Started work on an undefined literal removal pass for the ocaml

backed.

Ocaml doesn't support undefined values, so we need a way to remove
them from the specification in order to generate good ocaml
code. There are more subtle issues to - like if we initialize a
mutable variable with an undefined list, then the ocaml runtime has no
way of telling what it's length should be (as this information is
removed by the simple_types pass).

We therefore rewrite undefined literals with calls to functions that
create undefined types, e.g.

(bool) undefined becomes undefined_bool ()

(vector<'n,'m,dec,bit>) undefined becomes undefined_vector(sizeof 'n, sizeof 'm, undefined_bit ())

We therefore have to generate undefined_X functions for any user
defined datatype X. initial_check seems to be the logical place for
this. This is straightforward provided the user defined types are
not-recursive (and it shouldn't be too bad even if they are).

1 files changed, 10 insertions, 0 deletions

diff --git a/src/ast_util.mli b/src/ast_util.mli
index b0ccb7b8..7580404d 100644
--- a/src/ast_util.mli
+++ b/src/ast_util.mli
@@ -47,10 +47,18 @@ open Ast
 val mk_nc : n_constraint_aux -> n_constraint
 val mk_nexp : nexp_aux -> nexp
 val mk_exp : unit exp_aux -> unit exp
+val mk_pat : unit pat_aux -> unit pat
 val mk_lit : lit_aux -> lit
+val mk_lit_exp : lit_aux -> unit exp
+val mk_funcl : id -> unit pat -> unit exp -> unit funcl
+val mk_fundef : (unit funcl) list -> unit def
+val mk_val_spec : val_spec_aux -> unit def
 
 val unaux_exp : 'a exp -> 'a exp_aux
 
+val inc_ord : order
+val dec_ord : order
+
 (* Functions to map over the annotations in sub-expressions *)
 val map_exp_annot : ('a annot -> 'b annot) -> 'a exp -> 'b exp
 val map_pat_annot : ('a annot -> 'b annot) -> 'a pat -> 'b pat
@@ -92,6 +100,8 @@ val id_of_fundef : 'a fundef -> id
 
 val id_of_kid : kid -> id
 
+val prepend_id : string -> id -> id
+
 module Id : sig
   type t = id
   val compare : id -> id -> int