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[libc++][C++26] constexpr std::stable_sort (part of P2562) #105379

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[libc++][C++26] constexpr std::stable_sort (part of P2562) #105379

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26d5a32
constexpr stable sort; tests
PaulXiCao Aug 20, 2024
55c19d3
stable_sort: stability test (keep relative order)
PaulXiCao Aug 20, 2024
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6 changes: 3 additions & 3 deletions libcxx/include/__algorithm/inplace_merge.h
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@ template <class _AlgPolicy,
class _InputIterator2,
class _Sent2,
class _OutputIterator>
_LIBCPP_HIDE_FROM_ABI void __half_inplace_merge(
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void __half_inplace_merge(
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Why not _LIBCPP_CONSTEXPR_SINCE_CXX26 (ditto below)?

_InputIterator1 __first1,
_Sent1 __last1,
_InputIterator2 __first2,
Expand All @@ -93,7 +93,7 @@ _LIBCPP_HIDE_FROM_ABI void __half_inplace_merge(
}

template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
_LIBCPP_HIDE_FROM_ABI void __buffered_inplace_merge(
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void __buffered_inplace_merge(
_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last,
Expand Down Expand Up @@ -124,7 +124,7 @@ _LIBCPP_HIDE_FROM_ABI void __buffered_inplace_merge(
}

template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
void __inplace_merge(
_LIBCPP_CONSTEXPR_SINCE_CXX23 void __inplace_merge(
_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last,
Expand Down
2 changes: 1 addition & 1 deletion libcxx/include/__algorithm/sort.h
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Original file line number Diff line number Diff line change
Expand Up @@ -283,7 +283,7 @@ __selection_sort(_BidirectionalIterator __first, _BidirectionalIterator __last,
// Sort the iterator range [__first, __last) using the comparator __comp using
// the insertion sort algorithm.
template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
_LIBCPP_HIDE_FROM_ABI void
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void
__insertion_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp) {
using _Ops = _IterOps<_AlgPolicy>;

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63 changes: 40 additions & 23 deletions libcxx/include/__algorithm/stable_sort.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
#include <__utility/move.h>
#include <__utility/pair.h>
#include <new>
#include <vector>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
Expand All @@ -35,7 +36,7 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD

template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
_LIBCPP_HIDE_FROM_ABI void __insertion_sort_move(
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI void __insertion_sort_move(
_BidirectionalIterator __first1,
_BidirectionalIterator __last1,
typename iterator_traits<_BidirectionalIterator>::value_type* __first2,
Expand Down Expand Up @@ -68,7 +69,7 @@ _LIBCPP_HIDE_FROM_ABI void __insertion_sort_move(
}

template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2>
_LIBCPP_HIDE_FROM_ABI void __merge_move_construct(
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI void __merge_move_construct(
_InputIterator1 __first1,
_InputIterator1 __last1,
_InputIterator2 __first2,
Expand Down Expand Up @@ -106,7 +107,7 @@ _LIBCPP_HIDE_FROM_ABI void __merge_move_construct(
}

template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
_LIBCPP_HIDE_FROM_ABI void __merge_move_assign(
_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI void __merge_move_assign(
_InputIterator1 __first1,
_InputIterator1 __last1,
_InputIterator2 __first2,
Expand Down Expand Up @@ -134,19 +135,21 @@ _LIBCPP_HIDE_FROM_ABI void __merge_move_assign(
}

template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
void __stable_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Compare __comp,
typename iterator_traits<_RandomAccessIterator>::difference_type __len,
typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
ptrdiff_t __buff_size);
_LIBCPP_CONSTEXPR_SINCE_CXX23 void __stable_sort(
_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Compare __comp,
typename iterator_traits<_RandomAccessIterator>::difference_type __len,
typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
ptrdiff_t __buff_size);

template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
void __stable_sort_move(_RandomAccessIterator __first1,
_RandomAccessIterator __last1,
_Compare __comp,
typename iterator_traits<_RandomAccessIterator>::difference_type __len,
typename iterator_traits<_RandomAccessIterator>::value_type* __first2) {
_LIBCPP_CONSTEXPR_SINCE_CXX23 void __stable_sort_move(
_RandomAccessIterator __first1,
_RandomAccessIterator __last1,
_Compare __comp,
typename iterator_traits<_RandomAccessIterator>::difference_type __len,
typename iterator_traits<_RandomAccessIterator>::value_type* __first2) {
using _Ops = _IterOps<_AlgPolicy>;

typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
Expand Down Expand Up @@ -190,12 +193,13 @@ struct __stable_sort_switch {
};

template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
void __stable_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Compare __comp,
typename iterator_traits<_RandomAccessIterator>::difference_type __len,
typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
ptrdiff_t __buff_size) {
_LIBCPP_CONSTEXPR_SINCE_CXX23 void __stable_sort(
_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Compare __comp,
typename iterator_traits<_RandomAccessIterator>::difference_type __len,
typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
ptrdiff_t __buff_size) {
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
switch (__len) {
Expand Down Expand Up @@ -235,32 +239,45 @@ void __stable_sort(_RandomAccessIterator __first,
}

template <class _AlgPolicy, class _RandomAccessIterator, class _Compare>
inline _LIBCPP_HIDE_FROM_ABI void
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void
__stable_sort_impl(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare& __comp) {
using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;

difference_type __len = __last - __first;
__unique_temporary_buffer<value_type> __unique_buf;
pair<value_type*, ptrdiff_t> __buf(0, 0);
std::vector<value_type> __h_vec;
if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value)) {
#if _LIBCPP_STD_VER >= 23
if consteval {
__h_vec.reserve(__len);
__buf.first = __h_vec.data();
__buf.second = __h_vec.size();
} else {
#else
__unique_buf = std::__allocate_unique_temporary_buffer<value_type>(__len);
__buf.first = __unique_buf.get();
__buf.second = __unique_buf.get_deleter().__count_;
#endif
#if _LIBCPP_STD_VER >= 23
}
#endif
}

std::__stable_sort<_AlgPolicy, __comp_ref_type<_Compare> >(__first, __last, __comp, __len, __buf.first, __buf.second);
std::__check_strict_weak_ordering_sorted(__first, __last, __comp);
}

template <class _RandomAccessIterator, class _Compare>
inline _LIBCPP_HIDE_FROM_ABI void
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void
stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
std::__stable_sort_impl<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp);
}

template <class _RandomAccessIterator>
inline _LIBCPP_HIDE_FROM_ABI void stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last) {
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void
stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last) {
std::stable_sort(__first, __last, __less<>());
}

Expand Down
14 changes: 7 additions & 7 deletions libcxx/include/__memory/destruct_n.h
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Expand Up @@ -25,25 +25,25 @@ struct __destruct_n {
size_t __size_;

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void __process(_Tp* __p, false_type) _NOEXCEPT {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void __process(_Tp* __p, false_type) _NOEXCEPT {
for (size_t __i = 0; __i < __size_; ++__i, ++__p)
__p->~_Tp();
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void __process(_Tp*, true_type) _NOEXCEPT {}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void __process(_Tp*, true_type) _NOEXCEPT {}

_LIBCPP_HIDE_FROM_ABI void __incr(false_type) _NOEXCEPT { ++__size_; }
_LIBCPP_HIDE_FROM_ABI void __incr(true_type) _NOEXCEPT {}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void __incr(false_type) _NOEXCEPT { ++__size_; }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void __incr(true_type) _NOEXCEPT {}

_LIBCPP_HIDE_FROM_ABI void __set(size_t __s, false_type) _NOEXCEPT { __size_ = __s; }
_LIBCPP_HIDE_FROM_ABI void __set(size_t, true_type) _NOEXCEPT {}

public:
_LIBCPP_HIDE_FROM_ABI explicit __destruct_n(size_t __s) _NOEXCEPT : __size_(__s) {}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 explicit __destruct_n(size_t __s) _NOEXCEPT : __size_(__s) {}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void __incr() _NOEXCEPT {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void __incr() _NOEXCEPT {
__incr(integral_constant<bool, is_trivially_destructible<_Tp>::value>());
}

Expand All @@ -53,7 +53,7 @@ struct __destruct_n {
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void operator()(_Tp* __p) _NOEXCEPT {
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void operator()(_Tp* __p) _NOEXCEPT {
__process(__p, integral_constant<bool, is_trivially_destructible<_Tp>::value>());
}
};
Expand Down
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