1. Precise Interprocedural Dataflow Analysis via Graph Reachibility
Thomas Reps
Susan Horwitz
Mooly Sagiv
Directed Reading Week # 4 Erkan Keremoglu

2. Contributions
A context sensitive framework for dataflow analysis on general class of problems
IFDS problems are transformed into a kind of graph-reachability problem
IFDS: Interprocedural – Finite – Distributive – Subset problems

3. Definitions A program is represented by its supergraph
Collection of CFGs Gs, each G has a unique start and exit node
In the graph, each statement is represented by a node, where procedure calls are represented by two nodes.

5. Definitions
A valid path is defined as follows

7. An IFDS Problem D – all variables in the program
F – The edges in the lattice
M – maps functions in F to CFG’s edges
Meet operator – same as we used before (like join)

8. Solution to IFDS problems
MVP solution: meet-over-all-valid paths solution
Don’t look at the formula – Intuitively it means “union of all solutions from initial state to node n”
Example: Possibly uninitialized variables problem

10. Converting it into a graph reachability problem
Represent functions as relations
Composition of two relations relates to the compositions of two functions
Using this property, we define exploded supergraph