llvm-project/libcxx/benchmarks/VariantBenchmarks.h

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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef BENCHMARK_VARIANT_BENCHMARKS_H
#define BENCHMARK_VARIANT_BENCHMARKS_H
#include <array>
#include <cstddef>
#include <tuple>
#include <type_traits>
#include <variant>
#include "benchmark/benchmark.h"
#include "GenerateInput.h"
namespace VariantBenchmarks {
template <std::size_t I>
struct S {
static constexpr size_t v = I;
};
template <std::size_t N, std::size_t... Is>
static auto genVariants(std::index_sequence<Is...>) {
using V = std::variant<S<Is>...>;
using F = V (*)();
static constexpr F fs[] = {[] { return V(std::in_place_index<Is>); }...};
std::array<V, N> result = {};
for (auto& v : result) {
v = fs[getRandomInteger(0ul, sizeof...(Is) - 1)]();
}
return result;
}
template <std::size_t N, std::size_t Alts>
static void BM_Visit(benchmark::State& state) {
auto args = genVariants<N>(std::make_index_sequence<Alts>{});
for (auto _ : state) {
benchmark::DoNotOptimize(std::apply(
[](auto... vs) {
return std::visit([](auto... is) { return (is.v + ... + 0); }, vs...);
},
args));
}
}
} // end namespace VariantBenchmarks
#endif // BENCHMARK_VARIANT_BENCHMARKS_H