gistfile1.txt

#include <eigen3/Eigen/Dense>
#include <cblas.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>

using namespace Eigen;

static double loop_dot(double* a, double* b, int d)
{
	asm("#loop start");
	double r = 0.0;
	for (int i=0; i<d; i++)
		r += a[i]*b[i];
	asm("#loop end");
	return r;
}

static double blas_dot(double* a, double* b, int d)
{
	asm("#blas start");
	double r = cblas_ddot(d,a,1,b,1);
	asm("#blas end");
	return r;
}

static double eigen_dot(double* a, double* b, int d)
{
	asm("#eigen start");
	Map<VectorXd> a_(a,d);
	Map<VectorXd> b_(b,d);
	double r = a_.dot(b_);
	asm("#eigen end");
	return r;
}

void measure(int d, int repeats, const char* name, double (*dot_impl)(double*,double*,int))
{
	double* a = (double*)malloc(sizeof(double)*d);
	double* b = (double*)malloc(sizeof(double)*d);
	srand(time(NULL));
	for (int i=0; i<d; i++)
	{
		a[i] = rand()/10.0;
		b[i] = rand()/10.0;
	}
	clock_t start = clock();
	for (int i=0; i<repeats; i++)
		dot_impl(a,b,d);
	clock_t end = clock();
	printf("%s elapsed %f clocks \n", name, double(end-start)/repeats);

	free(a);
	free(b);
}

int main()
{
	measure(1000000,20000,"",&blas_dot);
	measure(1000000,20000,"blas",&blas_dot);
	measure(1000000,20000,"loop",&loop_dot);
	measure(1000000,20000,"eigen",&eigen_dot);
	return 0;
}