py: Allow tail call optimisation in mp_call_function_n_kw.

dpgeorge · dpgeorge · commit 3f5226246517 · 2014-06-03T13:40:16.000+01:00
This saves 4 words of stack space per Python call.
diff --git a/py/objtype.c b/py/objtype.c
@@ -516,7 +516,7 @@ STATIC mp_obj_t instance_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp
     mp_obj_t member[2] = {MP_OBJ_NULL};
     mp_obj_class_lookup(self, self->base.type, MP_QSTR___call__, offsetof(mp_obj_type_t, call), member);
     if (member[0] == MP_OBJ_NULL) {
-        return MP_OBJ_NULL;
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "'%s' object is not callable", mp_obj_get_type_str(self_in)));
     }
     if (member[0] == MP_OBJ_SENTINEL) {
         return mp_call_function_n_kw(self->subobj[0], n_args, n_kw, args);
diff --git a/py/runtime.c b/py/runtime.c
@@ -526,10 +526,7 @@ mp_obj_t mp_call_function_n_kw(mp_obj_t fun_in, uint n_args, uint n_kw, const mp
 
     // do the call
     if (type->call != NULL) {
-        mp_obj_t res = type->call(fun_in, n_args, n_kw, args);
-        if (res != NULL) {
-            return res;
-        }
+        return type->call(fun_in, n_args, n_kw, args);
     }
 
     nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "'%s' object is not callable", mp_obj_get_type_str(fun_in)));

Original file line number	Diff line number	Diff line change
`@@ -516,7 +516,7 @@ STATIC mp_obj_t instance_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp`
`516`	`516`	`mp_obj_t member[2] = {MP_OBJ_NULL};`
`517`	`517`	`mp_obj_class_lookup(self, self->base.type, MP_QSTR___call__, offsetof(mp_obj_type_t, call), member);`
`518`	`518`	`if (member[0] == MP_OBJ_NULL) {`
`519`		`- return MP_OBJ_NULL;`
	`519`	`+ nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "'%s' object is not callable", mp_obj_get_type_str(self_in)));`
`520`	`520`	`}`
`521`	`521`	`if (member[0] == MP_OBJ_SENTINEL) {`
`522`	`522`	`return mp_call_function_n_kw(self->subobj[0], n_args, n_kw, args);`