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bpo-46541: Replace core use of _Py_IDENTIFIER() with statically initialized global objects. (gh-30928)

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We're no longer using _Py_IDENTIFIER() (or _Py_static_string()) in any core CPython code.  It is still used in a number of non-builtin stdlib modules.

The replacement is: PyUnicodeObject (not pointer) fields under _PyRuntimeState, statically initialized as part of _PyRuntime.  A new _Py_GET_GLOBAL_IDENTIFIER() macro facilitates lookup of the fields (along with _Py_GET_GLOBAL_STRING() for non-identifier strings).

https://bugs.python.org/issue46541#msg411799 explains the rationale for this change.

The core of the change is in:

* (new) Include/internal/pycore_global_strings.h - the declarations for the global strings, along with the macros
* Include/internal/pycore_runtime_init.h - added the static initializers for the global strings
* Include/internal/pycore_global_objects.h - where the struct in pycore_global_strings.h is hooked into _PyRuntimeState
* Tools/scripts/generate_global_objects.py - added generation of the global string declarations and static initializers

I've also added a --check flag to generate_global_objects.py (along with make check-global-objects) to check for unused global strings.  That check is added to the PR CI config.

The remainder of this change updates the core code to use _Py_GET_GLOBAL_IDENTIFIER() instead of _Py_IDENTIFIER() and the related _Py*Id functions (likewise for _Py_GET_GLOBAL_STRING() instead of _Py_static_string()).  This includes adding a few functions where there wasn't already an alternative to _Py*Id(), replacing the _Py_Identifier * parameter with PyObject *.

The following are not changed (yet):

* stop using _Py_IDENTIFIER() in the stdlib modules
* (maybe) get rid of _Py_IDENTIFIER(), etc. entirely -- this may not be doable as at least one package on PyPI using this (private) API
* (maybe) intern the strings during runtime init

https://bugs.python.org/issue46541
This commit is contained in:
Eric Snow 2022-02-08 13:39:07 -07:00 • committed by GitHub
parent c018d3037b
commit 81c72044a1
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GPG key ID: 4AEE18F83AFDEB23
108 changed files with 2282 additions and 1573 deletions
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22
Python/specialize.c
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@ -1,6 +1,7 @@
#include "Python.h"
#include "pycore_code.h"
#include "pycore_dict.h"
#include "pycore_global_strings.h" // _Py_ID()
#include "pycore_long.h"
#include "pycore_moduleobject.h"
#include "pycore_object.h"
@ -596,8 +597,6 @@ specialize_module_load_attr(
{
PyModuleObject *m = (PyModuleObject *)owner;
PyObject *value = NULL;
PyObject *getattr;
_Py_IDENTIFIER(__getattr__);
assert((owner->ob_type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0);
PyDictObject *dict = (PyDictObject *)m->md_dict;
if (dict == NULL) {
@ -608,13 +607,8 @@ specialize_module_load_attr(
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_NON_STRING_OR_SPLIT);
return -1;
}
getattr = _PyUnicode_FromId(&PyId___getattr__); /* borrowed */
if (getattr == NULL) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_OVERRIDDEN);
PyErr_Clear();
return -1;
}
Py_ssize_t index = _PyDict_GetItemHint(dict, getattr, -1, &value);
Py_ssize_t index = _PyDict_GetItemHint(dict, &_Py_ID(__getattr__), -1,
&value);
assert(index != DKIX_ERROR);
if (index != DKIX_EMPTY) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_MODULE_ATTR_NOT_FOUND);
@ -1223,7 +1217,6 @@ binary_subscr_fail_kind(PyTypeObject *container_type, PyObject *sub)
}
#endif
_Py_IDENTIFIER(__getitem__);
#define SIMPLE_FUNCTION 0
@ -1268,7 +1261,7 @@ _Py_Specialize_BinarySubscr(
goto success;
}
PyTypeObject *cls = Py_TYPE(container);
PyObject *descriptor = _PyType_LookupId(cls, &PyId___getitem__);
PyObject *descriptor = _PyType_Lookup(cls, &_Py_ID(__getitem__));
if (descriptor && Py_TYPE(descriptor) == &PyFunction_Type) {
PyFunctionObject *func = (PyFunctionObject *)descriptor;
PyCodeObject *code = (PyCodeObject *)func->func_code;
@ -1385,8 +1378,7 @@ _Py_Specialize_StoreSubscr(PyObject *container, PyObject *sub, _Py_CODEUNIT *ins
}
goto fail;
}
_Py_IDENTIFIER(__setitem__);
PyObject *descriptor = _PyType_LookupId(container_type, &PyId___setitem__);
PyObject *descriptor = _PyType_Lookup(container_type, &_Py_ID(__setitem__));
if (descriptor && Py_TYPE(descriptor) == &PyFunction_Type) {
PyFunctionObject *func = (PyFunctionObject *)descriptor;
PyCodeObject *code = (PyCodeObject *)func->func_code;
@ -1474,7 +1466,6 @@ builtin_call_fail_kind(int ml_flags)
#endif
static PyMethodDescrObject *_list_append = NULL;
_Py_IDENTIFIER(append);
static int
specialize_method_descriptor(
@ -1486,7 +1477,8 @@ specialize_method_descriptor(
return -1;
}
if (_list_append == NULL) {
_list_append = (PyMethodDescrObject *)_PyType_LookupId(&PyList_Type, &PyId_append);
_list_append = (PyMethodDescrObject *)_PyType_Lookup(&PyList_Type,
&_Py_ID(append));
}
assert(_list_append != NULL);
if (nargs == 2 && descr == _list_append) {