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- This loop is interchangeable: the top-to-bottom,
left-to-right execution order is also valid since all
dependence constraints (as shown by the arrows) are still
satisfied.
- How can you tell whether a loop can be interchanged?
- Look at it's dependence direction vectors:
- If any dependence direction vector
has the form (<,>), interchange is
invalid
- Because the arrows would be traversed
backwards
- All other dependence directions are OK.
Paul H J Kelly
Thu Dec 4 18:15:31 GMT 1997