Loop Fission

Loop Fission (splitting) or loop distribution:
- improve memory locality by splitting out loops that refer to different independent arrays

for(i=1; i<n; i++){

a[i] = a[i] + b[i-1];

b[i] = c[i-1]*x + y;

c[i] = 1/b[i];

d[i] = sqrt(c[i]);

}

for(i=0; i<n-1; i++){

b[i+1] = c[i]*x + y;

c[i+1] = 1/b[i+1];

}

for(i=0; i<n-1; i++)

a[i+1] = a[i+1] + b[i];

for(i=0; i<n-1; i++)

d[i+1] = sqrt(c[i+1]);

i=n+1

-LNO:fission=[0,1,2] (default 1)

0 no fission

1 normal fission

3 fission tried before fussion

attempts to distribute inner loops

Loop Fission (splitting) or loop distribution: