75 lines · 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-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++1710 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 22auto compute_median(auto first, auto last) {23 std::vector v(first, last);24 auto middle = v.begin() + v.size() / 2;25 std::nth_element(v.begin(), middle, v.end());26 return *middle;27}28 29int main(int argc, char** argv) {30 auto std_partition_point = [](auto first, auto last, auto pred) { return std::partition_point(first, last, pred); };31 32 auto bm = []<class Container>(std::string name, auto partition_point) {33 benchmark::RegisterBenchmark(34 name,35 [partition_point](auto& st) {36 std::size_t const size = st.range(0);37 using ValueType = typename Container::value_type;38 Container c;39 std::generate_n(std::back_inserter(c), size, [] { return Generate<ValueType>::random(); });40 41 // Partition the container in two equally-sized halves. Based on experimentation, the running42 // time of the algorithm doesn't change much depending on the size of the halves.43 ValueType median = compute_median(c.begin(), c.end());44 auto pred = [median](auto const& element) { return element < median; };45 std::partition(c.begin(), c.end(), pred);46 assert(std::is_partitioned(c.begin(), c.end(), pred));47 48 for ([[maybe_unused]] auto _ : st) {49 benchmark::DoNotOptimize(c);50 auto result = partition_point(c.begin(), c.end(), pred);51 benchmark::DoNotOptimize(result);52 }53 })54 ->Arg(32)55 ->Arg(50) // non power-of-two56 ->Arg(1024)57 ->Arg(8192);58 };59 60 // std::partition_point61 bm.operator()<std::vector<int>>("std::partition_point(vector<int>)", std_partition_point);62 bm.operator()<std::deque<int>>("std::partition_point(deque<int>)", std_partition_point);63 bm.operator()<std::list<int>>("std::partition_point(list<int>)", std_partition_point);64 65 // ranges::partition_point66 bm.operator()<std::vector<int>>("rng::partition_point(vector<int>)", std::ranges::partition_point);67 bm.operator()<std::deque<int>>("rng::partition_point(deque<int>)", std::ranges::partition_point);68 bm.operator()<std::list<int>>("rng::partition_point(list<int>)", std::ranges::partition_point);69 70 benchmark::Initialize(&argc, argv);71 benchmark::RunSpecifiedBenchmarks();72 benchmark::Shutdown();73 return 0;74}75