merge: hs-f into architecture — JIT Phase 1 (tiered compilation)

# Conflicts:
#	hosts/ocaml/lib/sx_primitives.ml

hosts/ocaml/lib/sx_vm.ml

@@ -57,6 +57,9 @@ let () = Sx_types._convert_vm_suspension := (fun exn ->
 let jit_compile_ref : (lambda -> (string, value) Hashtbl.t -> vm_closure option) ref =
   ref (fun _ _ -> None)
 
+(* JIT threshold and counters live in Sx_types so primitives can read them
+   without creating a sx_primitives → sx_vm dependency cycle. *)
+
 (** Sentinel closure indicating JIT compilation was attempted and failed.
     Prevents retrying compilation on every call. *)
 let jit_failed_sentinel = {
@@ -364,13 +367,21 @@ and vm_call vm f args =
      | None ->
        if l.l_name <> None
        then begin
-         l.l_compiled <- Some jit_failed_sentinel;
-         match !jit_compile_ref l vm.globals with
-         | Some cl ->
-           l.l_compiled <- Some cl;
-           push_closure_frame vm cl args
-         | None ->
+         l.l_call_count <- l.l_call_count + 1;
+         if l.l_call_count >= !Sx_types.jit_threshold then begin
+           l.l_compiled <- Some jit_failed_sentinel;
+           match !jit_compile_ref l vm.globals with
+           | Some cl ->
+             incr Sx_types.jit_compiled_count;
+             l.l_compiled <- Some cl;
+             push_closure_frame vm cl args
+           | None ->
+             incr Sx_types.jit_skipped_count;
+             push vm (cek_call_or_suspend vm f (List args))
+         end else begin
+           incr Sx_types.jit_threshold_skipped_count;
            push vm (cek_call_or_suspend vm f (List args))
+         end
        end
        else
          push vm (cek_call_or_suspend vm f (List args)))