A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 8. DEPENDANT TYPE QUALIFIERS 63
let context for call (c : ctxt) (fe : exp) (args : exp list) : ctxt =
match typeOf fe with
| TFun( , Some stal, , ) →
let formals = L.map fst3 stal in
let actuals = list take (L.length stal) args in
L.fold left2 ctxt add exp c formals actuals
| → c
When compiling a eld access, the function context for struct extends a context with mappings
from eld names to expressions accessing those elds through the given lval. It is used for compiling
the type of a structure eld, which may refer to other elds of the same structure.
let context for struct (c : ctxt) (loc : location) (lv : lval) : ctxt =
let blv, off = removeOffsetLval lv in
match off with
| NoOffset | Index → c
| Field(fi, NoOffset) → L.fold left (ctxt add field blv) c fi.fcomp.cfields
| → E.s(E.bug "%a: Expected field w/o offset: %a" d loc loc d lval lv)
8.1.3 Compiling type qualiers
Now that we can build a context for compiling the type qualiers, we can go ahead with the actual
compilation. In particular, we need to translate a CIL attribute parameter into an CIL expression.
Once we have compiled the type qualiers, we'll be able to enforce rules about what sorts of
color combinations can be on the same type. In particular, a type can have either no color, an exact
color, or at most one lower bound and one upper bound.
Below, the function exp of ap translates attrparams into CIL exps in a given context. If the
attrparam uses a name not mapped in the context, we print an error and stop compilation.
let rec exp of ap (c : ctxt) (loc : location) (ap : attrparam) : exp =
let eoap = exp of ap c loc in
match ap with
| AInt i → integer i
| AStr s → mkString s
| ACons(s, [ ]) → begin
try exp of string c s
with Not found →
E.s (E.error "%a: %s not in context for %a"
d loc loc s d attrparam ap)
end
| AUnOp(uop, ap) →
let e = eoap ap in