Therefore,
out = gen U (in prsv) for all i
out = gen (in V prsv) for all i

in(i) = S out(j) for all predecessors of i
in(i) = W out(j) for all predecessors of i

Taxonomy of Dataflow Problems

Categorized along several dimensions

• The information they are designed to provide
• The direction of flow
• Tonfluence operator

Techniques

• Iterative dataflow analysis
• Control tree based method using intervals
• Control tree based method using structural analysis

Four Kinds of Dataflow Problems

Four varieties are distinguished by two orthogonal characteristic

• The operator used for confluence or divergence
• Data flows backward or forward

Transfer Function

• In forward dataflow out(B) is a transfer function of in(B)
• In backward dataflow in(B) is a transfer function of out(B)