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import dis
import sys
from cStringIO import StringIO
import unittest
def disassemble(func):
f = StringIO()
tmp = sys.stdout
sys.stdout = f
dis.dis(func)
sys.stdout = tmp
result = f.getvalue()
f.close()
return result
def dis_single(line):
return disassemble(compile(line, '', 'single'))
class TestTranforms(unittest.TestCase):
def test_unot(self):
# UNARY_NOT POP_JUMP_IF_FALSE --> POP_JUMP_IF_TRUE
def unot(x):
if not x == 2:
del x
asm = disassemble(unot)
for elem in ('UNARY_NOT', 'POP_JUMP_IF_FALSE'):
self.assertNotIn(elem, asm)
self.assertIn('POP_JUMP_IF_TRUE', asm)
def test_elim_inversion_of_is_or_in(self):
for line, elem in (
('not a is b', '(is not)',),
('not a in b', '(not in)',),
('not a is not b', '(is)',),
('not a not in b', '(in)',),
):
asm = dis_single(line)
self.assertIn(elem, asm)
def test_none_as_constant(self):
# LOAD_GLOBAL None --> LOAD_CONST None
def f(x):
None
return x
asm = disassemble(f)
for elem in ('LOAD_GLOBAL',):
self.assertNotIn(elem, asm)
for elem in ('LOAD_CONST', '(None)'):
self.assertIn(elem, asm)
def f():
'Adding a docstring made this test fail in Py2.5.0'
return None
self.assertIn('LOAD_CONST', disassemble(f))
self.assertNotIn('LOAD_GLOBAL', disassemble(f))
def test_while_one(self):
# Skip over: LOAD_CONST trueconst POP_JUMP_IF_FALSE xx
def f():
while 1:
pass
return list
asm = disassemble(f)
for elem in ('LOAD_CONST', 'POP_JUMP_IF_FALSE'):
self.assertNotIn(elem, asm)
for elem in ('JUMP_ABSOLUTE',):
self.assertIn(elem, asm)
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',),
):
asm = dis_single(line)
self.assertIn(elem, asm)
self.assertNotIn('BUILD_TUPLE', asm)
self.assertNotIn('UNPACK_TUPLE', asm)
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))'),
):
asm = dis_single(line)
self.assertIn(elem, asm)
self.assertNotIn('BUILD_TUPLE', asm)
# 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
):
asm = dis_single(line)
self.assertIn(elem, asm, asm)
self.assertNotIn('BINARY_', asm)
# Verify that unfoldables are skipped
asm = dis_single('a=2+"b"')
self.assertIn('(2)', asm)
self.assertIn("('b')", asm)
# Verify that large sequences do not result from folding
asm = dis_single('a="x"*1000')
self.assertIn('(1000)', asm)
def test_folding_of_unaryops_on_constants(self):
for line, elem in (
('`1`', "('1')"), # unary convert
('-0.5', '(-0.5)'), # unary negative
('~-2', '(1)'), # unary invert
):
asm = dis_single(line)
self.assertIn(elem, asm, asm)
self.assertNotIn('UNARY_', asm)
# Verify that unfoldables are skipped
for line, elem in (
('-"abc"', "('abc')"), # unary negative
('~"abc"', "('abc')"), # unary invert
):
asm = dis_single(line)
self.assertIn(elem, asm, asm)
self.assertIn('UNARY_', asm)
def test_elim_extra_return(self):
# RETURN LOAD_CONST None RETURN --> RETURN
def f(x):
return x
asm = disassemble(f)
self.assertNotIn('LOAD_CONST', asm)
self.assertNotIn('(None)', asm)
self.assertEqual(asm.split().count('RETURN_VALUE'), 1)
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
asm = disassemble(f)
self.assertNotIn('JUMP_FORWARD', asm)
self.assertNotIn('JUMP_ABSOLUTE', asm)
self.assertEqual(asm.split().count('RETURN_VALUE'), 2)
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
asm = disassemble(f)
self.assertNotIn('JUMP_FORWARD', asm)
self.assertNotIn('JUMP_ABSOLUTE', asm)
self.assertEqual(asm.split().count('RETURN_VALUE'), 6)
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
asm = disassemble(f)
self.assertNotIn('JUMP_FORWARD', asm)
# There should be one jump for the while loop.
self.assertEqual(asm.split().count('JUMP_ABSOLUTE'), 1)
self.assertEqual(asm.split().count('RETURN_VALUE'), 2)
def test_main(verbose=None):
import sys
from test import test_support
test_classes = (TestTranforms,)
with test_support.check_py3k_warnings(
("backquote not supported", SyntaxWarning)):
test_support.run_unittest(*test_classes)
# verify reference counting
if verbose and hasattr(sys, "gettotalrefcount"):
import gc
counts = [None] * 5
for i in xrange(len(counts)):
test_support.run_unittest(*test_classes)
gc.collect()
counts[i] = sys.gettotalrefcount()
print counts
if __name__ == "__main__":
test_main(verbose=True)
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