test_peepholer.py
import dis
import unittest
from test.support.bytecode_helper import BytecodeTestCase
def count_instr_recursively(f, opname):
count = 0
for instr in dis.get_instructions(f):
if instr.opname == opname:
count += 1
if hasattr(f, '__code__'):
f = f.__code__
for c in f.co_consts:
if hasattr(c, 'co_code'):
count += count_instr_recursively(c, opname)
return count
class TestTranforms(BytecodeTestCase):
def check_jump_targets(self, code):
instructions = list(dis.get_instructions(code))
targets = {instr.offset: instr for instr in instructions}
for instr in instructions:
if 'JUMP_' not in instr.opname:
continue
tgt = targets[instr.argval]
# jump to unconditional jump
if tgt.opname in ('JUMP_ABSOLUTE', 'JUMP_FORWARD'):
self.fail(f'{instr.opname} at {instr.offset} '
f'jumps to {tgt.opname} at {tgt.offset}')
# unconditional jump to RETURN_VALUE
if (instr.opname in ('JUMP_ABSOLUTE', 'JUMP_FORWARD') and
tgt.opname == 'RETURN_VALUE'):
self.fail(f'{instr.opname} at {instr.offset} '
f'jumps to {tgt.opname} at {tgt.offset}')
# JUMP_IF_*_OR_POP jump to conditional jump
if '_OR_POP' in instr.opname and 'JUMP_IF_' in tgt.opname:
self.fail(f'{instr.opname} at {instr.offset} '
f'jumps to {tgt.opname} at {tgt.offset}')
def check_lnotab(self, code):
"Check that the lnotab byte offsets are sensible."
code = dis._get_code_object(code)
lnotab = list(dis.findlinestarts(code))
# Don't bother checking if the line info is sensible, because
# most of the line info we can get at comes from lnotab.
min_bytecode = min(t[0] for t in lnotab)
max_bytecode = max(t[0] for t in lnotab)
self.assertGreaterEqual(min_bytecode, 0)
self.assertLess(max_bytecode, len(code.co_code))
# This could conceivably test more (and probably should, as there
# aren't very many tests of lnotab), if peepholer wasn't scheduled
# to be replaced anyway.
def test_unot(self):
# UNARY_NOT POP_JUMP_IF_FALSE --> POP_JUMP_IF_TRUE'
def unot(x):
if not x == 2:
del x
self.assertNotInBytecode(unot, 'UNARY_NOT')
self.assertNotInBytecode(unot, 'POP_JUMP_IF_FALSE')
self.assertInBytecode(unot, 'POP_JUMP_IF_TRUE')
self.check_lnotab(unot)
def test_elim_inversion_of_is_or_in(self):
for line, cmp_op, invert in (
('not a is b', 'IS_OP', 1,),
('not a is not b', 'IS_OP', 0,),
('not a in b', 'CONTAINS_OP', 1,),
('not a not in b', 'CONTAINS_OP', 0,),
):
code = compile(line, '', 'single')
self.assertInBytecode(code, cmp_op, invert)
self.check_lnotab(code)
def test_global_as_constant(self):
# LOAD_GLOBAL None/True/False --> LOAD_CONST None/True/False
def f():
x = None
x = None
return x
def g():
x = True
return x
def h():
x = False
return x
for func, elem in ((f, None), (g, True), (h, False)):
self.assertNotInBytecode(func, 'LOAD_GLOBAL')
self.assertInBytecode(func, 'LOAD_CONST', elem)
self.check_lnotab(func)
def f():
'Adding a docstring made this test fail in Py2.5.0'
return None
self.assertNotInBytecode(f, 'LOAD_GLOBAL')
self.assertInBytecode(f, 'LOAD_CONST', None)
self.check_lnotab(f)
def test_while_one(self):
# Skip over: LOAD_CONST trueconst POP_JUMP_IF_FALSE xx
def f():
while 1:
pass
return list
for elem in ('LOAD_CONST', 'POP_JUMP_IF_FALSE'):
self.assertNotInBytecode(f, elem)
for elem in ('JUMP_ABSOLUTE',):
self.assertInBytecode(f, elem)
self.check_lnotab(f)
def test_pack_unpack(self):
for line, elem in (
('a, = a,', 'LOAD_CONST',),
('a, b = a, b', 'ROT_TWO',),
('a, b, c = a, b, c', 'ROT_THREE',),
):
code = compile(line,'','single')
self.assertInBytecode(code, elem)
self.assertNotInBytecode(code, 'BUILD_TUPLE')
self.assertNotInBytecode(code, 'UNPACK_TUPLE')
self.check_lnotab(code)
def test_folding_of_tuples_of_constants(self):
for line, elem in (
('a = 1,2,3', (1, 2, 3)),
('("a","b","c")', ('a', 'b', 'c')),
('a,b,c = 1,2,3', (1, 2, 3)),
('(None, 1, None)', (None, 1, None)),
('((1, 2), 3, 4)', ((1, 2), 3, 4)),
):
code = compile(line,'','single')
self.assertInBytecode(code, 'LOAD_CONST', elem)
self.assertNotInBytecode(code, 'BUILD_TUPLE')
self.check_lnotab(code)
# Long tuples should be folded too.
code = compile(repr(tuple(range(10000))),'','single')
self.assertNotInBytecode(code, 'BUILD_TUPLE')
# One LOAD_CONST for the tuple, one for the None return value
load_consts = [instr for instr in dis.get_instructions(code)
if instr.opname == 'LOAD_CONST']
self.assertEqual(len(load_consts), 2)
self.check_lnotab(code)
# Bug 1053819: Tuple of constants misidentified when presented with:
# . . . opcode_with_arg 100 unary_opcode BUILD_TUPLE 1 . . .
# The following would segfault upon compilation
def crater():
(~[
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
],)
self.check_lnotab(crater)
def test_folding_of_lists_of_constants(self):
for line, elem in (
# in/not in constants with BUILD_LIST should be folded to a tuple:
('a in [1,2,3]', (1, 2, 3)),
('a not in ["a","b","c"]', ('a', 'b', 'c')),
('a in [None, 1, None]', (None, 1, None)),
('a not in [(1, 2), 3, 4]', ((1, 2), 3, 4)),
):
code = compile(line, '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', elem)
self.assertNotInBytecode(code, 'BUILD_LIST')
self.check_lnotab(code)
def test_folding_of_sets_of_constants(self):
for line, elem in (
# in/not in constants with BUILD_SET should be folded to a frozenset:
('a in {1,2,3}', frozenset({1, 2, 3})),
('a not in {"a","b","c"}', frozenset({'a', 'c', 'b'})),
('a in {None, 1, None}', frozenset({1, None})),
('a not in {(1, 2), 3, 4}', frozenset({(1, 2), 3, 4})),
('a in {1, 2, 3, 3, 2, 1}', frozenset({1, 2, 3})),
):
code = compile(line, '', 'single')
self.assertNotInBytecode(code, 'BUILD_SET')
self.assertInBytecode(code, 'LOAD_CONST', elem)
self.check_lnotab(code)
# Ensure that the resulting code actually works:
def f(a):
return a in {1, 2, 3}
def g(a):
return a not in {1, 2, 3}
self.assertTrue(f(3))
self.assertTrue(not f(4))
self.check_lnotab(f)
self.assertTrue(not g(3))
self.assertTrue(g(4))
self.check_lnotab(g)
def test_folding_of_binops_on_constants(self):
for line, elem in (
('a = 2+3+4', 9), # chained fold
('"@"*4', '@@@@'), # check string ops
('a="abc" + "def"', 'abcdef'), # check string ops
('a = 3**4', 81), # binary power
('a = 3*4', 12), # binary multiply
('a = 13//4', 3), # binary floor divide
('a = 14%4', 2), # binary modulo
('a = 2+3', 5), # binary add
('a = 13-4', 9), # binary subtract
('a = (12,13)[1]', 13), # binary subscr
('a = 13 << 2', 52), # binary lshift
('a = 13 >> 2', 3), # binary rshift
('a = 13 & 7', 5), # binary and
('a = 13 ^ 7', 10), # binary xor
('a = 13 | 7', 15), # binary or
):
code = compile(line, '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', elem)
for instr in dis.get_instructions(code):
self.assertFalse(instr.opname.startswith('BINARY_'))
self.check_lnotab(code)
# Verify that unfoldables are skipped
code = compile('a=2+"b"', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 2)
self.assertInBytecode(code, 'LOAD_CONST', 'b')
self.check_lnotab(code)
# Verify that large sequences do not result from folding
code = compile('a="x"*10000', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 10000)
self.assertNotIn("x"*10000, code.co_consts)
self.check_lnotab(code)
code = compile('a=1<<1000', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 1000)
self.assertNotIn(1<<1000, code.co_consts)
self.check_lnotab(code)
code = compile('a=2**1000', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 1000)
self.assertNotIn(2**1000, code.co_consts)
self.check_lnotab(code)
def test_binary_subscr_on_unicode(self):
# valid code get optimized
code = compile('"foo"[0]', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 'f')
self.assertNotInBytecode(code, 'BINARY_SUBSCR')
self.check_lnotab(code)
code = compile('"\u0061\uffff"[1]', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', '\uffff')
self.assertNotInBytecode(code,'BINARY_SUBSCR')
self.check_lnotab(code)
# With PEP 393, non-BMP char get optimized
code = compile('"\U00012345"[0]', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', '\U00012345')
self.assertNotInBytecode(code, 'BINARY_SUBSCR')
self.check_lnotab(code)
# invalid code doesn't get optimized
# out of range
code = compile('"fuu"[10]', '', 'single')
self.assertInBytecode(code, 'BINARY_SUBSCR')
self.check_lnotab(code)
def test_folding_of_unaryops_on_constants(self):
for line, elem in (
('-0.5', -0.5), # unary negative
('-0.0', -0.0), # -0.0
('-(1.0-1.0)', -0.0), # -0.0 after folding
('-0', 0), # -0
('~-2', 1), # unary invert
('+1', 1), # unary positive
):
code = compile(line, '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', elem)
for instr in dis.get_instructions(code):
self.assertFalse(instr.opname.startswith('UNARY_'))
self.check_lnotab(code)
# Check that -0.0 works after marshaling
def negzero():
return -(1.0-1.0)
for instr in dis.get_instructions(negzero):
self.assertFalse(instr.opname.startswith('UNARY_'))
self.check_lnotab(negzero)
# Verify that unfoldables are skipped
for line, elem, opname in (
('-"abc"', 'abc', 'UNARY_NEGATIVE'),
('~"abc"', 'abc', 'UNARY_INVERT'),
):
code = compile(line, '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', elem)
self.assertInBytecode(code, opname)
self.check_lnotab(code)
def test_elim_extra_return(self):
# RETURN LOAD_CONST None RETURN --> RETURN
def f(x):
return x
self.assertNotInBytecode(f, 'LOAD_CONST', None)
returns = [instr for instr in dis.get_instructions(f)
if instr.opname == 'RETURN_VALUE']
self.assertEqual(len(returns), 1)
self.check_lnotab(f)
def test_elim_jump_to_return(self):
# JUMP_FORWARD to RETURN --> RETURN
def f(cond, true_value, false_value):
# Intentionally use two-line expression to test issue37213.
return (true_value if cond
else false_value)
self.check_jump_targets(f)
self.assertNotInBytecode(f, 'JUMP_FORWARD')
self.assertNotInBytecode(f, 'JUMP_ABSOLUTE')
returns = [instr for instr in dis.get_instructions(f)
if instr.opname == 'RETURN_VALUE']
self.assertEqual(len(returns), 2)
self.check_lnotab(f)
def test_elim_jump_to_uncond_jump(self):
# POP_JUMP_IF_FALSE to JUMP_FORWARD --> POP_JUMP_IF_FALSE to non-jump
def f():
if a:
# Intentionally use two-line expression to test issue37213.
if (c
or d):
foo()
else:
baz()
self.check_jump_targets(f)
self.check_lnotab(f)
def test_elim_jump_to_uncond_jump2(self):
# POP_JUMP_IF_FALSE to JUMP_ABSOLUTE --> POP_JUMP_IF_FALSE to non-jump
def f():
while a:
# Intentionally use two-line expression to test issue37213.
if (c
or d):
a = foo()
self.check_jump_targets(f)
self.check_lnotab(f)
def test_elim_jump_to_uncond_jump3(self):
# Intentionally use two-line expressions to test issue37213.
# JUMP_IF_FALSE_OR_POP to JUMP_IF_FALSE_OR_POP --> JUMP_IF_FALSE_OR_POP to non-jump
def f(a, b, c):
return ((a and b)
and c)
self.check_jump_targets(f)
self.check_lnotab(f)
self.assertEqual(count_instr_recursively(f, 'JUMP_IF_FALSE_OR_POP'), 2)
# JUMP_IF_TRUE_OR_POP to JUMP_IF_TRUE_OR_POP --> JUMP_IF_TRUE_OR_POP to non-jump
def f(a, b, c):
return ((a or b)
or c)
self.check_jump_targets(f)
self.check_lnotab(f)
self.assertEqual(count_instr_recursively(f, 'JUMP_IF_TRUE_OR_POP'), 2)
# JUMP_IF_FALSE_OR_POP to JUMP_IF_TRUE_OR_POP --> POP_JUMP_IF_FALSE to non-jump
def f(a, b, c):
return ((a and b)
or c)
self.check_jump_targets(f)
self.check_lnotab(f)
self.assertNotInBytecode(f, 'JUMP_IF_FALSE_OR_POP')
self.assertInBytecode(f, 'JUMP_IF_TRUE_OR_POP')
self.assertInBytecode(f, 'POP_JUMP_IF_FALSE')
# JUMP_IF_TRUE_OR_POP to JUMP_IF_FALSE_OR_POP --> POP_JUMP_IF_TRUE to non-jump
def f(a, b, c):
return ((a or b)
and c)
self.check_jump_targets(f)
self.check_lnotab(f)
self.assertNotInBytecode(f, 'JUMP_IF_TRUE_OR_POP')
self.assertInBytecode(f, 'JUMP_IF_FALSE_OR_POP')
self.assertInBytecode(f, 'POP_JUMP_IF_TRUE')
def test_elim_jump_after_return1(self):
# Eliminate dead code: jumps immediately after returns can't be reached
def f(cond1, cond2):
if cond1: return 1
if cond2: return 2
while 1:
return 3
while 1:
if cond1: return 4
return 5
return 6
self.assertNotInBytecode(f, 'JUMP_FORWARD')
self.assertNotInBytecode(f, 'JUMP_ABSOLUTE')
returns = [instr for instr in dis.get_instructions(f)
if instr.opname == 'RETURN_VALUE']
self.assertLessEqual(len(returns), 6)
self.check_lnotab(f)
def test_elim_jump_after_return2(self):
# Eliminate dead code: jumps immediately after returns can't be reached
def f(cond1, cond2):
while 1:
if cond1: return 4
self.assertNotInBytecode(f, 'JUMP_FORWARD')
# There should be one jump for the while loop.
returns = [instr for instr in dis.get_instructions(f)
if instr.opname == 'JUMP_ABSOLUTE']
self.assertEqual(len(returns), 1)
returns = [instr for instr in dis.get_instructions(f)
if instr.opname == 'RETURN_VALUE']
self.assertLessEqual(len(returns), 2)
self.check_lnotab(f)
def test_make_function_doesnt_bail(self):
def f():
def g()->1+1:
pass
return g
self.assertNotInBytecode(f, 'BINARY_ADD')
self.check_lnotab(f)
def test_constant_folding(self):
# Issue #11244: aggressive constant folding.
exprs = [
'3 * -5',
'-3 * 5',
'2 * (3 * 4)',
'(2 * 3) * 4',
'(-1, 2, 3)',
'(1, -2, 3)',
'(1, 2, -3)',
'(1, 2, -3) * 6',
'lambda x: x in {(3 * -5) + (-1 - 6), (1, -2, 3) * 2, None}',
]
for e in exprs:
code = compile(e, '', 'single')
for instr in dis.get_instructions(code):
self.assertFalse(instr.opname.startswith('UNARY_'))
self.assertFalse(instr.opname.startswith('BINARY_'))
self.assertFalse(instr.opname.startswith('BUILD_'))
self.check_lnotab(code)
def test_in_literal_list(self):
def containtest():
return x in [a, b]
self.assertEqual(count_instr_recursively(containtest, 'BUILD_LIST'), 0)
self.check_lnotab(containtest)
def test_iterate_literal_list(self):
def forloop():
for x in [a, b]:
pass
self.assertEqual(count_instr_recursively(forloop, 'BUILD_LIST'), 0)
self.check_lnotab(forloop)
def test_condition_with_binop_with_bools(self):
def f():
if True or False:
return 1
return 0
self.assertEqual(f(), 1)
self.check_lnotab(f)
def test_if_with_if_expression(self):
# Check bpo-37289
def f(x):
if (True if x else False):
return True
return False
self.assertTrue(f(True))
self.check_lnotab(f)
def test_trailing_nops(self):
# Check the lnotab of a function that even after trivial
# optimization has trailing nops, which the lnotab adjustment has to
# handle properly (bpo-38115).
def f(x):
while 1:
return 3
while 1:
return 5
return 6
self.check_lnotab(f)
def test_assignment_idiom_in_comprehensions(self):
def listcomp():
return [y for x in a for y in [f(x)]]
self.assertEqual(count_instr_recursively(listcomp, 'FOR_ITER'), 1)
def setcomp():
return {y for x in a for y in [f(x)]}
self.assertEqual(count_instr_recursively(setcomp, 'FOR_ITER'), 1)
def dictcomp():
return {y: y for x in a for y in [f(x)]}
self.assertEqual(count_instr_recursively(dictcomp, 'FOR_ITER'), 1)
def genexpr():
return (y for x in a for y in [f(x)])
self.assertEqual(count_instr_recursively(genexpr, 'FOR_ITER'), 1)
class TestBuglets(unittest.TestCase):
def test_bug_11510(self):
# folded constant set optimization was commingled with the tuple
# unpacking optimization which would fail if the set had duplicate
# elements so that the set length was unexpected
def f():
x, y = {1, 1}
return x, y
with self.assertRaises(ValueError):
f()
if __name__ == "__main__":
unittest.main()
