Summary

• Original loop interchangeable but not vectorisable.
• We skewed inner loop by outer loop by factor 1.
• Still not vectorisable, but interchangeable.
• Interchanged, skewed loop is vectorisable.
• Bounds of new loop not simple!
• Is this the best vectorisable version of this loop?
  (Banerjee skews the outer loop by the inner loop, see []).

Questions about skewing:

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Is skewing ever invalid?

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Does skewing affect interchangeability?

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Does skewing affect dependence distances?

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Can you predict the usefulness of skewing?