Loop Reversal

Run a loop backward.

All dependence directions are reversed.

It is only legal for loops that have no loop carried

dependences.

Can be used to allow fusion

(1) for i=1 to N do

(2) A[i] = B[i] + 1

(3) C[i] = A[i]/2

(4) endfor

(5) for i=1 to N do

(6) D[i] = 1/C[i+1]

(7) endfor

(1) for i=N downto 1 do

(2) A[i] = B[i] + 1

(3) C[i] = A[i]/2

(4) endfor

(5) for i=N downto 1 do

(6) D[i] = 1/C[i+1]

(7) endfor

(1) for i=N downto 1 do

(2) A[i] = B[i] + 1

(3) C[i] = A[i]/2

(6) D[i] = 1/C[i+1]

(7) endfor

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