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gh-127271: Replace use of PyCell_GET/SET (gh-127272)

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* Replace uses of `PyCell_GET` and `PyCell_SET`.  These macros are not
  safe to use in the free-threaded build.  Use `PyCell_GetRef()` and
  `PyCell_SetTakeRef()` instead. 

* Since `PyCell_GetRef()` returns a strong rather than borrowed ref, some
  code restructuring was required, e.g. `frame_get_var()` returns a strong
  ref now.

* Add critical sections to `PyCell_GET` and `PyCell_SET`.

* Move critical_section.h earlier in the Python.h file.

* Add `PyCell_GET` to the free-threading howto table of APIs that return
  borrowed refs.

* Add additional unit tests for free-threading.
This commit is contained in:
Neil Schemenauer
2024-12-03 10:33:06 -08:00
committed by GitHub
parent 276cd66ccb
commit fc5a0dc224
8 changed files with 231 additions and 48 deletions
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28
Objects/frameobject.c
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@@ -8,6 +8,7 @@
#include "pycore_moduleobject.h" // _PyModule_GetDict()
#include "pycore_modsupport.h" // _PyArg_CheckPositional()
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
#include "pycore_cell.h" // PyCell_GetRef() PyCell_SetTakeRef()
#include "pycore_opcode_metadata.h" // _PyOpcode_Deopt, _PyOpcode_Caches
@@ -187,11 +188,8 @@ framelocalsproxy_setitem(PyObject *self, PyObject *key, PyObject *value)
}
}
if (cell != NULL) {
PyObject *oldvalue_o = PyCell_GET(cell);
if (value != oldvalue_o) {
PyCell_SET(cell, Py_XNewRef(value));
Py_XDECREF(oldvalue_o);
}
Py_XINCREF(value);
PyCell_SetTakeRef((PyCellObject *)cell, value);
} else if (value != PyStackRef_AsPyObjectBorrow(oldvalue)) {
PyStackRef_XCLOSE(fast[i]);
fast[i] = PyStackRef_FromPyObjectNew(value);
@@ -1987,19 +1985,25 @@ frame_get_var(_PyInterpreterFrame *frame, PyCodeObject *co, int i,
if (kind & CO_FAST_FREE) {
// The cell was set by COPY_FREE_VARS.
assert(value != NULL && PyCell_Check(value));
value = PyCell_GET(value);
value = PyCell_GetRef((PyCellObject *)value);
}
else if (kind & CO_FAST_CELL) {
if (value != NULL) {
if (PyCell_Check(value)) {
assert(!_PyFrame_IsIncomplete(frame));
value = PyCell_GET(value);
value = PyCell_GetRef((PyCellObject *)value);
}
else {
// (likely) Otherwise it is an arg (kind & CO_FAST_LOCAL),
// with the initial value set when the frame was created...
// (unlikely) ...or it was set via the f_locals proxy.
Py_INCREF(value);
}
// (likely) Otherwise it is an arg (kind & CO_FAST_LOCAL),
// with the initial value set when the frame was created...
// (unlikely) ...or it was set via the f_locals proxy.
}
}
else {
Py_XINCREF(value);
}
}
*pvalue = value;
return 1;
@@ -2076,14 +2080,14 @@ PyFrame_GetVar(PyFrameObject *frame_obj, PyObject *name)
continue;
}
PyObject *value; // borrowed reference
PyObject *value;
if (!frame_get_var(frame, co, i, &value)) {
break;
}
if (value == NULL) {
break;
}
return Py_NewRef(value);
return value;
}
PyErr_Format(PyExc_NameError, "variable %R does not exist", name);