[Python-checkins] cpython: Issue #27809: map_next() uses fast call
victor.stinner
python-checkins at python.org
Tue Aug 23 18:09:09 EDT 2016
https://hg.python.org/cpython/rev/70f88b097f60
changeset: 102873:70f88b097f60
user: Victor Stinner <victor.stinner at gmail.com>
date: Tue Aug 23 17:56:06 2016 +0200
summary:
Issue #27809: map_next() uses fast call
Use a small stack allocated in the C stack for up to 5 iterator functions,
otherwise allocates a stack on the heap memory.
files:
Python/bltinmodule.c | 50 +++++++++++++++++++++----------
1 files changed, 33 insertions(+), 17 deletions(-)
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1156,27 +1156,43 @@
static PyObject *
map_next(mapobject *lz)
{
- PyObject *val;
- PyObject *argtuple;
- PyObject *result;
- Py_ssize_t numargs, i;
+ PyObject *small_stack[5];
+ PyObject **stack;
+ Py_ssize_t niters, nargs, i;
+ PyObject *result = NULL;
- numargs = PyTuple_GET_SIZE(lz->iters);
- argtuple = PyTuple_New(numargs);
- if (argtuple == NULL)
- return NULL;
-
- for (i=0 ; i<numargs ; i++) {
- PyObject *it = PyTuple_GET_ITEM(lz->iters, i);
- val = Py_TYPE(it)->tp_iternext(it);
- if (val == NULL) {
- Py_DECREF(argtuple);
+ niters = PyTuple_GET_SIZE(lz->iters);
+ if (niters <= (Py_ssize_t)Py_ARRAY_LENGTH(small_stack)) {
+ stack = small_stack;
+ }
+ else {
+ stack = PyMem_Malloc(niters * sizeof(PyObject*));
+ if (stack == NULL) {
+ PyErr_NoMemory();
return NULL;
}
- PyTuple_SET_ITEM(argtuple, i, val);
}
- result = PyObject_Call(lz->func, argtuple, NULL);
- Py_DECREF(argtuple);
+
+ nargs = 0;
+ for (i=0; i < niters; i++) {
+ PyObject *it = PyTuple_GET_ITEM(lz->iters, i);
+ PyObject *val = Py_TYPE(it)->tp_iternext(it);
+ if (val == NULL) {
+ goto exit;
+ }
+ stack[i] = val;
+ nargs++;
+ }
+
+ result = _PyObject_FastCall(lz->func, stack, nargs);
+
+exit:
+ 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
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