py, compiler: Add basic support for A=const(123).
You can now do:
X = const(123)
Y = const(456 + X)
and the compiler will replace X and Y with their values.
See discussion in issue #266 and issue #573.
diff --git a/py/compile.c b/py/compile.c
index bc9d7ae..8a26f6d 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -115,17 +115,77 @@
.table = (mp_map_elem_t*)mp_constants_table,
};
-STATIC mp_parse_node_t fold_constants(mp_parse_node_t pn) {
- if (MP_PARSE_NODE_IS_STRUCT(pn)) {
+// 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) {
+ if (0) {
+ // dummy
+#if MICROPY_ENABLE_CONST
+ } else if (MP_PARSE_NODE_IS_ID(pn)) {
+ // lookup identifier in table of dynamic constants
+ qstr qst = MP_PARSE_NODE_LEAF_ARG(pn);
+ mp_map_elem_t *elem = mp_map_lookup(consts, MP_OBJ_NEW_QSTR(qst), MP_MAP_LOOKUP);
+ if (elem != NULL) {
+ pn = mp_parse_node_new_leaf(MP_PARSE_NODE_SMALL_INT, MP_OBJ_SMALL_INT_VALUE(elem->value));
+ }
+#endif
+ } else if (MP_PARSE_NODE_IS_STRUCT(pn)) {
mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
- int n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
- // fold arguments first
- for (int i = 0; i < n; i++) {
- pns->nodes[i] = fold_constants(pns->nodes[i]);
+ // fold some parse nodes before folding their arguments
+ switch (MP_PARSE_NODE_STRUCT_KIND(pns)) {
+#if MICROPY_ENABLE_CONST
+ case PN_expr_stmt:
+ if (!MP_PARSE_NODE_IS_NULL(pns->nodes[1])) {
+ mp_parse_node_struct_t *pns1 = (mp_parse_node_struct_t*)pns->nodes[1];
+ if (MP_PARSE_NODE_STRUCT_KIND(pns1) == PN_expr_stmt_assign) {
+ if (MP_PARSE_NODE_IS_ID(pns->nodes[0])
+ && MP_PARSE_NODE_IS_STRUCT_KIND(pns1->nodes[0], PN_power)
+ && MP_PARSE_NODE_IS_ID(((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[0])
+ && MP_PARSE_NODE_LEAF_ARG(((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[0]) == MP_QSTR_const
+ && MP_PARSE_NODE_IS_STRUCT_KIND(((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[1], PN_trailer_paren)
+ && MP_PARSE_NODE_IS_NULL(((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[2])
+ ) {
+ // code to assign dynamic constants: id = const(value)
+
+ // get the id
+ qstr id_qstr = MP_PARSE_NODE_LEAF_ARG(pns->nodes[0]);
+
+ // get the value
+ mp_parse_node_t pn_value = ((mp_parse_node_struct_t*)((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[1])->nodes[0];
+ pn_value = fold_constants(comp, pn_value, consts);
+ if (!MP_PARSE_NODE_IS_SMALL_INT(pn_value)) {
+ compile_syntax_error(comp, (mp_parse_node_t)pns, "constant must be an integer");
+ break;
+ }
+ machine_int_t value = MP_PARSE_NODE_LEAF_SMALL_INT(pn_value);
+
+ // store the value in the table of dynamic constants
+ mp_map_elem_t *elem = mp_map_lookup(consts, MP_OBJ_NEW_QSTR(id_qstr), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
+ if (elem->value != MP_OBJ_NULL) {
+ compile_syntax_error(comp, (mp_parse_node_t)pns, "constant redefined");
+ break;
+ }
+ elem->value = MP_OBJ_NEW_SMALL_INT(value);
+
+ // replace const(value) with value
+ pns1->nodes[0] = pn_value;
+
+ // finished folding this assignment
+ return pn;
+ }
+ }
+ }
+ break;
+#endif
}
- // now try to fold this parse node
+ // fold arguments
+ int n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
+ for (int i = 0; i < n; i++) {
+ pns->nodes[i] = fold_constants(comp, pns->nodes[i], consts);
+ }
+
+ // try to fold this parse node
switch (MP_PARSE_NODE_STRUCT_KIND(pns)) {
case PN_atom_paren:
if (n == 1 && MP_PARSE_NODE_IS_SMALL_INT(pns->nodes[0])) {
@@ -2045,36 +2105,7 @@
c_assign(comp, ((mp_parse_node_struct_t*)pns1->nodes[i])->nodes[0], ASSIGN_STORE); // middle store
}
} else if (kind == PN_expr_stmt_assign) {
- if (0) {
- // dummy
-#if 0
- // code to compile constants: id = const(...)
- } else if (MP_PARSE_NODE_IS_ID(pns->nodes[0])
- && MP_PARSE_NODE_IS_STRUCT_KIND(pns1->nodes[0], PN_power)
- && MP_PARSE_NODE_IS_ID(((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[0])
- && MP_PARSE_NODE_LEAF_ARG(((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[0]) == MP_QSTR_const
- && MP_PARSE_NODE_IS_STRUCT_KIND(((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[1], PN_trailer_paren)
- && MP_PARSE_NODE_IS_NULL(((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[2])
- ) {
- if (comp->pass == MP_PASS_SCOPE) {
- qstr const_id = MP_PARSE_NODE_LEAF_ARG(pns->nodes[0]);
-
- if (!MP_PARSE_NODE_IS_SMALL_INT(((mp_parse_node_struct_t*)((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[1])->nodes[0])) {
- compile_syntax_error(comp, (mp_parse_node_t)pns, "constant must be an integer");
- }
- machine_int_t value = MP_PARSE_NODE_LEAF_SMALL_INT(((mp_parse_node_struct_t*)((mp_parse_node_struct_t*)pns1->nodes[0])->nodes[1])->nodes[0]);
-
- printf("assign const: %s = %ld\n", qstr_str(const_id), value);
- mp_map_elem_t *elem = mp_map_lookup(&comp->module_consts, MP_OBJ_NEW_QSTR(const_id), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
- if (elem->value != MP_OBJ_NULL) {
- compile_syntax_error(comp, (mp_parse_node_t)pns, "constant redefined");
- }
- elem->value = MP_OBJ_NEW_SMALL_INT(value);
- }
- goto no_optimisation;
-
-#endif
- } else if (MP_PARSE_NODE_IS_STRUCT_KIND(pns1->nodes[0], PN_testlist_star_expr)
+ if (MP_PARSE_NODE_IS_STRUCT_KIND(pns1->nodes[0], PN_testlist_star_expr)
&& MP_PARSE_NODE_IS_STRUCT_KIND(pns->nodes[0], PN_testlist_star_expr)
&& MP_PARSE_NODE_STRUCT_NUM_NODES((mp_parse_node_struct_t*)pns1->nodes[0]) == 2
&& MP_PARSE_NODE_STRUCT_NUM_NODES((mp_parse_node_struct_t*)pns->nodes[0]) == 2) {
@@ -3424,7 +3455,10 @@
comp->is_repl = is_repl;
// optimise constants
- pn = fold_constants(pn);
+ mp_map_t consts;
+ mp_map_init(&consts, 0);
+ pn = fold_constants(comp, pn, &consts);
+ mp_map_deinit(&consts);
// set the outer scope
scope_t *module_scope = scope_new_and_link(comp, SCOPE_MODULE, pn, emit_opt);