Loop fission is a compiler optimization

Compiler optimization

Compiler optimization is the process of tuning the output of a compiler to minimize or maximize some attributes of an executable computer program. The most common requirement is to minimize the time taken to execute a program; a less common one is to minimize the amount of memory occupied...

 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

Locality of reference

In computer science, locality of reference, also known as the principle of locality, is the phenomenon of the same value or related storage locations being frequently accessed. There are two basic types of reference locality. Temporal locality refers to the reuse of specific data and/or resources...

. It is the reverse action to loop fusion

Loop fusion

Loop fusion, also called loop jamming, is a compiler optimization, a loop transformation, which replaces multiple loops with a single one.- Example in C : int i, a[100], b[100]; for Loop fusion, also called loop jamming, is a compiler optimization, a loop transformation, which replaces multiple...

. 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; }

Further reading