...

Unroll:

S1:   
:= 0

S21: 
:= 
+ B[1]

S22: A[2] := 
+ B[2]

S23: A[3] := A[2] + B[3]

S24: A[4] := A[3] + B[4]

S25: A[5] := A[4] + B[5]

• In this case, there is a data dependence $S_2^{i-1} ~\delta_{}~ S_2^i$
• This is a loop-carried dependence - the dependence spans a loop iteration
• This loop is inherently sequential