New submission from STINNER Victor:
The peephole optimizer computes 2**(2**100), but if I press CTRL+c (the result
will probably kills my memory anyway), I get an assertion error (with a Python
compiled in debug mode).
$ ./python
>>> 2**(2**100)
^C
python: Python/ceval.c:1218: PyEval_EvalFrameEx: Assertion `!PyErr_Occurred()'
failed.
Abandon (core dumped)
fold_binops_on_constants() returns 0 with an exception (KeyboardInterrupt)
raised. The problem is in the caller which doesn't handle the exception
properly:
if (h >= 0 &&
ISBASICBLOCK(blocks, h, i-h+1) &&
fold_binops_on_constants(&codestr[i], consts,
CONST_STACK_LASTN(2))) {
i -= 2;
memset(&codestr[h], NOP, i - h);
assert(codestr[i] == LOAD_CONST);
CONST_STACK_POP(2);
CONST_STACK_PUSH_OP(i);
}
There is probably the same error on fold_unaryops_on_constants().
Python 2.7 looks to behave correctly:
$ python2.7
>>> 2**(2**100)
^C
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyboardInterrupt
But in fact Python 2.7 is much worse :-D Peephole optimizer of Python 2.7
clears *all* exceptions (!) and it only optimizes 2**100, but not 2**(2**100).
That's why the bug is not easily reproduced on Python 2.7.
fold_binops_on_constants():
if (newconst == NULL) {
if(!PyErr_ExceptionMatches(PyExc_KeyboardInterrupt))
PyErr_Clear();
return 0;
}
----------
messages: 256143
nosy: haypo
priority: normal
severity: normal
status: open
title: PyCode_Optimize() (peephole optimizer) doesn't handle KeyboardInterrupt
correctly
type: crash
versions: Python 2.7, Python 3.5, Python 3.6
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Python tracker <[email protected]>
<http://bugs.python.org/issue25828>
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