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//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include <cassert>
#include <cstddef>
#include <utility>
#include "benchmark/benchmark.h"
template <std::size_t Indx, std::size_t Depth>
struct C : public virtual C<Indx, Depth - 1>, public virtual C<Indx + 1, Depth - 1> {
virtual ~C() {}
};
template <std::size_t Indx>
struct C<Indx, 0> {
virtual ~C() {}
};
template <std::size_t Indx, std::size_t Depth>
struct B : public virtual C<Indx, Depth - 1>, public virtual C<Indx + 1, Depth - 1> {};
template <class Indx, std::size_t Depth>
struct makeB;
template <std::size_t... Indx, std::size_t Depth>
struct makeB<std::index_sequence<Indx...>, Depth> : public B<Indx, Depth>... {};
template <std::size_t Width, std::size_t Depth>
struct A : public makeB<std::make_index_sequence<Width>, Depth> {};
constexpr std::size_t Width = 10;
constexpr std::size_t Depth = 5;
template <typename Destination>
void CastTo(benchmark::State& state) {
A<Width, Depth> a;
auto base = static_cast<C<Width / 2, 0>*>(&a);
Destination* b = nullptr;
for (auto _ : state) {
b = dynamic_cast<Destination*>(base);
benchmark::DoNotOptimize(b);
}
assert(b != 0);
}
BENCHMARK(CastTo<B<Width / 2, Depth>>);
BENCHMARK(CastTo<A<Width, Depth>>);
BENCHMARK_MAIN();
/**
* Benchmark results: (release builds)
*
* libcxxabi:
* ----------------------------------------------------------------------
* Benchmark Time CPU Iterations
* ----------------------------------------------------------------------
* CastTo<B<Width / 2, Depth>> 1997 ns 1997 ns 349247
* CastTo<A<Width, Depth>> 256 ns 256 ns 2733871
*
* libsupc++:
* ----------------------------------------------------------------------
* Benchmark Time CPU Iterations
* ----------------------------------------------------------------------
* CastTo<B<Width / 2, Depth>> 5240 ns 5240 ns 133091
* CastTo<A<Width, Depth>> 866 ns 866 ns 808600
*
*
*/
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