Issue #19512: add some common identifiers to only create common strings once,
instead of creating temporary Unicode string objects

Add also more identifiers in pythonrun.c to avoid temporary Unicode string
objets for the interactive interpreter.
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 61d0352..e510e6f 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -35,6 +35,21 @@
 #define PATH_MAX MAXPATHLEN
 #endif
 
+/* Common identifiers */
+_Py_Identifier _PyId_argv = _Py_static_string_init("argv");
+_Py_Identifier _PyId_path = _Py_static_string_init("path");
+_Py_Identifier _PyId_stdin = _Py_static_string_init("stdin");
+_Py_Identifier _PyId_stdout = _Py_static_string_init("stdout");
+_Py_Identifier _PyId_stderr = _Py_static_string_init("stderr");
+
+/* local identifiers */
+_Py_IDENTIFIER(excepthook);
+_Py_IDENTIFIER(ps1);
+_Py_IDENTIFIER(ps2);
+_Py_IDENTIFIER(last_type);
+_Py_IDENTIFIER(last_value);
+_Py_IDENTIFIER(last_traceback);
+
 #ifdef Py_REF_DEBUG
 static
 void _print_total_refs(void) {
@@ -412,7 +427,7 @@
     pstderr = PyFile_NewStdPrinter(fileno(stderr));
     if (pstderr == NULL)
         Py_FatalError("Py_Initialize: can't set preliminary stderr");
-    PySys_SetObject("stderr", pstderr);
+    _PySys_SetObjectId(&_PyId_stderr, pstderr);
     PySys_SetObject("__stderr__", pstderr);
     Py_DECREF(pstderr);
 
@@ -497,8 +512,8 @@
 static void
 flush_std_files(void)
 {
-    PyObject *fout = PySys_GetObject("stdout");
-    PyObject *ferr = PySys_GetObject("stderr");
+    PyObject *fout = _PySys_GetObjectId(&_PyId_stdout);
+    PyObject *ferr = _PySys_GetObjectId(&_PyId_stderr);
     PyObject *tmp;
     _Py_IDENTIFIER(flush);
 
@@ -776,7 +791,7 @@
         pstderr = PyFile_NewStdPrinter(fileno(stderr));
         if (pstderr == NULL)
             Py_FatalError("Py_Initialize: can't set preliminary stderr");
-        PySys_SetObject("stderr", pstderr);
+        _PySys_SetObjectId(&_PyId_stderr, pstderr);
         PySys_SetObject("__stderr__", pstderr);
         Py_DECREF(pstderr);
 
@@ -1170,7 +1185,7 @@
             goto error;
     } /* if (fd < 0) */
     PySys_SetObject("__stdin__", std);
-    PySys_SetObject("stdin", std);
+    _PySys_SetObjectId(&_PyId_stdin, std);
     Py_DECREF(std);
 
     /* Set sys.stdout */
@@ -1185,7 +1200,7 @@
             goto error;
     } /* if (fd < 0) */
     PySys_SetObject("__stdout__", std);
-    PySys_SetObject("stdout", std);
+    _PySys_SetObjectId(&_PyId_stdout, std);
     Py_DECREF(std);
 
 #if 1 /* Disable this if you have trouble debugging bootstrap stuff */
@@ -1219,7 +1234,7 @@
         Py_DECREF(std);
         goto error;
     }
-    if (PySys_SetObject("stderr", std) < 0) {
+    if (_PySys_SetObjectId(&_PyId_stderr, std) < 0) {
         Py_DECREF(std);
         goto error;
     }
@@ -1281,14 +1296,14 @@
         flags = &local_flags;
         local_flags.cf_flags = 0;
     }
-    v = PySys_GetObject("ps1");
+    v = _PySys_GetObjectId(&PyId_ps1);
     if (v == NULL) {
-        PySys_SetObject("ps1", v = PyUnicode_FromString(">>> "));
+        _PySys_SetObjectId(&PyId_ps1, v = PyUnicode_FromString(">>> "));
         Py_XDECREF(v);
     }
-    v = PySys_GetObject("ps2");
+    v = _PySys_GetObjectId(&PyId_ps2);
     if (v == NULL) {
-        PySys_SetObject("ps2", v = PyUnicode_FromString("... "));
+        _PySys_SetObjectId(&PyId_ps2, v = PyUnicode_FromString("... "));
         Py_XDECREF(v);
     }
     err = -1;
@@ -1351,7 +1366,7 @@
 
     if (fp == stdin) {
         /* Fetch encoding from sys.stdin if possible. */
-        v = PySys_GetObject("stdin");
+        v = _PySys_GetObjectId(&_PyId_stdin);
         if (v && v != Py_None) {
             oenc = _PyObject_GetAttrId(v, &PyId_encoding);
             if (oenc)
@@ -1360,7 +1375,7 @@
                 PyErr_Clear();
         }
     }
-    v = PySys_GetObject("ps1");
+    v = _PySys_GetObjectId(&PyId_ps1);
     if (v != NULL) {
         v = PyObject_Str(v);
         if (v == NULL)
@@ -1373,7 +1388,7 @@
             }
         }
     }
-    w = PySys_GetObject("ps2");
+    w = _PySys_GetObjectId(&PyId_ps2);
     if (w != NULL) {
         w = PyObject_Str(w);
         if (w == NULL)
@@ -1752,7 +1767,7 @@
     if (PyLong_Check(value))
         exitcode = (int)PyLong_AsLong(value);
     else {
-        PyObject *sys_stderr = PySys_GetObject("stderr");
+        PyObject *sys_stderr = _PySys_GetObjectId(&_PyId_stderr);
         if (sys_stderr != NULL && sys_stderr != Py_None) {
             PyFile_WriteObject(value, sys_stderr, Py_PRINT_RAW);
         } else {
@@ -1795,11 +1810,11 @@
         return;
     /* Now we know v != NULL too */
     if (set_sys_last_vars) {
-        PySys_SetObject("last_type", exception);
-        PySys_SetObject("last_value", v);
-        PySys_SetObject("last_traceback", tb);
+        _PySys_SetObjectId(&PyId_last_type, exception);
+        _PySys_SetObjectId(&PyId_last_value, v);
+        _PySys_SetObjectId(&PyId_last_traceback, tb);
     }
-    hook = PySys_GetObject("excepthook");
+    hook = _PySys_GetObjectId(&PyId_excepthook);
     if (hook) {
         PyObject *args = PyTuple_Pack(3, exception, v, tb);
         PyObject *result = PyEval_CallObject(hook, args);
@@ -2009,7 +2024,7 @@
 PyErr_Display(PyObject *exception, PyObject *value, PyObject *tb)
 {
     PyObject *seen;
-    PyObject *f = PySys_GetObject("stderr");
+    PyObject *f = _PySys_GetObjectId(&_PyId_stderr);
     if (PyExceptionInstance_Check(value)
         && tb != NULL && PyTraceBack_Check(tb)) {
         /* Put the traceback on the exception, otherwise it won't get
@@ -2107,7 +2122,7 @@
     /* Save the current exception */
     PyErr_Fetch(&type, &value, &traceback);
 
-    f = PySys_GetObject("stderr");
+    f = _PySys_GetObjectId(&_PyId_stderr);
     if (f != NULL) {
         r = _PyObject_CallMethodId(f, &PyId_flush, "");
         if (r)
@@ -2115,7 +2130,7 @@
         else
             PyErr_Clear();
     }
-    f = PySys_GetObject("stdout");
+    f = _PySys_GetObjectId(&_PyId_stdout);
     if (f != NULL) {
         r = _PyObject_CallMethodId(f, &PyId_flush, "");
         if (r)