SSE horizontal sum

[unrue]

Dear Intel developers,

I have to do an horizontal sum of float by using SSE and adding the results on another float. I wrote this:

float x=0;
float denom_arr_tmp[4];
_mm128 denom_tmp;

for(.....) {

//calculate denom_tmp

}
_mm_store_ps(denom_arr_tmp, denom_tmp);
x+= denom_arr_tmp[0] + denom_arr_tmp[1] + denom_arr_tmp[2] + denom_arr_tmp[3]

I'm not sure is the best way. What is the fastest way to do float horizontal sum?

Thanks.