From 53c214344038341ce86fcf7efa12dc33be9d5b45 Mon Sep 17 00:00:00 2001 From: Jeroen Demeyer Date: Wed, 3 Jul 2019 12:54:00 +0200 Subject: bpo-37233: optimize method_vectorcall in case of totalargs == 0 (GH-14550) --- Objects/classobject.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/Objects/classobject.c b/Objects/classobject.c index 3062890..46525a7 100644 --- a/Objects/classobject.c +++ b/Objects/classobject.c @@ -62,9 +62,13 @@ method_vectorcall(PyObject *method, PyObject *const *args, } else { Py_ssize_t nkwargs = (kwnames == NULL) ? 0 : PyTuple_GET_SIZE(kwnames); - PyObject **newargs; Py_ssize_t totalargs = nargs + nkwargs; + if (totalargs == 0) { + return _PyObject_Vectorcall(func, &self, 1, NULL); + } + PyObject *newargs_stack[_PY_FASTCALL_SMALL_STACK]; + PyObject **newargs; if (totalargs <= (Py_ssize_t)Py_ARRAY_LENGTH(newargs_stack) - 1) { newargs = newargs_stack; } @@ -77,11 +81,11 @@ method_vectorcall(PyObject *method, PyObject *const *args, } /* use borrowed references */ newargs[0] = self; - if (totalargs) { /* bpo-37138: if totalargs == 0, then args may be - * NULL and calling memcpy() with a NULL pointer - * is undefined behaviour. */ - memcpy(newargs + 1, args, totalargs * sizeof(PyObject *)); - } + /* bpo-37138: since totalargs > 0, it's impossible that args is NULL. + * We need this, since calling memcpy() with a NULL pointer is + * undefined behaviour. */ + assert(args != NULL); + memcpy(newargs + 1, args, totalargs * sizeof(PyObject *)); result = _PyObject_Vectorcall(func, newargs, nargs+1, kwnames); if (newargs != newargs_stack) { PyMem_Free(newargs); -- cgit v0.12