circuitpython/py/emitcommon.c
Damien George 8588525868 py/compile: De-duplicate constant objects in module's constant table.
The recent rework of bytecode made all constants global with respect to the
module (previously, each function had its own constant table).  That means
the constant table for a module is shared among all functions/methods/etc
within the module.

This commit add support to the compiler to de-duplicate constants in this
module constant table.  So if a constant is used more than once -- eg 1.0
or (None, None) -- then the same object is reused for all instances.

For example, if there is code like `print(1.0, 1.0)` then the parser will
create two independent constants 1.0 and 1.0.  The compiler will then (with
this commit) notice they are the same and only put one of them in the
constant table.  The bytecode will then reuse that constant twice in the
print expression.  That allows the second 1.0 to be reclaimed by the GC,
also means the constant table has one less entry so saves a word.

Signed-off-by: Damien George <damien@micropython.org>
2022-05-18 15:23:11 +10:00

123 lines
4.6 KiB
C

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013, 2014 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <assert.h>
#include "py/emit.h"
#include "py/nativeglue.h"
#if MICROPY_ENABLE_COMPILER
#if MICROPY_EMIT_BYTECODE_USES_QSTR_TABLE
qstr_short_t mp_emit_common_use_qstr(mp_emit_common_t *emit, qstr qst) {
mp_map_elem_t *elem = mp_map_lookup(&emit->qstr_map, MP_OBJ_NEW_QSTR(qst), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
if (elem->value == MP_OBJ_NULL) {
elem->value = MP_OBJ_NEW_SMALL_INT(emit->qstr_map.used - 1);
}
return MP_OBJ_SMALL_INT_VALUE(elem->value);
}
#endif
// Compare two objects for strict equality, including equality of type. This is
// different to the semantics of mp_obj_equal which, eg, has (True,) == (1.0,).
static bool strictly_equal(mp_obj_t a, mp_obj_t b) {
if (a == b) {
return true;
}
#if MICROPY_EMIT_NATIVE
if (a == MP_OBJ_FROM_PTR(&mp_fun_table) || b == MP_OBJ_FROM_PTR(&mp_fun_table)) {
return false;
}
#endif
const mp_obj_type_t *a_type = mp_obj_get_type(a);
const mp_obj_type_t *b_type = mp_obj_get_type(b);
if (a_type != b_type) {
return false;
}
if (a_type == &mp_type_tuple) {
mp_obj_tuple_t *a_tuple = MP_OBJ_TO_PTR(a);
mp_obj_tuple_t *b_tuple = MP_OBJ_TO_PTR(b);
if (a_tuple->len != b_tuple->len) {
return false;
}
for (size_t i = 0; i < a_tuple->len; ++i) {
if (!strictly_equal(a_tuple->items[i], b_tuple->items[i])) {
return false;
}
}
return true;
} else {
return mp_obj_equal(a, b);
}
}
size_t mp_emit_common_use_const_obj(mp_emit_common_t *emit, mp_obj_t const_obj) {
for (size_t i = 0; i < emit->const_obj_list.len; ++i) {
if (strictly_equal(emit->const_obj_list.items[i], const_obj)) {
return i;
}
}
mp_obj_list_append(MP_OBJ_FROM_PTR(&emit->const_obj_list), const_obj);
return emit->const_obj_list.len - 1;
}
void mp_emit_common_get_id_for_modification(scope_t *scope, qstr qst) {
// name adding/lookup
id_info_t *id = scope_find_or_add_id(scope, qst, ID_INFO_KIND_GLOBAL_IMPLICIT);
if (id->kind == ID_INFO_KIND_GLOBAL_IMPLICIT) {
if (SCOPE_IS_FUNC_LIKE(scope->kind)) {
// rebind as a local variable
id->kind = ID_INFO_KIND_LOCAL;
} else {
// mark this as assigned, to prevent it from being closed over
id->kind = ID_INFO_KIND_GLOBAL_IMPLICIT_ASSIGNED;
}
}
}
void mp_emit_common_id_op(emit_t *emit, const mp_emit_method_table_id_ops_t *emit_method_table, scope_t *scope, qstr qst) {
// assumes pass is greater than 1, ie that all identifiers are defined in the scope
id_info_t *id = scope_find(scope, qst);
assert(id != NULL);
// call the emit backend with the correct code
if (id->kind == ID_INFO_KIND_GLOBAL_IMPLICIT || id->kind == ID_INFO_KIND_GLOBAL_IMPLICIT_ASSIGNED) {
emit_method_table->global(emit, qst, MP_EMIT_IDOP_GLOBAL_NAME);
} else if (id->kind == ID_INFO_KIND_GLOBAL_EXPLICIT) {
emit_method_table->global(emit, qst, MP_EMIT_IDOP_GLOBAL_GLOBAL);
} else if (id->kind == ID_INFO_KIND_LOCAL) {
emit_method_table->local(emit, qst, id->local_num, MP_EMIT_IDOP_LOCAL_FAST);
} else {
assert(id->kind == ID_INFO_KIND_CELL || id->kind == ID_INFO_KIND_FREE);
emit_method_table->local(emit, qst, id->local_num, MP_EMIT_IDOP_LOCAL_DEREF);
}
}
#endif // MICROPY_ENABLE_COMPILER