[Python-checkins] cpython: _PyObject_CallFunctionVa() uses fast call

Thu Dec 8 20:16:59 EST 2016

https://hg.python.org/cpython/rev/69948a157507
changeset: 105537:69948a157507
user: Victor Stinner <victor.stinner at gmail.com>
date: Fri Dec 09 00:31:47 2016 +0100
summary:
 _PyObject_CallFunctionVa() uses fast call
Issue #28915: Use _Py_VaBuildStack() to build a C array of PyObject* and then
use _PyObject_FastCall().
The function has a special case if the stack only contains one parameter and
the parameter is a tuple: "unpack" the tuple of arguments in this case.
files:
 Objects/abstract.c | 34 +++++++++++++++++++++++++---------
 1 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/Objects/abstract.c b/Objects/abstract.c
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -2523,7 +2523,12 @@
 _PyObject_CallFunctionVa(PyObject *callable, const char *format,
 va_list va, int is_size_t)
 {
- PyObject *args, *result;
+ PyObject* small_stack[5];
+ /*const Py_ssize_t small_stack_len = Py_ARRAY_LENGTH(small_stack);*/
+ const Py_ssize_t small_stack_len = 0;
+ PyObject **stack;
+ Py_ssize_t nargs, i;
+ PyObject *result;
 
 if (callable == NULL) {
 return null_error();
@@ -2534,24 +2539,35 @@
 }
 
 if (is_size_t) {
- args = Py_VaBuildValue(format, va);
+ stack = _Py_VaBuildStack(small_stack, small_stack_len, format, va, &nargs);
 }
 else {
- args = _Py_VaBuildValue_SizeT(format, va);
+ stack = _Py_VaBuildStack_SizeT(small_stack, small_stack_len, format, va, &nargs);
 }
- if (args == NULL) {
+ if (stack == NULL) {
 return NULL;
 }
 
- if (!PyTuple_Check(args)) {
- PyObject *stack[1] = {args};
- result = _PyObject_FastCall(callable, stack, 1);
+ if (nargs == 1 && PyTuple_Check(stack[0])) {
+ /* Special cases:
+ - PyObject_CallFunction(func, "O", tuple) calls func(*tuple)
+ - PyObject_CallFunction(func, "(OOO)", arg1, arg2, arg3) calls
+ func(*(arg1, arg2, arg3)): func(arg1, arg2, arg3) */
+ PyObject *args = stack[0];
+ result = _PyObject_FastCall(callable,
+ &PyTuple_GET_ITEM(args, 0),
+ PyTuple_GET_SIZE(args));
 }
 else {
- result = PyObject_Call(callable, args, NULL);
+ result = _PyObject_FastCall(callable, stack, nargs);
 }
 
- Py_DECREF(args);
+ for (i = 0; i < nargs; ++i) {
+ Py_DECREF(stack[i]);
+ }
+ if (stack != small_stack) {
+ PyMem_Free(stack);
+ }
 return result;
 }
 
-- 
Repository URL: https://hg.python.org/cpython
