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/unix/ffi.c b/unix/ffi.c
index ef9c6ea9d2..a25e54b54a 100644
--- a/unix/ffi.c
+++ b/unix/ffi.c
@@ -9,6 +9,7 @@
 #include "mpconfig.h"
 #include "qstr.h"
 #include "obj.h"
+#include "map.h"
 #include "runtime.h"
 #include "binary.h"
 
@@ -216,19 +217,20 @@ static mp_obj_t ffimod_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const
     return o;
 }
 
-static const mp_method_t ffimod_type_methods[] = {
-        { "func", &ffimod_func_obj },
-        { "var", &ffimod_var_obj },
-        { "close", &ffimod_close_obj },
-        { NULL, NULL },
+static const mp_map_elem_t ffimod_locals_dict_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR_func), (mp_obj_t) &ffimod_func_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_var), (mp_obj_t) &ffimod_var_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_close), (mp_obj_t) &ffimod_close_obj },
 };
 
+STATIC MP_DEFINE_CONST_DICT(ffimod_locals_dict, ffimod_locals_dict_table);
+
 static const mp_obj_type_t ffimod_type = {
     { &mp_type_type },
     .name = MP_QSTR_ffimod,
     .print = ffimod_print,
     .make_new = ffimod_make_new,
-    .methods = ffimod_type_methods,
+    .locals_dict = (mp_obj_t)&ffimod_locals_dict,
 };
 
 // FFI function