Once a compiler must resort to register spilling, any advantage of maintainingmultiple accumulators will most likely be lost.

Loop unrolling can improve performance in two ways. First,it reduces the number of operations that do not contribute directly to the programresult, such as loop indexing and conditional branching. Second, it exposes waysin which we can further transform the code to reduce the number of operationsin the critical paths of the overall computation.

For an operation with latency L and capacity C, thisrequires an unrolling factor k ≥ C