Flow Functions For The Flow–graph in The Example

Fentry

Iterative (forward) Data-flow Analysis

Compute in (B) and out (B) L for each B flow graph

Out (B) = (in(B))

Control Tree Based Data-Flow Analysis

• These methods are known as elimination methods
• Applies to both intervals and structures
• Significantly harder to implement - requiring node splitting, iteration, solving of data flow problems over improper regions
• Can be easily adapted to incremental updating of data flow information
• It makes two passes over the control tree
  • First pass (bottom up) constructs flow functions
  • Second pass (top down) constructs and evaluates data-flow equations for each region

If-then Construct