CPU med in order eller out of order/ C++ kod

#include <ctime>
#include <iostream>
#include <math.h>
using namespace std;
 
int identity(int x) { return x; }
int sum1(int num) {
   int a = 3, b, c, d, e, f, g, h, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, z1, z2, z3, z4, z5, z6 ;
   
  for (int i = 0; i < 2000000; i++)
    num += i;
    t= r/a;
    s= o/a;
    r= a/a;
    p= 2*a;
    o= b/a;
    h = b/a;
    g= h%a;
    f= b/a;
    e= c%a;
    d= c/a;
    b=3*a;
    c=a/a;
    p= k+a+d;
    q= p+b+m;
    n= k+a;
    m= 1+b+l;
    l=3*a+k;
    k=a+b+3;
    t= r/a;
    u = t/a;
    v= h/a;
    w= b/z6;
    x= c/a;
    y= c/a +p;
    z=3*a;
    z1=z5/a;
    z2= k+a+d;
    z3= p+b+m;
    z4= k+a;
    z5= 1+b+l;
      
    a= a+b;
   

  return num;
}
 int sum2(int num) {
   int a1 = 3, b1, c1, d1, e1, f1, g1, h1, k1, l1, m1, n1, o1, p1, q1, r1, s1, t1;
   float x1, y1 ,z1, u1, w1, x3, y3 ,z3, u3, w3, x5, y5 ,z5, u5, w5;
  for (int i = 0; i < 2000000; i++)
    num += i;
    t1= r1/s1;
    s1= o1/p1;
    r1= a1/b1;
    p1= 2*a1;
    o1= a1/b1;
    h1 = b1/a1;
    g1= h1/a1;
    f1= b1/c1;
    e1= c1/a1;
    d1= c1/b1;
    b1=3*a1;
    c1=a1/b1;
    p1= k1+a1+d1;
    q1= p1+b1+m1;
    n1= k1+a1;
    m1= 1+b1+l1;
    l1=3*a1+k1;
    k1=a1+b1+3;
    x1= sqrt (w1);
    y1= 1/z1;
    z1= (float) c1;
    u1= 1/x1;
    w1= (float) h1;
    x3= sqrt (w1);
    y3= 1/z1;
    z3= (float) c1;
    u3= 1/x1;
    w3= (float) h1;
    x5= sqrt (w1);
    y5= 1/z3;
    z5= (float) m1;
    u5= 1/x1;
    w5= (float) e1;
    a1= a1+b1;

  return num;
}

 int sum3(int num) {
   int j1 = 3, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15, j16, j17, j18;
   float s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14, s15 ;
  for (int i = 0; i < 2000000; i++)
    num += i;
    j18= j17/j1;
    j17= j16/j3;
    j16= j15/j4;
    j15= j1/j3;
    j2 = j1/j1;
    j3= j2/j1;
    j4= j2/j2;
    j5= j1/j2;
    j6= j1/j3;
    j7=3*j1;
    j8=j1/j7;
    j9 = j1+j2+j3;
    j10= j1+j9+j5;
    j11= j1+j10+j3;
    j12= j1+j2;
    j13= 1+j8+j4;
    j14=3*j1+j11;
   
    s1= sqrt (10);
    s2= 1/s1;
    s3= (float) j7;
    s4= 1/s3;
    s5= (float) j1;
    s6= sqrt (10);
    s7= 1/s1;
    s8= (float) j7;
    s9= 1/s3;
    s10= (float) j3;
    s11= sqrt (10);
    s12= 1/s1;
    s13= (float) j7;
    s14= 1/s3;
    s15= (float) j8;
    j1=j1+j2;
  return num;
}

 int sum4(int num) {
   int j1 = 3, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15, j16, j17, j18;
   float s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14, s15 ;
  for (int i = 0; i < 2000000; i++)
    num += i;
    j7=3*j1;
    j3= j2/j1;
    j4= j2/j2;
    
    j6= j1/j3;
     j13= 1+j8+j4;
    j8=j1/j7;
    j9 = j1+j2+j3;
    j10= j1+j9+j5;
    j11= j1+j10+j3;
    j12= j1+j2;
    j5= j1/j2;
    j14=3*j1;
    j2 = j1/j1;
    s11= sqrt (5+j2);
    s9= 1/s3;
    s2= 1/s1;
    s3= (float) j7;
    s4= 1/s3;
     j18= j17/j1;
    j17= j16/j3;
    j16= j15/j4;
    j15= j1/j3;
    s6= sqrt (10);
    s7= 1/s1;
    s8= (float) j7;
    s5= (float) j1;
    s10= (float) j3;
    s1= sqrt (10+j2);
    s12= 1/s1;
    s13= (float) j7;
    s14= 1/s3;
    s15= (float) j8;
    j1= j1+j2;
  return num;
}
 int sum5(int num) {
  
  float s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14, s15, s16, s17, s18, s19, s20, s21, s22, s23, s24, s25, s26, s27, s28, s29, s30;
  for (int i = 0; i < 2000000; i++)
    num += i;
    s30= sqrt (5);
    s29= 1/s3;
    s28= 1/s1;
    s27= sqrt(s30);    
    s26= sqrt (10);
    s25= sqrt (5);
    s24= 1/s3;
    s23= 1/s1;
    s22= 1/s30;
    s21= 1/s3;
    s20= sqrt(10);
    s19=s20/s30;
    s17=sqrt(s20);
    s16=s15+s23;
    s7= 1/s1;
    s8=  s7*s7;
    s5=  s1+s1;
    s10= s3+s1;
    s1= sqrt(10);
    s12= 1/s1;
    s13= s2/s3;
    s14= 1/s3;
    s15=  5;
    s2=s1/s5;
    s3=s10/s17;
    s4=s5/s2;
    
  return num;
}

double time_it(int (*action)(int), int arg) {
  clock_t start_time = clock();
  action(arg);
  clock_t finis_time = clock();
  return ((double) 1000*(finis_time - start_time)) /CLOCKS_PER_SEC;
}
 
int main() {
  cout << "Identity(100) takes " << time_it(identity, 100) << " mseconds." << endl;
  cout << "Sum1(100) takes " << time_it(sum1, 100) << " mseconds." << endl;
  cout << "Sum2(100) takes " << time_it(sum2, 100) << " mseconds." << endl;
  cout << "Sum3(100) takes " << time_it(sum3, 100) << " mseconds." << endl;
  cout << "Sum4(100) takes " << time_it(sum4, 100) << " mseconds." << endl;
  cout << "Sum5(100) takes " << time_it(sum4, 100) << " mseconds." << endl;
  return 0;
}

  for (int i = 0; i < 2000000; i++)
    num += i;
    t= r/a;
    s= o/a;
    ...

  for (int i = 0; i < 2000000; i++) {
    num += i;
    t= r/a;
    s= o/a;
    ...
  }

  for (int i = 0; i < 2000000; i++) {
    num += i;
  }
  t= r/a;
  s= o/a;
  ...