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don't expand the operand to Py_XINCREF/XDECREF/CLEAR/DECREF multiple times (closes #17206)

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A patch from Illia Polosukhin.
This commit is contained in:
Benjamin Peterson 2013-05-27 14:46:14 -07:00
parent e7b47dda64
commit da5eb5a31c
4 changed files with 71 additions and 14 deletions
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34
Include/object.h
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@ -680,12 +680,6 @@ is not considered to be a reference to the type object, to save
complications in the deallocation function. (This is actually a
decision that's up to the implementer of each new type so if you want,
you can count such references to the type object.)
*** WARNING*** The Py_DECREF macro must have a side-effect-free argument
since it may evaluate its argument multiple times. (The alternative
would be to mace it a proper function or assign it to a global temporary
variable first, both of which are slower; and in a multi-threaded
environment the global variable trick is not safe.)
*/
/* First define a pile of simple helper macros, one set per special
@ -764,15 +758,16 @@ PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
#define Py_INCREF(op) ( \
_Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
((PyObject*)(op))->ob_refcnt++)
((PyObject *)(op))->ob_refcnt++)
#define Py_DECREF(op) \
do { \
PyObject *_py_decref_tmp = (PyObject *)(op); \
if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \
--((PyObject*)(op))->ob_refcnt != 0) \
_Py_CHECK_REFCNT(op) \
--(_py_decref_tmp)->ob_refcnt != 0) \
_Py_CHECK_REFCNT(_py_decref_tmp) \
else \
_Py_Dealloc((PyObject *)(op)); \
_Py_Dealloc(_py_decref_tmp); \
} while (0)
/* Safely decref `op` and set `op` to NULL, especially useful in tp_clear
@ -811,16 +806,27 @@ PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
*/
#define Py_CLEAR(op) \
do { \
if (op) { \
PyObject *_py_tmp = (PyObject *)(op); \
PyObject *_py_tmp = (PyObject *)(op); \
if (_py_tmp != NULL) { \
(op) = NULL; \
Py_DECREF(_py_tmp); \
} \
} while (0)
/* Macros to use in case the object pointer may be NULL: */
#define Py_XINCREF(op) do { if ((op) == NULL) ; else Py_INCREF(op); } while (0)
#define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0)
#define Py_XINCREF(op) \
do { \
PyObject *_py_xincref_tmp = (PyObject *)(op); \
if (_py_xincref_tmp != NULL) \
Py_INCREF(_py_xincref_tmp); \
} while (0)
#define Py_XDECREF(op) \
do { \
PyObject *_py_xdecref_tmp = (PyObject *)(op); \
if (_py_xdecref_tmp != NULL) \
Py_DECREF(_py_xdecref_tmp); \
} while (0)
/*
These are provided as conveniences to Python runtime embedders, so that