gcc/libstdc++-v3/include/ext/vstring_util.h
Paolo Carlini fa9d7d3b70 re PR libstdc++/44413 (inefficient code for std::string::compare on x86-64)
2010-06-09  Paolo Carlini  <paolo.carlini@oracle.com>

	PR libstdc++/44413
	* include/ext/vstring_util.h (__vstring_utility<>::_S_compare):
	Simplify, just return -1, 0, 1.

From-SVN: r160456
2010-06-09 09:15:51 +00:00

176 lines
5.5 KiB
C++

// Versatile string utility -*- C++ -*-
// Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010
// 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.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file ext/vstring_util.h
* This file is a GNU extension to the Standard C++ Library.
* This is an internal header file, included by other library headers.
* You should not attempt to use it directly.
*/
#ifndef _VSTRING_UTIL_H
#define _VSTRING_UTIL_H 1
#pragma GCC system_header
#include <ext/vstring_fwd.h>
#include <debug/debug.h>
#include <bits/stl_function.h> // For less
#include <bits/functexcept.h>
#include <bits/localefwd.h>
#include <bits/ostream_insert.h>
#include <bits/stl_iterator.h>
#include <ext/numeric_traits.h>
#include <bits/move.h>
_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
template<typename _CharT, typename _Traits, typename _Alloc>
struct __vstring_utility
{
typedef typename _Alloc::template rebind<_CharT>::other _CharT_alloc_type;
typedef _Traits traits_type;
typedef typename _Traits::char_type value_type;
typedef typename _CharT_alloc_type::size_type size_type;
typedef typename _CharT_alloc_type::difference_type difference_type;
typedef typename _CharT_alloc_type::pointer pointer;
typedef typename _CharT_alloc_type::const_pointer const_pointer;
// For __sso_string.
typedef __gnu_cxx::
__normal_iterator<pointer, __gnu_cxx::
__versa_string<_CharT, _Traits, _Alloc,
__sso_string_base> >
__sso_iterator;
typedef __gnu_cxx::
__normal_iterator<const_pointer, __gnu_cxx::
__versa_string<_CharT, _Traits, _Alloc,
__sso_string_base> >
__const_sso_iterator;
// For __rc_string.
typedef __gnu_cxx::
__normal_iterator<pointer, __gnu_cxx::
__versa_string<_CharT, _Traits, _Alloc,
__rc_string_base> >
__rc_iterator;
typedef __gnu_cxx::
__normal_iterator<const_pointer, __gnu_cxx::
__versa_string<_CharT, _Traits, _Alloc,
__rc_string_base> >
__const_rc_iterator;
// NB: When the allocator is empty, deriving from it saves space
// (http://www.cantrip.org/emptyopt.html).
template<typename _Alloc1>
struct _Alloc_hider
: public _Alloc1
{
_Alloc_hider(_CharT* __ptr)
: _Alloc1(), _M_p(__ptr) { }
_Alloc_hider(const _Alloc1& __a, _CharT* __ptr)
: _Alloc1(__a), _M_p(__ptr) { }
_CharT* _M_p; // The actual data.
};
// When __n = 1 way faster than the general multichar
// traits_type::copy/move/assign.
static void
_S_copy(_CharT* __d, const _CharT* __s, size_type __n)
{
if (__n == 1)
traits_type::assign(*__d, *__s);
else
traits_type::copy(__d, __s, __n);
}
static void
_S_move(_CharT* __d, const _CharT* __s, size_type __n)
{
if (__n == 1)
traits_type::assign(*__d, *__s);
else
traits_type::move(__d, __s, __n);
}
static void
_S_assign(_CharT* __d, size_type __n, _CharT __c)
{
if (__n == 1)
traits_type::assign(*__d, __c);
else
traits_type::assign(__d, __n, __c);
}
// _S_copy_chars is a separate template to permit specialization
// to optimize for the common case of pointers as iterators.
template<typename _Iterator>
static void
_S_copy_chars(_CharT* __p, _Iterator __k1, _Iterator __k2)
{
for (; __k1 != __k2; ++__k1, ++__p)
traits_type::assign(*__p, *__k1); // These types are off.
}
static void
_S_copy_chars(_CharT* __p, __sso_iterator __k1, __sso_iterator __k2)
{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
static void
_S_copy_chars(_CharT* __p, __const_sso_iterator __k1,
__const_sso_iterator __k2)
{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
static void
_S_copy_chars(_CharT* __p, __rc_iterator __k1, __rc_iterator __k2)
{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
static void
_S_copy_chars(_CharT* __p, __const_rc_iterator __k1,
__const_rc_iterator __k2)
{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
static void
_S_copy_chars(_CharT* __p, _CharT* __k1, _CharT* __k2)
{ _S_copy(__p, __k1, __k2 - __k1); }
static void
_S_copy_chars(_CharT* __p, const _CharT* __k1, const _CharT* __k2)
{ _S_copy(__p, __k1, __k2 - __k1); }
static int
_S_compare(size_type __n1, size_type __n2)
{
const difference_type __d = __n1 - __n2;
return __d == 0 ? 0 : (__d > 0 ? 1 : -1);
}
};
_GLIBCXX_END_NAMESPACE
#endif /* _VSTRING_UTIL_H */