1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef BENCHMARK_VARIANT_BENCHMARKS_H
11#define BENCHMARK_VARIANT_BENCHMARKS_H
12
13#include <array>
14#include <cstddef>
15#include <tuple>
16#include <type_traits>
17#include <variant>
18
19#include "benchmark/benchmark.h"
20
21#include "GenerateInput.h"
22
23namespace VariantBenchmarks {
24
25template <std::size_t I>
26struct S {
27 static constexpr size_t v = I;
28};
29
30template <std::size_t N, std::size_t... Is>
31static auto genVariants(std::index_sequence<Is...>) {
32 using V = std::variant<S<Is>...>;
33 using F = V (*)();
34 static constexpr F fs[] = {[] { return V(std::in_place_index<Is>); }...};
35
36 std::array<V, N> result = {};
37 for (auto& v : result) {
38 v = fs[getRandomInteger(Min: 0ul, Max: sizeof...(Is) - 1)]();
39 }
40
41 return result;
42}
43
44template <std::size_t N, std::size_t Alts>
45static void BM_Visit(benchmark::State& state) {
46 auto args = genVariants<N>(std::make_index_sequence<Alts>{});
47 for (auto _ : state) {
48 benchmark::DoNotOptimize(
49 std::apply([](auto... vs) { return std::visit([](auto... is) { return (is.v + ... + 0); }, vs...); }, args));
50 }
51}
52
53} // end namespace VariantBenchmarks
54
55#endif // BENCHMARK_VARIANT_BENCHMARKS_H
56

source code of libcxx/benchmarks/VariantBenchmarks.h