Remove mp_obj_type_t.methods entry and use .locals_dict instead.

Originally, .methods was used for methods in a ROM class, and
locals_dict for methods in a user-created class.  That distinction is
unnecessary, and we can use locals_dict for ROM classes now that we have
ROMable maps.

This removes an entry in the bloated mp_obj_type_t struct, saving a word
for each ROM object and each RAM object.  ROM objects that have a
methods table (now a locals_dict) need an extra word in total (removed
the methods pointer (1 word), no longer need the sentinel (2 words), but
now need an mp_obj_dict_t wrapper (4 words)).  But RAM objects save a
word because they never used the methods entry.

Overall the ROM usage is down by a few hundred bytes, and RAM usage is
down 1 word per user-defined type/class.

There is less code (no need to check 2 tables), and now consistent with
the way ROM modules have their tables initialised.

Efficiency is very close to equivaluent.

1 files changed, 8 insertions, 6 deletions

diff --git a/stm/led.c b/stm/led.c
index ceae49ca7..bfb98f9b5 100644
--- a/stm/led.c
+++ b/stm/led.c
@@ -6,6 +6,7 @@
 #include "mpconfig.h"
 #include "qstr.h"
 #include "obj.h"
+#include "map.h"
 #include "led.h"
 #include "pin.h"
 #include "build/pins.h"
@@ -109,18 +110,19 @@ static MP_DEFINE_CONST_FUN_OBJ_1(led_obj_on_obj, led_obj_on);
 static MP_DEFINE_CONST_FUN_OBJ_1(led_obj_off_obj, led_obj_off);
 static MP_DEFINE_CONST_FUN_OBJ_1(led_obj_toggle_obj, led_obj_toggle);
 
-static const mp_method_t led_methods[] = {
-    { MP_QSTR_on, &led_obj_on_obj },
-    { MP_QSTR_off, &led_obj_off_obj },
-    { MP_QSTR_toggle, &led_obj_toggle_obj },
-    { MP_QSTR_NULL, NULL },
+STATIC const mp_map_elem_t led_locals_dict_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR_on), (mp_obj_t)&led_obj_on_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_off), (mp_obj_t)&led_obj_off_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_toggle), (mp_obj_t)&led_obj_toggle_obj },
 };
 
+STATIC MP_DEFINE_CONST_DICT(led_locals_dict, led_locals_dict_table);
+
 static const mp_obj_type_t led_obj_type = {
     { &mp_type_type },
     .name = MP_QSTR_Led,
     .print = led_obj_print,
-    .methods = led_methods,
+    .locals_dict = (mp_obj_t)&led_locals_dict,
 };
 
 static mp_obj_t pyb_Led(mp_obj_t led_id) {