Rework of struct member offsets for debug info.

The struct member byte and bit offsets are now set based upon the new
function `struct_layout` from Ctypes.v, thus using the same code to
compute as used to generate the actual struct access.

The struct offset member information is addded using the types computed
after the translation in C2C. Therefore we need to store the new internal
names of the members as well as the composites and use them
when adding the offset information.

Fixes: #445

1 files changed, 45 insertions, 12 deletions

diff --git a/cfrontend/C2C.ml b/cfrontend/C2C.ml
index 65f290ba..b0dc8e8a 100644
--- a/cfrontend/C2C.ml
+++ b/cfrontend/C2C.ml
@@ -624,9 +624,10 @@ let rec convertTypAnnotArgs env = function
       Tcons(convertTyp env (Cutil.unary_conversion env e1.etyp),
             convertTypAnnotArgs env el)
 
-let convertField env f =
+let convertField env sid f =
   let id = intern_string f.fld_name
   and ty = convertTyp env ?bitwidth: f.fld_bitfield f.fld_typ in
+  Debug.set_member_atom ~str_id:sid f.fld_name ~fld_id:id;
   match f.fld_bitfield with
   | None -> Member_plain(id, ty)
   | Some w ->
@@ -639,17 +640,13 @@ let convertField env f =
 let convertCompositedef env su id attr members =
   if Cutil.find_custom_attributes ["packed";"__packed__"] attr <> [] then
     unsupported "packed struct (consider adding option [-fpacked-structs])";
-  let t = match su with
-  | C.Struct ->
-      let layout = Cutil.struct_layout env attr members in
-      List.iter (fun (a,b) -> Debug.set_member_offset id a b) layout;
-      TStruct (id,attr)
-  | C.Union -> TUnion (id,attr) in
-  Debug.set_composite_size id su (Cutil.sizeof env t);
-  Composite(intern_string id.name,
-            begin match su with C.Struct -> Ctypes.Struct | C.Union -> Ctypes.Union end,
-            List.map (convertField env) members,
-            convertAttr attr)
+  let intern_name = intern_string id.name in
+  let (t, su') = match su with
+    | C.Struct -> TStruct (id, attr), Ctypes.Struct
+    | C.Union -> TUnion (id, attr), Ctypes.Union in
+  Debug.set_composite_size id intern_name su (Cutil.sizeof env t);
+  let ms = List.map (convertField env intern_name) members in
+  Composite(intern_name, su', ms, convertAttr attr)
 
 let rec projFunType env ty =
   match Cutil.unroll env ty with
@@ -1527,6 +1524,41 @@ let public_globals gl =
     (fun accu (id, g) -> if atom_is_static id then accu else id :: accu)
     [] gl
 
+(** Complete the debug information of struct/unions *)
+
+(* [debug_set_struct_mem_ofs sid ((id,byte_ofs), bits)] sets the
+   byte and bit offset information of the member [id] of the struct
+   [sid] *)
+let debug_set_struct_mem_ofs sid ((id, byte_ofs), bits) =
+  let byte_ofs = Z.to_int byte_ofs in
+  match bits with
+  | Full ->
+    Debug.set_member_offset ~str_id:sid ~fld_id:id byte_ofs
+  | Bits (sz, sg, bit_pos, width) ->
+    let bit_pos = Z.to_int bit_pos in
+    let sz = Z.to_int (bitalignof_intsize sz) in
+    let bit_pos = if not !Machine.config.Machine.bitfields_msb_first then
+        sz - bit_pos - (Z.to_int width)
+      else
+        bit_pos in
+    let size = sz / 8 in
+    Debug.set_bitfield_offset ~str_id:sid ~fld_id:id ~bit_ofs:bit_pos ~byte_ofs:byte_ofs ~size:size
+
+(* [debug_set_struct_ofs env types] sets the missing offset information
+   of all structs in the list of composites in [types] if we compile
+   with debug information. *)
+let debug_set_struct_ofs env typs =
+  if !Clflags.option_g then
+    List.iter (function
+        | Composite (sid, Ctypes.Struct, ms, a) ->
+          let layout = Ctypes.layout_struct env ms in
+          begin match layout with
+            | Errors.OK layout ->
+              List.iter (debug_set_struct_mem_ofs sid) layout
+            | Errors.Error _ -> ()
+          end
+        | _ -> ()) typs
+
 (** Convert a [C.program] into a [Csyntax.program] *)
 
 let convertProgram p =
@@ -1555,6 +1587,7 @@ let convertProgram p =
             prog_main = intern_string !Clflags.main_function_name;
             prog_types = typs;
             prog_comp_env = ce } in
+        debug_set_struct_ofs ce typs;
         Diagnostics.check_errors ();
         p'
   with Env.Error msg ->