[New-bugs-announce] [issue43541] PyEval_EvalCodeEx() can no longer be called with code which has (CO_NEWLOCALS | CO_OPTIMIZED) flags
STINNER Victor
report at bugs.python.org
Thu Mar 18 07:11:14 EDT 2021
New submission from STINNER Victor <vstinner at python.org>:
Cython generates a __Pyx_PyFunction_FastCallDict() function which calls PyEval_EvalCodeEx(). With Python 3.9, it worked well. With Python 3.10 in debug mode, it fails with an assertion error:
python3.10: Python/ceval.c:5148: PyEval_EvalCodeEx: Assertion `(((PyCodeObject *)_co)->co_flags & (CO_NEWLOCALS | CO_OPTIMIZED)) == 0' failed.
With Python 3.10 in release mode, it does crash.
Context of the failed assertion:
* Assertion added recently to CPython 3.10 by python/cpython at 0332e56
* The code object flags = (CO_NEWLOCALS | CO_OPTIMIZED | CO_NOFREE)
* Code co_argcount = 2
* Code co_kwonlyargcount = 0
* Cython __Pyx_PyFunction_FastCallDict() called with: nargs=1 and kwargs=NULL
See the Cython issue to a reproducer: https://github.com/cython/cython/issues/4025#issuecomment-801829541
In Python 3.9, _PyFunction_Vectorcall() has the following fast-path:
if (co->co_kwonlyargcount == 0 && nkwargs == 0 &&
(co->co_flags & ~PyCF_MASK) == (CO_OPTIMIZED | CO_NEWLOCALS | CO_NOFREE))
{
if (argdefs == NULL && co->co_argcount == nargs) {
return function_code_fastcall(tstate, co, stack, nargs, globals);
}
else if (nargs == 0 && argdefs != NULL
&& co->co_argcount == PyTuple_GET_SIZE(argdefs)) {
/* function called with no arguments, but all parameters have
a default value: use default values as arguments .*/
stack = _PyTuple_ITEMS(argdefs);
return function_code_fastcall(tstate, co,
stack, PyTuple_GET_SIZE(argdefs),
globals);
}
}
When the bug occurs, __Pyx_PyFunction_FastCallDict() doesn't take the fast-path because nargs < co_argcount (1 < 2).
In Python 3.10, _PyFunction_Vectorcall() is very different:
if (((PyCodeObject *)f->fc_code)->co_flags & CO_OPTIMIZED) {
return _PyEval_Vector(tstate, f, NULL, stack, nargs, kwnames);
}
else {
return _PyEval_Vector(tstate, f, f->fc_globals, stack, nargs, kwnames);
}
PyEval_EvalCodeEx() must not crash if the code object has (CO_NEWLOCALS | CO_OPTIMIZED | CO_NOFREE) flags.
----------
components: C API
messages: 389009
nosy: Mark.Shannon, pablogsal, vstinner
priority: normal
severity: normal
status: open
title: PyEval_EvalCodeEx() can no longer be called with code which has (CO_NEWLOCALS | CO_OPTIMIZED) flags
versions: Python 3.10
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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43541>
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