410754410f
This patch adds benchmarks for std::partition, is_partitioned, etc and their ranges:: variants.
97 lines
4.1 KiB
C++
97 lines
4.1 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17
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#include <algorithm>
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#include <cassert>
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#include <cstddef>
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#include <deque>
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#include <iterator>
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#include <list>
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#include <string>
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#include <vector>
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#include "benchmark/benchmark.h"
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#include "../../GenerateInput.h"
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auto compute_median(auto first, auto last) {
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std::vector v(first, last);
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auto middle = v.begin() + v.size() / 2;
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std::nth_element(v.begin(), middle, v.end());
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return *middle;
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}
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int main(int argc, char** argv) {
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auto std_is_partitioned = [](auto first, auto last, auto pred) { return std::is_partitioned(first, last, pred); };
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auto bm = []<class Container, bool Partitioned>(std::string name, auto is_partitioned) {
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benchmark::RegisterBenchmark(
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name,
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[is_partitioned](auto& st) {
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std::size_t const size = st.range(0);
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using ValueType = typename Container::value_type;
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Container c;
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std::generate_n(std::back_inserter(c), size, [] { return Generate<ValueType>::random(); });
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// Partition the container in two equally-sized halves, ensuring the median
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// value appears in the left half. Note that the median value isn't located
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// in the middle -- this isn't std::nth_element.
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ValueType median = compute_median(c.begin(), c.end());
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auto pred = [median](auto const& element) { return element <= median; };
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std::partition(c.begin(), c.end(), pred);
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assert(std::is_partitioned(c.begin(), c.end(), pred));
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if constexpr (!Partitioned) {
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// De-partition the container by swapping the element containing the median
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// value with the last one.
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auto median_it = std::find(c.begin(), c.end(), median);
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auto last_it = std::next(c.begin(), c.size() - 1);
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std::iter_swap(median_it, last_it);
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assert(!std::is_partitioned(c.begin(), c.end(), pred));
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}
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for ([[maybe_unused]] auto _ : st) {
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benchmark::DoNotOptimize(c);
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auto result = is_partitioned(c.begin(), c.end(), pred);
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benchmark::DoNotOptimize(result);
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}
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})
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->Arg(32)
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->Arg(50) // non power-of-two
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->Arg(1024)
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->Arg(8192);
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};
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// std::is_partitioned
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bm.operator()<std::vector<int>, true>("std::is_partitioned(vector<int>) (partitioned)", std_is_partitioned);
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bm.operator()<std::vector<int>, false>("std::is_partitioned(vector<int>) (unpartitioned)", std_is_partitioned);
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bm.operator()<std::deque<int>, true>("std::is_partitioned(deque<int>) (partitioned)", std_is_partitioned);
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bm.operator()<std::deque<int>, false>("std::is_partitioned(deque<int>) (unpartitioned)", std_is_partitioned);
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bm.operator()<std::list<int>, true>("std::is_partitioned(list<int>) (partitioned)", std_is_partitioned);
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bm.operator()<std::list<int>, false>("std::is_partitioned(list<int>) (unpartitioned)", std_is_partitioned);
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// ranges::is_partitioned
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bm.operator()<std::vector<int>, true>("rng::is_partitioned(vector<int>) (partitioned)", std::ranges::is_partitioned);
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bm.operator()<std::vector<int>, false>(
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"rng::is_partitioned(vector<int>) (unpartitioned)", std::ranges::is_partitioned);
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bm.operator()<std::deque<int>, true>("rng::is_partitioned(deque<int>) (partitioned)", std::ranges::is_partitioned);
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bm.operator()<std::deque<int>, false>("rng::is_partitioned(deque<int>) (unpartitioned)", std::ranges::is_partitioned);
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bm.operator()<std::list<int>, true>("rng::is_partitioned(list<int>) (partitioned)", std::ranges::is_partitioned);
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bm.operator()<std::list<int>, false>("rng::is_partitioned(list<int>) (unpartitioned)", std::ranges::is_partitioned);
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benchmark::Initialize(&argc, argv);
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benchmark::RunSpecifiedBenchmarks();
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benchmark::Shutdown();
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return 0;
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}
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