UGC NET CSE | July 2016 | Part 2 | Question: 33

Question

In ____, the bodies of the two loops are merged together to form a single loop provided that they do not make any references to each other.

• A. Loop unrolling
• B. Strength reductions
• C. Loop concatenation
• D. Loop jamming

Answer 1

Ans is D

In computer science, loop fusion (or loop jamming) is a compiler optimization and loop transformation which replaces multiple loops with a single one. It is possible when two loops iterate over the same range and do not reference each other's data.

Loop fusion does not always improve run-time speed. On some architectures, two loops may actually perform better than one loop because, for example, there is increased data locality within each loop. In these cases, a single loop may be transformed into two, which is called loop fission.

Answer 2

Let's examine each option:

A) Loop Unrolling: This technique reduces the number of jumps by replicating the body of the loop, provided that the number of iterations is constant and known at compile time. However, if the body of the loop is large, unrolling may not be beneficial.

B) Strength Reduction: Strength reduction involves replacing a computationally expensive operation with an equivalent operation that is less costly. For example, the multiplication operator (*) can be replaced by a lower-cost operator, such as addition (+).

 

In conclusion, the correct answer is D) Loop Jamming.