mirror of https://github.com/python/cpython
271 lines
8.7 KiB
C
271 lines
8.7 KiB
C
#ifndef Py_INTERNAL_STACKREF_H
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#define Py_INTERNAL_STACKREF_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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#include "pycore_object_deferred.h"
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#include <stddef.h>
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#include <stdbool.h>
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/*
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This file introduces a new API for handling references on the stack, called
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_PyStackRef. This API is inspired by HPy.
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There are 3 main operations, that convert _PyStackRef to PyObject* and
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vice versa:
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1. Borrow (discouraged)
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2. Steal
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3. New
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Borrow means that the reference is converted without any change in ownership.
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This is discouraged because it makes verification much harder. It also makes
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unboxed integers harder in the future.
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Steal means that ownership is transferred to something else. The total
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number of references to the object stays the same.
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New creates a new reference from the old reference. The old reference
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is still valid.
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With these 3 API, a strict stack discipline must be maintained. All
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_PyStackRef must be operated on by the new reference operations:
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1. DUP
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2. CLOSE
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DUP is roughly equivalent to Py_NewRef. It creates a new reference from an old
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reference. The old reference remains unchanged.
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CLOSE is roughly equivalent to Py_DECREF. It destroys a reference.
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Note that it is unsafe to borrow a _PyStackRef and then do normal
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CPython refcounting operations on it!
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*/
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typedef union _PyStackRef {
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uintptr_t bits;
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} _PyStackRef;
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#define Py_TAG_DEFERRED (1)
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#define Py_TAG_PTR ((uintptr_t)0)
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#define Py_TAG_BITS ((uintptr_t)1)
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#ifdef Py_GIL_DISABLED
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static const _PyStackRef PyStackRef_NULL = { .bits = Py_TAG_DEFERRED};
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#define PyStackRef_IsNull(stackref) ((stackref).bits == PyStackRef_NULL.bits)
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#define PyStackRef_True ((_PyStackRef){.bits = ((uintptr_t)&_Py_TrueStruct) | Py_TAG_DEFERRED })
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#define PyStackRef_False ((_PyStackRef){.bits = ((uintptr_t)&_Py_FalseStruct) | Py_TAG_DEFERRED })
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#define PyStackRef_None ((_PyStackRef){.bits = ((uintptr_t)&_Py_NoneStruct) | Py_TAG_DEFERRED })
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static inline PyObject *
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PyStackRef_AsPyObjectBorrow(_PyStackRef stackref)
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{
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PyObject *cleared = ((PyObject *)((stackref).bits & (~Py_TAG_BITS)));
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return cleared;
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}
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#define PyStackRef_IsDeferred(ref) (((ref).bits & Py_TAG_BITS) == Py_TAG_DEFERRED)
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static inline PyObject *
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PyStackRef_NotDeferred_AsPyObject(_PyStackRef stackref)
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{
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assert(!PyStackRef_IsDeferred(stackref));
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return (PyObject *)stackref.bits;
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}
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static inline PyObject *
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PyStackRef_AsPyObjectSteal(_PyStackRef stackref)
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{
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assert(!PyStackRef_IsNull(stackref));
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if (PyStackRef_IsDeferred(stackref)) {
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return Py_NewRef(PyStackRef_AsPyObjectBorrow(stackref));
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}
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return PyStackRef_AsPyObjectBorrow(stackref);
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}
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static inline _PyStackRef
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_PyStackRef_FromPyObjectSteal(PyObject *obj)
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{
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assert(obj != NULL);
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// Make sure we don't take an already tagged value.
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assert(((uintptr_t)obj & Py_TAG_BITS) == 0);
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return (_PyStackRef){ .bits = (uintptr_t)obj };
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}
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# define PyStackRef_FromPyObjectSteal(obj) _PyStackRef_FromPyObjectSteal(_PyObject_CAST(obj))
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static inline _PyStackRef
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PyStackRef_FromPyObjectNew(PyObject *obj)
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{
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// Make sure we don't take an already tagged value.
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assert(((uintptr_t)obj & Py_TAG_BITS) == 0);
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assert(obj != NULL);
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if (_Py_IsImmortal(obj) || _PyObject_HasDeferredRefcount(obj)) {
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return (_PyStackRef){ .bits = (uintptr_t)obj | Py_TAG_DEFERRED };
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}
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else {
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return (_PyStackRef){ .bits = (uintptr_t)(Py_NewRef(obj)) | Py_TAG_PTR };
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}
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}
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#define PyStackRef_FromPyObjectNew(obj) PyStackRef_FromPyObjectNew(_PyObject_CAST(obj))
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static inline _PyStackRef
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PyStackRef_FromPyObjectImmortal(PyObject *obj)
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{
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// Make sure we don't take an already tagged value.
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assert(((uintptr_t)obj & Py_TAG_BITS) == 0);
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assert(obj != NULL);
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assert(_Py_IsImmortal(obj));
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return (_PyStackRef){ .bits = (uintptr_t)obj | Py_TAG_DEFERRED };
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}
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#define PyStackRef_FromPyObjectImmortal(obj) PyStackRef_FromPyObjectImmortal(_PyObject_CAST(obj))
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#define PyStackRef_CLOSE(REF) \
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do { \
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_PyStackRef _close_tmp = (REF); \
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assert(!PyStackRef_IsNull(_close_tmp)); \
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if (!PyStackRef_IsDeferred(_close_tmp)) { \
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Py_DECREF(PyStackRef_AsPyObjectBorrow(_close_tmp)); \
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} \
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} while (0)
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static inline _PyStackRef
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PyStackRef_DUP(_PyStackRef stackref)
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{
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assert(!PyStackRef_IsNull(stackref));
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if (PyStackRef_IsDeferred(stackref)) {
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assert(_Py_IsImmortal(PyStackRef_AsPyObjectBorrow(stackref)) ||
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_PyObject_HasDeferredRefcount(PyStackRef_AsPyObjectBorrow(stackref))
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);
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return stackref;
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}
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Py_INCREF(PyStackRef_AsPyObjectBorrow(stackref));
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return stackref;
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}
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// Convert a possibly deferred reference to a strong reference.
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static inline _PyStackRef
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PyStackRef_AsStrongReference(_PyStackRef stackref)
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{
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return PyStackRef_FromPyObjectSteal(PyStackRef_AsPyObjectSteal(stackref));
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}
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#define PyStackRef_CLOSE_SPECIALIZED(stackref, dealloc) PyStackRef_CLOSE(stackref)
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#else // Py_GIL_DISABLED
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// With GIL
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static const _PyStackRef PyStackRef_NULL = { .bits = 0 };
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#define PyStackRef_IsNull(stackref) ((stackref).bits == 0)
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#define PyStackRef_True ((_PyStackRef){.bits = (uintptr_t)&_Py_TrueStruct })
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#define PyStackRef_False ((_PyStackRef){.bits = ((uintptr_t)&_Py_FalseStruct) })
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#define PyStackRef_None ((_PyStackRef){.bits = ((uintptr_t)&_Py_NoneStruct) })
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#define PyStackRef_AsPyObjectBorrow(stackref) ((PyObject *)(stackref).bits)
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#define PyStackRef_AsPyObjectSteal(stackref) PyStackRef_AsPyObjectBorrow(stackref)
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#define PyStackRef_FromPyObjectSteal(obj) ((_PyStackRef){.bits = ((uintptr_t)(obj))})
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#define PyStackRef_FromPyObjectNew(obj) ((_PyStackRef){ .bits = (uintptr_t)(Py_NewRef(obj)) })
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#define PyStackRef_FromPyObjectImmortal(obj) ((_PyStackRef){ .bits = (uintptr_t)(obj) })
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#define PyStackRef_CLOSE(stackref) Py_DECREF(PyStackRef_AsPyObjectBorrow(stackref))
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#define PyStackRef_DUP(stackref) PyStackRef_FromPyObjectSteal(Py_NewRef(PyStackRef_AsPyObjectBorrow(stackref)))
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#define PyStackRef_CLOSE_SPECIALIZED(stackref, dealloc) _Py_DECREF_SPECIALIZED(PyStackRef_AsPyObjectBorrow(stackref), dealloc)
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#endif // Py_GIL_DISABLED
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// Check if a stackref is exactly the same as another stackref, including the
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// the deferred bit. This can only be used safely if you know that the deferred
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// bits of `a` and `b` match.
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#define PyStackRef_IsExactly(a, b) \
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(assert(((a).bits & Py_TAG_BITS) == ((b).bits & Py_TAG_BITS)), (a).bits == (b).bits)
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// Checks that mask out the deferred bit in the free threading build.
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#define PyStackRef_IsNone(ref) (PyStackRef_AsPyObjectBorrow(ref) == Py_None)
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#define PyStackRef_IsTrue(ref) (PyStackRef_AsPyObjectBorrow(ref) == Py_True)
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#define PyStackRef_IsFalse(ref) (PyStackRef_AsPyObjectBorrow(ref) == Py_False)
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// Converts a PyStackRef back to a PyObject *, converting the
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// stackref to a new reference.
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#define PyStackRef_AsPyObjectNew(stackref) Py_NewRef(PyStackRef_AsPyObjectBorrow(stackref))
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#define PyStackRef_TYPE(stackref) Py_TYPE(PyStackRef_AsPyObjectBorrow(stackref))
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#define PyStackRef_CLEAR(op) \
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do { \
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_PyStackRef *_tmp_op_ptr = &(op); \
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_PyStackRef _tmp_old_op = (*_tmp_op_ptr); \
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if (!PyStackRef_IsNull(_tmp_old_op)) { \
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*_tmp_op_ptr = PyStackRef_NULL; \
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PyStackRef_CLOSE(_tmp_old_op); \
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} \
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} while (0)
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#define PyStackRef_XCLOSE(stackref) \
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do { \
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_PyStackRef _tmp = (stackref); \
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if (!PyStackRef_IsNull(_tmp)) { \
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PyStackRef_CLOSE(_tmp); \
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} \
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} while (0);
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// StackRef type checks
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static inline bool
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PyStackRef_GenCheck(_PyStackRef stackref)
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{
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return PyGen_Check(PyStackRef_AsPyObjectBorrow(stackref));
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}
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static inline bool
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PyStackRef_BoolCheck(_PyStackRef stackref)
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{
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return PyBool_Check(PyStackRef_AsPyObjectBorrow(stackref));
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}
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static inline bool
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PyStackRef_LongCheck(_PyStackRef stackref)
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{
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return PyLong_Check(PyStackRef_AsPyObjectBorrow(stackref));
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}
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static inline bool
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PyStackRef_ExceptionInstanceCheck(_PyStackRef stackref)
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{
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return PyExceptionInstance_Check(PyStackRef_AsPyObjectBorrow(stackref));
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}
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static inline bool
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PyStackRef_CodeCheck(_PyStackRef stackref)
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{
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return PyCode_Check(PyStackRef_AsPyObjectBorrow(stackref));
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}
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static inline bool
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PyStackRef_FunctionCheck(_PyStackRef stackref)
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{
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return PyFunction_Check(PyStackRef_AsPyObjectBorrow(stackref));
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_INTERNAL_STACKREF_H */
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