Commit ffae48d7 authored by Damien George's avatar Damien George
Browse files

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.
parent c1c32d65
......@@ -115,17 +115,77 @@ STATIC const mp_map_t mp_constants_map = {
.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
// 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
}
// fold arguments
int n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns);
for (int i = 0; i < n; i++) {
pns->nodes[i] = fold_constants(pns->nodes[i]);
pns->nodes[i] = fold_constants(comp, pns->nodes[i], consts);
}
// now try to fold this parse node
// 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 @@ void compile_expr_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
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 @@ mp_obj_t mp_compile(mp_parse_node_t pn, qstr source_file, uint emit_opt, bool is
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);
......
......@@ -109,6 +109,11 @@
/*****************************************************************************/
/* Fine control over Python features */
// Whether to enable constant optimisation; id = const(value)
#ifndef MICROPY_ENABLE_CONST
#define MICROPY_ENABLE_CONST (1)
#endif
// Whether to include the garbage collector
#ifndef MICROPY_ENABLE_GC
#define MICROPY_ENABLE_GC (0)
......
......@@ -64,6 +64,7 @@ Q(micropython)
Q(byte_code)
Q(native)
Q(viper)
Q(const)
#if MICROPY_EMIT_INLINE_THUMB
Q(asm_thumb)
......
# test constant optimisation
X = const(123)
Y = const(X + 456)
print(X, Y + 1)
def f():
print(X, Y + 1)
f()
......@@ -112,7 +112,7 @@ def main():
if len(args.files) == 0:
if pyb is None:
# run PC tests
test_dirs = ('basics', 'float', 'import', 'io', 'misc')
test_dirs = ('basics', 'micropython', 'float', 'import', 'io', 'misc')
else:
# run pyboard tests
test_dirs = ('basics', 'float', 'pyb', 'pybnative', 'inlineasm')
......
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