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_backward = [](auto first, auto last, auto out) { return std::copy_backward(first, last, out); };
25
26 // {std,ranges}::copy_n(normal container)
27 {
28 auto bm = []<class Container>(std::string name, auto copy_backward) {
29 benchmark::RegisterBenchmark(name, [copy_backward](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_backward(c.begin(), c.end(), out.end());
41 benchmark::DoNotOptimize(result);
42 }
43 })->Range(8, 1 << 20);
44 };
45 bm.operator()<std::vector<int>>("std::copy_backward(vector<int>)", std_copy_backward);
46 bm.operator()<std::deque<int>>("std::copy_backward(deque<int>)", std_copy_backward);
47 bm.operator()<std::list<int>>("std::copy_backward(list<int>)", std_copy_backward);
48 bm.operator()<std::vector<int>>("rng::copy_backward(vector<int>)", std::ranges::copy_backward);
49 bm.operator()<std::deque<int>>("rng::copy_backward(deque<int>)", std::ranges::copy_backward);
50 bm.operator()<std::list<int>>("rng::copy_backward(list<int>)", std::ranges::copy_backward);
51 }
52
53 // {std,ranges}::copy_n(vector<bool>)
54 {
55 auto bm = []<bool Aligned>(std::string name, auto copy_backward) {
56 benchmark::RegisterBenchmark(name, [copy_backward](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 benchmark::DoNotOptimize(&in);
61 auto first = in.begin();
62 auto last = in.end();
63 auto dst = Aligned ? out.end() : out.end() - 4;
64 for ([[maybe_unused]] auto _ : st) {
65 benchmark::DoNotOptimize(in);
66 benchmark::DoNotOptimize(out);
67 auto result = copy_backward(first, last, dst);
68 benchmark::DoNotOptimize(result);
69 }
70 })->Range(64, 1 << 20);
71 };
72 bm.operator()<true>("std::copy_backward(vector<bool>) (aligned)", std_copy_backward);
73 bm.operator()<false>("std::copy_backward(vector<bool>) (unaligned)", std_copy_backward);
74#if TEST_STD_VER >= 23 // vector<bool>::iterator is not an output_iterator before C++23
75 bm.operator()<true>("rng::copy_backward(vector<bool>) (aligned)", std::ranges::copy_backward);
76 bm.operator()<false>("rng::copy_backward(vector<bool>) (unaligned)", std::ranges::copy_backward);
77#endif
78 }
79
80 benchmark::Initialize(&argc, argv);
81 benchmark::RunSpecifiedBenchmarks();
82 benchmark::Shutdown();
83 return 0;
84}
85

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