spot/spot/misc/fixpool.cc
Maximilien Colange c9131aee72 add a pool allocator for STL containers
* spot/priv/allocator.hh, spot/priv/Makefile.am: add a STL-compliant
  allocator based on spot::fixed_size_pool
* spot/misc/fixpool.hh, spot/misc/fixpool.cc, spot/misc/Makefile.am:
  refactor the existing spot::fixed_size_pool
* spot/ltsmin/ltsmin.cc, spot/twa/twaproduct.cc: reflect changes in the
  interface of spot::fixed_size_pool
* tests/core/mempool.cc: test the new allocator
2018-06-20 14:26:45 +02:00

112 lines
2.7 KiB
C++

// -*- coding: utf-8 -*-
// Copyright (C) 2017-2018 Laboratoire de Recherche et
// Développement de l'Epita (LRDE)
//
// This file is part of Spot, a model checking library.
//
// Spot 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 of the License, or
// (at your option) any later version.
//
// Spot 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 program. If not, see <http://www.gnu.org/licenses/>.
#include "config.h"
#include <spot/misc/fixpool.hh>
#include <climits>
#include <cstddef>
namespace spot
{
namespace
{
// use gcc and clang built-in functions
// both compilers use the same function names, and define __GNUC__
#if __GNUC__
template<class T>
struct _clz;
template<>
struct _clz<unsigned>
{
unsigned
operator()(unsigned n) const noexcept
{
return __builtin_clz(n);
}
};
template<>
struct _clz<unsigned long>
{
unsigned long
operator()(unsigned long n) const noexcept
{
return __builtin_clzl(n);
}
};
template<>
struct _clz<unsigned long long>
{
unsigned long long
operator()(unsigned long long n) const noexcept
{
return __builtin_clzll(n);
}
};
static
size_t
clz(size_t n)
{
return _clz<size_t>()(n);
}
#else
size_t
clz(size_t n)
{
size_t res = CHAR_BIT*sizeof(size_t);
while (n)
{
--res;
n >>= 1;
}
return res;
}
#endif
}
fixed_size_pool::fixed_size_pool(size_t size)
: size_(
[](size_t size)
{
// to properly store chunks and freelist, we need size to be at
// least the size of a block_
if (size < sizeof(block_))
size = sizeof(block_);
// powers of 2 are a good alignment
if (!(size & (size-1)))
return size;
// small numbers are best aligned to the next power of 2
else if (size < alignof(std::max_align_t))
return size_t{1} << (CHAR_BIT*sizeof(size_t) - clz(size));
else
{
size_t mask = alignof(std::max_align_t)-1;
return (size + mask) & ~mask;
}
}(size)),
freelist_(nullptr), free_start_(nullptr),
free_end_(nullptr), chunklist_(nullptr)
{}
}