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basic_string.tcc (_S_create): Use consistently the exponential policy, simplify.

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2004-10-13  Paolo Carlini  <pcarlini@suse.de>

	* include/bits/basic_string.tcc (_S_create): Use consistently
	the exponential policy, simplify.
	* testsuite/performance/21_strings/string_append_2.cc: New.

	* include/ext/array_allocator.h (allocate): Fix bad_alloc check.
	* testsuite/ext/array_allocator/2.cc: Fix wrt 64-bit archs (in
	that case sizeof(_Rep) == 24).

From-SVN: r88972
This commit is contained in:
Paolo Carlini 2004-10-13 08:58:41 +00:00 committed by Paolo Carlini
parent f76ccf602e
commit cbb0dcef12
5 changed files with 73 additions and 22 deletions
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10
libstdc++-v3/ChangeLog
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@ -1,3 +1,13 @@
2004-10-13 Paolo Carlini <pcarlini@suse.de>
* include/bits/basic_string.tcc (_S_create): Use consistently
the exponential policy, simplify.
* testsuite/performance/21_strings/string_append_2.cc: New.
* include/ext/array_allocator.h (allocate): Fix bad_alloc check.
* testsuite/ext/array_allocator/2.cc: Fix wrt 64-bit archs (in
that case sizeof(_Rep) == 24).
2004-10-12 Paolo Carlini <pcarlini@suse.de>
PR libstdc++/17948

20
libstdc++-v3/include/bits/basic_string.tcc
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@ -503,9 +503,8 @@ namespace std
// low-balling it (especially when this algorithm is used with
// malloc implementations that allocate memory blocks rounded up
// to a size which is a power of 2).
const size_type __pagesize = 4096; // must be 2^i * __subpagesize
const size_type __subpagesize = 128; // should be >> __malloc_header_size
const size_type __malloc_header_size = 4 * sizeof (void*);
const size_type __pagesize = 4096;
const size_type __malloc_header_size = 4 * sizeof(void*);
// The below implements an exponential growth policy, necessary to
// meet amortized linear time requirements of the library: see
@ -513,14 +512,7 @@ namespace std
// It's active for allocations requiring an amount of memory above
// system pagesize. This is consistent with the requirements of the
// standard: http://gcc.gnu.org/ml/libstdc++/2001-07/msg00130.html
// The biggest string which fits in a memory page
const size_type __page_capacity = ((__pagesize - __malloc_header_size
- sizeof(_Rep) - sizeof(_CharT))
/ sizeof(_CharT));
if (__capacity > __old_capacity && __capacity < 2 * __old_capacity
&& __capacity > __page_capacity)
if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
__capacity = 2 * __old_capacity;
// NB: Need an array of char_type[__capacity], plus a terminating
@ -538,12 +530,6 @@ namespace std
__capacity = _S_max_size;
__size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);
}
else if (__size > __subpagesize)
{
const size_type __extra = __subpagesize - __adj_size % __subpagesize;
__capacity += __extra / sizeof(_CharT);
__size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);
}
// NB: Might throw, but no worries about a leak, mate: _Rep()
// does not throw.

8
libstdc++-v3/include/ext/array_allocator.h
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@ -116,11 +116,11 @@ namespace __gnu_cxx
pointer
allocate(size_type __n, const void* = 0)
{
static size_type used;
if (__builtin_expect(used > array_type::_S_index, false))
static size_type __used;
if (__builtin_expect(__used + __n > array_type::_S_index, false))
throw std::bad_alloc();
pointer __ret = _M_array->begin() + used;
used += __n;
pointer __ret = _M_array->begin() + __used;
__used += __n;
return __ret;
}
};

2
libstdc++-v3/testsuite/ext/array_allocator/2.cc
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@ -32,7 +32,7 @@
typedef char char_type;
typedef std::char_traits<char_type> traits_type;
typedef std::tr1::array<char_type, 17> array_type;
typedef std::tr1::array<char_type, 32> array_type;
array_type extern_array;

55
libstdc++-v3/testsuite/performance/21_strings/string_append_2.cc Normal file
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@ -0,0 +1,55 @@
// Copyright (C) 2004 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 2, 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 COPYING. If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
#include <string>
#include <testsuite_performance.h>
// Short strings didn't grow quickly...
void test01()
{
using namespace __gnu_test;
time_counter time;
resource_counter resource;
start_counters(time, resource);
for (unsigned i = 0; i < 200000; ++i)
{
std::string a;
for (unsigned j = 0; j < 400; ++j)
a.append(1, 'x');
}
stop_counters(time, resource);
report_performance(__FILE__, "", time, resource);
clear_counters(time, resource);
}
int main()
{
test01();
return 0;
}