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Optimize ranges::swap_ranges for vector<bool>::iterator
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7 files changed

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‎libcxx/docs/ReleaseNotes/21.rst

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -46,6 +46,8 @@ Improvements and New Features
4646
- The ``std::ranges::{copy, copy_n, copy_backward}`` algorithms have been optimized for ``std::vector<bool>::iterator``\s,
4747
resulting in a performance improvement of up to 2000x.
4848

49+
- The ``std::ranges::swap_ranges`` algorithm has been optimized for ``std::vector<bool>::iterator``, resulting in a
50+
performance improvement of up to 611x.
4951

5052
Deprecations and Removals
5153
-------------------------

‎libcxx/include/__algorithm/swap_ranges.h

Lines changed: 162 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -10,9 +10,12 @@
1010
#define _LIBCPP___ALGORITHM_SWAP_RANGES_H
1111

1212
#include <__algorithm/iterator_operations.h>
13+
#include <__algorithm/min.h>
1314
#include <__config>
15+
#include <__fwd/bit_reference.h>
1416
#include <__utility/move.h>
1517
#include <__utility/pair.h>
18+
#include <__utility/swap.h>
1619

1720
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
1821
# pragma GCC system_header
@@ -23,6 +26,165 @@ _LIBCPP_PUSH_MACROS
2326

2427
_LIBCPP_BEGIN_NAMESPACE_STD
2528

29+
template <class _Cl, class _Cr>
30+
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cr, false> __swap_ranges_aligned(
31+
__bit_iterator<_Cl, false> __first, __bit_iterator<_Cl, false> __last, __bit_iterator<_Cr, false> __result) {
32+
using _I1 = __bit_iterator<_Cl, false>;
33+
using difference_type = typename _I1::difference_type;
34+
using __storage_type = typename _I1::__storage_type;
35+
36+
const int __bits_per_word = _I1::__bits_per_word;
37+
difference_type __n = __last - __first;
38+
if (__n > 0) {
39+
// do first word
40+
if (__first.__ctz_ != 0) {
41+
unsigned __clz = __bits_per_word - __first.__ctz_;
42+
difference_type __dn = std::min(static_cast<difference_type>(__clz), __n);
43+
__n -= __dn;
44+
__storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
45+
__storage_type __b1 = *__first.__seg_ & __m;
46+
*__first.__seg_ &= ~__m;
47+
__storage_type __b2 = *__result.__seg_ & __m;
48+
*__result.__seg_ &= ~__m;
49+
*__result.__seg_ |= __b1;
50+
*__first.__seg_ |= __b2;
51+
__result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
52+
__result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_) % __bits_per_word);
53+
++__first.__seg_;
54+
// __first.__ctz_ = 0;
55+
}
56+
// __first.__ctz_ == 0;
57+
// do middle words
58+
for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_, ++__result.__seg_)
59+
swap(*__first.__seg_, *__result.__seg_);
60+
// do last word
61+
if (__n > 0) {
62+
__storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
63+
__storage_type __b1 = *__first.__seg_ & __m;
64+
*__first.__seg_ &= ~__m;
65+
__storage_type __b2 = *__result.__seg_ & __m;
66+
*__result.__seg_ &= ~__m;
67+
*__result.__seg_ |= __b1;
68+
*__first.__seg_ |= __b2;
69+
__result.__ctz_ = static_cast<unsigned>(__n);
70+
}
71+
}
72+
return __result;
73+
}
74+
75+
template <class _Cl, class _Cr>
76+
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __bit_iterator<_Cr, false> __swap_ranges_unaligned(
77+
__bit_iterator<_Cl, false> __first, __bit_iterator<_Cl, false> __last, __bit_iterator<_Cr, false> __result) {
78+
using _I1 = __bit_iterator<_Cl, false>;
79+
using difference_type = typename _I1::difference_type;
80+
using __storage_type = typename _I1::__storage_type;
81+
82+
const int __bits_per_word = _I1::__bits_per_word;
83+
difference_type __n = __last - __first;
84+
if (__n > 0) {
85+
// do first word
86+
if (__first.__ctz_ != 0) {
87+
unsigned __clz_f = __bits_per_word - __first.__ctz_;
88+
difference_type __dn = std::min(static_cast<difference_type>(__clz_f), __n);
89+
__n -= __dn;
90+
__storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
91+
__storage_type __b1 = *__first.__seg_ & __m;
92+
*__first.__seg_ &= ~__m;
93+
unsigned __clz_r = __bits_per_word - __result.__ctz_;
94+
__storage_type __ddn = std::min<__storage_type>(__dn, __clz_r);
95+
__m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
96+
__storage_type __b2 = *__result.__seg_ & __m;
97+
*__result.__seg_ &= ~__m;
98+
if (__result.__ctz_ > __first.__ctz_) {
99+
unsigned __s = __result.__ctz_ - __first.__ctz_;
100+
*__result.__seg_ |= __b1 << __s;
101+
*__first.__seg_ |= __b2 >> __s;
102+
} else {
103+
unsigned __s = __first.__ctz_ - __result.__ctz_;
104+
*__result.__seg_ |= __b1 >> __s;
105+
*__first.__seg_ |= __b2 << __s;
106+
}
107+
__result.__seg_ += (__ddn + __result.__ctz_) / __bits_per_word;
108+
__result.__ctz_ = static_cast<unsigned>((__ddn + __result.__ctz_) % __bits_per_word);
109+
__dn -= __ddn;
110+
if (__dn > 0) {
111+
__m = ~__storage_type(0) >> (__bits_per_word - __dn);
112+
__b2 = *__result.__seg_ & __m;
113+
*__result.__seg_ &= ~__m;
114+
unsigned __s = __first.__ctz_ + __ddn;
115+
*__result.__seg_ |= __b1 >> __s;
116+
*__first.__seg_ |= __b2 << __s;
117+
__result.__ctz_ = static_cast<unsigned>(__dn);
118+
}
119+
++__first.__seg_;
120+
// __first.__ctz_ = 0;
121+
}
122+
// __first.__ctz_ == 0;
123+
// do middle words
124+
__storage_type __m = ~__storage_type(0) << __result.__ctz_;
125+
unsigned __clz_r = __bits_per_word - __result.__ctz_;
126+
for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_) {
127+
__storage_type __b1 = *__first.__seg_;
128+
__storage_type __b2 = *__result.__seg_ & __m;
129+
*__result.__seg_ &= ~__m;
130+
*__result.__seg_ |= __b1 << __result.__ctz_;
131+
*__first.__seg_ = __b2 >> __result.__ctz_;
132+
++__result.__seg_;
133+
__b2 = *__result.__seg_ & ~__m;
134+
*__result.__seg_ &= __m;
135+
*__result.__seg_ |= __b1 >> __clz_r;
136+
*__first.__seg_ |= __b2 << __clz_r;
137+
}
138+
// do last word
139+
if (__n > 0) {
140+
__m = ~__storage_type(0) >> (__bits_per_word - __n);
141+
__storage_type __b1 = *__first.__seg_ & __m;
142+
*__first.__seg_ &= ~__m;
143+
__storage_type __dn = std::min<__storage_type>(__n, __clz_r);
144+
__m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
145+
__storage_type __b2 = *__result.__seg_ & __m;
146+
*__result.__seg_ &= ~__m;
147+
*__result.__seg_ |= __b1 << __result.__ctz_;
148+
*__first.__seg_ |= __b2 >> __result.__ctz_;
149+
__result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
150+
__result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_) % __bits_per_word);
151+
__n -= __dn;
152+
if (__n > 0) {
153+
__m = ~__storage_type(0) >> (__bits_per_word - __n);
154+
__b2 = *__result.__seg_ & __m;
155+
*__result.__seg_ &= ~__m;
156+
*__result.__seg_ |= __b1 >> __dn;
157+
*__first.__seg_ |= __b2 << __dn;
158+
__result.__ctz_ = static_cast<unsigned>(__n);
159+
}
160+
}
161+
}
162+
return __result;
163+
}
164+
165+
// 2+1 iterators: size2 >= size1; used by std::swap_ranges.
166+
template <class, class _Cl, class _Cr>
167+
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<__bit_iterator<_Cl, false>, __bit_iterator<_Cr, false> >
168+
__swap_ranges(__bit_iterator<_Cl, false> __first1,
169+
__bit_iterator<_Cl, false> __last1,
170+
__bit_iterator<_Cr, false> __first2) {
171+
if (__first1.__ctz_ == __first2.__ctz_)
172+
return std::make_pair(__last1, std::__swap_ranges_aligned(__first1, __last1, __first2));
173+
return std::make_pair(__last1, std::__swap_ranges_unaligned(__first1, __last1, __first2));
174+
}
175+
176+
// 2+2 iterators: used by std::ranges::swap_ranges.
177+
template <class _AlgPolicy, class _Cl, class _Cr>
178+
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<__bit_iterator<_Cl, false>, __bit_iterator<_Cr, false> >
179+
__swap_ranges(__bit_iterator<_Cl, false> __first1,
180+
__bit_iterator<_Cl, false> __last1,
181+
__bit_iterator<_Cr, false> __first2,
182+
__bit_iterator<_Cr, false> __last2) {
183+
if (__last1 - __first1 < __last2 - __first2)
184+
return std::make_pair(__last1, std::__swap_ranges<_AlgPolicy>(__first1, __last1, __first2).second);
185+
return std::make_pair(std::__swap_ranges<_AlgPolicy>(__first2, __last2, __first1).second, __last2);
186+
}
187+
26188
// 2+2 iterators: the shorter size will be used.
27189
template <class _AlgPolicy, class _ForwardIterator1, class _Sentinel1, class _ForwardIterator2, class _Sentinel2>
28190
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator1, _ForwardIterator2>

‎libcxx/include/__bit_reference

Lines changed: 6 additions & 151 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@
1414
#include <__algorithm/copy_backward.h>
1515
#include <__algorithm/copy_n.h>
1616
#include <__algorithm/min.h>
17+
#include <__algorithm/swap_ranges.h>
1718
#include <__bit/countr.h>
1819
#include <__compare/ordering.h>
1920
#include <__config>
@@ -202,152 +203,6 @@ inline _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, false> move_backward(
202203
return std::copy_backward(__first, __last, __result);
203204
}
204205

205-
// swap_ranges
206-
207-
template <class _Cl, class _Cr>
208-
_LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cr, false> __swap_ranges_aligned(
209-
__bit_iterator<_Cl, false> __first, __bit_iterator<_Cl, false> __last, __bit_iterator<_Cr, false> __result) {
210-
using _I1 = __bit_iterator<_Cl, false>;
211-
using difference_type = typename _I1::difference_type;
212-
using __storage_type = typename _I1::__storage_type;
213-
214-
const int __bits_per_word = _I1::__bits_per_word;
215-
difference_type __n = __last - __first;
216-
if (__n > 0) {
217-
// do first word
218-
if (__first.__ctz_ != 0) {
219-
unsigned __clz = __bits_per_word - __first.__ctz_;
220-
difference_type __dn = std::min(static_cast<difference_type>(__clz), __n);
221-
__n -= __dn;
222-
__storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
223-
__storage_type __b1 = *__first.__seg_ & __m;
224-
*__first.__seg_ &= ~__m;
225-
__storage_type __b2 = *__result.__seg_ & __m;
226-
*__result.__seg_ &= ~__m;
227-
*__result.__seg_ |= __b1;
228-
*__first.__seg_ |= __b2;
229-
__result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
230-
__result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_) % __bits_per_word);
231-
++__first.__seg_;
232-
// __first.__ctz_ = 0;
233-
}
234-
// __first.__ctz_ == 0;
235-
// do middle words
236-
for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_, ++__result.__seg_)
237-
swap(*__first.__seg_, *__result.__seg_);
238-
// do last word
239-
if (__n > 0) {
240-
__storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
241-
__storage_type __b1 = *__first.__seg_ & __m;
242-
*__first.__seg_ &= ~__m;
243-
__storage_type __b2 = *__result.__seg_ & __m;
244-
*__result.__seg_ &= ~__m;
245-
*__result.__seg_ |= __b1;
246-
*__first.__seg_ |= __b2;
247-
__result.__ctz_ = static_cast<unsigned>(__n);
248-
}
249-
}
250-
return __result;
251-
}
252-
253-
template <class _Cl, class _Cr>
254-
_LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cr, false> __swap_ranges_unaligned(
255-
__bit_iterator<_Cl, false> __first, __bit_iterator<_Cl, false> __last, __bit_iterator<_Cr, false> __result) {
256-
using _I1 = __bit_iterator<_Cl, false>;
257-
using difference_type = typename _I1::difference_type;
258-
using __storage_type = typename _I1::__storage_type;
259-
260-
const int __bits_per_word = _I1::__bits_per_word;
261-
difference_type __n = __last - __first;
262-
if (__n > 0) {
263-
// do first word
264-
if (__first.__ctz_ != 0) {
265-
unsigned __clz_f = __bits_per_word - __first.__ctz_;
266-
difference_type __dn = std::min(static_cast<difference_type>(__clz_f), __n);
267-
__n -= __dn;
268-
__storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
269-
__storage_type __b1 = *__first.__seg_ & __m;
270-
*__first.__seg_ &= ~__m;
271-
unsigned __clz_r = __bits_per_word - __result.__ctz_;
272-
__storage_type __ddn = std::min<__storage_type>(__dn, __clz_r);
273-
__m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
274-
__storage_type __b2 = *__result.__seg_ & __m;
275-
*__result.__seg_ &= ~__m;
276-
if (__result.__ctz_ > __first.__ctz_) {
277-
unsigned __s = __result.__ctz_ - __first.__ctz_;
278-
*__result.__seg_ |= __b1 << __s;
279-
*__first.__seg_ |= __b2 >> __s;
280-
} else {
281-
unsigned __s = __first.__ctz_ - __result.__ctz_;
282-
*__result.__seg_ |= __b1 >> __s;
283-
*__first.__seg_ |= __b2 << __s;
284-
}
285-
__result.__seg_ += (__ddn + __result.__ctz_) / __bits_per_word;
286-
__result.__ctz_ = static_cast<unsigned>((__ddn + __result.__ctz_) % __bits_per_word);
287-
__dn -= __ddn;
288-
if (__dn > 0) {
289-
__m = ~__storage_type(0) >> (__bits_per_word - __dn);
290-
__b2 = *__result.__seg_ & __m;
291-
*__result.__seg_ &= ~__m;
292-
unsigned __s = __first.__ctz_ + __ddn;
293-
*__result.__seg_ |= __b1 >> __s;
294-
*__first.__seg_ |= __b2 << __s;
295-
__result.__ctz_ = static_cast<unsigned>(__dn);
296-
}
297-
++__first.__seg_;
298-
// __first.__ctz_ = 0;
299-
}
300-
// __first.__ctz_ == 0;
301-
// do middle words
302-
__storage_type __m = ~__storage_type(0) << __result.__ctz_;
303-
unsigned __clz_r = __bits_per_word - __result.__ctz_;
304-
for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_) {
305-
__storage_type __b1 = *__first.__seg_;
306-
__storage_type __b2 = *__result.__seg_ & __m;
307-
*__result.__seg_ &= ~__m;
308-
*__result.__seg_ |= __b1 << __result.__ctz_;
309-
*__first.__seg_ = __b2 >> __result.__ctz_;
310-
++__result.__seg_;
311-
__b2 = *__result.__seg_ & ~__m;
312-
*__result.__seg_ &= __m;
313-
*__result.__seg_ |= __b1 >> __clz_r;
314-
*__first.__seg_ |= __b2 << __clz_r;
315-
}
316-
// do last word
317-
if (__n > 0) {
318-
__m = ~__storage_type(0) >> (__bits_per_word - __n);
319-
__storage_type __b1 = *__first.__seg_ & __m;
320-
*__first.__seg_ &= ~__m;
321-
__storage_type __dn = std::min<__storage_type>(__n, __clz_r);
322-
__m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
323-
__storage_type __b2 = *__result.__seg_ & __m;
324-
*__result.__seg_ &= ~__m;
325-
*__result.__seg_ |= __b1 << __result.__ctz_;
326-
*__first.__seg_ |= __b2 >> __result.__ctz_;
327-
__result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
328-
__result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_) % __bits_per_word);
329-
__n -= __dn;
330-
if (__n > 0) {
331-
__m = ~__storage_type(0) >> (__bits_per_word - __n);
332-
__b2 = *__result.__seg_ & __m;
333-
*__result.__seg_ &= ~__m;
334-
*__result.__seg_ |= __b1 >> __dn;
335-
*__first.__seg_ |= __b2 << __dn;
336-
__result.__ctz_ = static_cast<unsigned>(__n);
337-
}
338-
}
339-
}
340-
return __result;
341-
}
342-
343-
template <class _Cl, class _Cr>
344-
inline _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cr, false> swap_ranges(
345-
__bit_iterator<_Cl, false> __first1, __bit_iterator<_Cl, false> __last1, __bit_iterator<_Cr, false> __first2) {
346-
if (__first1.__ctz_ == __first2.__ctz_)
347-
return std::__swap_ranges_aligned(__first1, __last1, __first2);
348-
return std::__swap_ranges_unaligned(__first1, __last1, __first2);
349-
}
350-
351206
// rotate
352207

353208
template <class _Cp>
@@ -752,14 +607,14 @@ private:
752607
template <class _AlgPolicy>
753608
friend struct __copy_backward_impl;
754609
template <class _Cl, class _Cr>
755-
friend __bit_iterator<_Cr, false>
610+
_LIBCPP_CONSTEXPR_SINCE_CXX20 friend __bit_iterator<_Cr, false>
756611
__swap_ranges_aligned(__bit_iterator<_Cl, false>, __bit_iterator<_Cl, false>, __bit_iterator<_Cr, false>);
757612
template <class _Cl, class _Cr>
758-
friend __bit_iterator<_Cr, false>
613+
_LIBCPP_CONSTEXPR_SINCE_CXX20 friend __bit_iterator<_Cr, false>
759614
__swap_ranges_unaligned(__bit_iterator<_Cl, false>, __bit_iterator<_Cl, false>, __bit_iterator<_Cr, false>);
760-
template <class _Cl, class _Cr>
761-
friend __bit_iterator<_Cr, false>
762-
swap_ranges(__bit_iterator<_Cl, false>, __bit_iterator<_Cl, false>, __bit_iterator<_Cr, false>);
615+
template <class, class _Cl, class _Cr>
616+
_LIBCPP_CONSTEXPR_SINCE_CXX20 friend pair<__bit_iterator<_Cl, false>, __bit_iterator<_Cr, false> >
617+
__swap_ranges(__bit_iterator<_Cl, false>, __bit_iterator<_Cl, false>, __bit_iterator<_Cr, false>);
763618
template <class _Dp>
764619
_LIBCPP_CONSTEXPR_SINCE_CXX20 friend __bit_iterator<_Dp, false>
765620
rotate(__bit_iterator<_Dp, false>, __bit_iterator<_Dp, false>, __bit_iterator<_Dp, false>);

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