libcxx/test/benchmarks/random.bench.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03
  10
  11 #include <algorithm>
  12 #include <array>
  13 #include <cstddef>
  14 #include <cstdint>
  15 #include <functional>
  16 #include <random>
  17
  18 #include "benchmark/benchmark.h"
  19
  20 constexpr std::size_t MAX_BUFFER_LEN = 256;
  21 constexpr std::size_t MAX_SEED_LEN   = 16;
  22
  23 static void BM_SeedSeq_Generate(benchmark::State& state) {
  24   std::array<std::uint32_t, MAX_BUFFER_LEN> buffer;
  25   std::array<std::uint32_t, MAX_SEED_LEN> seeds;
  26   {
  27     std::random_device rd;
  28     std::generate(std::begin(seeds), std::begin(seeds) + state.range(0), [&]() { return rd(); });
  29   }
  30   std::seed_seq seed(std::begin(seeds), std::begin(seeds) + state.range(0));
  31   for (auto _ : state) {
  32     seed.generate(std::begin(buffer), std::begin(buffer) + state.range(1));
  33   }
  34 }
  35 BENCHMARK(BM_SeedSeq_Generate)->Ranges({{1, MAX_SEED_LEN}, {1, MAX_BUFFER_LEN}});
  36
  37 BENCHMARK_MAIN();