py/obj: Add MICROPY_OBJ_IMMEDIATE_OBJS option to reduce code size.

This option (enabled by default for object representation A, B, C) makes
None/False/True objects immediate objects, ie they are no longer a concrete
object in ROM but are rather just values, eg None=0x6 for representation A.

Doing this saves a considerable amount of code size, due to these objects
being widely used:

   bare-arm:  -392 -0.591%
minimal x86:  -252 -0.170% [incl +52(data)]
   unix x64:  -624 -0.125% [incl -128(data)]
unix nanbox:    +0 +0.000%
      stm32: -1940 -0.510% PYBV10
     cc3200: -1216 -0.659%
    esp8266:  -404 -0.062% GENERIC
      esp32:  -732 -0.064% GENERIC[incl +48(data)]
        nrf:  -988 -0.675% pca10040
       samd:  -564 -0.556% ADAFRUIT_ITSYBITSY_M4_EXPRESS

Thanks go to @Jongy aka Yonatan Goldschmidt for the idea.

1 files changed, 19 insertions, 7 deletions

diff --git a/py/objbool.c b/py/objbool.c
index 5755b188e..4c046ac8f 100644
--- a/py/objbool.c
+++ b/py/objbool.c
@@ -28,21 +28,31 @@
 
 #include "py/runtime.h"
 
+#if MICROPY_OBJ_IMMEDIATE_OBJS
+
+#define BOOL_VALUE(o) ((o) == mp_const_false ? 0 : 1)
+
+#else
+
+#define BOOL_VALUE(o) (((mp_obj_bool_t*)MP_OBJ_TO_PTR(o))->value)
+
 typedef struct _mp_obj_bool_t {
     mp_obj_base_t base;
     bool value;
 } mp_obj_bool_t;
 
+#endif
+
 STATIC void bool_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
-    mp_obj_bool_t *self = MP_OBJ_TO_PTR(self_in);
+    bool value = BOOL_VALUE(self_in);
     if (MICROPY_PY_UJSON && kind == PRINT_JSON) {
-        if (self->value) {
+        if (value) {
             mp_print_str(print, "true");
         } else {
             mp_print_str(print, "false");
         }
     } else {
-        if (self->value) {
+        if (value) {
             mp_print_str(print, "True");
         } else {
             mp_print_str(print, "False");
@@ -65,13 +75,13 @@ STATIC mp_obj_t bool_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
     if (op == MP_UNARY_OP_LEN) {
         return MP_OBJ_NULL;
     }
-    mp_obj_bool_t *self = MP_OBJ_TO_PTR(o_in);
-    return mp_unary_op(op, MP_OBJ_NEW_SMALL_INT(self->value));
+    bool value = BOOL_VALUE(o_in);
+    return mp_unary_op(op, MP_OBJ_NEW_SMALL_INT(value));
 }
 
 STATIC mp_obj_t bool_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
-    mp_obj_bool_t *self = MP_OBJ_TO_PTR(lhs_in);
-    return mp_binary_op(op, MP_OBJ_NEW_SMALL_INT(self->value), rhs_in);
+    bool value = BOOL_VALUE(lhs_in);
+    return mp_binary_op(op, MP_OBJ_NEW_SMALL_INT(value), rhs_in);
 }
 
 const mp_obj_type_t mp_type_bool = {
@@ -83,5 +93,7 @@ const mp_obj_type_t mp_type_bool = {
     .binary_op = bool_binary_op,
 };
 
+#if !MICROPY_OBJ_IMMEDIATE_OBJS
 const mp_obj_bool_t mp_const_false_obj = {{&mp_type_bool}, false};
 const mp_obj_bool_t mp_const_true_obj = {{&mp_type_bool}, true};
+#endif