The modified program is the first phase of FAST's front-end for the specific algorithm. These groups correspond to the basic computational blocks of the algorithm. The tasks start executing upon receipt of all incoming data and continue to completion without interruption. Upon completion their results are forwarded to adjacent nodes.
Edges correspond to Send-Receive pairs and represent the data dependencies between the nodes.
The annotation of the task-flow graph is straightforward. Nodes are assigned the sum of the costs of their corresponding IR-operations.