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, 5 insertions, 0 deletions

diff --git a/py/map.h b/py/map.h
index afebfda6ec..692ae92e38 100644
--- a/py/map.h
+++ b/py/map.h
@@ -24,6 +24,11 @@ typedef enum _mp_map_lookup_kind_t {
     MP_MAP_LOOKUP_FIRST = 4,
 } mp_map_lookup_kind_t;
 
+typedef struct _mp_obj_dict_t {
+    mp_obj_base_t base;
+    mp_map_t map;
+} mp_obj_dict_t;
+
 int get_doubling_prime_greater_or_equal_to(int x);
 void mp_map_init(mp_map_t *map, int n);
 void mp_map_init_fixed_table(mp_map_t *map, int n, const mp_obj_t *table);