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PR libstdc++/90634 reduce allocations in filesystem::path construction

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PR libstdc++/90634
	* include/experimental/bits/fs_path.h (path::path(path&&)): Only call
	_M_split_cmpts() for a path with multiple components.
	(path::_S_is_dir_sep()): Add missing 'static' keyword to function.
	* src/filesystem/path.cc (path::_M_split_cmpts()): Count number of
	components and reserve space in vector. Return early when there is
	only one component.
	* testsuite/27_io/filesystem/path/construct/90634.cc: New test.
	* testsuite/experimental/filesystem/path/construct/90634.cc: New test.

From-SVN: r271717
This commit is contained in:
Jonathan Wakely 2019-05-28 20:39:48 +01:00 • committed by Jonathan Wakely
parent d9b401df8f
commit 441ed45ca2
5 changed files with 215 additions and 4 deletions
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10
libstdc++-v3/ChangeLog
View file

@ -1,5 +1,15 @@
2019-05-28 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/90634
* include/experimental/bits/fs_path.h (path::path(path&&)): Only call
_M_split_cmpts() for a path with multiple components.
(path::_S_is_dir_sep()): Add missing 'static' keyword to function.
* src/filesystem/path.cc (path::_M_split_cmpts()): Count number of
components and reserve space in vector. Return early when there is
only one component.
* testsuite/27_io/filesystem/path/construct/90634.cc: New test.
* testsuite/experimental/filesystem/path/construct/90634.cc: New test.
* testsuite/util/testsuite_fs.h (compare_paths): Use three-argument
form of std::equals for C++11 compatibility.

5
libstdc++-v3/include/experimental/bits/fs_path.h
View file

@ -195,7 +195,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
path(path&& __p) noexcept
: _M_pathname(std::move(__p._M_pathname)), _M_type(__p._M_type)
{
_M_split_cmpts();
if (_M_type == _Type::_Multi)
_M_split_cmpts();
__p.clear();
}
@ -490,7 +491,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
return _S_convert_loc(__s.data(), __s.data() + __s.size(), __loc);
}
bool _S_is_dir_sep(value_type __ch)
static bool _S_is_dir_sep(value_type __ch)
{
#ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS
return __ch == L'/' || __ch == preferred_separator;

51
libstdc++-v3/src/filesystem/path.cc
View file

@ -340,6 +340,28 @@ path::_M_split_cmpts()
if (_M_pathname.empty())
return;
{
// Approximate count of components, to reserve space in _M_cmpts vector:
int count = 1;
bool saw_sep_last = _S_is_dir_sep(_M_pathname[0]);
bool saw_non_sep = !saw_sep_last;
for (value_type c : _M_pathname)
{
if (_S_is_dir_sep(c))
saw_sep_last = true;
else if (saw_sep_last)
{
++count;
saw_sep_last = false;
saw_non_sep = true;
}
}
if (saw_non_sep && saw_sep_last)
++count; // empty filename after trailing slash
if (count > 1)
_M_cmpts.reserve(count);
}
size_t pos = 0;
const size_t len = _M_pathname.size();
@ -362,9 +384,13 @@ path::_M_split_cmpts()
pos = 3;
while (pos < len && !_S_is_dir_sep(_M_pathname[pos]))
++pos;
if (pos == len)
{
_M_type = _Type::_Root_name;
return;
}
_M_add_root_name(pos);
if (pos < len) // also got root directory
_M_add_root_dir(pos);
_M_add_root_dir(pos);
}
else
{
@ -373,6 +399,11 @@ path::_M_split_cmpts()
_M_add_root_dir(0);
}
}
else if (len == 1) // got root directory only
{
_M_type = _Type::_Root_dir;
return;
}
else // got root directory
_M_add_root_dir(0);
++pos;
@ -381,12 +412,28 @@ path::_M_split_cmpts()
else if (len > 1 && _M_pathname[1] == L':')
{
// got disk designator
if (len == 2)
{
_M_type = _Type::_Root_name;
return;
}
_M_add_root_name(2);
if (len > 2 && _S_is_dir_sep(_M_pathname[2]))
_M_add_root_dir(2);
pos = 2;
}
#endif
else
{
size_t n = 1;
for (; n < _M_pathname.size() && !_S_is_dir_sep(_M_pathname[n]); ++n)
{ }
if (n == _M_pathname.size())
{
_M_type = _Type::_Filename;
return;
}
}
size_t back = pos;
while (pos < len)

78
libstdc++-v3/testsuite/27_io/filesystem/path/construct/90634.cc Normal file
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@ -0,0 +1,78 @@
// Copyright (C) 2019 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++17" }
// { dg-do run { target c++17 } }
#include <filesystem>
#include <cstdlib>
#include <testsuite_hooks.h>
std::size_t bytes_allocated = 0;
void* operator new(std::size_t n)
{
bytes_allocated += n;
return std::malloc(n);
}
void operator delete(void* p) noexcept { std::free(p); }
#if __cpp_sized_deallocation
void operator delete(void* p, std::size_t) noexcept { std::free(p); }
#endif
void
test01()
{
#ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS
std::wstring s0;
std::wstring s1 = L"/";
std::wstring s2 = L"///";
std::wstring s3 = L"file";
std::wstring s4 = L"C:";
std::wstring s5 = L"\\";
#else
std::string s0;
std::string s1 = "/";
std::string s2 = "///";
std::string s3 = "file";
std::string s4 = "C:";
std::string s5 = "\\";
#endif
using std::filesystem::path;
bytes_allocated = 0;
path p0 = std::move(s0);
VERIFY( bytes_allocated == 0 );
path p1 = std::move(s1);
VERIFY( bytes_allocated == 0 );
path p2 = std::move(s2);
VERIFY( bytes_allocated == 0 );
path p3 = std::move(s3);
VERIFY( bytes_allocated == 0 );
path p4 = std::move(s4);
VERIFY( bytes_allocated == 0 );
path p5 = std::move(s5);
VERIFY( bytes_allocated == 0 );
}
int
main()
{
test01();
}

75
libstdc++-v3/testsuite/experimental/filesystem/path/construct/90634.cc Normal file
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@ -0,0 +1,75 @@
// Copyright (C) 2019 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-DUSE_FILESYSTEM_TS -lstdc++fs" }
// { dg-do run { target c++11 } }
// { dg-require-filesystem-ts "" }
#include <experimental/filesystem>
#include <cstdlib>
#include <testsuite_hooks.h>
std::size_t bytes_allocated = 0;
void* operator new(std::size_t n)
{
bytes_allocated += n;
return std::malloc(n);
}
void operator delete(void* p) noexcept { std::free(p); }
#if __cpp_sized_deallocation
void operator delete(void* p, std::size_t) noexcept { std::free(p); }
#endif
void
test01()
{
#ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS
std::wstring s0;
std::wstring s1 = L"/";
std::wstring s2 = L"file";
std::wstring s3 = L"C:";
std::wstring s4 = L"\\";
#else
std::string s0;
std::string s1 = "/";
std::string s2 = "file";
std::string s3 = "C:";
std::string s4 = "\\";
#endif
using std::experimental::filesystem::path;
bytes_allocated = 0;
path p0 = std::move(s0);
VERIFY( bytes_allocated == 0 );
path p1 = std::move(s1);
VERIFY( bytes_allocated == 0 );
path p2 = std::move(s2);
VERIFY( bytes_allocated == 0 );
path p3 = std::move(s3);
VERIFY( bytes_allocated == 0 );
path p4 = std::move(s4);
VERIFY( bytes_allocated == 0 );
}
int
main()
{
test01();
}