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Loop Interchange

Interchange nested loops

DO I = 1, N
  DO J = 1, N
    ...
  ENDDO
ENDDO

|

V

DO J = 1, N
  DO I = 1, N
    ...
  ENDDO
ENDDO

• Increase iteration count
• Achieve most efficient vector stride (+1)
• Avoid non-vectorizable recurrences