A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 9. TYPE QUALIFIER INFERENCE 75
class graphBuilder (g : graph) (fd : fundec) = object(self)
inherit nopCilVisitor
method vinst (i : instr) =
match i with
| Set(lv, e, loc) →
typesAddEdge g (typeOf e) (typeOfLval lv);
DoChildren
(∗ ... ∗)
end
The function functionBuildGraph invokes the visitor graphBuilder on function fd, building the
graph in the mutable array g.
let functionBuildGraph (g : graph) (fd : fundec) (loc : location) : unit =
let vis = new graphBuilder g fd in
ignore(visitCilFunction vis fd)
The function fileBuildGraph simply calls the functions we dened above, rst for marking the
AST with "Node" type attributes, and second building the graph. The function returns the resulting
graph.
let fileBuildGraph (f : file) : graph =
let g = f | > addNodeMarks | > graphCreate in
functionBuildGraph g
|> onlyFunctions
|> iterGlobals f;
g
9.1.3 Inferene Algorithm
The inference algorithm must be seeded somehow. In this example, the nodeColorFinder visitor
takes any type qualiers that the programmer added explicitly to the program, and puts them into
our graph. However, in a dierent application, depending on the meanings of the type qualiers, it
may be possible to deduce some of the missing type qualiers before the inference stage begins.
class nodeColorFinder (g : graph) = object(self)
inherit nopCilVisitor
method vtype (t : typ) =
let id = node of type t in
let c = T.colors of type t in
g.(id).ncolors ← c;
DoChildren
end