Question

Which loop transformation can increase the code size?

(a) loop permutation

(b) loop fusion

(c) loop fission

(d) loop unrolling

The question was posed to me in an online interview.

My question is based upon High Level Optimization topic in portion Implementing Embedded System: Hardware/Software Codesign of Embedded Systems

Answer 1

The correct choice is (d) loop unrolling

Explanation: The loop unrolling can decrease the loop overhead, the fewer branches per execution of the loop body and this can increase the speed but is only restricted to loops with a constant number of iteration and thus the loop unrolling can increase the code size.