diff options
| author | Jonathan Wakely <jwakely@redhat.com> | 2017-06-05 11:34:13 +0100 |
|---|---|---|
| committer | Jonathan Wakely <redi@gcc.gnu.org> | 2017-06-05 11:34:13 +0100 |
| commit | 6c2417786217d33b27e7079647ed5f1b10b235c7 (patch) | |
| tree | 6bc2ea8896e22b2dcc0ccc167b52b5e8895759e7 /libstdc++-v3 | |
| parent | d08606ce6ceef0cb9fb2620e7dc2685867ce00df (diff) | |
| download | gcc-6c2417786217d33b27e7079647ed5f1b10b235c7.zip gcc-6c2417786217d33b27e7079647ed5f1b10b235c7.tar.gz gcc-6c2417786217d33b27e7079647ed5f1b10b235c7.tar.bz2 | |
Optimize std::advance for single increments
* include/bits/stl_iterator_base_funcs.h
(__advance<_RandomAccessIterator, _Distance>): Optimize for next/prev
cases where incrementing or decrementing a single step.
From-SVN: r248875
Diffstat (limited to 'libstdc++-v3')
| -rw-r--r-- | libstdc++-v3/ChangeLog | 4 | ||||
| -rw-r--r-- | libstdc++-v3/include/bits/stl_iterator_base_funcs.h | 7 |
2 files changed, 10 insertions, 1 deletions
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 4ee4c42..0b08810 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,9 @@ 2017-06-05 Jonathan Wakely <jwakely@redhat.com> + * include/bits/stl_iterator_base_funcs.h + (__advance<_RandomAccessIterator, _Distance>): Optimize for next/prev + cases where incrementing or decrementing a single step. + * include/bits/shared_ptr_base.h (__shared_ptr::owner_before) (__weak_ptr::owner_before, _Sp_owner_less::operator()): Add noexcept specifiers as per LWG 2873 and LWG 2942. diff --git a/libstdc++-v3/include/bits/stl_iterator_base_funcs.h b/libstdc++-v3/include/bits/stl_iterator_base_funcs.h index ce6c3d2..e14a22c 100644 --- a/libstdc++-v3/include/bits/stl_iterator_base_funcs.h +++ b/libstdc++-v3/include/bits/stl_iterator_base_funcs.h @@ -177,7 +177,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // concept requirements __glibcxx_function_requires(_RandomAccessIteratorConcept< _RandomAccessIterator>) - __i += __n; + if (__builtin_constant_p(__n) && __n == 1) + ++__i; + else if (__builtin_constant_p(__n) && __n == -1) + --__i; + else + __i += __n; } /** |