6_3_5.cpp

#include"5_refactored_allcaches.cpp"
#include<vector>
#include<random>
#include<chrono>
using namespace std::chrono;
using std::vector;
using std::size_t;
using std::cout;
using std::endl;
constexpr int genpoly = 0x11d;
using GF2 = GF2Five::GF2<genpoly>;

auto makeRandomInts(int howmany){
    vector<int> ret(howmany);
    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<int> dis(1,214800000);
    for(size_t i=0;i<howmany;++i){
        ret[i]= dis(gen);
        if(ret[i]%2==0) ret[i]--;
    }
    return ret;
}

auto makeRandomPairs(int howmany){
    vector<GF2> ret(howmany);
    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<int> dis(1,255);
    for(size_t i=0;i<howmany;++i){
        ret[i] = GF2(dis(gen));
    }
    return ret; // is RVO applied here?
}

int main(){
    int howmany = 20000000;
    auto testees = makeRandomPairs(howmany);
    
    GF2 sum {GF2(1)};
    for(size_t i=0;i<howmany;i++){
        sum *= testees[i];
    }
    cout << "actual result of multiplication is:" << sum << endl;

    GF2 sum1 {GF2(1)};
    GF2 sum2 {GF2(1)};
    GF2 sum3 {GF2(1)};
    GF2 sum4 {GF2(1)};
    GF2 sum5 {GF2(1)};
    GF2 sum6 {GF2(1)};
    GF2 sum7 {GF2(1)};
    GF2 sum8 {GF2(1)};
    GF2 sum9 {GF2(1)};
    GF2 sum10 {GF2(1)};
    GF2 sum11 {GF2(1)};
    GF2 sum12 {GF2(1)};
    GF2 sum13 {GF2(1)};
    GF2 sum14 {GF2(1)};
    GF2 sum15 {GF2(1)};
    GF2 sum16 {GF2(1)};
    GF2 sum17 {GF2(1)};
    GF2 sum18 {GF2(1)};
    GF2 sum19 {GF2(1)};
    GF2 sum20 {GF2(1)};
    GF2 sum21 {GF2(1)};
    GF2 sum22 {GF2(1)};
    GF2 sum23 {GF2(1)};
    GF2 sum24 {GF2(1)};
    GF2 sum25 {GF2(1)};
    GF2 sum26 {GF2(1)};
    GF2 sum27 {GF2(1)};
    GF2 sum28 {GF2(1)};
    GF2 sum29 {GF2(1)};
    GF2 sum30 {GF2(1)};
    GF2 sum31 {GF2(1)};
    GF2 sum32 {GF2(1)};

    auto aa = system_clock::now();
    for(size_t i=0;i<howmany;i+=32){
        sum1 *= testees[i];
        sum2 *= testees[i+1];
        sum3 *= testees[i+2];
        sum4 *= testees[i+3];
        sum5 *= testees[i+4];
        sum6 *= testees[i+5];
        sum7 *= testees[i+6];
        sum8 *= testees[i+7];
        sum9 *= testees[i+8];
        sum10 *= testees[i+9];
        sum11 *= testees[i+10];
        sum12 *= testees[i+11];
        sum13 *= testees[i+12];
        sum14 *= testees[i+13];
        sum15 *= testees[i+14];
        sum16 *= testees[i+15];
        sum17 *= testees[i+16];
        sum18 *= testees[i+17];
        sum19 *= testees[i+18];
        sum20 *= testees[i+19];
        sum21 *= testees[i+20];
        sum22 *= testees[i+21];
        sum23 *= testees[i+22];
        sum24 *= testees[i+23];
        sum25 *= testees[i+24];
        sum26 *= testees[i+25];
        sum27 *= testees[i+26];
        sum28 *= testees[i+27];
        sum29 *= testees[i+28];
        sum30 *= testees[i+29];
        sum31 *= testees[i+30];
        sum32 *= testees[i+31];

    }

    sum1 = sum1*sum2*sum3*sum4*sum5*sum6*sum7*sum8*sum9*sum10*sum11*sum12*sum13*sum14*sum15*sum16*sum17*sum18*sum19*sum20*sum21*sum22*sum23*sum24*sum25*sum26*sum27*sum28*sum29*sum30*sum31*sum32;
    auto bb = system_clock::now();
    cout << "result(should be the same as above): " << sum1 << endl;
    cout << duration_cast<microseconds>(bb-aa).count() << " us (loop unrolled manually)" << endl;
}