gh-102192: Replace PyErr_Fetch/Restore etc by more efficient alternatives (in Objects/)

Objects/dictobject.c

@@ -119,7 +119,7 @@ As a consequence of this, split keys have a maximum size of 16.
 #include "pycore_dict.h" // PyDictKeysObject
 #include "pycore_gc.h" // _PyObject_GC_IS_TRACKED()
 #include "pycore_object.h" // _PyObject_GC_TRACK()
-#include "pycore_pyerrors.h" // _PyErr_Fetch()
+#include "pycore_pyerrors.h" // _PyErr_GetRaisedException()
 #include "pycore_pystate.h" // _PyThreadState_GET()
 #include "stringlib/eq.h" // unicode_eq()
 

Objects/exceptions.c

@@ -3781,16 +3781,13 @@ PyObject *
 _PyErr_TrySetFromCause(const char *format, ...)
 {
  PyObject* msg_prefix;
- PyObject *exc, *val, *tb;
- PyTypeObject *caught_type;
  PyObject *instance_args;
  Py_ssize_t num_args, caught_type_size, base_exc_size;
- PyObject *new_exc, *new_val, *new_tb;
  va_list vargs;
  int same_basic_size;
 
-PyErr_Fetch(&exc, &val, &tb);
- caught_type = (PyTypeObject *)exc;
+PyObject *exc = PyErr_GetRaisedException();
+PyTypeObject *caught_type = Py_TYPE(exc);
  /* Ensure type info indicates no extra state is stored at the C level
  * and that the type can be reinstantiated using PyErr_Format
  */
@@ -3810,31 +3807,30 @@ _PyErr_TrySetFromCause(const char *format, ...)
  * more state than just the exception type. Accordingly, we just
  * leave it alone.
  */
-PyErr_Restore(exc, val, tb);
+PyErr_SetRaisedException(exc);
  return NULL;
  }
 
  /* Check the args are empty or contain a single string */
- PyErr_NormalizeException(&exc, &val, &tb);
- instance_args = ((PyBaseExceptionObject *)val)->args;
+ instance_args = ((PyBaseExceptionObject *)exc)->args;
  num_args = PyTuple_GET_SIZE(instance_args);
  if (num_args > 1 ||
  (num_args == 1 &&
  !PyUnicode_CheckExact(PyTuple_GET_ITEM(instance_args, 0)))){
  /* More than 1 arg, or the one arg we do have isn't a string
  */
-PyErr_Restore(exc, val, tb);
+PyErr_SetRaisedException(exc);
  return NULL;
  }
 
  /* Ensure the instance dict is also empty */
- if (!_PyObject_IsInstanceDictEmpty(val)){
+ if (!_PyObject_IsInstanceDictEmpty(exc)){
  /* While we could potentially copy a non-empty instance dictionary
  * to the replacement exception, for now we take the more
  * conservative path of leaving exceptions with attributes set
  * alone.
  */
-PyErr_Restore(exc, val, tb);
+PyErr_SetRaisedException(exc);
  return NULL;
  }
 
@@ -3847,28 +3843,19 @@ _PyErr_TrySetFromCause(const char *format, ...)
  * types as well, but that's quite a bit trickier due to the extra
  * state potentially stored on OSError instances.
  */
- /* Ensure the traceback is set correctly on the existing exception */
- if (tb != NULL){
- PyException_SetTraceback(val, tb);
- Py_DECREF(tb);
- }
-
  va_start(vargs, format);
  msg_prefix = PyUnicode_FromFormatV(format, vargs);
  va_end(vargs);
  if (msg_prefix == NULL){
  Py_DECREF(exc);
- Py_DECREF(val);
  return NULL;
  }
 
- PyErr_Format(exc, "%U (%s: %S)",
- msg_prefix, Py_TYPE(val)->tp_name, val);
- Py_DECREF(exc);
+ PyErr_Format((PyObject*)Py_TYPE(exc), "%U (%s: %S)",
+ msg_prefix, Py_TYPE(exc)->tp_name, exc);
  Py_DECREF(msg_prefix);
- PyErr_Fetch(&new_exc, &new_val, &new_tb);
- PyErr_NormalizeException(&new_exc, &new_val, &new_tb);
- PyException_SetCause(new_val, val);
- PyErr_Restore(new_exc, new_val, new_tb);
- return new_val;
+ PyObject *new_exc = PyErr_GetRaisedException();
+ PyException_SetCause(new_exc, exc);
+ PyErr_SetRaisedException(new_exc);
+ return new_exc;
 }

Objects/frameobject.c

@@ -1308,7 +1308,6 @@ _PyFrame_LocalsToFast(_PyInterpreterFrame *frame, int clear)
  /* Merge locals into fast locals */
  PyObject *locals;
  PyObject **fast;
- PyObject *error_type, *error_value, *error_traceback;
  PyCodeObject *co;
  locals = frame->f_locals;
  if (locals == NULL){
@@ -1317,7 +1316,7 @@ _PyFrame_LocalsToFast(_PyInterpreterFrame *frame, int clear)
  fast = _PyFrame_GetLocalsArray(frame);
  co = frame->f_code;
 
-PyErr_Fetch(&error_type, &error_value, &error_traceback);
+PyObject *exc = PyErr_GetRaisedException();
  for (int i = 0; i < co->co_nlocalsplus; i++){
  _PyLocals_Kind kind = _PyLocals_GetKind(co->co_localspluskinds, i);
 
@@ -1374,7 +1373,7 @@ _PyFrame_LocalsToFast(_PyInterpreterFrame *frame, int clear)
  }
  Py_XDECREF(value);
  }
-PyErr_Restore(error_type, error_value, error_traceback);
+PyErr_SetRaisedException(exc);
 }
 
 void

Objects/genobject.c

@@ -69,8 +69,6 @@ void
 _PyGen_Finalize(PyObject *self)
 {
  PyGenObject *gen = (PyGenObject *)self;
- PyObject *res = NULL;
- PyObject *error_type, *error_value, *error_traceback;
 
  if (gen->gi_frame_state >= FRAME_COMPLETED){
  /* Generator isn't paused, so no need to close */
@@ -82,23 +80,22 @@ _PyGen_Finalize(PyObject *self)
  PyObject *finalizer = agen->ag_origin_or_finalizer;
  if (finalizer && !agen->ag_closed){
  /* Save the current exception, if any. */
- PyErr_Fetch(&error_type, &error_value, &error_traceback);
-
- res = PyObject_CallOneArg(finalizer, self);
+ PyObject *exc = PyErr_GetRaisedException();
 
+ PyObject *res = PyObject_CallOneArg(finalizer, self);
  if (res == NULL){
  PyErr_WriteUnraisable(self);
  } else{
  Py_DECREF(res);
  }
  /* Restore the saved exception. */
-PyErr_Restore(error_type, error_value, error_traceback);
+PyErr_SetRaisedException(exc);
  return;
  }
  }
 
  /* Save the current exception, if any. */
-PyErr_Fetch(&error_type, &error_value, &error_traceback);
+PyObject *exc = PyErr_GetRaisedException();
 
  /* If `gen` is a coroutine, and if it was never awaited on,
  issue a RuntimeWarning. */
@@ -109,20 +106,19 @@ _PyGen_Finalize(PyObject *self)
  _PyErr_WarnUnawaitedCoroutine((PyObject *)gen);
  }
  else{
- res = gen_close(gen, NULL);
- }
-
- if (res == NULL){
- if (PyErr_Occurred()){
- PyErr_WriteUnraisable(self);
+ PyObject *res = gen_close(gen, NULL);
+ if (res == NULL){
+ if (PyErr_Occurred()){
+ PyErr_WriteUnraisable(self);
+ }
+ }
+ else{
+ Py_DECREF(res);
  }
- }
- else{
- Py_DECREF(res);
  }
 
  /* Restore the saved exception. */
-PyErr_Restore(error_type, error_value, error_traceback);
+PyErr_SetRaisedException(exc);
 }
 
 static void
@@ -648,39 +644,11 @@ _PyGen_SetStopIterationValue(PyObject *value)
 int
 _PyGen_FetchStopIterationValue(PyObject **pvalue)
 {
- PyObject *et, *ev, *tb;
  PyObject *value = NULL;
-
  if (PyErr_ExceptionMatches(PyExc_StopIteration)){
- PyErr_Fetch(&et, &ev, &tb);
- if (ev){
- /* exception will usually be normalised already */
- if (PyObject_TypeCheck(ev, (PyTypeObject *) et)){
- value = Py_NewRef(((PyStopIterationObject *)ev)->value);
- Py_DECREF(ev);
- } else if (et == PyExc_StopIteration && !PyTuple_Check(ev)){
- /* Avoid normalisation and take ev as value.
- *
- * Normalization is required if the value is a tuple, in
- * that case the value of StopIteration would be set to
- * the first element of the tuple.
- *
- * (See _PyErr_CreateException code for details.)
- */
- value = ev;
- } else{
- /* normalisation required */
- PyErr_NormalizeException(&et, &ev, &tb);
- if (!PyObject_TypeCheck(ev, (PyTypeObject *)PyExc_StopIteration)){
- PyErr_Restore(et, ev, tb);
- return -1;
- }
- value = Py_NewRef(((PyStopIterationObject *)ev)->value);
- Py_DECREF(ev);
- }
- }
- Py_XDECREF(et);
- Py_XDECREF(tb);
+ PyObject *exc = PyErr_GetRaisedException();
+ value = Py_NewRef(((PyStopIterationObject *)exc)->value);
+ Py_DECREF(exc);
  } else if (PyErr_Occurred()){
  return -1;
  }

Objects/object.c

@@ -370,13 +370,12 @@ _PyObject_Dump(PyObject* op)
  fflush(stderr);
 
  PyGILState_STATE gil = PyGILState_Ensure();
- PyObject *error_type, *error_value, *error_traceback;
- PyErr_Fetch(&error_type, &error_value, &error_traceback);
+ PyObject *exc = PyErr_GetRaisedException();
 
  (void)PyObject_Print(op, stderr, 0);
  fflush(stderr);
 
-PyErr_Restore(error_type, error_value, error_traceback);
+PyErr_SetRaisedException(exc);
  PyGILState_Release(gil);
 
  fprintf(stderr, "\n");
@@ -860,25 +859,22 @@ set_attribute_error_context(PyObject* v, PyObject* name)
  return 0;
  }
  // Intercept AttributeError exceptions and augment them to offer suggestions later.
- PyObject *type, *value, *traceback;
- PyErr_Fetch(&type, &value, &traceback);
- PyErr_NormalizeException(&type, &value, &traceback);
- // Check if the normalized exception is indeed an AttributeError
- if (!PyErr_GivenExceptionMatches(value, PyExc_AttributeError)){
+ PyObject *exc = PyErr_GetRaisedException();
+ if (!PyErr_GivenExceptionMatches(exc, PyExc_AttributeError)){
  goto restore;
  }
- PyAttributeErrorObject* the_exc = (PyAttributeErrorObject*) value;
+ PyAttributeErrorObject* the_exc = (PyAttributeErrorObject*) exc;
  // Check if this exception was already augmented
  if (the_exc->name || the_exc->obj){
  goto restore;
  }
  // Augment the exception with the name and object
- if (PyObject_SetAttr(value, &_Py_ID(name), name) ||
- PyObject_SetAttr(value, &_Py_ID(obj), v)){
+ if (PyObject_SetAttr(exc, &_Py_ID(name), name) ||
+ PyObject_SetAttr(exc, &_Py_ID(obj), v)){
  return 1;
  }
 restore:
-PyErr_Restore(type, value, traceback);
+PyErr_SetRaisedException(exc);
  return 0;
 }
 
@@ -2190,9 +2186,8 @@ Py_ReprLeave(PyObject *obj)
  PyObject *dict;
  PyObject *list;
  Py_ssize_t i;
- PyObject *error_type, *error_value, *error_traceback;
 
-PyErr_Fetch(&error_type, &error_value, &error_traceback);
+PyObject *exc = PyErr_GetRaisedException();
 
  dict = PyThreadState_GetDict();
  if (dict == NULL)
@@ -2213,7 +2208,7 @@ Py_ReprLeave(PyObject *obj)
 
 finally:
  /* ignore exceptions because there is no way to report them. */
-PyErr_Restore(error_type, error_value, error_traceback);
+PyErr_SetRaisedException(exc);
 }
 
 /* Trashcan support. */

Objects/odictobject.c

@@ -1556,10 +1556,9 @@ _PyODict_SetItem_KnownHash(PyObject *od, PyObject *key, PyObject *value,
  res = _odict_add_new_node((PyODictObject *)od, key, hash);
  if (res < 0){
  /* Revert setting the value on the dict */
- PyObject *exc, *val, *tb;
- PyErr_Fetch(&exc, &val, &tb);
+ PyObject *exc = PyErr_GetRaisedException();
  (void) _PyDict_DelItem_KnownHash(od, key, hash);
-_PyErr_ChainExceptions(exc, val, tb);
+_PyErr_ChainExceptions1(exc);
  }
  }
  return res;

Objects/typeobject.c

@@ -4397,10 +4397,9 @@ static void
 type_dealloc_common(PyTypeObject *type)
 {
  if (type->tp_bases != NULL){
- PyObject *tp, *val, *tb;
- PyErr_Fetch(&tp, &val, &tb);
+ PyObject *exc = PyErr_GetRaisedException();
  remove_all_subclasses(type, type->tp_bases);
-PyErr_Restore(tp, val, tb);
+PyErr_SetRaisedException(exc);
  }
 }
 
@@ -8445,10 +8444,9 @@ slot_tp_finalize(PyObject *self)
 {
  int unbound;
  PyObject *del, *res;
- PyObject *error_type, *error_value, *error_traceback;
 
  /* Save the current exception, if any. */
-PyErr_Fetch(&error_type, &error_value, &error_traceback);
+PyObject *exc = PyErr_GetRaisedException();
 
  /* Execute __del__ method, if any. */
  del = lookup_maybe_method(self, &_Py_ID(__del__), &unbound);
@@ -8462,7 +8460,7 @@ slot_tp_finalize(PyObject *self)
  }
 
  /* Restore the saved exception. */
-PyErr_Restore(error_type, error_value, error_traceback);
+PyErr_SetRaisedException(exc);
 }
 
 static PyObject *

Objects/weakrefobject.c

@@ -959,9 +959,8 @@ PyObject_ClearWeakRefs(PyObject *object)
  if (*list != NULL){
  PyWeakReference *current = *list;
  Py_ssize_t count = _PyWeakref_GetWeakrefCount(current);
- PyObject *err_type, *err_value, *err_tb;
+ PyObject *exc = PyErr_GetRaisedException();
 
- PyErr_Fetch(&err_type, &err_value, &err_tb);
  if (count == 1){
  PyObject *callback = current->wr_callback;
 
@@ -980,7 +979,7 @@ PyObject_ClearWeakRefs(PyObject *object)
 
  tuple = PyTuple_New(count * 2);
  if (tuple == NULL){
-_PyErr_ChainExceptions(err_type, err_value, err_tb);
+_PyErr_ChainExceptions1(exc);
  return;
  }
 
@@ -1010,7 +1009,7 @@ PyObject_ClearWeakRefs(PyObject *object)
  Py_DECREF(tuple);
  }
  assert(!PyErr_Occurred());
-PyErr_Restore(err_type, err_value, err_tb);
+PyErr_SetRaisedException(exc);
  }
 }