#6343, #5537, #5573: improving access to values in nested modules.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14452 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

asmcomp/clambda.ml

@@ -82,3 +82,4 @@ type value_approximation =
   | Value_tuple of value_approximation array
   | Value_unknown
   | Value_const of uconstant
+  | Value_global_field of string * int

asmcomp/clambda.mli

@@ -82,3 +82,4 @@ type value_approximation =
   | Value_tuple of value_approximation array
   | Value_unknown
   | Value_const of uconstant
+  | Value_global_field of string * int

asmcomp/closure.ml

@@ -465,6 +465,15 @@ let strengthen_approx appl approx =
 let check_constant_result lam ulam approx =
   match approx with
     Value_const c when is_pure lam -> make_const c
+  | Value_global_field (id, i) when is_pure lam ->
+      begin match ulam with
+      | Uprim(Pfield _, [Uprim(Pgetglobal _, _, _)], _) -> (ulam, approx)
+      | _ ->
+          let glb =
+            Uprim(Pgetglobal (Ident.create_persistent id), [], Debuginfo.none)
+          in
+          Uprim(Pfield i, [glb], Debuginfo.none), approx
+      end
   | _ -> (ulam, approx)
 
 (* Evaluate an expression with known value for its side effects only,
@@ -679,7 +688,8 @@ let rec close fenv cenv = function
                             fieldapprox
   | Lprim(Psetfield(n, _), [Lprim(Pgetglobal id, []); lam]) ->
       let (ulam, approx) = close fenv cenv lam in
-      (!global_approx).(n) <- approx;
+      if approx <> Value_unknown then
+        (!global_approx).(n) <- approx;
       (Uprim(Psetfield(n, false), [getglobal id; ulam], Debuginfo.none),
        Value_unknown)
   | Lprim(Praise k, [Levent(arg, ev)]) ->
@@ -910,7 +920,7 @@ let collect_exported_structured_constants a =
         end
     | Value_tuple a -> Array.iter approx a
     | Value_const c -> const c
-    | Value_unknown -> ()
+    | Value_unknown | Value_global_field _ -> ()
   and const = function
     | Uconst_ref (s, c) ->
         Compilenv.add_exported_constant s;
@@ -953,7 +963,8 @@ let collect_exported_structured_constants a =
 
 let intro size lam =
   function_nesting_depth := 0;
-  global_approx := Array.create size Value_unknown;
+  let id = Compilenv.make_symbol None in
+  global_approx := Array.init size (fun i -> Value_global_field (id, i));
   Compilenv.set_global_approx(Value_tuple !global_approx);
   let (ulam, approx) = close Tbl.empty Tbl.empty lam in
   collect_exported_structured_constants (Value_tuple !global_approx);

asmcomp/printclambda.ml

@@ -171,3 +171,6 @@ let rec approx ppf = function
       Format.fprintf ppf "_"
   | Value_const c ->
       fprintf ppf "@[const(%a)@]" uconstant c
+  | Value_global_field (s, i) ->
+      fprintf ppf "@[global(%s,%i)@]" s i
+