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, c++11, c++14, c++17
10
11#include <algorithm>
12#include <cstddef>
13#include <deque>
14#include <iterator>
15#include <list>
16#include <string>
17#include <vector>
18
19#include "benchmark/benchmark.h"
20#include "../../GenerateInput.h"
21#include "test_macros.h"
22
23int main(int argc, char** argv) {
24 auto std_copy_n = [](auto first, auto n, auto out) { return std::copy_n(first, n, out); };
25
26 // {std,ranges}::copy_n(normal container)
27 {
28 auto bm = []<class Container>(std::string name, auto copy_n) {
29 benchmark::RegisterBenchmark(name, [copy_n](auto& st) {
30 std::size_t const n = st.range(0);
31 using ValueType = typename Container::value_type;
32 Container c;
33 std::generate_n(std::back_inserter(c), n, [] { return Generate<ValueType>::random(); });
34
35 std::vector<ValueType> out(n);
36
37 for ([[maybe_unused]] auto _ : st) {
38 benchmark::DoNotOptimize(c);
39 benchmark::DoNotOptimize(out);
40 auto result = copy_n(c.begin(), n, out.begin());
41 benchmark::DoNotOptimize(result);
42 }
43 })->Range(8, 1 << 20);
44 };
45 bm.operator()<std::vector<int>>("std::copy_n(vector<int>)", std_copy_n);
46 bm.operator()<std::deque<int>>("std::copy_n(deque<int>)", std_copy_n);
47 bm.operator()<std::list<int>>("std::copy_n(list<int>)", std_copy_n);
48 bm.operator()<std::vector<int>>("rng::copy_n(vector<int>)", std::ranges::copy_n);
49 bm.operator()<std::deque<int>>("rng::copy_n(deque<int>)", std::ranges::copy_n);
50 bm.operator()<std::list<int>>("rng::copy_n(list<int>)", std::ranges::copy_n);
51 }
52
53 // {std,ranges}::copy_n(vector<bool>)
54 {
55 auto bm = []<bool Aligned>(std::string name, auto copy_n) {
56 benchmark::RegisterBenchmark(name, [copy_n](auto& st) {
57 std::size_t const n = st.range(0);
58 std::vector<bool> in(n, true);
59 std::vector<bool> out(Aligned ? n : n + 8);
60 auto first = in.begin();
61 auto dst = Aligned ? out.begin() : out.begin() + 4;
62 for ([[maybe_unused]] auto _ : st) {
63 benchmark::DoNotOptimize(in);
64 benchmark::DoNotOptimize(out);
65 auto result = copy_n(first, n, dst);
66 benchmark::DoNotOptimize(result);
67 }
68 })->Range(64, 1 << 20);
69 };
70 bm.operator()<true>("std::copy_n(vector<bool>) (aligned)", std_copy_n);
71 bm.operator()<false>("std::copy_n(vector<bool>) (unaligned)", std_copy_n);
72#if TEST_STD_VER >= 23 // vector<bool>::iterator is not an output_iterator before C++23
73 bm.operator()<true>("rng::copy_n(vector<bool>) (aligned)", std::ranges::copy_n);
74 bm.operator()<false>("rng::copy_n(vector<bool>) (unaligned)", std::ranges::copy_n);
75#endif
76 }
77
78 benchmark::Initialize(&argc, argv);
79 benchmark::RunSpecifiedBenchmarks();
80 benchmark::Shutdown();
81 return 0;
82}
83

source code of libcxx/test/benchmarks/algorithms/modifying/copy_n.bench.cpp