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 
23 namespace VariantBenchmarks {
24 
25 template <std::size_t I>
26 struct S {
27   static constexpr size_t v = I;
28 };
29 
30 template <std::size_t N, std::size_t... Is>
genVariants(std::index_sequence<Is...>)31 static 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(0ul, sizeof...(Is) - 1)]();
39   }
40 
41   return result;
42 }
43 
44 template <std::size_t N, std::size_t Alts>
BM_Visit(benchmark::State & state)45 static void BM_Visit(benchmark::State& state) {
46   auto args = genVariants<N>(std::make_index_sequence<Alts>{});
47   for (auto _ : state) {
48     benchmark::DoNotOptimize(std::apply(
49         [](auto... vs) {
50           return std::visit([](auto... is) { return (is.v + ... + 0); }, vs...);
51         },
52         args));
53   }
54 }
55 
56 } // end namespace VariantBenchmarks
57 
58 #endif // BENCHMARK_VARIANT_BENCHMARKS_H
59