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Loop Unrolling Transformation: Difference between revisions
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→Loop Unrolling Transformation in emmtrix Studio
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emmtrix Studio implements loop unrolling using #pragma directives or via the GUI. Unrolling will reduce the iteration count and increase the body of the loop, processing statements from multiple iteration steps in a single iteration. | emmtrix Studio implements loop unrolling using #pragma directives or via the GUI. Unrolling will reduce the iteration count and increase the body of the loop, processing statements from multiple iteration steps in a single iteration. | ||
By default, the transformation performs partial loop unrolling and creates two loops. The first loop is the partial unrolled loop and the second loop for the remaining iterations. | |||
emmtrix Studio tries to calculate the trip count that enables two optimizations: | |||
# Full unrolling is applied if the unroll factor >= trip count. | |||
# The loop for the remaining iterations is removed if trip count is dividable by the unroll factor. | |||
===Example=== | ===Example=== | ||
In the following example, partial loop unrolling is applied with an unroll factor of 3. | |||
Please note that a condition of <code>i < n - 2</code> would be incorrect in case of an overflow e.g. for <code>n = INT_MIN</code>. | |||
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