Loop fission (or loop distribution) is a compiler optimization technique attempting to break a loop into multiple loops over the same index range but each taking only a part of the loop's body. The goal is to break down large loop body into smaller ones to achieve better utilization of locality of reference. It is the reverse action to loop fusion. This optimization is most efficient in multi-core processors that can split a task into multiple tasks for each processor.
| Original loop | After loop fission |
|---|---|
int i, a[100], b[100];
for (i = 0; i < 100; i++) {
a[i] = 1;
b[i] = 2;
}
|
int i, a[100], b[100];
for (i = 0; i < 100; i++) {
a[i] = 1;
}
for (i = 0; i < 100; i++) {
b[i] = 2;
}
|
Kennedy, Ken; & Allen, Randy. (2001). Optimizing Compilers for Modern Architectures: A Dependence-based Approach. Morgan Kaufmann. ISBN 1-55860-286-0.