A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 9. TYPE QUALIFIER INFERENCE 77
let processQueue (g : graph) (q : int Q.t) : unit =
while ¬(Q.is empty q) do
let id = Q.pop q in
if processNode g id then begin
L.iter (fun id' → Q.add id' q) g.(id).outgoing
end
done
The function attr of color builds a new type attribute from the color c.
let attr of color (c : T.color) : attribute = Attr(T.string of color c, [ ])
Once the inference algorithm is nished, we can add its results to the types in the program. If an
inferred type qualier disagrees with one that the programmer has added explicitly, we keep the
programmer's annotation, but issue a warning.
The visitor colorAdder visits typ nodes in the AST. It reads the inferred color type using the
typ's "Node" attribute, and adds it to the typ, respecting the above policy.
class colorAdder (g : graph) = object(self)
inherit nopCilVisitor
method vtype (t : typ) =
let oc = T.colors of type t in
let ic = (t | > node of type | > A.get g).ncolors in
if oc ≠ [ ] ∧ ¬(colors equal ic oc) then DoChildren
else if list equal (=) ic oc then DoChildren else
let nattr = L.map attr of color ic in
ChangeTo (typeAddAttributes nattr t)
end
The function addInferredColors invokes the visitor colorAdder on the le f using the inference
results in graph g.
let addInferredColors (f : file) (g : graph) : unit =
let vis = new colorAdder g in
visitCilFile vis f
Finally, we tie everything together with the function tut9, which is the entry point into the module.
We must also remember to remove the node attributes we added for building the graph. We leave the
inferred colors since these will need to be checked by a type-checking pass like the one in Chapter 7.