cpython: aff41a6421c2 (original) (raw)

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changeset 83937:aff41a6421c2

don't expand the operand to Py_XINCREF/XDECREF/CLEAR/DECREF multiple times (closes #17206) A patch from Illia Polosukhin. [#17206]

Benjamin Peterson benjamin@python.org
date	Mon, 27 May 2013 14:46:14 -0700
parents	39e0be9106c1
children	789f8bbf0ae7
files	Include/object.h Misc/ACKS Misc/NEWS Modules/_testcapimodule.c
diffstat	4 files changed, 71 insertions(+), 14 deletions(-)[+] [-] Include/object.h 34 Misc/ACKS 1 Misc/NEWS 4 Modules/_testcapimodule.c 46

line wrap: on

line diff

--- a/Include/object.h +++ b/Include/object.h @@ -680,12 +680,6 @@ is not considered to be a reference to t 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) ( [](#l1.18) _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA [](#l1.19)

((PyObject*)(op))->ob_refcnt++)

((PyObject *)(op))->ob_refcnt++)

#define Py_DECREF(op) [](#l1.23) do { [](#l1.24)

   PyObject *_py_decref_tmp = (PyObject *)(op);    \[](#l1.25)
   if (_Py_DEC_REFTOTAL  _Py_REF_DEBUG_COMMA       \[](#l1.26)

   --((PyObject*)(op))->ob_refcnt != 0)            \[](#l1.27)

       _Py_CHECK_REFCNT(op)                        \[](#l1.28)

   --(_py_decref_tmp)->ob_refcnt != 0)             \[](#l1.29)

       _Py_CHECK_REFCNT(_py_decref_tmp)            \[](#l1.30)
   else                                            \[](#l1.31)

   _Py_Dealloc((PyObject *)(op));                  \[](#l1.32)

```
   _Py_Dealloc(_py_decref_tmp);                    \[](#l1.33)
```
} 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) [](#l1.39) do { [](#l1.40)

   if (op) {                               \[](#l1.41)

       PyObject *_py_tmp = (PyObject *)(op);               \[](#l1.42)

   PyObject *_py_tmp = (PyObject *)(op);   \[](#l1.43)

```
   if (_py_tmp != NULL) {                  \[](#l1.44)
       (op) = NULL;                        \[](#l1.45)
       Py_DECREF(_py_tmp);                 \[](#l1.46)
   }                                       \[](#l1.47)
```
} 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) [](#l1.53)
do { [](#l1.54)

   PyObject *_py_xincref_tmp = (PyObject *)(op); \[](#l1.55)

   if (_py_xincref_tmp != NULL)                  \[](#l1.56)

       Py_INCREF(_py_xincref_tmp);               \[](#l1.57)

} while (0)

+ +#define Py_XDECREF(op) [](#l1.60)

do { [](#l1.61)

   PyObject *_py_xdecref_tmp = (PyObject *)(op); \[](#l1.62)

   if (_py_xdecref_tmp != NULL)                  \[](#l1.63)

       Py_DECREF(_py_xdecref_tmp);               \[](#l1.64)

} while (0)

/* These are provided as conveniences to Python runtime embedders, so that

--- a/Misc/ACKS +++ b/Misc/ACKS @@ -983,6 +983,7 @@ Oleg Plakhotnyuk Remi Pointel Ariel Poliak Guilherme Polo +Illia Polosukhin Michael Pomraning Iustin Pop Claudiu Popa

--- a/Misc/NEWS +++ b/Misc/NEWS @@ -10,6 +10,10 @@ What's New in Python 3.4.0 Alpha 1? Core and Builtins ----------------- +- Issue #17206: Py_CLEAR(), Py_DECREF(), Py_XINCREF() and Py_XDECREF() now

expands their arguments once instead of multiple times.
Patch written by Illia Polosukhin. +

Issue #17937: Try harder to collect cyclic garbage at shutdown.
Issue #12370: Prevent class bodies from interfering with the class

--- a/Modules/_testcapimodule.c +++ b/Modules/_testcapimodule.c @@ -2468,6 +2468,48 @@ test_pytime_object_to_timespec(PyObject return Py_BuildValue("Nl", _PyLong_FromTime_t(sec), nsec); } +static PyObject * +_test_incref(PyObject *ob) +{

Py_INCREF(ob);
return ob;

+} + +static PyObject * +test_xincref_doesnt_leak(PyObject *ob) +{

PyObject *obj = PyLong_FromLong(0);
Py_XINCREF(_test_incref(obj));
Py_DECREF(obj);
Py_DECREF(obj);
Py_DECREF(obj);
Py_RETURN_NONE;

+} + +static PyObject * +test_incref_doesnt_leak(PyObject *ob) +{

PyObject *obj = PyLong_FromLong(0);
Py_INCREF(_test_incref(obj));
Py_DECREF(obj);
Py_DECREF(obj);
Py_DECREF(obj);
Py_RETURN_NONE;

+} + +static PyObject * +test_xdecref_doesnt_leak(PyObject *ob) +{

Py_XDECREF(PyLong_FromLong(0));
Py_RETURN_NONE;

+} + +static PyObject * +test_decref_doesnt_leak(PyObject *ob) +{

Py_DECREF(PyLong_FromLong(0));
Py_RETURN_NONE;

+} static PyMethodDef TestMethods[] = { {"raise_exception", raise_exception, METH_VARARGS}, @@ -2478,6 +2520,10 @@ static PyMethodDef TestMethods[] = { {"test_dict_iteration", (PyCFunction)test_dict_iteration,METH_NOARGS}, {"test_lazy_hash_inheritance", (PyCFunction)test_lazy_hash_inheritance,METH_NOARGS}, {"test_long_api", (PyCFunction)test_long_api, METH_NOARGS},

{"test_xincref_doesnt_leak",(PyCFunction)test_xincref_doesnt_leak, METH_NOARGS},
{"test_incref_doesnt_leak", (PyCFunction)test_incref_doesnt_leak, METH_NOARGS},
{"test_xdecref_doesnt_leak",(PyCFunction)test_xdecref_doesnt_leak, METH_NOARGS},
{"test_decref_doesnt_leak", (PyCFunction)test_decref_doesnt_leak, METH_NOARGS}, {"test_long_and_overflow", (PyCFunction)test_long_and_overflow, METH_NOARGS}, {"test_long_as_double", (PyCFunction)test_long_as_double,METH_NOARGS},