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re PR libstdc++/54075 ([4.7.1] unordered_map insert still slower than 4.6.2) 

2012-07-29  François Dumont  <fdumont@gcc.gnu.org>

	PR libstdc++/54075
	* include/bits/hashtable_policy.h
	(_Prime_rehash_policy::_M_next_bkt): Add a growth factor set to 2
	to boost growth in the number of buckets.
	* testsuite/performance/23_containers/insert/unordered_set.cc: New.

From-SVN: r189938
This commit is contained in:
François Dumont 2012-07-29 16:44:18 +00:00
parent 231464b227
commit 78aa145d9e
3 changed files with 66 additions and 15 deletions
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8
libstdc++-v3/ChangeLog
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@ -1,3 +1,11 @@
2012-07-29 François Dumont <fdumont@gcc.gnu.org>
PR libstdc++/54075
* include/bits/hashtable_policy.h
(_Prime_rehash_policy::_M_next_bkt): Add a growth factor set to 2
to boost growth in the number of buckets.
* testsuite/performance/23_containers/insert/unordered_set.cc: New.
2012-07-25 François Dumont <fdumont@gcc.gnu.org>
PR libstdc++/54075

31
libstdc++-v3/include/bits/hashtable_policy.h
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@ -395,6 +395,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
enum { _S_n_primes = sizeof(unsigned long) != 8 ? 256 : 256 + 48 };
static const std::size_t _S_growth_factor = 2;
float _M_max_load_factor;
mutable std::size_t _M_prev_resize;
mutable std::size_t _M_next_resize;
@ -415,28 +417,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static const unsigned char __fast_bkt[12]
= { 2, 2, 2, 3, 5, 5, 7, 7, 11, 11, 11, 11 };
if (__n <= 11)
const std::size_t __grown_n = __n * _S_growth_factor;
if (__grown_n <= 11)
{
_M_prev_resize = 0;
_M_next_resize
= __builtin_ceil(__fast_bkt[__n] * (long double)_M_max_load_factor);
return __fast_bkt[__n];
= __builtin_ceil(__fast_bkt[__grown_n]
* (long double)_M_max_load_factor);
return __fast_bkt[__grown_n];
}
const unsigned long* __p
= std::lower_bound(__prime_list + 5, __prime_list + _S_n_primes, __n);
const unsigned long* __next_bkt
= std::lower_bound(__prime_list + 5, __prime_list + _S_n_primes,
__grown_n);
const unsigned long* __prev_bkt
= std::lower_bound(__prime_list + 1, __next_bkt, __n / _S_growth_factor);
// Shrink will take place only if the number of elements is small enough
// so that the prime number 2 steps before __p is large enough to still
// conform to the max load factor:
_M_prev_resize
= __builtin_floor(*(__p - 2) * (long double)_M_max_load_factor);
// Let's guaranty that a minimal grow step of 11 is used
if (*__p - __n < 11)
__p = std::lower_bound(__p, __prime_list + _S_n_primes, __n + 11);
_M_next_resize = __builtin_ceil(*__p * (long double)_M_max_load_factor);
return *__p;
= __builtin_floor(*(__prev_bkt - 1) * (long double)_M_max_load_factor);
_M_next_resize
= __builtin_ceil(*__next_bkt * (long double)_M_max_load_factor);
return *__next_bkt;
}
// Return the smallest prime p such that alpha p >= n, where alpha

42
libstdc++-v3/testsuite/performance/23_containers/insert/unordered_set.cc Normal file
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@ -0,0 +1,42 @@
// Copyright (C) 2012 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=c++11" }
#include <unordered_set>
#include <testsuite_performance.h>
int main()
{
using namespace __gnu_test;
time_counter time;
resource_counter resource;
const int sz = 10000000;
std::unordered_set<int> s;
start_counters(time, resource);
for (int i = 0; i != sz ; ++i)
s.insert(i);
stop_counters(time, resource);
report_performance(__FILE__, "unordered_set 10000000 insertions",
time, resource);
return 0;
}