[sledge] Fix crashing frontned

Summary:
When LLVM is built with assertions, it crash
`add_sym` if you try to get the global scope of a non global value.

This patch special cases add_sym, to just do nothing when `llv` is
an `UndefValue`.

Also enhances debuging printout of transalte to include the number of
functions and globals.

Reviewed By: jvillard

Differential Revision: D15669447

fbshipit-source-id: 4b5483810

sledge/src/llair/frontend.ml

@@ -72,14 +72,23 @@ let ( (scan_names_and_locs : Llvm.llmodule -> unit)
       ~col:(Llvm.get_debug_loc_column i)
   in
   let add_sym llv loc =
-    let next, void_tbl =
-      let scope =
+    let maybe_scope =
       match Llvm.classify_value llv with
-        | Argument -> `Fun (Llvm.param_parent llv)
-        | BasicBlock -> `Fun (Llvm.block_parent (Llvm.block_of_value llv))
-        | Instruction _ -> `Fun (Llvm.block_parent (Llvm.instr_parent llv))
-        | _ -> `Mod (Llvm.global_parent llv)
+      | Argument -> Some (`Fun (Llvm.param_parent llv))
+      | BasicBlock ->
+          Some (`Fun (Llvm.block_parent (Llvm.block_of_value llv)))
+      | Instruction _ ->
+          Some (`Fun (Llvm.block_parent (Llvm.instr_parent llv)))
+      | GlobalVariable | Function -> Some (`Mod (Llvm.global_parent llv))
+      | UndefValue -> None
+      | _ ->
+          warn "Unexpected type of llv, might crash: %a" pp_llvalue llv () ;
+          Some (`Mod (Llvm.global_parent llv))
     in
+    match maybe_scope with
+    | None -> ()
+    | Some scope ->
+        let next, void_tbl =
           Hashtbl.find_or_add scope_tbl scope ~default:(fun () ->
               (ref 0, Hashtbl.Poly.create ()) )
         in
@@ -103,7 +112,8 @@ let ( (scan_names_and_locs : Llvm.llmodule -> unit)
                   fname ^ ".void"
               | Some count ->
                   Hashtbl.set void_tbl ~key:fname ~data:(count + 1) ;
-              String.concat_array [|fname; ".void."; Int.to_string count|] )
+                  String.concat_array
+                    [|fname; ".void."; Int.to_string count|] )
           | _ -> (
             match Llvm.value_name llv with
             | "" ->
@@ -1404,4 +1414,6 @@ let translate : string list -> Llair.t =
   Llvm.dispose_module llmodule ;
   Llair.mk ~globals ~functions
   |>
-  [%Trace.retn fun {pf} _ -> pf ""]
+  [%Trace.retn fun {pf} _ ->
+    pf "number of globals %d, number of functions %d" (List.length globals)
+      (List.length functions)]