterator_traits<_BidirectionalIterator>::value_type* __first2, _Compare __comp)
{
typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
if (__first1 != __last1)
{
__destruct_n __d(0);
unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
value_type* __last2 = __first2;
::new ((void*)__last2) value_type(_VSTD::move(*__first1));
__d.template __incr<value_type>();
for (++__last2; ++__first1 != __last1; ++__last2)
{
value_type* __j2 = __last2;
value_type* __i2 = __j2;
if (__comp(*__first1, *--__i2))
{
::new ((void*)__j2) value_type(_VSTD::move(*__i2));
__d.template __incr<value_type>();
for (--__j2; __i2 != __first2 && __comp(*__first1, *--__i2); --__j2)
*__j2 = _VSTD::move(*__i2);
*__j2 = _VSTD::move(*__first1);
}
else
{
::new ((void*)__j2) value_type(_VSTD::move(*__first1));
__d.template __incr<value_type>();
}
}
__h.release();
}
}
template <class _Compare, class _RandomAccessIterator>
void
__introsort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
typename iterator_traits<_RandomAccessIterator>::difference_type __depth)
{
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
const difference_type __limit = is_trivially_copy_constructible<value_type>::value &&
is_trivially_copy_assignable<value_type>::value ? 30 : 6;
while (true)
{
__restart:
difference_type __len = __last - __first;
switch (__len)
{
case 0:
case 1:
return;
case 2:
if (__comp(*--__last, *__first))
swap(*__first, *__last);
return;
case 3:
_VSTD::__sort3<_Compare>(__first, __first+difference_type(1), --__last, __comp);
return;
case 4:
_VSTD::__sort4<_Compare>(__first, __first+difference_type(1), __first+difference_type(2), --__last, __comp);
return;
case 5:
_VSTD::__sort5<_Compare>(__first, __first+difference_type(1), __first+difference_type(2), __first+difference_type(3), --__last, __comp);
return;
}
if (__len <= __limit)
{
_VSTD::__insertion_sort_3<_Compare>(__first, __last, __comp);
return;
}
// __len > 5
if (__depth == 0)
{
// Fallback to heap sort as Introsort suggests.
_VSTD::__partial_sort<_Compare>(__first, __last, __last, __comp);
return;
}
--__depth;
_RandomAccessIterator __m = __first;
_RandomAccessIterator __lm1 = __last;
--__lm1;
unsigned __n_swaps;
{
difference_type __delta;
if (__len >= 1000)
{
__delta = __len/2;
__m += __delta;
__delta /= 2;
__n_swaps = _VSTD::__sort5<_Compare>(__first, __first + __delta, __m, __m+__delta, __lm1, __comp);
}
else
{
__delta = __len/2;
__m += __delta;
__n_swaps = _VSTD::__sort3<_Compare>(__first, __m, __lm1, __comp);
}
}
// *__m is median
// partition [__first, __m) < *__m and *__m <= [__m, __last)
// (this inhibits tossing elements equivalent to __m around unnecessarily)
_RandomAccessIterator __i = __first;
_RandomAccessIterator __j = __lm1;
// j points beyond range to be tested, *__m is known to be <= *__lm1
// The search going up is known to be guarded but the search coming down isn't.
// Prime the downward search with a guard.
if (!__comp(*__i, *__m)) // if *__first == *__m
{
// *__first == *__m, *__first doesn't go in first part
// manually guard downward moving __j against __i
while (true)
{
if (__i == --__j)
{
// *__first == *__m, *__m <= all other elements
// Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
++__i; // __first + 1
__j = __last;
if (!__comp(*__first, *--__j)) // we need a guard if *__first == *(__last-1)
{
while (true)
{
if (__i == __j)
return; // [__first, __last) all equivalent elements
if (__comp(*__first, *__i))
{
swap(*__i, *__j);
++__n_swaps;
++__i;
break;
}
++__i;
}
}
// [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
if (__i == __j)
return;
while (true)
{
while (!__comp(*__first, *__i))
++__i;
while (__comp(*__first, *--__j))
;
if (__i >= __j)
break;
swap(*__i, *__j);
++__n_swaps;
++__i;
}
// [__first, __i) == *__first and *__first < [__i, __last)
// The first part is sorted, sort the second part
// _VSTD::__sort<_Compare>(__i, __last, __comp);
__first = __i;
goto __restart;
}
if (__comp(*__j, *__m))
{
swap(*__i, *__j);
++__n_swaps;
break; // found guard for downward moving __j, now use unguarded partition
}
}
}
// It is known that *__i < *__m
++__i;
// j points beyond range to be tested, *__m is known to be <= *__lm1
// if not yet partitioned...
if (__i < __j)
{
// known that *(__i - 1) < *__m
// known that __i <= __m
while (true)
{
// __m still guards upward moving __i
while (__comp(*__i, *__m))
++__i;
// It is now known that a guard exists for downward moving __j
while (!__comp(*--__j, *__m))
;
if (__i > __j)
break;
swap(*__i, *__j);
++__n_swaps;
// It is known that __m != __j
// If __m just moved, follow it
if (__m == __i)
__m = __j;
++__i;
}
}
// [__first, __i) < *__m and *__m <= [__i, __last)
if (__i != __m && __comp(*__m, *__i))
{
swap(*__i, *__m);
++__n_swaps;
}
// [__first, __i) < *__i and *__i <= [__i+1, __last)
// If we were given a perfect partition, see if insertion sort is quick...
if (__n_swaps == 0)
{
bool __fs = _VSTD::__insertion_sort_incomplete<_Compare>(__first, __i, __comp);
if (_VSTD::__insertion_sort_incomplete<_Compare>(__i+difference_type(1), __last, __comp))
{
if (__fs)
return;
__last = __i;
continue;
}
else
{
if (__fs)
{
__first = ++__i;
continue;
}
}
}
// sort smaller range with recursive call and larger with tail recursion elimination
if (__i - __first < __last - __i)
{
_VSTD::__introsort<_Compare>(__first, __i, __comp, __depth);
__first = ++__i;
}
else
{
_VSTD::__introsort<_Compare>(__i + difference_type(1), __last, __comp, __depth);
__last = __i;
}
}
}
template <typename _Number>
inline _LIBCPP_HIDE_FROM_ABI _Number __log2i(_Number __n) {
_Number __log2 = 0;
while (__n > 1) {
__log2++;
__n >>= 1;
}
return __log2;
}
template <class _Compare, class _RandomAccessIterator>
void __sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
difference_type __depth_limit = 2 * __log2i(__last - __first);
_VSTD::__introsort<_Compare>(__first, __last, __comp, __depth_limit);
}
template <class _Compare, class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
void
__sort(_Tp** __first, _Tp** __last, __less<_Tp*>&)
{
__less<uintptr_t> __comp;
_VSTD::__sort<__less<uintptr_t>&, uintptr_t*>((uintptr_t*)__first, (uintptr_t*)__last, __comp);
}
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
#endif
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<short>&, short*>(short*, short*, __less<short>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<int>&, int*>(int*, int*, __less<int>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long>&, long*>(long*, long*, __less<long>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<float>&, float*>(float*, float*, __less<float>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<double>&, double*>(double*, double*, __less<double>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<char>&, char*>(char*, char*, __less<char>&))
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
#endif
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<short>&, short*>(short*, short*, __less<short>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<int>&, int*>(int*, int*, __less<int>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long>&, long*>(long*, long*, __less<long>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<float>&, float*>(float*, float*, __less<float>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<double>&, double*>(double*, double*, __less<double>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS unsigned __sort5<__less<long double>&, long double*>(long double*, long double*, long double*, long double*, long double*, __less<long double>&))
template <class _RandomAccessIterator, class _Compare>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
void
sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
{
_LIBCPP_DEBUG_RANDOMIZE_RANGE(__first, __last);
typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
if (__libcpp_is_constant_evaluated()) {
_VSTD::__partial_sort<_Comp_ref>(__first, __last, __last, _Comp_ref(__comp));
} else {
_VSTD::__sort<_Comp_ref>(_VSTD::__unwrap_iter(__first), _VSTD::__unwrap_iter(__last), _Comp_ref(__comp));
}
}
template <class _RandomAccessIterator>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
void
sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
{
_VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
}
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ALGORITHM_SORT_H
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