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-rw-r--r--libcxx/include/__algorithm/make_heap.h20
-rw-r--r--libcxx/include/__algorithm/partial_sort.h2
-rw-r--r--libcxx/include/__algorithm/partial_sort_copy.h2
-rw-r--r--libcxx/include/__algorithm/sift_down.h37
4 files changed, 37 insertions, 24 deletions
diff --git a/libcxx/include/__algorithm/make_heap.h b/libcxx/include/__algorithm/make_heap.h
index e8f0cdb..8cfeda2 100644
--- a/libcxx/include/__algorithm/make_heap.h
+++ b/libcxx/include/__algorithm/make_heap.h
@@ -12,9 +12,11 @@
#include <__algorithm/comp.h>
#include <__algorithm/comp_ref_type.h>
#include <__algorithm/iterator_operations.h>
+#include <__algorithm/push_heap.h>
#include <__algorithm/sift_down.h>
#include <__config>
#include <__iterator/iterator_traits.h>
+#include <__type_traits/is_arithmetic.h>
#include <__utility/move.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -31,13 +33,23 @@ inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
__make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare&& __comp) {
__comp_ref_type<_Compare> __comp_ref = __comp;
- using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;
- difference_type __n = __last - __first;
+ using __diff_t = __iter_diff_t<_RandomAccessIterator>;
+ const __diff_t __n = __last - __first;
+
+ static const bool __assume_both_children = is_arithmetic<__iter_value_type<_RandomAccessIterator> >::value;
+
+ // While it would be correct to always assume we have both children, in practice we observed this to be a performance
+ // improvement only for arithmetic types.
+ const __diff_t __sift_down_n = __assume_both_children ? ((__n & 1) ? __n : __n - 1) : __n;
+
if (__n > 1) {
// start from the first parent, there is no need to consider children
- for (difference_type __start = (__n - 2) / 2; __start >= 0; --__start) {
- std::__sift_down<_AlgPolicy>(__first, __comp_ref, __n, __first + __start);
+
+ for (__diff_t __start = (__sift_down_n - 2) / 2; __start >= 0; --__start) {
+ std::__sift_down<_AlgPolicy, __assume_both_children>(__first, __comp_ref, __sift_down_n, __start);
}
+ if _LIBCPP_CONSTEXPR (__assume_both_children)
+ std::__sift_up<_AlgPolicy>(__first, __last, __comp, __n);
}
}
diff --git a/libcxx/include/__algorithm/partial_sort.h b/libcxx/include/__algorithm/partial_sort.h
index 7f8d0c4..4b39ae0 100644
--- a/libcxx/include/__algorithm/partial_sort.h
+++ b/libcxx/include/__algorithm/partial_sort.h
@@ -45,7 +45,7 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _RandomAccessIterator __part
for (; __i != __last; ++__i) {
if (__comp(*__i, *__first)) {
_IterOps<_AlgPolicy>::iter_swap(__i, __first);
- std::__sift_down<_AlgPolicy>(__first, __comp, __len, __first);
+ std::__sift_down<_AlgPolicy, false>(__first, __comp, __len, 0);
}
}
std::__sort_heap<_AlgPolicy>(std::move(__first), std::move(__middle), __comp);
diff --git a/libcxx/include/__algorithm/partial_sort_copy.h b/libcxx/include/__algorithm/partial_sort_copy.h
index 172f53b..2230dfc 100644
--- a/libcxx/include/__algorithm/partial_sort_copy.h
+++ b/libcxx/include/__algorithm/partial_sort_copy.h
@@ -60,7 +60,7 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InputIterator, _Random
for (; __first != __last; ++__first)
if (std::__invoke(__comp, std::__invoke(__proj1, *__first), std::__invoke(__proj2, *__result_first))) {
*__result_first = *__first;
- std::__sift_down<_AlgPolicy>(__result_first, __projected_comp, __len, __result_first);
+ std::__sift_down<_AlgPolicy, false>(__result_first, __projected_comp, __len, 0);
}
std::__sort_heap<_AlgPolicy>(__result_first, __r, __projected_comp);
}
diff --git a/libcxx/include/__algorithm/sift_down.h b/libcxx/include/__algorithm/sift_down.h
index 42803e3..e01c9b2 100644
--- a/libcxx/include/__algorithm/sift_down.h
+++ b/libcxx/include/__algorithm/sift_down.h
@@ -24,59 +24,60 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
-template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
+template <class _AlgPolicy, bool __assume_both_children, class _Compare, class _RandomAccessIterator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
__sift_down(_RandomAccessIterator __first,
_Compare&& __comp,
- typename iterator_traits<_RandomAccessIterator>::difference_type __len,
- _RandomAccessIterator __start) {
+ __iter_diff_t<_RandomAccessIterator> __len,
+ __iter_diff_t<_RandomAccessIterator> __start) {
using _Ops = _IterOps<_AlgPolicy>;
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
// left-child of __start is at 2 * __start + 1
// right-child of __start is at 2 * __start + 2
- difference_type __child = __start - __first;
+ difference_type __child = __start;
if (__len < 2 || (__len - 2) / 2 < __child)
return;
- __child = 2 * __child + 1;
- _RandomAccessIterator __child_i = __first + __child;
+ __child = 2 * __child + 1;
- if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + difference_type(1)))) {
+ if _LIBCPP_CONSTEXPR (__assume_both_children) {
+ // right-child exists and is greater than left-child
+ __child += __comp(__first[__child], __first[__child + 1]);
+ } else if ((__child + 1) < __len && __comp(__first[__child], __first[__child + 1])) {
// right-child exists and is greater than left-child
- ++__child_i;
++__child;
}
// check if we are in heap-order
- if (__comp(*__child_i, *__start))
+ if (__comp(__first[__child], __first[__start]))
// we are, __start is larger than its largest child
return;
- value_type __top(_Ops::__iter_move(__start));
+ value_type __top(_Ops::__iter_move(__first + __start));
do {
// we are not in heap-order, swap the parent with its largest child
- *__start = _Ops::__iter_move(__child_i);
- __start = __child_i;
+ __first[__start] = _Ops::__iter_move(__first + __child);
+ __start = __child;
if ((__len - 2) / 2 < __child)
break;
// recompute the child based off of the updated parent
- __child = 2 * __child + 1;
- __child_i = __first + __child;
+ __child = 2 * __child + 1;
- if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + difference_type(1)))) {
+ if _LIBCPP_CONSTEXPR (__assume_both_children) {
+ __child += __comp(__first[__child], __first[__child + 1]);
+ } else if ((__child + 1) < __len && __comp(__first[__child], __first[__child + 1])) {
// right-child exists and is greater than left-child
- ++__child_i;
++__child;
}
// check if we are in heap-order
- } while (!__comp(*__child_i, __top));
- *__start = std::move(__top);
+ } while (!__comp(__first[__child], __top));
+ __first[__start] = std::move(__top);
}
template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
generated by cgit v1.1 at 2025-09-30 23:43:44 +0000