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mfem/tests/benchmarks/bench_virtuals.cpp
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// Copyright (c) 2010-2025, Lawrence Livermore National Security, LLC. Produced
// at the Lawrence Livermore National Laboratory. All Rights reserved. See files
// LICENSE and NOTICE for details. LLNL-CODE-806117.
//
// This file is part of the MFEM library. For more information and source code
// availability visit https://mfem.org.
//
// MFEM is free software; you can redistribute it and/or modify it under the
// terms of the BSD-3 license. We welcome feedback and contributions, see file
// CONTRIBUTING.md for details.
#include "bench.hpp"
#ifdef MFEM_USE_BENCHMARK
using namespace mfem;
// Default macro to register the tests
#define MFEM_VIRTUALS_BENCHMARK(x) BENCHMARK(x)->Arg(1);
// Base class, no virtuals
struct Base
{
void NoOperation()
{
int unused;
benchmark::DoNotOptimize(unused);
asm volatile("nop" : "=r" (unused));
}
};
static void Base(benchmark::State& state)
{
struct Base b;
for (auto _ : state) { b.NoOperation(); }
}
MFEM_VIRTUALS_BENCHMARK(Base);
// Base class, with virtuals
class Base_Virtuals
{
public:
virtual void NoOperation()
{
int unused;
benchmark::DoNotOptimize(unused);
asm volatile("nop" : "=r" (unused));
}
};
static void Base_Virtuals_inlined(benchmark::State& state)
{
// it will be resolved at compile time, so it can be inlined
Base_Virtuals b;
for (auto _ : state) { b.NoOperation(); }
}
MFEM_VIRTUALS_BENCHMARK(Base_Virtuals_inlined);
// Base derived class, with virtuals
class Base_Virtuals_Derived: public Base_Virtuals
{
public:
void NoOperation()
{
int unused;
benchmark::DoNotOptimize(unused);
asm volatile("nop" : "=r" (unused));
}
};
static void Base_Virtuals_Derived_not_inlined(benchmark::State& state)
{
// cannot be inlined through the pointer
Base_Virtuals *ptr = new Base_Virtuals_Derived();
for (auto _ : state) { ptr->NoOperation(); }
}
MFEM_VIRTUALS_BENCHMARK(Base_Virtuals_Derived_not_inlined);
// --benchmark_filter=all
int main(int argc, char *argv[])
{
mfem::Reporter mfem_reporter;
::benchmark::Initialize(&argc, argv);
if (::benchmark::ReportUnrecognizedArguments(argc, argv)) { return 1; }
::benchmark::RunSpecifiedBenchmarks(&mfem_reporter);
return 0;
}
#endif // MFEM_USE_BENCHMARK