Question

2) Consider the following C function:

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int vdiv(double * a, double * b, double *c, int siz)
{// divide vectors element-wise: c=a/b; 
 // replaces divide by almost 0 with 1e99 and returns count

        int result=0;
        int i=0; 

1:      while(i<siz)
2:      {       if( abs(b[i])<1e-10 ){ // close to 0
3:                      c[i]=1e99;
4:                      result++;
5:              }else{
6:                      c[i]=a[i]/b[i]; 
7:              }
8:              i++;
9:      }
10:     return result;  
}

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Executable lines are numbered. 
-Find all basic blocks, 
-draw control flow graph of executable code, 
-indicate which lines are in each block.

Answer 1

I have divided the working code in to basic blocks. For your reference, a basic block has

• One entry point
• One exit point

A while(i<siz)
B      {       if( abs(b[i])<1e-10 ){ // close to 0
C                      c[i]=1e99;
C                      result++;
D              }else{
D                      c[i]=a[i]/b[i];
D             }
E             i++;
E       }
F      return result;

So for the given code, we have 6 basic blocks namely Block A to Block F and you can find them from above context

And the control flow graph of the above code is given below

I hope I have answered all your queries. If incase you still have any query, please feel free to comment below. I shall be glad to help you.