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Merged
merged 10 commits into from
Jan 9, 2018
Merged

bpo-24340: Fix estimation of the code stack size. #5076

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e34670a
bpo-24340: Fix estimation of the code stack size.
serhiy-storchaka Jan 1, 2018
3d04b53
Add comments.
serhiy-storchaka Jan 1, 2018
4b1697d
Simplify the algorithm, add comments and asserts.
serhiy-storchaka Jan 3, 2018
dc25d14
Merge branch 'master' into stack-size
serhiy-storchaka Jan 3, 2018
44c7d39
Add more tests.
serhiy-storchaka Jan 3, 2018
0317c9d
Add more comments.
serhiy-storchaka Jan 3, 2018
7a33146
Define all stack effects in a single place.
serhiy-storchaka Jan 4, 2018
68e35bb
Make stack_effect() static.
serhiy-storchaka Jan 5, 2018
6056bc7
Add braces for PEP 7.
serhiy-storchaka Jan 7, 2018
44e1e1e
Merge branch 'master' into stack-size
serhiy-storchaka Jan 7, 2018
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291 changes: 290 additions & 1 deletion Lib/test/test_compile.py
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Original file line number Diff line number Diff line change
Expand Up @@ -672,7 +672,7 @@ def __fspath__(self):
compile("42", PathLike("test_compile_pathlike"), "single")


class TestStackSize(unittest.TestCase):
class TestExpressionStackSize(unittest.TestCase):
# These tests check that the computed stack size for a code object
# stays within reasonable bounds (see issue #21523 for an example
# dysfunction).
Expand Down Expand Up @@ -710,5 +710,294 @@ def test_func_and(self):
self.check_stack_size(code)


class TestStackSizeStability(unittest.TestCase):
# Check that repeating certain snippets doesn't increase the stack size
# beyond what a single snippet requires.

def check_stack_size(self, snippet, async_=False):
def compile_snippet(i):
ns = {}
script = """def func():\n""" + i * snippet
if async_:
script = "async " + script
code = compile(script, "<script>", "exec")
exec(code, ns, ns)
return ns['func'].__code__

sizes = [compile_snippet(i).co_stacksize for i in range(2, 5)]
if len(set(sizes)) != 1:
import dis, io
out = io.StringIO()
dis.dis(compile_snippet(1), file=out)
self.fail("stack sizes diverge with # of consecutive snippets: "
"%s\n%s\n%s" % (sizes, snippet, out.getvalue()))

def test_if(self):
snippet = """
if x:
a
"""
self.check_stack_size(snippet)

def test_if_else(self):
snippet = """
if x:
a
elif y:
b
else:
c
"""
self.check_stack_size(snippet)

def test_try_except_bare(self):
snippet = """
try:
a
except:
b
"""
self.check_stack_size(snippet)

def test_try_except_qualified(self):
snippet = """
try:
a
except ImportError:
b
except:
c
else:
d
"""
self.check_stack_size(snippet)

def test_try_except_as(self):
snippet = """
try:
a
except ImportError as e:
b
except:
c
else:
d
"""
self.check_stack_size(snippet)

def test_try_finally(self):
snippet = """
try:
a
finally:
b
"""
self.check_stack_size(snippet)

def test_with(self):
snippet = """
with x as y:
a
"""
self.check_stack_size(snippet)

def test_while_else(self):
snippet = """
while x:
a
else:
b
"""
self.check_stack_size(snippet)

def test_for(self):
snippet = """
for x in y:
a
"""
self.check_stack_size(snippet)

def test_for_else(self):
snippet = """
for x in y:
a
else:
b
"""
self.check_stack_size(snippet)

def test_for_break_continue(self):
snippet = """
for x in y:
if z:
break
elif u:
continue
else:
a
else:
b
"""
self.check_stack_size(snippet)

def test_for_break_continue_inside_try_finally_block(self):
snippet = """
for x in y:
try:
if z:
break
elif u:
continue
else:
a
finally:
f
else:
b
"""
self.check_stack_size(snippet)

def test_for_break_inside_finally_block(self):
snippet = """
for x in y:
try:
t
finally:
if z:
break
else:
a
else:
b
"""
self.check_stack_size(snippet)

def test_for_break_continue_inside_except_block(self):
snippet = """
for x in y:
try:
t
except:
if z:
break
elif u:
continue
else:
a
else:
b
"""
self.check_stack_size(snippet)

def test_for_break_continue_inside_with_block(self):
snippet = """
for x in y:
with c:
if z:
break
elif u:
continue
else:
a
else:
b
"""
self.check_stack_size(snippet)

def test_return_inside_try_finally_block(self):
snippet = """
try:
if z:
return
else:
a
finally:
f
"""
self.check_stack_size(snippet)

def test_return_inside_finally_block(self):
snippet = """
try:
t
finally:
if z:
return
else:
a
"""
self.check_stack_size(snippet)

def test_return_inside_except_block(self):
snippet = """
try:
t
except:
if z:
return
else:
a
"""
self.check_stack_size(snippet)

def test_return_inside_with_block(self):
snippet = """
with c:
if z:
return
else:
a
"""
self.check_stack_size(snippet)

def test_async_with(self):
snippet = """
async with x as y:
a
"""
self.check_stack_size(snippet, async_=True)

def test_async_for(self):
snippet = """
async for x in y:
a
"""
self.check_stack_size(snippet, async_=True)

def test_async_for_else(self):
snippet = """
async for x in y:
a
else:
b
"""
self.check_stack_size(snippet, async_=True)

def test_for_break_continue_inside_async_with_block(self):
snippet = """
for x in y:
async with c:
if z:
break
elif u:
continue
else:
a
else:
b
"""
self.check_stack_size(snippet, async_=True)

def test_return_inside_async_with_block(self):
snippet = """
async with c:
if z:
return
else:
a
"""
self.check_stack_size(snippet, async_=True)


if __name__ == "__main__":
unittest.main()
16 changes: 8 additions & 8 deletions Lib/test/test_dis.py
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Original file line number Diff line number Diff line change
Expand Up @@ -284,18 +284,18 @@ def bug1333982(x=[]):
22 POP_TOP
24 STORE_FAST 0 (e)
26 POP_TOP
28 SETUP_FINALLY 12 (to 42)
28 SETUP_FINALLY 10 (to 40)

%3d 30 LOAD_FAST 0 (e)
32 LOAD_ATTR 1 (__traceback__)
34 STORE_FAST 1 (tb)
36 POP_BLOCK
38 POP_EXCEPT
40 LOAD_CONST 0 (None)
>> 42 LOAD_CONST 0 (None)
44 STORE_FAST 0 (e)
46 DELETE_FAST 0 (e)
48 END_FINALLY
38 LOAD_CONST 0 (None)
>> 40 LOAD_CONST 0 (None)
42 STORE_FAST 0 (e)
44 DELETE_FAST 0 (e)
46 END_FINALLY
48 POP_EXCEPT
50 JUMP_FORWARD 2 (to 54)
>> 52 END_FINALLY

Expand Down Expand Up @@ -741,7 +741,7 @@ async def async_def():
Argument count: 0
Kw-only arguments: 0
Number of locals: 2
Stack size: 17
Stack size: 10
Flags: OPTIMIZED, NEWLOCALS, NOFREE, COROUTINE
Constants:
0: None
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2018-01-01-21-59-31.bpo-24340.hmKBvg.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fixed estimation of the code stack size.
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