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libstdc++ Two simplifications for lexicographical_compare

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* include/bits/ranges_algo.h (__lexicographical_compare_fn): Declare
	variables in smaller scope and avoid calling ranges::distance when we
	know they are pointers. Remove statically-unreachable use of
	__builtin_unreachable().
	* include/bits/stl_algobase.h (__lexicographical_compare::__lc):
	Define inline.
This commit is contained in:
Jonathan Wakely 2020-02-26 15:19:44 +00:00
parent 8017d95c7f
commit 113f0a639d
3 changed files with 19 additions and 19 deletions
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7
libstdc++-v3/ChangeLog
View file

@ -1,5 +1,12 @@
2020-02-26 Jonathan Wakely <jwakely@redhat.com>
* include/bits/ranges_algo.h (__lexicographical_compare_fn): Declare
variables in smaller scope and avoid calling ranges::distance when we
know they are pointers. Remove statically-unreachable use of
__builtin_unreachable().
* include/bits/stl_algobase.h (__lexicographical_compare::__lc):
Define inline.
* include/std/ranges (__detail::__maybe_empty_t): Define new helper
alias.
(__detail::__maybe_const_t): Likewise.

10
libstdc++-v3/include/bits/ranges_algo.h
View file

@ -3464,9 +3464,6 @@ namespace ranges
&& sized_sentinel_for<_Sent2, _Iter2>);
if constexpr (__sized_iters)
{
auto __d1 = ranges::distance(__first1, __last1);
auto __d2 = ranges::distance(__first2, __last2);
using _ValueType1 = iter_value_t<_Iter1>;
using _ValueType2 = iter_value_t<_Iter2>;
constexpr bool __use_memcmp
@ -3480,6 +3477,9 @@ namespace ranges
&& is_same_v<_Proj2, identity>);
if constexpr (__use_memcmp)
{
const auto __d1 = __last1 - __first1;
const auto __d2 = __last2 - __first2;
if (const auto __len = std::min(__d1, __d2))
{
const auto __c
@ -3498,10 +3498,8 @@ namespace ranges
if (__c < 0)
return false;
}
else
__builtin_unreachable();
}
return (__last1 - __first1 < __last2 - __first2);
return __d1 < __d2;
}
}

21
libstdc++-v3/include/bits/stl_algobase.h
View file

@ -1254,21 +1254,16 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
{
template<typename _II1, typename _II2>
_GLIBCXX20_CONSTEXPR
static bool __lc(_II1, _II1, _II2, _II2);
static bool
__lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
{
using __gnu_cxx::__ops::__iter_less_iter;
return std::__lexicographical_compare_impl(__first1, __last1,
__first2, __last2,
__iter_less_iter());
}
};
template<bool _BoolType>
template<typename _II1, typename _II2>
_GLIBCXX20_CONSTEXPR
bool
__lexicographical_compare<_BoolType>::
__lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
{
return std::__lexicographical_compare_impl(__first1, __last1,
__first2, __last2,
__gnu_cxx::__ops::__iter_less_iter());
}
template<>
struct __lexicographical_compare<true>
{