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Normalized Iteration Vector
- Iterations are labeled 0, 1, 2, . . .
- Advantage
- Later iterations always have larger vector than earlier iterations if
 then is always executed before 
- next iteration is always one more than the current iteration
Dependence Distance
Vector difference between iteration vector of the source and the target iterations. 
Direction Vector
- Frequently used but less precise
- It is ordering vector relating the source and the target iteration vectors
- For some optimizations direction information is sufficient
- Some times distance is not fixed but the direction is fixed
for i = 1 to 10 do
A[2*I] = B[I] + 1
C[I] = A[I]
endfor |
- Distance varies from 1 to 5, therefore
- Direction is constant,
Loop Carried Dependence Relations
for i = 1 to n do
for j = 1 to n do
A[i,j] =
= A[i,j]
B[i,j+1] =
= B[i,j]
C[i+1,j] =
= C[i,j+1]
endfor
endfor |
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