Loop fusion

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.