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Do not check immortality at PyStackRef_FromPyObjectSteal

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This commit is contained in:
Mikhail Efimov 2025-12-20 20:06:12 +03:00
parent 5989095dfd
commit 2cc17c7959
2 changed files with 17 additions and 39 deletions
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52
Include/internal/pycore_stackref.h
View file

@ -8,7 +8,7 @@ extern "C" {
# error "this header requires Py_BUILD_CORE define"
#endif
#include "pycore_object.h" // Py_DECREF_MORTAL
#include "pycore_object.h" // _Py_DECREF_SPECIALIZED
#include "pycore_object_deferred.h" // _PyObject_HasDeferredRefcount()
#include <stdbool.h> // bool
@ -195,11 +195,7 @@ static inline _PyStackRef
_PyStackRef_FromPyObjectSteal(PyObject *obj, const char *filename, int linenumber)
{
assert(obj != NULL);
uint16_t flags = 0;
if (_Py_IsImmortal(obj)) {
flags = Py_TAG_REFCNT;
}
return _Py_stackref_create(obj, flags, filename, linenumber);
return _Py_stackref_create(obj, 0, filename, linenumber);
}
#define PyStackRef_FromPyObjectSteal(obj) _PyStackRef_FromPyObjectSteal(_PyObject_CAST(obj), __FILE__, __LINE__)
@ -347,8 +343,8 @@ static inline _PyStackRef
_PyStackRef_FromPyObjectNewMortal(PyObject *obj, const char *filename, int linenumber)
{
assert(obj != NULL);
assert(!_Py_IsStaticImmortal(obj));
Py_INCREF(obj);
assert(!_Py_IsImmortal(obj));
_Py_INCREF_MORTAL(obj);
return _Py_stackref_create(obj, 0, filename, linenumber);
}
#define PyStackRef_FromPyObjectNewMortal(obj) _PyStackRef_FromPyObjectNewMortal(_PyObject_CAST(obj), __FILE__, __LINE__)
@ -483,24 +479,14 @@ static const _PyStackRef PyStackRef_NULL = { .bits = PyStackRef_NULL_BITS };
#define PyStackRef_IsNullOrInt(stackref) (PyStackRef_IsNull(stackref) || PyStackRef_IsTaggedInt(stackref))
#if defined(Py_DEBUG) && !defined(Py_GIL_DISABLED)
#if defined(Py_DEBUG)
static inline void
PyStackRef_CheckValid(_PyStackRef ref)
{
assert(ref.bits != 0);
int tag = ref.bits & Py_TAG_BITS;
PyObject *obj = BITS_TO_PTR_MASKED(ref);
switch (tag) {
case 0:
/* Can be immortal if object was made immortal after reference came into existence */
assert(!_Py_IsStaticImmortal(obj));
break;
case Py_TAG_REFCNT:
break;
default:
assert(0);
}
assert((tag == 0) || (tag == Py_TAG_REFCNT));
}
#else
@ -514,7 +500,7 @@ PyStackRef_CheckValid(_PyStackRef ref)
#define PyStackRef_AsPyObjectBorrow BITS_TO_PTR_MASKED
#define PyStackRef_Borrow(REF) (_PyStackRef){ .bits = ((REF).bits) | Py_TAG_REFCNT};
#else
/* Does this ref not have an embedded refcount and thus not refer to a declared immmortal object? */
/* Does this ref not have an embedded refcount? */
static inline int
PyStackRef_RefcountOnObject(_PyStackRef ref)
{
@ -552,18 +538,9 @@ static inline _PyStackRef
PyStackRef_FromPyObjectSteal(PyObject *obj)
{
assert(obj != NULL);
#ifdef Py_GIL_DISABLED
return (_PyStackRef){ .bits = (uintptr_t)obj };
#else
# if SIZEOF_VOID_P > 4
unsigned int tag = obj->ob_flags & Py_TAG_REFCNT;
# else
unsigned int tag = _Py_IsImmortal(obj) ? Py_TAG_REFCNT : 0;
# endif
_PyStackRef ref = ((_PyStackRef){.bits = ((uintptr_t)(obj)) | tag});
_PyStackRef ref = (_PyStackRef){ .bits = (uintptr_t)obj };
PyStackRef_CheckValid(ref);
return ref;
#endif
}
static inline _PyStackRef
@ -600,6 +577,7 @@ static inline _PyStackRef
_PyStackRef_FromPyObjectNewMortal(PyObject *obj)
{
assert(obj != NULL);
assert(!_Py_IsImmortal(obj));
_Py_INCREF_MORTAL(obj);
_PyStackRef ref = (_PyStackRef){ .bits = (uintptr_t)obj };
PyStackRef_CheckValid(ref);
@ -618,14 +596,14 @@ PyStackRef_FromPyObjectBorrow(PyObject *obj)
/* WARNING: This macro evaluates its argument more than once */
#ifdef _WIN32
#define PyStackRef_DUP(REF) \
(PyStackRef_RefcountOnObject(REF) ? (_Py_INCREF_MORTAL(BITS_TO_PTR(REF)), (REF)) : (REF))
(PyStackRef_RefcountOnObject(REF) ? (Py_INCREF(BITS_TO_PTR(REF)), (REF)) : (REF))
#else
static inline _PyStackRef
PyStackRef_DUP(_PyStackRef ref)
{
assert(!PyStackRef_IsNull(ref));
if (PyStackRef_RefcountOnObject(ref)) {
_Py_INCREF_MORTAL(BITS_TO_PTR(ref));
Py_INCREF(BITS_TO_PTR(ref));
}
return ref;
}
@ -669,7 +647,7 @@ PyStackRef_AsStrongReference(_PyStackRef stackref)
#define PyStackRef_CLOSE(REF) \
do { \
_PyStackRef _temp = (REF); \
if (PyStackRef_RefcountOnObject(_temp)) Py_DECREF_MORTAL(BITS_TO_PTR(_temp)); \
if (PyStackRef_RefcountOnObject(_temp)) Py_DECREF(BITS_TO_PTR(_temp)); \
} while (0)
#else
static inline void
@ -677,7 +655,7 @@ PyStackRef_CLOSE(_PyStackRef ref)
{
assert(!PyStackRef_IsNull(ref));
if (PyStackRef_RefcountOnObject(ref)) {
Py_DECREF_MORTAL(BITS_TO_PTR(ref));
Py_DECREF(BITS_TO_PTR(ref));
}
}
#endif
@ -687,7 +665,7 @@ PyStackRef_CLOSE_SPECIALIZED(_PyStackRef ref, destructor destruct)
{
assert(!PyStackRef_IsNull(ref));
if (PyStackRef_RefcountOnObject(ref)) {
Py_DECREF_MORTAL_SPECIALIZED(BITS_TO_PTR(ref), destruct);
_Py_DECREF_SPECIALIZED(BITS_TO_PTR(ref), destruct);
}
}
@ -700,7 +678,7 @@ PyStackRef_XCLOSE(_PyStackRef ref)
assert(ref.bits != 0);
if (PyStackRef_RefcountOnObject(ref)) {
assert(!PyStackRef_IsNull(ref));
Py_DECREF_MORTAL(BITS_TO_PTR(ref));
Py_DECREF(BITS_TO_PTR(ref));
}
}
#endif

4
InternalDocs/stackrefs.md
View file

@ -21,8 +21,8 @@ to avoid refcount contention on commonly shared objects.
Three conversions control ownership:
- `PyStackRef_FromPyObjectNew(obj)` - create a new reference (INCREF if mortal).
- `PyStackRef_FromPyObjectSteal(obj)` - take over ownership without changing the count unless the
object is immortal.
- `PyStackRef_FromPyObjectSteal(obj)` - take over ownership without changing the count;
this function is very lightweight since it does not check or modify any refcount.
- `PyStackRef_FromPyObjectBorrow(obj)` - create a borrowed stackref (never decref on close).
The `obj` argument must not be `NULL`.