py: Add config option MICROPY_COMP_MODULE_CONST for module consts.

Compiler optimises lookup of module.CONST when enabled (an existing
feature).  Disabled by default; enabled for unix, windows, stmhal.
Costs about 100 bytes ROM on stmhal.

bare-arm/mpconfigport.h

@@ -6,6 +6,8 @@
 #define MICROPY_EMIT_X64            (0)
 #define MICROPY_EMIT_THUMB          (0)
 #define MICROPY_EMIT_INLINE_THUMB   (0)
+#define MICROPY_COMP_MODULE_CONST   (0)
+#define MICROPY_COMP_CONST          (0)
 #define MICROPY_MEM_STATS           (0)
 #define MICROPY_DEBUG_PRINTERS      (0)
 #define MICROPY_ENABLE_GC           (0)

py/compile.c

@@ -98,6 +98,7 @@ STATIC void compile_syntax_error(compiler_t *comp, mp_parse_node_t pn, const cha
     comp->compile_error = exc;
 }
 
+#if MICROPY_COMP_MODULE_CONST
 STATIC const mp_map_elem_t mp_constants_table[] = {
     #if MICROPY_PY_UCTYPES
     { MP_OBJ_NEW_QSTR(MP_QSTR_uctypes), (mp_obj_t)&mp_module_uctypes },
@@ -105,14 +106,8 @@ STATIC const mp_map_elem_t mp_constants_table[] = {
     // Extra constants as defined by a port
     MICROPY_PORT_CONSTANTS
 };
-
-STATIC const mp_map_t mp_constants_map = {
-    .all_keys_are_qstrs = 1,
-    .table_is_fixed_array = 1,
-    .used = MP_ARRAY_SIZE(mp_constants_table),
-    .alloc = MP_ARRAY_SIZE(mp_constants_table),
-    .table = (mp_map_elem_t*)mp_constants_table,
-};
+STATIC MP_DEFINE_CONST_MAP(mp_constants_map, mp_constants_table);
+#endif
 
 // this function is essentially a simple preprocessor
 STATIC mp_parse_node_t fold_constants(compiler_t *comp, mp_parse_node_t pn, mp_map_t *consts) {
@@ -327,6 +322,7 @@ STATIC mp_parse_node_t fold_constants(compiler_t *comp, mp_parse_node_t pn, mp_m
                         }
                     }
 #endif
+#if MICROPY_COMP_MODULE_CONST
                 } else if (MP_PARSE_NODE_IS_ID(pns->nodes[0]) && MP_PARSE_NODE_IS_STRUCT_KIND(pns->nodes[1], PN_trailer_period) && MP_PARSE_NODE_IS_NULL(pns->nodes[2])) {
                     // id.id
                     // look it up in constant table, see if it can be replaced with an integer
@@ -340,11 +336,10 @@ STATIC mp_parse_node_t fold_constants(compiler_t *comp, mp_parse_node_t pn, mp_m
                         mp_load_method_maybe(elem->value, q_attr, dest);
                         if (MP_OBJ_IS_SMALL_INT(dest[0]) && dest[1] == NULL) {
                             mp_int_t val = MP_OBJ_SMALL_INT_VALUE(dest[0]);
-                            if (MP_SMALL_INT_FITS(val)) {
-                                pn = mp_parse_node_new_leaf(MP_PARSE_NODE_SMALL_INT, val);
-                            }
+                            pn = mp_parse_node_new_leaf(MP_PARSE_NODE_SMALL_INT, val);
                         }
                     }
+#endif
                 }
                 break;
         }

py/mpconfig.h

@@ -152,6 +152,11 @@
 /*****************************************************************************/
 /* Compiler configuration                                                    */
 
+// Whether to enable lookup of constants in modules; eg module.CONST
+#ifndef MICROPY_COMP_MODULE_CONST
+#define MICROPY_COMP_MODULE_CONST (0)
+#endif
+
 // Whether to enable constant optimisation; id = const(value)
 #ifndef MICROPY_COMP_CONST
 #define MICROPY_COMP_CONST (1)

stmhal/mpconfigport.h

@@ -33,6 +33,7 @@
 #define MICROPY_ALLOC_PATH_MAX      (128)
 #define MICROPY_EMIT_THUMB          (1)
 #define MICROPY_EMIT_INLINE_THUMB   (1)
+#define MICROPY_COMP_MODULE_CONST   (1)
 #define MICROPY_ENABLE_GC           (1)
 #define MICROPY_ENABLE_FINALISER    (1)
 #define MICROPY_STACK_CHECK         (1)

unix/mpconfigport.h

@@ -39,6 +39,7 @@
 #if !defined(MICROPY_EMIT_ARM) && defined(__arm__)
     #define MICROPY_EMIT_ARM        (1)
 #endif
+#define MICROPY_COMP_MODULE_CONST   (1)
 #define MICROPY_ENABLE_GC           (1)
 #define MICROPY_ENABLE_FINALISER    (1)
 #define MICROPY_STACK_CHECK         (1)

windows/mpconfigport.h

@@ -35,6 +35,7 @@
 #define MICROPY_EMIT_X64            (0)
 #define MICROPY_EMIT_THUMB          (0)
 #define MICROPY_EMIT_INLINE_THUMB   (0)
+#define MICROPY_COMP_MODULE_CONST   (1)
 #define MICROPY_ENABLE_GC           (1)
 #define MICROPY_ENABLE_FINALISER    (1)
 #define MICROPY_MEM_STATS           (1)