From 304197b3820309e3ed695ff3e6a71461881a1728 Mon Sep 17 00:00:00 2001
From: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
Date: Fri, 11 Mar 2022 20:07:14 +0530
Subject: [PATCH] bpo-46944: use FASTCALL calling convention in generator.throw
 (GH-31723)

---
 .../2022-03-08-10-50-42.bpo-46944.cnaIK3.rst  |  1 +
 Objects/genobject.c                           | 37 ++++++++++++-------
 2 files changed, 24 insertions(+), 14 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2022-03-08-10-50-42.bpo-46944.cnaIK3.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-03-08-10-50-42.bpo-46944.cnaIK3.rst b/Misc/NEWS.d/next/Core and Builtins/2022-03-08-10-50-42.bpo-46944.cnaIK3.rst
new file mode 100644
index 00000000000..f940ebbbd1f
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-03-08-10-50-42.bpo-46944.cnaIK3.rst	
@@ -0,0 +1 @@
+Speed up throwing exception in generator with :const:`METH_FASTCALL` calling convention. Patch by Kumar Aditya.
diff --git a/Objects/genobject.c b/Objects/genobject.c
index bfa1ea5c45f..4fac0ce241c 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -561,16 +561,23 @@ failed_throw:
 
 
 static PyObject *
-gen_throw(PyGenObject *gen, PyObject *args)
+gen_throw(PyGenObject *gen, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *typ;
     PyObject *tb = NULL;
     PyObject *val = NULL;
 
-    if (!PyArg_UnpackTuple(args, "throw", 1, 3, &typ, &val, &tb)) {
+    if (!_PyArg_CheckPositional("throw", nargs, 1, 3)) {
         return NULL;
     }
-
+    typ = args[0];
+    if (nargs == 3) {
+        val = args[1];
+        tb = args[2];
+    }
+    else if (nargs == 2) {
+        val = args[1];
+    }
     return _gen_throw(gen, 1, typ, val, tb);
 }
 
@@ -813,7 +820,7 @@ PyDoc_STRVAR(sizeof__doc__,
 
 static PyMethodDef gen_methods[] = {
     {"send",(PyCFunction)gen_send, METH_O, send_doc},
-    {"throw",(PyCFunction)gen_throw, METH_VARARGS, throw_doc},
+    {"throw",(PyCFunction)(void(*)(void))gen_throw, METH_FASTCALL, throw_doc},
     {"close",(PyCFunction)gen_close, METH_NOARGS, close_doc},
     {"__sizeof__", (PyCFunction)gen_sizeof, METH_NOARGS, sizeof__doc__},
     {NULL, NULL}        /* Sentinel */
@@ -1159,7 +1166,7 @@ PyDoc_STRVAR(coro_close_doc,
 
 static PyMethodDef coro_methods[] = {
     {"send",(PyCFunction)gen_send, METH_O, coro_send_doc},
-    {"throw",(PyCFunction)gen_throw, METH_VARARGS, coro_throw_doc},
+    {"throw",(PyCFunction)(void(*)(void))gen_throw, METH_FASTCALL, coro_throw_doc},
     {"close",(PyCFunction)gen_close, METH_NOARGS, coro_close_doc},
     {"__sizeof__", (PyCFunction)gen_sizeof, METH_NOARGS, sizeof__doc__},
     {NULL, NULL}        /* Sentinel */
@@ -1246,9 +1253,9 @@ coro_wrapper_send(PyCoroWrapper *cw, PyObject *arg)
 }
 
 static PyObject *
-coro_wrapper_throw(PyCoroWrapper *cw, PyObject *args)
+coro_wrapper_throw(PyCoroWrapper *cw, PyObject *const *args, Py_ssize_t nargs)
 {
-    return gen_throw((PyGenObject *)cw->cw_coroutine, args);
+    return gen_throw((PyGenObject *)cw->cw_coroutine, args, nargs);
 }
 
 static PyObject *
@@ -1266,7 +1273,8 @@ coro_wrapper_traverse(PyCoroWrapper *cw, visitproc visit, void *arg)
 
 static PyMethodDef coro_wrapper_methods[] = {
     {"send",(PyCFunction)coro_wrapper_send, METH_O, coro_send_doc},
-    {"throw",(PyCFunction)coro_wrapper_throw, METH_VARARGS, coro_throw_doc},
+    {"throw",(PyCFunction)(void(*)(void))coro_wrapper_throw,
+    METH_FASTCALL, coro_throw_doc},
     {"close",(PyCFunction)coro_wrapper_close, METH_NOARGS, coro_close_doc},
     {NULL, NULL}        /* Sentinel */
 };
@@ -1789,7 +1797,7 @@ async_gen_asend_iternext(PyAsyncGenASend *o)
 
 
 static PyObject *
-async_gen_asend_throw(PyAsyncGenASend *o, PyObject *args)
+async_gen_asend_throw(PyAsyncGenASend *o, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *result;
 
@@ -1800,7 +1808,7 @@ async_gen_asend_throw(PyAsyncGenASend *o, PyObject *args)
         return NULL;
     }
 
-    result = gen_throw((PyGenObject*)o->ags_gen, args);
+    result = gen_throw((PyGenObject*)o->ags_gen, args, nargs);
     result = async_gen_unwrap_value(o->ags_gen, result);
 
     if (result == NULL) {
@@ -1821,7 +1829,7 @@ async_gen_asend_close(PyAsyncGenASend *o, PyObject *args)
 
 static PyMethodDef async_gen_asend_methods[] = {
     {"send", (PyCFunction)async_gen_asend_send, METH_O, send_doc},
-    {"throw", (PyCFunction)async_gen_asend_throw, METH_VARARGS, throw_doc},
+    {"throw", (PyCFunction)(void(*)(void))async_gen_asend_throw, METH_FASTCALL, throw_doc},
     {"close", (PyCFunction)async_gen_asend_close, METH_NOARGS, close_doc},
     {NULL, NULL}        /* Sentinel */
 };
@@ -2183,7 +2191,7 @@ check_error:
 
 
 static PyObject *
-async_gen_athrow_throw(PyAsyncGenAThrow *o, PyObject *args)
+async_gen_athrow_throw(PyAsyncGenAThrow *o, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *retval;
 
@@ -2194,7 +2202,7 @@ async_gen_athrow_throw(PyAsyncGenAThrow *o, PyObject *args)
         return NULL;
     }
 
-    retval = gen_throw((PyGenObject*)o->agt_gen, args);
+    retval = gen_throw((PyGenObject*)o->agt_gen, args, nargs);
     if (o->agt_args) {
         return async_gen_unwrap_value(o->agt_gen, retval);
     } else {
@@ -2239,7 +2247,8 @@ async_gen_athrow_close(PyAsyncGenAThrow *o, PyObject *args)
 
 static PyMethodDef async_gen_athrow_methods[] = {
     {"send", (PyCFunction)async_gen_athrow_send, METH_O, send_doc},
-    {"throw", (PyCFunction)async_gen_athrow_throw, METH_VARARGS, throw_doc},
+    {"throw", (PyCFunction)(void(*)(void))async_gen_athrow_throw,
+    METH_FASTCALL, throw_doc},
     {"close", (PyCFunction)async_gen_athrow_close, METH_NOARGS, close_doc},
     {NULL, NULL}        /* Sentinel */
 };