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* [Bug libstdc++/107367] New: All standard library algorithms should detect whether they are contiguous iterators after C++20
@ 2022-10-24 2:28 unlvsur at live dot com
2022-10-24 2:33 ` [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when " unlvsur at live dot com
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: unlvsur at live dot com @ 2022-10-24 2:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107367
Bug ID: 107367
Summary: All standard library algorithms should detect whether
they are contiguous iterators after C++20
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: unlvsur at live dot com
Target Milestone: ---
https://github.com/gcc-mirror/gcc/blob/00716b776200c2de6813ce706d2757eec4cb2735/libstdc%2B%2B-v3/include/bits/stl_algo.h#L3229
Take is_sorted for example:
template<typename _ForwardIterator>
_GLIBCXX20_CONSTEXPR
inline bool
is_sorted(_ForwardIterator __first, _ForwardIterator __last)
{ return std::is_sorted_until(__first, __last) == __last; }
It should be optimized to
template<typename _ForwardIterator>
_GLIBCXX20_CONSTEXPR
inline bool
is_sorted(_ForwardIterator __first, _ForwardIterator __last)
{
if
constexpr(contiguous_iterator<_ForwardIterator>&&!is_pointer_v<_ForwardIterator>)
{
return is_sorted(to_address(__first),to_address(__last));
}
else
{
return std::is_sorted_until(__first, __last) == __last;
}
}
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when they are contiguous iterators after C++20
2022-10-24 2:28 [Bug libstdc++/107367] New: All standard library algorithms should detect whether they are contiguous iterators after C++20 unlvsur at live dot com
@ 2022-10-24 2:33 ` unlvsur at live dot com
2022-10-25 3:36 ` unlvsur at live dot com
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: unlvsur at live dot com @ 2022-10-24 2:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107367
--- Comment #1 from cqwrteur <unlvsur at live dot com> ---
This optimization will prevent duplications of templates over iterators and
pointers. (vector<int>::iterator and int* duplications for example)
For example:
https://godbolt.org/z/9zEajxxa8
vs
https://godbolt.org/z/n61vEddj1
579 vs 879
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when they are contiguous iterators after C++20
2022-10-24 2:28 [Bug libstdc++/107367] New: All standard library algorithms should detect whether they are contiguous iterators after C++20 unlvsur at live dot com
2022-10-24 2:33 ` [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when " unlvsur at live dot com
@ 2022-10-25 3:36 ` unlvsur at live dot com
2023-12-16 18:40 ` unlvsur at live dot com
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: unlvsur at live dot com @ 2022-10-25 3:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107367
--- Comment #2 from cqwrteur <unlvsur at live dot com> ---
(In reply to cqwrteur from comment #1)
> This optimization will prevent duplications of templates over iterators and
> pointers. (vector<int>::iterator and int* duplications for example)
>
> For example:
>
> https://godbolt.org/z/9zEajxxa8
> vs
> https://godbolt.org/z/n61vEddj1
>
> 579 vs 879
For debugging. You can do something like this
template<typename ForwardIterator>
concept can_optimize_to_pointer_impl =
#ifdef _GLIBCXX_DEBUG
false;
#else
std::contiguous_iterator<ForwardIterator>&&!std::is_pointer_v<ForwardIterator>;
#endif
template<typename ForwardIterator>
constexpr void my_sort(ForwardIterator first,ForwardIterator last)
{
if constexpr(can_optimize_to_pointer_impl<ForwardIterator>)
{
std::sort(std::to_address(first),std::to_address(last));
}
else
{
std::sort(first,last);
}
}
https://godbolt.org/z/jj38MoWen
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when they are contiguous iterators after C++20
2022-10-24 2:28 [Bug libstdc++/107367] New: All standard library algorithms should detect whether they are contiguous iterators after C++20 unlvsur at live dot com
2022-10-24 2:33 ` [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when " unlvsur at live dot com
2022-10-25 3:36 ` unlvsur at live dot com
@ 2023-12-16 18:40 ` unlvsur at live dot com
2023-12-17 13:44 ` redi at gcc dot gnu.org
2023-12-17 13:45 ` redi at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: unlvsur at live dot com @ 2023-12-16 18:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107367
cqwrteur <unlvsur at live dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |MOVED
Status|UNCONFIRMED |RESOLVED
--- Comment #3 from cqwrteur <unlvsur at live dot com> ---
moved and restart
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when they are contiguous iterators after C++20
2022-10-24 2:28 [Bug libstdc++/107367] New: All standard library algorithms should detect whether they are contiguous iterators after C++20 unlvsur at live dot com
` (2 preceding siblings ...)
2023-12-16 18:40 ` unlvsur at live dot com
@ 2023-12-17 13:44 ` redi at gcc dot gnu.org
2023-12-17 13:45 ` redi at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2023-12-17 13:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107367
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
*** Bug 113046 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when they are contiguous iterators after C++20
2022-10-24 2:28 [Bug libstdc++/107367] New: All standard library algorithms should detect whether they are contiguous iterators after C++20 unlvsur at live dot com
` (3 preceding siblings ...)
2023-12-17 13:44 ` redi at gcc dot gnu.org
@ 2023-12-17 13:45 ` redi at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2023-12-17 13:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107367
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-12-17
Ever confirmed|0 |1
Keywords| |missed-optimization
Resolution|MOVED |---
Status|RESOLVED |NEW
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-12-17 13:45 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2022-10-24 2:28 [Bug libstdc++/107367] New: All standard library algorithms should detect whether they are contiguous iterators after C++20 unlvsur at live dot com
2022-10-24 2:33 ` [Bug libstdc++/107367] All standard library algorithms should optimize to pointers internally when " unlvsur at live dot com
2022-10-25 3:36 ` unlvsur at live dot com
2023-12-16 18:40 ` unlvsur at live dot com
2023-12-17 13:44 ` redi at gcc dot gnu.org
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