Avoid iterating ty parts on drop when there are no heap pointers in ty. Wins several tens of kb on rustc.

2 files changed, 31 insertions, 5 deletions

diff --git a/src/boot/me/semant.ml b/src/boot/me/semant.ml
index 7d1b21ef109..f0fca1a8ca0 100644
--- a/src/boot/me/semant.ml
+++ b/src/boot/me/semant.ml
@@ -947,12 +947,38 @@ let type_is_structured (t:Ast.ty) : bool =
   let fold = { fold with
                  ty_fold_tup = (fun _ -> true);
                  ty_fold_vec = (fun _ -> true);
+                 ty_fold_str = (fun _ -> true);
                  ty_fold_rec = (fun _ -> true);
                  ty_fold_tag = (fun _ -> true);
                  ty_fold_iso = (fun _ -> true);
                  ty_fold_idx = (fun _ -> true);
                  ty_fold_fn = (fun _ -> true);
-                 ty_fold_obj = (fun _ -> true) }
+                 ty_fold_obj = (fun _ -> true);
+
+                 ty_fold_chan = (fun _ -> true);
+                 ty_fold_port = (fun _ -> true);
+                 ty_fold_box = (fun _ -> true);
+                 ty_fold_task = (fun _ -> true);
+             }
+
+  in
+    fold_ty fold t
+;;
+
+
+let type_points_to_heap (t:Ast.ty) : bool =
+  let fold = ty_fold_bool_or false in
+  let fold = { fold with
+                 ty_fold_vec = (fun _ -> true);
+                 ty_fold_str = (fun _ -> true);
+                 ty_fold_fn = (fun _ -> true);
+                 ty_fold_obj = (fun _ -> true);
+
+                 ty_fold_chan = (fun _ -> true);
+                 ty_fold_port = (fun _ -> true);
+                 ty_fold_box = (fun _ -> true);
+                 ty_fold_task = (fun _ -> true);
+             }
   in
     fold_ty fold t
 ;;
diff --git a/src/boot/me/trans.ml b/src/boot/me/trans.ml
index e3587bdd0d1..914645ff601 100644
--- a/src/boot/me/trans.ml
+++ b/src/boot/me/trans.ml
@@ -2738,11 +2738,11 @@ let trans_visitor
                   patch null_jmp;
                   note_drop_step ty "drop_ty: done box-drop path";
 
-            | MEM_interior when type_is_structured ty ->
-                note_drop_step ty "drop_ty structured-interior path";
+            | MEM_interior when type_points_to_heap ty ->
+                note_drop_step ty "drop_ty heap-referencing path";
                 iter_ty_parts ty_params cell ty
                   (drop_ty ty_params) curr_iso;
-                note_drop_step ty "drop_ty: done structured-interior path";
+                note_drop_step ty "drop_ty: done heap-referencing path";
 
 
             | MEM_interior ->
@@ -2785,7 +2785,7 @@ let trans_visitor
                 MEM_gc ->
                   sever_box cell
 
-              | MEM_interior when type_is_structured ty ->
+              | MEM_interior when type_points_to_heap ty ->
                   iter_ty_parts ty_params cell ty
                     (sever_ty ty_params) curr_iso