Loop Index Set Merging Optimization for Program Instructions

A computer implemented method for merging loops. A number of processor units identifies loops in computer code. The loops are sequences of instructions that are repeated until conditions for the loops are reached. The number of processor units creates a tree comprising nodes that represent the loops and edges that represent relationships between nodes. The number of processor units utilizes the tree to identify a pair of candidate loops from sibling nodes. The number of processor units creates a new loop from the pair of candidate loops with an expanded iteration space based on iteration spaces for the pair of candidate loops in response to the pair of candidate loops being eligible for merging.