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Micro-optimization to avoid creating temporary path 

Now that path::operator/=(basic_string_view<value_type>) works directly
from the string argument, instead of constructing a temporary path from
the string, it's potentially more efficient to do 'path(x) /= s' instead
of 'x / s'. This changes the only relevant place in the library.

	* src/filesystem/std-dir.cc (filesystem::_Dir::advance): Append
	string to lvalue to avoid creating temporary path.

From-SVN: r267236
This commit is contained in:
Jonathan Wakely 2018-12-18 15:52:37 +00:00 committed by Jonathan Wakely
parent 36313a6bce
commit 8d53154813
2 changed files with 6 additions and 1 deletions
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3
libstdc++-v3/ChangeLog
View File

@ -1,5 +1,8 @@
2018-12-18 Jonathan Wakely <jwakely@redhat.com> 2018-12-18 Jonathan Wakely <jwakely@redhat.com>
* src/filesystem/std-dir.cc (filesystem::_Dir::advance): Append
string to lvalue to avoid creating temporary path.
* include/bits/fs_path.h (path::compare(const string_type&)) * include/bits/fs_path.h (path::compare(const string_type&))
(path::compare(const value_type*)): Add noexcept and construct a (path::compare(const value_type*)): Add noexcept and construct a
string view to compare to instead of a path. string view to compare to instead of a path.

4
libstdc++-v3/src/filesystem/std-dir.cc
View File

@ -61,7 +61,9 @@ struct fs::_Dir : _Dir_base
{ {
if (const auto entp = _Dir_base::advance(skip_permission_denied, ec)) if (const auto entp = _Dir_base::advance(skip_permission_denied, ec))
{ {
entry = fs::directory_entry{path / entp->d_name, get_file_type(*entp)}; auto name = path;
name /= entp->d_name;
entry = fs::directory_entry{name, get_file_type(*entp)};
return true; return true;
} }
else if (!ec) else if (!ec)