Stefan Behnel wrote:
> Hugues Salamin wrote:
>> The following code will crash with a segfault when compiled using cython
>> (v0.11)
>>
>> def func():
>> for (a, b) ,c ,d in zip(zip(range(3), range(3)), range(3), range(3)):
>> print a, b
>> print c
>> print d # This line segfault
>>
>> Compilation is done using distutils.
>>
>> If the module is imported in python and func is called, I got a segmentation
>> fault at the line "print d".
>
> Yes, this works for me in the latest (unstable) developer branch, but fails
> in the release branch:
>
> $ cd cython-unstable
> $ cat rangeloop.pyx
> def func():
> for (a, b) ,c ,d in zip(zip(range(3), range(3)), range(3), range(3)):
> print a, b
> print c
> print d # This line segfault
>
> $ python2.6 -c 'import pyximport; pyximport.install(); \
> import rangeloop; rangeloop.func()'
> 0 0
> 0
> 0
> 1 1
> 1
> 1
> 2 2
> 2
> 2
>
> $ cd ../cython-release
> $ python2.6 -c 'import pyximport; pyximport.install(); \
> import rangeloop; rangeloop.func()'
> 0 0
> 0
> Segmentation fault
The generated code is incorrect in this case. Note how the (old-style) temp
var __pyx_4 is used for both the 'a' and 'd' variables.
if (PyTuple_CheckExact(__pyx_t_5) && \
likely(PyTuple_GET_SIZE(__pyx_t_5) == 3)) {
PyObject* tuple = __pyx_t_5;
__pyx_2 = PyTuple_GET_ITEM(tuple, 0); __Pyx_INCREF(__pyx_2);
__pyx_3 = PyTuple_GET_ITEM(tuple, 1); __Pyx_INCREF(__pyx_3);
__pyx_4 = PyTuple_GET_ITEM(tuple, 2); __Pyx_INCREF(__pyx_4);
__Pyx_DECREF(__pyx_t_5); __pyx_t_5 = 0;
if (PyTuple_CheckExact(__pyx_2) && \
likely(PyTuple_GET_SIZE(__pyx_2) == 2)) {
PyObject* tuple = __pyx_2;
__pyx_4 = PyTuple_GET_ITEM(tuple, 0); __Pyx_INCREF(__pyx_4);
__pyx_5 = PyTuple_GET_ITEM(tuple, 1); __Pyx_INCREF(__pyx_5);
__Pyx_DECREF(__pyx_2); __pyx_2 = 0;
__Pyx_DECREF(__pyx_v_a);
__pyx_v_a = __pyx_4;
__pyx_4 = 0;
__Pyx_DECREF(__pyx_v_b);
__pyx_v_b = __pyx_5;
__pyx_5 = 0;
...
}
__Pyx_DECREF(__pyx_v_c);
__pyx_v_c = __pyx_3;
__pyx_3 = 0;
__Pyx_DECREF(__pyx_v_d);
__pyx_v_d = __pyx_4;
__pyx_4 = 0;
Given that this works in cython-unstable (and I know that there were many,
many changes regarding temp allocation there again, it now uses new-style
temps everywhere), the backport may not be as simple as "copy one line".
Dag, any idea?
Stefan
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