c++11 direct function call, virtual function call, functor and std::function(using a lambda) performance test

functionperformance.cpp

#include <iostream>
#include <chrono>
#include <memory>
#include <functional>

using namespace std;
using namespace std::chrono;

class Base
{
public:
	Base(){}
	virtual ~Base(){}
	virtual int func(int i) = 0;
};

class Derived : public Base
{
public:
	Derived(int base = 10) : base{base}
	{

	}
	~Derived(){}

	virtual int func(int i)
	{
		return i*base;
	}
private:
	int base;
};

struct Func
{
	int base;
	int operator()(int i)
	{
		return i*base;
	}
	Func(int base) : base {base}
	{

	}
};
const int base = 10;
int calculate(int i)
{
	return base*i;
}

int main()
{
	const int num = 10000;
	Base *p = new Derived{10};
	int total = 0;
	auto start = high_resolution_clock::now();
	for (int i = 0; i < num; ++i)
	{
		total += p->func(i);
	}
	auto end = high_resolution_clock::now();
	std::cout<<"result: "<<total<<"\nvirtual call elapsed: \t"<<duration_cast<nanoseconds>(end-start).count()<<" nanoseconds.\n"<<std::endl;

	total = 0;
	start = high_resolution_clock::now();
	for (int i = 0; i < num; ++i)
	{
		total += calculate(i);
	}
	end = high_resolution_clock::now();
	std::cout<<"result: "<<total<<"\ndirect function call elapsed: \t"<<duration_cast<nanoseconds>(end-start).count()<<" nanoseconds.\n"<<std::endl;

	Func functor{10};
	total = 0;
	start = high_resolution_clock::now();
	for (int i = 0; i < num; ++i)
	{
		total += functor(i);
	}
	end = high_resolution_clock::now();
	std::cout<<"result: "<<total<<"\nfunctor call elapsed: \t"<<duration_cast<nanoseconds>(end-start).count()<<" nanoseconds.\n"<<std::endl;
	int base = 10;
	function<int(int)> lambda = [base](int i)
	{
		return i*base;
	};
	total = 0;
	start = high_resolution_clock::now();
	for (int i = 0; i < num; ++i)
	{
		total += lambda(i);
	}
	end = high_resolution_clock::now();
	std::cout<<"result: "<<total<<"\nlambda call elapsed: \t"<<duration_cast<nanoseconds>(end-start).count()<<" nanoseconds.\n"<<std::endl;
	return 0;
}

/*
test on mac mini i7 2.7GHz
clang++ -std=c++11 chronotest.cpp -O0
output:
result: 499950000
virtual call elapsed: 	43171 nanoseconds.

result: 499950000
direct function call elapsed: 	31379 nanoseconds.

result: 499950000
functor call elapsed: 	41497 nanoseconds.

result: 499950000
lambda call elapsed: 	207416 nanoseconds.
===================================================
clang++ -std=c++11 chronotest.cpp -O1
output:
result: 499950000
virtual call elapsed: 	26144 nanoseconds.

result: 499950000
direct function call elapsed: 	22384 nanoseconds.

result: 499950000
functor call elapsed: 	33477 nanoseconds.

result: 499950000
lambda call elapsed: 	55799 nanoseconds.
===================================================
clang++ -std=c++11 chronotest.cpp -O2
result: 499950000
virtual call elapsed: 	22284 nanoseconds.

result: 499950000
direct function call elapsed: 	36 nanoseconds.

result: 499950000
functor call elapsed: 	30 nanoseconds.

result: 499950000
lambda call elapsed: 	28292 nanoseconds.

===================================================
clang++ -std=c++11 chronotest.cpp -O3
result: 499950000
virtual call elapsed: 	18975 nanoseconds.

result: 499950000
direct function call elapsed: 	29 nanoseconds.

result: 499950000
functor call elapsed: 	30 nanoseconds.

result: 499950000
lambda call elapsed: 	22542 nanoseconds.
===================================================
clang++ -std=c++11 chronotest.cpp -O4

result: 499950000
virtual call elapsed: 	22141 nanoseconds.

result: 499950000
direct function call elapsed: 	30 nanoseconds.

result: 499950000
functor call elapsed: 	30 nanoseconds.

result: 499950000
lambda call elapsed: 	22584 nanoseconds.
*/