def accessed_attributes_of_local(f, local_name):
"""
Get a list of attributes of ``local_name`` accessed by ``f``.
The analysis performed by this function is conservative, meaning that
it's not guaranteed to find **all** attributes used.
"""
used = set()
# Find sequences of the form: LOAD_FAST(local_name), LOAD_ATTR(<name>).
# This will find all usages of the form ``local_name.<name>``.
#
# It will **NOT** find usages in which ``local_name`` is aliased to
# another name.
for first, second in sliding_window(dis.get_instructions(f), 2):
if first.opname == 'LOAD_FAST' and first.argval == local_name:
if second.opname in ('LOAD_ATTR', 'STORE_ATTR'):
used.add(second.argval)
return used
python类get_instructions()的实例源码
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.assertEqual(len(returns), 6)
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_'))
def _get_instructions(code_obj):
if hasattr(dis, 'get_instructions'):
return list(dis.get_instructions(code_obj))
instructions = []
instruction = None
for byte in code_obj.co_code:
byte = _six_ord(byte)
if instruction is None:
instruction = [byte]
else:
instruction.append(byte)
if instruction[0] < dis.HAVE_ARGUMENT or len(instruction) == 3:
op_code = instruction[0]
op_name = dis.opname[op_code]
if instruction[0] < dis.HAVE_ARGUMENT:
instructions.append(_Instruction(op_code, op_name, None, None))
else:
arg = instruction[1]
instructions.append(_Instruction(op_code, op_name, arg, arg))
instruction = None
return instructions
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.assertEqual(len(returns), 6)
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_'))
def assertInBytecode(self, x, opname, argval=_UNSPECIFIED):
"""Returns instr if op is found, otherwise throws AssertionError"""
for instr in dis.get_instructions(x):
if instr.opname == opname:
if argval is _UNSPECIFIED or instr.argval == argval:
return instr
disassembly = self.get_disassembly_as_string(x)
if argval is _UNSPECIFIED:
msg = '%s not found in bytecode:\n%s' % (opname, disassembly)
else:
msg = '(%s,%r) not found in bytecode:\n%s'
msg = msg % (opname, argval, disassembly)
self.fail(msg)
def assertNotInBytecode(self, x, opname, argval=_UNSPECIFIED):
"""Throws AssertionError if op is found"""
for instr in dis.get_instructions(x):
if instr.opname == opname:
disassembly = self.get_disassembly_as_string(co)
if opargval is _UNSPECIFIED:
msg = '%s occurs in bytecode:\n%s' % (opname, disassembly)
elif instr.argval == argval:
msg = '(%s,%r) occurs in bytecode:\n%s'
msg = msg % (opname, argval, disassembly)
self.fail(msg)
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')
# 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)
# 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,
],)
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_'))
# Verify that unfoldables are skipped
code = compile('a=2+"b"', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 2)
self.assertInBytecode(code, 'LOAD_CONST', 'b')
# Verify that large sequences do not result from folding
code = compile('a="x"*1000', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 1000)
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_'))
# Check that -0.0 works after marshaling
def negzero():
return -(1.0-1.0)
for instr in dis.get_instructions(code):
self.assertFalse(instr.opname.startswith('UNARY_'))
# 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)
def test_elim_jump_to_return(self):
# JUMP_FORWARD to RETURN --> RETURN
def f(cond, true_value, false_value):
return true_value if cond else false_value
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)
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.assertEqual(len(returns), 2)
def test_default_first_line(self):
actual = dis.get_instructions(simple)
self.assertEqual(list(actual), expected_opinfo_simple)
def test_outer(self):
actual = dis.get_instructions(outer, first_line=expected_outer_line)
self.assertEqual(list(actual), expected_opinfo_outer)
def test_nested(self):
with captured_stdout():
f = outer()
actual = dis.get_instructions(f, first_line=expected_f_line)
self.assertEqual(list(actual), expected_opinfo_f)
def test_doubly_nested(self):
with captured_stdout():
inner = outer()()
actual = dis.get_instructions(inner, first_line=expected_inner_line)
self.assertEqual(list(actual), expected_opinfo_inner)
def test_jumpy(self):
actual = dis.get_instructions(jumpy, first_line=expected_jumpy_line)
self.assertEqual(list(actual), expected_opinfo_jumpy)
# get_instructions has its own tests above, so can rely on it to validate
# the object oriented API
def test_iteration(self):
for obj in [_f, _C(1).__init__, "a=1", _f.__code__]:
with self.subTest(obj=obj):
via_object = list(dis.Bytecode(obj))
via_generator = list(dis.get_instructions(obj))
self.assertEqual(via_object, via_generator)
def instructions(self):
if not self._instructions:
self._instructions = list(dis.get_instructions(self))
return self._instructions
def assertInBytecode(self, x, opname, argval=_UNSPECIFIED):
"""Returns instr if op is found, otherwise throws AssertionError"""
for instr in dis.get_instructions(x):
if instr.opname == opname:
if argval is _UNSPECIFIED or instr.argval == argval:
return instr
disassembly = self.get_disassembly_as_string(x)
if argval is _UNSPECIFIED:
msg = '%s not found in bytecode:\n%s' % (opname, disassembly)
else:
msg = '(%s,%r) not found in bytecode:\n%s'
msg = msg % (opname, argval, disassembly)
self.fail(msg)
def assertNotInBytecode(self, x, opname, argval=_UNSPECIFIED):
"""Throws AssertionError if op is found"""
for instr in dis.get_instructions(x):
if instr.opname == opname:
disassembly = self.get_disassembly_as_string(co)
if opargval is _UNSPECIFIED:
msg = '%s occurs in bytecode:\n%s' % (opname, disassembly)
elif instr.argval == argval:
msg = '(%s,%r) occurs in bytecode:\n%s'
msg = msg % (opname, argval, disassembly)
self.fail(msg)
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')
# 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)
# 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,
],)
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_'))
# Verify that unfoldables are skipped
code = compile('a=2+"b"', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 2)
self.assertInBytecode(code, 'LOAD_CONST', 'b')
# Verify that large sequences do not result from folding
code = compile('a="x"*1000', '', 'single')
self.assertInBytecode(code, 'LOAD_CONST', 1000)
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_'))
# Check that -0.0 works after marshaling
def negzero():
return -(1.0-1.0)
for instr in dis.get_instructions(code):
self.assertFalse(instr.opname.startswith('UNARY_'))
# 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)
def test_elim_jump_to_return(self):
# JUMP_FORWARD to RETURN --> RETURN
def f(cond, true_value, false_value):
return true_value if cond else false_value
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)
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.assertEqual(len(returns), 2)
def test_default_first_line(self):
actual = dis.get_instructions(simple)
self.assertEqual(list(actual), expected_opinfo_simple)
def test_outer(self):
actual = dis.get_instructions(outer, first_line=expected_outer_line)
self.assertEqual(list(actual), expected_opinfo_outer)
def test_nested(self):
with captured_stdout():
f = outer()
actual = dis.get_instructions(f, first_line=expected_f_line)
self.assertEqual(list(actual), expected_opinfo_f)
