gh-90370: Argument Clinic: avoid temporary tuple creation for varargs (#126064)

Avoid temporary tuple creation when all arguments either positional-only
or vararg.

Objects/setobject.c and Modules/gcmodule.c adapted. This fixes slight
performance regression for set methods, introduced by gh-115112.

2 files changed, 65 insertions, 93 deletions

diff --git a/Objects/clinic/setobject.c.h b/Objects/clinic/setobject.c.h
index 3853ce3..d6e381a 100644
--- a/Objects/clinic/setobject.c.h
+++ b/Objects/clinic/setobject.c.h
@@ -41,28 +41,22 @@ PyDoc_STRVAR(set_update__doc__,
     {"update", _PyCFunction_CAST(set_update), METH_FASTCALL, set_update__doc__},
 
 static PyObject *
-set_update_impl(PySetObject *so, PyObject *args);
+set_update_impl(PySetObject *so, Py_ssize_t nargs, PyObject *const *args);
 
 static PyObject *
 set_update(PySetObject *so, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *return_value = NULL;
-    PyObject *__clinic_args = NULL;
+    Py_ssize_t nvararg = nargs - 0;
+    PyObject *const *__clinic_args = NULL;
 
     if (!_PyArg_CheckPositional("update", nargs, 0, PY_SSIZE_T_MAX)) {
         goto exit;
     }
-    __clinic_args = PyTuple_New(nargs - 0);
-    if (!__clinic_args) {
-        goto exit;
-    }
-    for (Py_ssize_t i = 0; i < nargs - 0; ++i) {
-        PyTuple_SET_ITEM(__clinic_args, i, Py_NewRef(args[0 + i]));
-    }
-    return_value = set_update_impl(so, __clinic_args);
+    __clinic_args = args + 0;
+    return_value = set_update_impl(so, nvararg, __clinic_args);
 
 exit:
-    Py_XDECREF(__clinic_args);
     return return_value;
 }
 
@@ -148,28 +142,22 @@ PyDoc_STRVAR(set_union__doc__,
     {"union", _PyCFunction_CAST(set_union), METH_FASTCALL, set_union__doc__},
 
 static PyObject *
-set_union_impl(PySetObject *so, PyObject *args);
+set_union_impl(PySetObject *so, Py_ssize_t nargs, PyObject *const *args);
 
 static PyObject *
 set_union(PySetObject *so, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *return_value = NULL;
-    PyObject *__clinic_args = NULL;
+    Py_ssize_t nvararg = nargs - 0;
+    PyObject *const *__clinic_args = NULL;
 
     if (!_PyArg_CheckPositional("union", nargs, 0, PY_SSIZE_T_MAX)) {
         goto exit;
     }
-    __clinic_args = PyTuple_New(nargs - 0);
-    if (!__clinic_args) {
-        goto exit;
-    }
-    for (Py_ssize_t i = 0; i < nargs - 0; ++i) {
-        PyTuple_SET_ITEM(__clinic_args, i, Py_NewRef(args[0 + i]));
-    }
-    return_value = set_union_impl(so, __clinic_args);
+    __clinic_args = args + 0;
+    return_value = set_union_impl(so, nvararg, __clinic_args);
 
 exit:
-    Py_XDECREF(__clinic_args);
     return return_value;
 }
 
@@ -183,28 +171,23 @@ PyDoc_STRVAR(set_intersection_multi__doc__,
     {"intersection", _PyCFunction_CAST(set_intersection_multi), METH_FASTCALL, set_intersection_multi__doc__},
 
 static PyObject *
-set_intersection_multi_impl(PySetObject *so, PyObject *args);
+set_intersection_multi_impl(PySetObject *so, Py_ssize_t nargs,
+                            PyObject *const *args);
 
 static PyObject *
 set_intersection_multi(PySetObject *so, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *return_value = NULL;
-    PyObject *__clinic_args = NULL;
+    Py_ssize_t nvararg = nargs - 0;
+    PyObject *const *__clinic_args = NULL;
 
     if (!_PyArg_CheckPositional("intersection", nargs, 0, PY_SSIZE_T_MAX)) {
         goto exit;
     }
-    __clinic_args = PyTuple_New(nargs - 0);
-    if (!__clinic_args) {
-        goto exit;
-    }
-    for (Py_ssize_t i = 0; i < nargs - 0; ++i) {
-        PyTuple_SET_ITEM(__clinic_args, i, Py_NewRef(args[0 + i]));
-    }
-    return_value = set_intersection_multi_impl(so, __clinic_args);
+    __clinic_args = args + 0;
+    return_value = set_intersection_multi_impl(so, nvararg, __clinic_args);
 
 exit:
-    Py_XDECREF(__clinic_args);
     return return_value;
 }
 
@@ -218,28 +201,23 @@ PyDoc_STRVAR(set_intersection_update_multi__doc__,
     {"intersection_update", _PyCFunction_CAST(set_intersection_update_multi), METH_FASTCALL, set_intersection_update_multi__doc__},
 
 static PyObject *
-set_intersection_update_multi_impl(PySetObject *so, PyObject *args);
+set_intersection_update_multi_impl(PySetObject *so, Py_ssize_t nargs,
+                                   PyObject *const *args);
 
 static PyObject *
 set_intersection_update_multi(PySetObject *so, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *return_value = NULL;
-    PyObject *__clinic_args = NULL;
+    Py_ssize_t nvararg = nargs - 0;
+    PyObject *const *__clinic_args = NULL;
 
     if (!_PyArg_CheckPositional("intersection_update", nargs, 0, PY_SSIZE_T_MAX)) {
         goto exit;
     }
-    __clinic_args = PyTuple_New(nargs - 0);
-    if (!__clinic_args) {
-        goto exit;
-    }
-    for (Py_ssize_t i = 0; i < nargs - 0; ++i) {
-        PyTuple_SET_ITEM(__clinic_args, i, Py_NewRef(args[0 + i]));
-    }
-    return_value = set_intersection_update_multi_impl(so, __clinic_args);
+    __clinic_args = args + 0;
+    return_value = set_intersection_update_multi_impl(so, nvararg, __clinic_args);
 
 exit:
-    Py_XDECREF(__clinic_args);
     return return_value;
 }
 
@@ -277,28 +255,23 @@ PyDoc_STRVAR(set_difference_update__doc__,
     {"difference_update", _PyCFunction_CAST(set_difference_update), METH_FASTCALL, set_difference_update__doc__},
 
 static PyObject *
-set_difference_update_impl(PySetObject *so, PyObject *args);
+set_difference_update_impl(PySetObject *so, Py_ssize_t nargs,
+                           PyObject *const *args);
 
 static PyObject *
 set_difference_update(PySetObject *so, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *return_value = NULL;
-    PyObject *__clinic_args = NULL;
+    Py_ssize_t nvararg = nargs - 0;
+    PyObject *const *__clinic_args = NULL;
 
     if (!_PyArg_CheckPositional("difference_update", nargs, 0, PY_SSIZE_T_MAX)) {
         goto exit;
     }
-    __clinic_args = PyTuple_New(nargs - 0);
-    if (!__clinic_args) {
-        goto exit;
-    }
-    for (Py_ssize_t i = 0; i < nargs - 0; ++i) {
-        PyTuple_SET_ITEM(__clinic_args, i, Py_NewRef(args[0 + i]));
-    }
-    return_value = set_difference_update_impl(so, __clinic_args);
+    __clinic_args = args + 0;
+    return_value = set_difference_update_impl(so, nvararg, __clinic_args);
 
 exit:
-    Py_XDECREF(__clinic_args);
     return return_value;
 }
 
@@ -312,28 +285,23 @@ PyDoc_STRVAR(set_difference_multi__doc__,
     {"difference", _PyCFunction_CAST(set_difference_multi), METH_FASTCALL, set_difference_multi__doc__},
 
 static PyObject *
-set_difference_multi_impl(PySetObject *so, PyObject *args);
+set_difference_multi_impl(PySetObject *so, Py_ssize_t nargs,
+                          PyObject *const *args);
 
 static PyObject *
 set_difference_multi(PySetObject *so, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *return_value = NULL;
-    PyObject *__clinic_args = NULL;
+    Py_ssize_t nvararg = nargs - 0;
+    PyObject *const *__clinic_args = NULL;
 
     if (!_PyArg_CheckPositional("difference", nargs, 0, PY_SSIZE_T_MAX)) {
         goto exit;
     }
-    __clinic_args = PyTuple_New(nargs - 0);
-    if (!__clinic_args) {
-        goto exit;
-    }
-    for (Py_ssize_t i = 0; i < nargs - 0; ++i) {
-        PyTuple_SET_ITEM(__clinic_args, i, Py_NewRef(args[0 + i]));
-    }
-    return_value = set_difference_multi_impl(so, __clinic_args);
+    __clinic_args = args + 0;
+    return_value = set_difference_multi_impl(so, nvararg, __clinic_args);
 
 exit:
-    Py_XDECREF(__clinic_args);
     return return_value;
 }
 
@@ -568,4 +536,4 @@ set___sizeof__(PySetObject *so, PyObject *Py_UNUSED(ignored))
 
     return return_value;
 }
-/*[clinic end generated code: output=de4ee725bd29f758 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=9d4b41191b2c602f input=a9049054013a1b77]*/
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 9f40e08..66d7fc7 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -1060,13 +1060,13 @@ Update the set, adding elements from all others.
 [clinic start generated code]*/
 
 static PyObject *
-set_update_impl(PySetObject *so, PyObject *args)
-/*[clinic end generated code: output=34f6371704974c8a input=df4fe486e38cd337]*/
+set_update_impl(PySetObject *so, Py_ssize_t nargs, PyObject *const *args)
+/*[clinic end generated code: output=050e2a21f8d7d16a input=df4fe486e38cd337]*/
 {
     Py_ssize_t i;
 
-    for (i=0 ; i<PyTuple_GET_SIZE(args) ; i++) {
-        PyObject *other = PyTuple_GET_ITEM(args, i);
+    for (i = 0; i < nargs; i++) {
+        PyObject *other = args[i];
         if (set_update_internal(so, other))
             return NULL;
     }
@@ -1289,8 +1289,8 @@ Return a new set with elements from the set and all others.
 [clinic start generated code]*/
 
 static PyObject *
-set_union_impl(PySetObject *so, PyObject *args)
-/*[clinic end generated code: output=2c83d05a446a1477 input=ddf088706e9577b2]*/
+set_union_impl(PySetObject *so, Py_ssize_t nargs, PyObject *const *args)
+/*[clinic end generated code: output=f68ec24d5c19d404 input=ddf088706e9577b2]*/
 {
     PySetObject *result;
     PyObject *other;
@@ -1300,8 +1300,8 @@ set_union_impl(PySetObject *so, PyObject *args)
     if (result == NULL)
         return NULL;
 
-    for (i=0 ; i<PyTuple_GET_SIZE(args) ; i++) {
-        other = PyTuple_GET_ITEM(args, i);
+    for (i = 0; i < nargs; i++) {
+        other = args[i];
         if ((PyObject *)so == other)
             continue;
         if (set_update_local(result, other)) {
@@ -1440,18 +1440,19 @@ Return a new set with elements common to the set and all others.
 [clinic start generated code]*/
 
 static PyObject *
-set_intersection_multi_impl(PySetObject *so, PyObject *args)
-/*[clinic end generated code: output=2406ef3387adbe2f input=0d9f3805ccbba6a4]*/
+set_intersection_multi_impl(PySetObject *so, Py_ssize_t nargs,
+                            PyObject *const *args)
+/*[clinic end generated code: output=ef0756ddb5f2dee9 input=0d9f3805ccbba6a4]*/
 {
     Py_ssize_t i;
 
-    if (PyTuple_GET_SIZE(args) == 0) {
+    if (nargs == 0) {
         return set_copy(so, NULL);
     }
 
     PyObject *result = Py_NewRef(so);
-    for (i=0 ; i<PyTuple_GET_SIZE(args) ; i++) {
-        PyObject *other = PyTuple_GET_ITEM(args, i);
+    for (i = 0; i < nargs; i++) {
+        PyObject *other = args[i];
         PyObject *newresult;
         Py_BEGIN_CRITICAL_SECTION2(result, other);
         newresult = set_intersection((PySetObject *)result, other);
@@ -1487,12 +1488,13 @@ Update the set, keeping only elements found in it and all others.
 [clinic start generated code]*/
 
 static PyObject *
-set_intersection_update_multi_impl(PySetObject *so, PyObject *args)
-/*[clinic end generated code: output=251c1f729063609d input=223c1e086aa669a9]*/
+set_intersection_update_multi_impl(PySetObject *so, Py_ssize_t nargs,
+                                   PyObject *const *args)
+/*[clinic end generated code: output=808d7ad1935b1dfe input=223c1e086aa669a9]*/
 {
     PyObject *tmp;
 
-    tmp = set_intersection_multi_impl(so, args);
+    tmp = set_intersection_multi_impl(so, nargs, args);
     if (tmp == NULL)
         return NULL;
     Py_BEGIN_CRITICAL_SECTION(so);
@@ -1676,13 +1678,14 @@ Update the set, removing elements found in others.
 [clinic start generated code]*/
 
 static PyObject *
-set_difference_update_impl(PySetObject *so, PyObject *args)
-/*[clinic end generated code: output=28685b2fc63e41c4 input=024e6baa6fbcbb3d]*/
+set_difference_update_impl(PySetObject *so, Py_ssize_t nargs,
+                           PyObject *const *args)
+/*[clinic end generated code: output=55f850c27748d312 input=024e6baa6fbcbb3d]*/
 {
     Py_ssize_t i;
 
-    for (i=0 ; i<PyTuple_GET_SIZE(args) ; i++) {
-        PyObject *other = PyTuple_GET_ITEM(args, i);
+    for (i = 0; i < nargs; i++) {
+        PyObject *other = args[i];
         int rv;
         Py_BEGIN_CRITICAL_SECTION2(so, other);
         rv = set_difference_update_internal(so, other);
@@ -1793,25 +1796,26 @@ Return a new set with elements in the set that are not in the others.
 [clinic start generated code]*/
 
 static PyObject *
-set_difference_multi_impl(PySetObject *so, PyObject *args)
-/*[clinic end generated code: output=3130c3bb3cac873d input=ba78ea5f099e58df]*/
+set_difference_multi_impl(PySetObject *so, Py_ssize_t nargs,
+                          PyObject *const *args)
+/*[clinic end generated code: output=8150d008c00523f3 input=ba78ea5f099e58df]*/
 {
     Py_ssize_t i;
     PyObject *result, *other;
 
-    if (PyTuple_GET_SIZE(args) == 0) {
+    if (nargs == 0) {
         return set_copy(so, NULL);
     }
 
-    other = PyTuple_GET_ITEM(args, 0);
+    other = args[0];
     Py_BEGIN_CRITICAL_SECTION2(so, other);
     result = set_difference(so, other);
     Py_END_CRITICAL_SECTION2();
     if (result == NULL)
         return NULL;
 
-    for (i=1 ; i<PyTuple_GET_SIZE(args) ; i++) {
-        other = PyTuple_GET_ITEM(args, i);
+    for (i = 1; i < nargs; i++) {
+        other = args[i];
         int rv;
         Py_BEGIN_CRITICAL_SECTION(other);
         rv = set_difference_update_internal((PySetObject *)result, other);