micropython/tests/cmdline/cmd_showbc_const.py

# cmdline: -v -v
# Test constant-related bytecode optimisations
# (constant folding, compile-time if/while evaluation, etc.)
from micropython import const
import sys

try:
    sys.settrace
    # if MICROPY_PY_SYS_SETTRACE is enabled, compile-time const optimizations
    # are disabled so the bytecode output is very different
    print("SKIP")
    raise SystemExit
except AttributeError:
    pass

_STR = const("foo")
_EMPTY_TUPLE = const(())
_TRUE = const(True)
_FALSE = const(False)
_SMALLINT = const(33)
_ZERO = const(0)

# Bytecode generated for these if/while statements should contain no JUMP_IF
# and no instances of string 'Eliminated'

if _STR or _EMPTY_TUPLE:
    print("Kept")
if _STR and _EMPTY_TUPLE:
    print("Eliminated")
if _TRUE:
    print("Kept")
if _SMALLINT:
    print("Kept")
if _ZERO and _SMALLINT:
    print("Eliminated")
if _FALSE:
    print("Eliminated")

while _SMALLINT:
    print("Kept")
    break
while _ZERO:
    print("Eliminated")
while _FALSE:
    print("Eliminated")

# These values are stored in variables, and therefore bytecode will contain JUMP_IF

a = _EMPTY_TUPLE or _STR
if a == _STR:
    print("Kept")

b = _SMALLINT and _STR
if b == _STR:
    print("Kept")

# The compiler is also unable to optimise these expressions, even though the arguments are const,
# so these also contain JUMP_IF

if (_EMPTY_TUPLE or _STR) == _STR:
    print("Kept")

if (_EMPTY_TUPLE and _STR) == _STR:
    print("Not Eliminated")

if (not _STR) == _FALSE:
    print("Kept")

assert True