Reapply "[libc++] Simplify the implementation of std::sort a bit (#104902)" #114023
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
llvmbot
added
the
libc++
|
@llvm/pr-subscribers-libcxx Author: Nikolas Klauser (philnik777) ChangesThis reverts commit ef44e46. Patch is 21.59 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/114023.diff 8 Files Affected:
diff --git a/libcxx/include/__algorithm/comp.h b/libcxx/include/__algorithm/comp.h
index 1f38f5d2d99b43..ab3c598418828a 100644
--- a/libcxx/include/__algorithm/comp.h
+++ b/libcxx/include/__algorithm/comp.h
@@ -42,6 +42,9 @@ struct __less<void, void> {
}
};
+template <class _Tp>
+inline const bool __desugars_to_v<__less_tag, __less<>, _Tp, _Tp> = true;
+
template <class _Tp>
inline const bool __desugars_to_v<__totally_ordered_less_tag, __less<>, _Tp, _Tp> = is_integral<_Tp>::value;
diff --git a/libcxx/include/__algorithm/ranges_minmax.h b/libcxx/include/__algorithm/ranges_minmax.h
index 4f2b2bf26382da..5f2e5cb2a1eeab 100644
--- a/libcxx/include/__algorithm/ranges_minmax.h
+++ b/libcxx/include/__algorithm/ranges_minmax.h
@@ -89,7 +89,7 @@ struct __minmax {
// vectorize the code.
if constexpr (contiguous_range<_Range> && is_integral_v<_ValueT> &&
__is_cheap_to_copy<_ValueT> & __is_identity<_Proj>::value &&
- __desugars_to_v<__totally_ordered_less_tag, _Comp, _ValueT, _ValueT>) {
+ __desugars_to_v<__less_tag, _Comp, _ValueT, _ValueT>) {
minmax_result<_ValueT> __result = {__r[0], __r[0]};
for (auto __e : __r) {
if (__e < __result.min)
diff --git a/libcxx/include/__algorithm/sort.h b/libcxx/include/__algorithm/sort.h
index 0b2137dee2f77e..39868b8b6a30ae 100644
--- a/libcxx/include/__algorithm/sort.h
+++ b/libcxx/include/__algorithm/sort.h
@@ -27,11 +27,13 @@
#include <__functional/ranges_operations.h>
#include <__iterator/iterator_traits.h>
#include <__type_traits/conditional.h>
+#include <__type_traits/desugars_to.h>
#include <__type_traits/disjunction.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_arithmetic.h>
#include <__type_traits/is_constant_evaluated.h>
#include <__type_traits/is_same.h>
+#include <__type_traits/is_trivially_copyable.h>
#include <__type_traits/remove_cvref.h>
#include <__utility/move.h>
#include <__utility/pair.h>
@@ -47,110 +49,11 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
-// stable, 2-3 compares, 0-2 swaps
-
-template <class _AlgPolicy, class _Compare, class _ForwardIterator>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 unsigned
-__sort3(_ForwardIterator __x, _ForwardIterator __y, _ForwardIterator __z, _Compare __c) {
- using _Ops = _IterOps<_AlgPolicy>;
-
- 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
- _Ops::iter_swap(__y, __z); // x <= z && y < z
- __r = 1;
- if (__c(*__y, *__x)) // if x > y
- {
- _Ops::iter_swap(__x, __y); // x < y && y <= z
- __r = 2;
- }
- return __r; // x <= y && y < z
- }
- if (__c(*__z, *__y)) // x > y, if y > z
- {
- _Ops::iter_swap(__x, __z); // x < y && y < z
- __r = 1;
- return __r;
- }
- _Ops::iter_swap(__x, __y); // x > y && y <= z
- __r = 1; // x < y && x <= z
- if (__c(*__z, *__y)) // if y > z
- {
- _Ops::iter_swap(__y, __z); // x <= y && y < z
- __r = 2;
- }
- return __r;
-} // x <= y && y <= z
-
-// stable, 3-6 compares, 0-5 swaps
-
-template <class _AlgPolicy, class _Compare, class _ForwardIterator>
-_LIBCPP_HIDE_FROM_ABI void
-__sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3, _ForwardIterator __x4, _Compare __c) {
- using _Ops = _IterOps<_AlgPolicy>;
- std::__sort3<_AlgPolicy, _Compare>(__x1, __x2, __x3, __c);
- if (__c(*__x4, *__x3)) {
- _Ops::iter_swap(__x3, __x4);
- if (__c(*__x3, *__x2)) {
- _Ops::iter_swap(__x2, __x3);
- if (__c(*__x2, *__x1)) {
- _Ops::iter_swap(__x1, __x2);
- }
- }
- }
-}
-
-// stable, 4-10 compares, 0-9 swaps
-
-template <class _AlgPolicy, class _Comp, class _ForwardIterator>
-_LIBCPP_HIDE_FROM_ABI void
-__sort5(_ForwardIterator __x1,
- _ForwardIterator __x2,
- _ForwardIterator __x3,
- _ForwardIterator __x4,
- _ForwardIterator __x5,
- _Comp __comp) {
- using _Ops = _IterOps<_AlgPolicy>;
-
- std::__sort4<_AlgPolicy, _Comp>(__x1, __x2, __x3, __x4, __comp);
- if (__comp(*__x5, *__x4)) {
- _Ops::iter_swap(__x4, __x5);
- if (__comp(*__x4, *__x3)) {
- _Ops::iter_swap(__x3, __x4);
- if (__comp(*__x3, *__x2)) {
- _Ops::iter_swap(__x2, __x3);
- if (__comp(*__x2, *__x1)) {
- _Ops::iter_swap(__x1, __x2);
- }
- }
- }
- }
-}
-
-// The comparator being simple is a prerequisite for using the branchless optimization.
-template <class _Tp>
-struct __is_simple_comparator : false_type {};
-template <>
-struct __is_simple_comparator<__less<>&> : true_type {};
-template <class _Tp>
-struct __is_simple_comparator<less<_Tp>&> : true_type {};
-template <class _Tp>
-struct __is_simple_comparator<greater<_Tp>&> : true_type {};
-#if _LIBCPP_STD_VER >= 20
-template <>
-struct __is_simple_comparator<ranges::less&> : true_type {};
-template <>
-struct __is_simple_comparator<ranges::greater&> : true_type {};
-#endif
-
template <class _Compare, class _Iter, class _Tp = typename iterator_traits<_Iter>::value_type>
-using __use_branchless_sort =
- integral_constant<bool,
- __libcpp_is_contiguous_iterator<_Iter>::value && sizeof(_Tp) <= sizeof(void*) &&
- is_arithmetic<_Tp>::value && __is_simple_comparator<_Compare>::value>;
+inline const bool __use_branchless_sort =
+ __libcpp_is_contiguous_iterator<_Iter>::value && __is_cheap_to_copy<_Tp> && is_arithmetic<_Tp>::value &&
+ (__desugars_to_v<__less_tag, __remove_cvref_t<_Compare>, _Tp, _Tp> ||
+ __desugars_to_v<__greater_tag, __remove_cvref_t<_Compare>, _Tp, _Tp>);
namespace __detail {
@@ -161,59 +64,88 @@ enum { __block_size = sizeof(uint64_t) * 8 };
// Ensures that __c(*__x, *__y) is true by swapping *__x and *__y if necessary.
template <class _Compare, class _RandomAccessIterator>
-inline _LIBCPP_HIDE_FROM_ABI void __cond_swap(_RandomAccessIterator __x, _RandomAccessIterator __y, _Compare __c) {
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
+__cond_swap(_RandomAccessIterator __x, _RandomAccessIterator __y, _Compare __c) {
// Note: this function behaves correctly even with proxy iterators (because it relies on `value_type`).
using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
bool __r = __c(*__x, *__y);
value_type __tmp = __r ? *__x : *__y;
*__y = __r ? *__y : *__x;
*__x = __tmp;
+ return !__r;
}
// Ensures that *__x, *__y and *__z are ordered according to the comparator __c,
// under the assumption that *__y and *__z are already ordered.
template <class _Compare, class _RandomAccessIterator>
-inline _LIBCPP_HIDE_FROM_ABI void
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
__partially_sorted_swap(_RandomAccessIterator __x, _RandomAccessIterator __y, _RandomAccessIterator __z, _Compare __c) {
// Note: this function behaves correctly even with proxy iterators (because it relies on `value_type`).
using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
- bool __r = __c(*__z, *__x);
- value_type __tmp = __r ? *__z : *__x;
- *__z = __r ? *__x : *__z;
- __r = __c(__tmp, *__y);
- *__x = __r ? *__x : *__y;
- *__y = __r ? *__y : __tmp;
+ bool __r1 = __c(*__z, *__x);
+ value_type __tmp = __r1 ? *__z : *__x;
+ *__z = __r1 ? *__x : *__z;
+ bool __r2 = __c(__tmp, *__y);
+ *__x = __r2 ? *__x : *__y;
+ *__y = __r2 ? *__y : __tmp;
+ return !__r1 || !__r2;
}
+// stable, 2-3 compares, 0-2 swaps
+
template <class,
class _Compare,
class _RandomAccessIterator,
- __enable_if_t<__use_branchless_sort<_Compare, _RandomAccessIterator>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI void __sort3_maybe_branchless(
- _RandomAccessIterator __x1, _RandomAccessIterator __x2, _RandomAccessIterator __x3, _Compare __c) {
- std::__cond_swap<_Compare>(__x2, __x3, __c);
- std::__partially_sorted_swap<_Compare>(__x1, __x2, __x3, __c);
+ __enable_if_t<__use_branchless_sort<_Compare, _RandomAccessIterator>, int> = 0>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
+__sort3(_RandomAccessIterator __x1, _RandomAccessIterator __x2, _RandomAccessIterator __x3, _Compare __c) {
+ bool __swapped1 = std::__cond_swap<_Compare>(__x2, __x3, __c);
+ bool __swapped2 = std::__partially_sorted_swap<_Compare>(__x1, __x2, __x3, __c);
+ return __swapped1 || __swapped2;
}
template <class _AlgPolicy,
class _Compare,
class _RandomAccessIterator,
- __enable_if_t<!__use_branchless_sort<_Compare, _RandomAccessIterator>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI void __sort3_maybe_branchless(
- _RandomAccessIterator __x1, _RandomAccessIterator __x2, _RandomAccessIterator __x3, _Compare __c) {
- std::__sort3<_AlgPolicy, _Compare>(__x1, __x2, __x3, __c);
-}
+ __enable_if_t<!__use_branchless_sort<_Compare, _RandomAccessIterator>, int> = 0>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 bool
+__sort3(_RandomAccessIterator __x, _RandomAccessIterator __y, _RandomAccessIterator __z, _Compare __c) {
+ using _Ops = _IterOps<_AlgPolicy>;
+
+ if (!__c(*__y, *__x)) // if x <= y
+ {
+ if (!__c(*__z, *__y)) // if y <= z
+ return false; // x <= y && y <= z
+ // x <= y && y > z
+ _Ops::iter_swap(__y, __z); // x <= z && y < z
+ if (__c(*__y, *__x)) // if x > y
+ _Ops::iter_swap(__x, __y); // x < y && y <= z
+ return true; // x <= y && y < z
+ }
+ if (__c(*__z, *__y)) // x > y, if y > z
+ {
+ _Ops::iter_swap(__x, __z); // x < y && y < z
+ return true;
+ }
+ _Ops::iter_swap(__x, __y); // x > y && y <= z
+ // x < y && x <= z
+ if (__c(*__z, *__y)) // if y > z
+ _Ops::iter_swap(__y, __z); // x <= y && y < z
+ return true;
+} // x <= y && y <= z
+
+// stable, 3-6 compares, 0-5 swaps
template <class,
class _Compare,
class _RandomAccessIterator,
- __enable_if_t<__use_branchless_sort<_Compare, _RandomAccessIterator>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI void __sort4_maybe_branchless(
- _RandomAccessIterator __x1,
- _RandomAccessIterator __x2,
- _RandomAccessIterator __x3,
- _RandomAccessIterator __x4,
- _Compare __c) {
+ __enable_if_t<__use_branchless_sort<_Compare, _RandomAccessIterator>, int> = 0>
+inline _LIBCPP_HIDE_FROM_ABI void
+__sort4(_RandomAccessIterator __x1,
+ _RandomAccessIterator __x2,
+ _RandomAccessIterator __x3,
+ _RandomAccessIterator __x4,
+ _Compare __c) {
std::__cond_swap<_Compare>(__x1, __x3, __c);
std::__cond_swap<_Compare>(__x2, __x4, __c);
std::__cond_swap<_Compare>(__x1, __x2, __c);
@@ -224,27 +156,39 @@ inline _LIBCPP_HIDE_FROM_ABI void __sort4_maybe_branchless(
template <class _AlgPolicy,
class _Compare,
class _RandomAccessIterator,
- __enable_if_t<!__use_branchless_sort<_Compare, _RandomAccessIterator>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI void __sort4_maybe_branchless(
- _RandomAccessIterator __x1,
- _RandomAccessIterator __x2,
- _RandomAccessIterator __x3,
- _RandomAccessIterator __x4,
- _Compare __c) {
- std::__sort4<_AlgPolicy, _Compare>(__x1, __x2, __x3, __x4, __c);
+ __enable_if_t<!__use_branchless_sort<_Compare, _RandomAccessIterator>, int> = 0>
+inline _LIBCPP_HIDE_FROM_ABI void
+__sort4(_RandomAccessIterator __x1,
+ _RandomAccessIterator __x2,
+ _RandomAccessIterator __x3,
+ _RandomAccessIterator __x4,
+ _Compare __c) {
+ using _Ops = _IterOps<_AlgPolicy>;
+ std::__sort3<_AlgPolicy, _Compare>(__x1, __x2, __x3, __c);
+ if (__c(*__x4, *__x3)) {
+ _Ops::iter_swap(__x3, __x4);
+ if (__c(*__x3, *__x2)) {
+ _Ops::iter_swap(__x2, __x3);
+ if (__c(*__x2, *__x1)) {
+ _Ops::iter_swap(__x1, __x2);
+ }
+ }
+ }
}
+// stable, 4-10 compares, 0-9 swaps
+
template <class _AlgPolicy,
class _Compare,
class _RandomAccessIterator,
- __enable_if_t<__use_branchless_sort<_Compare, _RandomAccessIterator>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI void __sort5_maybe_branchless(
- _RandomAccessIterator __x1,
- _RandomAccessIterator __x2,
- _RandomAccessIterator __x3,
- _RandomAccessIterator __x4,
- _RandomAccessIterator __x5,
- _Compare __c) {
+ __enable_if_t<__use_branchless_sort<_Compare, _RandomAccessIterator>, int> = 0>
+inline _LIBCPP_HIDE_FROM_ABI void
+__sort5(_RandomAccessIterator __x1,
+ _RandomAccessIterator __x2,
+ _RandomAccessIterator __x3,
+ _RandomAccessIterator __x4,
+ _RandomAccessIterator __x5,
+ _Compare __c) {
std::__cond_swap<_Compare>(__x1, __x2, __c);
std::__cond_swap<_Compare>(__x4, __x5, __c);
std::__partially_sorted_swap<_Compare>(__x3, __x4, __x5, __c);
@@ -256,16 +200,29 @@ inline _LIBCPP_HIDE_FROM_ABI void __sort5_maybe_branchless(
template <class _AlgPolicy,
class _Compare,
class _RandomAccessIterator,
- __enable_if_t<!__use_branchless_sort<_Compare, _RandomAccessIterator>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI void __sort5_maybe_branchless(
- _RandomAccessIterator __x1,
- _RandomAccessIterator __x2,
- _RandomAccessIterator __x3,
- _RandomAccessIterator __x4,
- _RandomAccessIterator __x5,
- _Compare __c) {
- std::__sort5<_AlgPolicy, _Compare, _RandomAccessIterator>(
- std::move(__x1), std::move(__x2), std::move(__x3), std::move(__x4), std::move(__x5), __c);
+ __enable_if_t<!__use_branchless_sort<_Compare, _RandomAccessIterator>, int> = 0>
+inline _LIBCPP_HIDE_FROM_ABI void
+__sort5(_RandomAccessIterator __x1,
+ _RandomAccessIterator __x2,
+ _RandomAccessIterator __x3,
+ _RandomAccessIterator __x4,
+ _RandomAccessIterator __x5,
+ _Compare __comp) {
+ using _Ops = _IterOps<_AlgPolicy>;
+
+ std::__sort4<_AlgPolicy, _Compare>(__x1, __x2, __x3, __x4, __comp);
+ if (__comp(*__x5, *__x4)) {
+ _Ops::iter_swap(__x4, __x5);
+ if (__comp(*__x4, *__x3)) {
+ _Ops::iter_swap(__x3, __x4);
+ if (__comp(*__x3, *__x2)) {
+ _Ops::iter_swap(__x2, __x3);
+ if (__comp(*__x2, *__x1)) {
+ _Ops::iter_swap(__x1, __x2);
+ }
+ }
+ }
+ }
}
// Assumes size > 0
@@ -355,14 +312,14 @@ __insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator
_Ops::iter_swap(__first, __last);
return true;
case 3:
- std::__sort3_maybe_branchless<_AlgPolicy, _Comp>(__first, __first + difference_type(1), --__last, __comp);
+ std::__sort3<_AlgPolicy, _Comp>(__first, __first + difference_type(1), --__last, __comp);
return true;
case 4:
- std::__sort4_maybe_branchless<_AlgPolicy, _Comp>(
+ std::__sort4<_AlgPolicy, _Comp>(
__first, __first + difference_type(1), __first + difference_type(2), --__last, __comp);
return true;
case 5:
- std::__sort5_maybe_branchless<_AlgPolicy, _Comp>(
+ std::__sort5<_AlgPolicy, _Comp>(
__first,
__first + difference_type(1),
__first + difference_type(2),
@@ -373,7 +330,7 @@ __insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator
}
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
_RandomAccessIterator __j = __first + difference_type(2);
- std::__sort3_maybe_branchless<_AlgPolicy, _Comp>(__first, __first + difference_type(1), __j, __comp);
+ std::__sort3<_AlgPolicy, _Comp>(__first, __first + difference_type(1), __j, __comp);
const unsigned __limit = 8;
unsigned __count = 0;
for (_RandomAccessIterator __i = __j + difference_type(1); __i != __last; ++__i) {
@@ -780,14 +737,14 @@ void __introsort(_RandomAccessIterator __first,
_Ops::iter_swap(__first, __last);
return;
case 3:
- std::__sort3_maybe_branchless<_AlgPolicy, _Compare>(__first, __first + difference_type(1), --__last, __comp);
+ std::__sort3<_AlgPolicy, _Compare>(__first, __first + difference_type(1), --__last, __comp);
return;
case 4:
- std::__sort4_maybe_branchless<_AlgPolicy, _Compare>(
+ std::__sort4<_AlgPolicy, _Compare>(
__first, __first + difference_type(1), __first + difference_type(2), --__last, __comp);
return;
case 5:
- std::__sort5_maybe_branchless<_AlgPolicy, _Compare>(
+ std::__sort5<_AlgPolicy, _Compare>(
__first,
__first + difference_type(1),
__first + difference_type(2),
@@ -928,10 +885,8 @@ __sort_dispatch(_RandomAccessIterator __first, _RandomAccessIterator __last, _Co
// Only use bitset partitioning for arithmetic types. We should also check
// that the default comparator is in use so that we are sure that there are no
// branches in the comparator.
- std::__introsort<_AlgPolicy,
- _Comp&,
- _RandomAccessIterator,
- __use_branchless_sort<_Comp, _RandomAccessIterator>::value>(__first, __last, __comp, __depth_limit);
+ std::__introsort<_AlgPolicy, _Comp&, _RandomAccessIterator, __use_branchless_sort<_Comp, _RandomAccessIterator> >(
+ __first, __last, __comp, __depth_limit);
}
template <class _Type, class... _Options>
diff --git a/libcxx/include/__functional/operations.h b/libcxx/include/__functional/operations.h
index 6022bd679ed3e3..67d9da289aead3 100644
--- a/libcxx/include/__functional/operations.h
+++ b/libcxx/include/__functional/operations.h
@@ -362,6 +362,9 @@ struct _LIBCPP_TEMPLATE_VIS less : __binary_function<_Tp, _Tp, bool> {
};
_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(less);
+template <class _Tp>
+inline const bool __desugars_to_v<__less_tag, less<_Tp>, _Tp, _Tp> = true;
+
template <class _Tp>
inline const bool __desugars_to_v<__totally_ordered_less_tag, less<_Tp>, _Tp, _Tp> = is_integral<_Tp>::value;
@@ -377,6 +380,9 @@ struct _LIBCPP_TEMPLATE_VIS less<void> {
typedef void is_transparent;
};
+template <class _Tp, class _Up>
+inline const bool __desugars_to_v<__less_tag, less<>, _Tp, _Up> = true;
+
template <class _Tp>
inline const bool __desugars_to_v<__totally_ordered_less_tag, less<>, _Tp, _Tp> = is_integral<_Tp>::value;
#endif
@@ -446,6 +452,9 @@ struct _LIBCPP_TEMPLATE_VIS greater : __binary_function<_Tp, _Tp, bool> {
};
_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(greater);
+template <class _Tp>
+inline const bool __desugars_to_v<__greater_tag, greater<_Tp>, _Tp, _Tp> = true;
+
#if _LIBCPP_STD_VER >= 14
template <>
struct _LIBCPP_TEMPLATE_VIS greater<void> {
@@ -457,6 +466,9 @@ struct _LIBCPP_TEMPLATE_VIS greater<void> {
}
typedef void is_transparent;
};
+
+template <class _Tp, class _Up>
+inline const bool __desugars_to_v<__greater_tag, greater<>, _Tp, _Up> = true;
#endif
// Logical operations
diff --git a/libcxx/include/__functional/ranges_operations.h b/libcxx/include/__functional/ranges_operations.h
index f023d765a6c8ab..df95843e7c9af6 100644
--- a/libcxx/include/__functional/ranges_operations.h
+++ b/libcxx/include/__functional/ranges_operations.h
@@ -102,6 +102,12 @@ inline const bool __desugars_to_v<__equal_tag, ranges::equal_to, _Tp, _Up> = tru
template <class _Tp, class _Up>
inline const bool __desugars_to_v<__totally_ordered_less_tag, ranges::less, _Tp, _Up> = true;
+template <class _Tp, class _Up>
+inline const bool __desugars_to_v<__less_tag, ranges::less, _Tp, _Up> = true;
+
+template <class _Tp, class _Up>
+inline const bool __desugars_to_v<__greater_tag, ranges::greater, _Tp, _Up> = true;
+
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/__type_traits/desugars_to.h b/libcxx/include/__type_traits/desugars_to.h
index b0ce7c414e5d77..452c70bfbad66d 100644
--- a/libcxx/include/__type_traits/desugars_to.h
+++ b/libcxx/include/__type_traits/desugars_to.h
@@ -25,6 +25,12 @@ struct __equal_tag {};
// syntactically, the operation is equivalent to calling `a + b`
struct __plus_tag {};
+// syntactically, the operation is equivalent to calling `a < b`
+struct __less_tag {};
+
+// syntactically, t...
[truncated]
|
|
The CI failures look unrelated. |
NoumanAmir657
pushed a commit
to NoumanAmir657/llvm-project
that referenced
this pull request
Nov 4, 2024
…m#104902)" (llvm#114023) This reverts commit ef44e46. The patch was originally reverted because it was deemed to introduce a performance regression for small inputs, however it also fixed a previous performance regression for larger inputs. So overall, this patch is desirable.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This reverts commit ef44e46. The patch was originally reverted because it was
deemed to introduce a performance regression for small inputs, however it also fixed
a previous performance regression for larger inputs. So overall, this patch is desirable.