This module consists of rules for fusion that involves WithAcc constructs. Currently, we support two non-trivial transformations: I. map-flatten-scatter: a map nest produces multi-dimensional index and values arrays that are then flattened and used in a scatter consumer. Such pattern can be fused by re-writing the scatter by means of a WithAcc containing a map-nest, thus eliminating the flatten operations. The obtained WithAcc can then be fused with the producer map nest, e.g., benefiting intra-group kernels. The eloquent target for this rule is an efficient implementation of radix-sort.

II. WithAcc-WithAcc fusion: two withaccs can be fused as long as the common accumulators use the same operator, and as long as the non-accumulator input of an WithAcc is not used as an accumulator in the other. This fusion opens the door for fusing the SOACs appearing inside the WithAccs. This is also intended to demonstrate that it is not so important where exactly the WithAccs were originally introduced in the code, it is more important that they can be transformed by various optimizations passes.