libstdc++-v3/testsuite/performance/26_numerics/random_dist.cc

   1 // Copyright (C) 2020-2022 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18
  19 #include <random>
  20 #include <testsuite_performance.h>
  21
  22 namespace counters
  23 {
  24   __gnu_test::time_counter time;
  25   __gnu_test::resource_counter resource;
  26 }
  27
  28
  29 template<typename Dist, typename Engine>
  30 void do_fill_with_uniform_ints(std::string name, Dist& d, Engine& e)
  31 {
  32   using counters::time;
  33   using counters::resource;
  34
  35   std::vector<typename Dist::result_type> r;
  36   int n = 10000000;
  37   {
  38     const auto suffix = "-e" + std::to_string((int)std::log10(n));
  39     r.resize(n);
  40
  41     start_counters(time, resource);
  42     for (auto& x : r)
  43       x = d(e);
  44     stop_counters(time, resource);
  45     report_performance(__FILE__, name+suffix, time, resource);
  46     clear_counters(time, resource);
  47
  48     d.reset();
  49
  50     start_counters(time, resource);
  51     d.__generate(begin(r), end(r), e);
  52     stop_counters(time, resource);
  53     report_performance(__FILE__, name+"-range"+suffix, time, resource);
  54     clear_counters(time, resource);
  55   }
  56 }
  57
  58 template<typename Engine>
  59 void fill_with_uniform_ints(std::string name, Engine& e)
  60 {
  61   using Dist = std::uniform_int_distribution<typename Engine::result_type>;
  62   using param_type = typename Dist::param_type;
  63
  64   unsigned maxima[]{6, 10, 32, 100, 1000, 1024, (1<<16)-1, 1<<16, 1<<20, -1u};
  65   for (auto hi : maxima)
  66   {
  67     Dist dist(param_type{0, hi});
  68     std::ostringstream s;
  69     s << name << "-uniform_int-" << (dist.max() - dist.min());
  70     do_fill_with_uniform_ints(s.str(), dist, e);
  71   }
  72 }
  73
  74 int main()
  75 {
  76   using namespace std;
  77
  78   std::mt19937 mt;
  79   fill_with_uniform_ints("mt19937", mt);
  80   std::mt19937_64 mt64;
  81   fill_with_uniform_ints("mt19937_64", mt64);
  82
  83   // Same as std::mt19937 but using uint32_t not uint_fast32_t for result_type
  84   using mt19937_32 = std::mersenne_twister_engine<uint32_t, 32, 624, 397, 31,
  85                                                   0x9908b0df, 11, 0xffffffff,
  86                                                   7, 0x9d2c5680, 15,
  87                                                   0xefc60000, 18, 1812433253>;
  88   mt19937_32 mt32;
  89   fill_with_uniform_ints("mt19937_32", mt32);
  90
  91   std::minstd_rand0 lcg;
  92   fill_with_uniform_ints("minstd_rand0", lcg);
  93
  94   // Same as std::minstd_rand0 but using uint32_t not uint_fast32_t
  95   using minstd_rand0_32 = std::linear_congruential_engine<uint32_t, 48271, 0,
  96                                                           2147483647>;
  97   minstd_rand0_32 lcg_32;
  98   fill_with_uniform_ints("minstd_rand0_32", lcg_32);
  99
 100   return 0;
 101 }
 102