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Optimize set.pop() to advance a pointer instead of indexing. (GH-10429)

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Gives approx 20% speed-up using clang depending on the number of elements in the set (the less dense the set, the more the speed-up).

Uses the same entry++ logic used elsewhere in the setobject.c code.
This commit is contained in:
Raymond Hettinger 2018-11-09 02:31:56 -08:00 • committed by Miss Islington (bot)
parent b83942c755
commit cf5863faab
1 changed files with 8 additions and 7 deletions
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15
Objects/setobject.c
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@ -701,8 +701,7 @@ static PyObject *
set_pop(PySetObject *so, PyObject *Py_UNUSED(ignored)) set_pop(PySetObject *so, PyObject *Py_UNUSED(ignored))
{ {
/* Make sure the search finger is in bounds */ /* Make sure the search finger is in bounds */
Py_ssize_t i = so->finger & so->mask; setentry *entry, *limit;
setentry *entry;
PyObject *key; PyObject *key;
assert (PyAnySet_Check(so)); assert (PyAnySet_Check(so));
@ -711,16 +710,18 @@ set_pop(PySetObject *so, PyObject *Py_UNUSED(ignored))
return NULL; return NULL;
} }
while ((entry = &so->table[i])->key == NULL || entry->key==dummy) { entry = so->table + (so->finger & so->mask);
i++; limit = so->table + so->mask;
if (i > so->mask) while (entry->key == NULL || entry->key==dummy) {
i = 0; entry++;
if (entry > limit)
entry = so->table;
} }
key = entry->key; key = entry->key;
entry->key = dummy; entry->key = dummy;
entry->hash = -1; entry->hash = -1;
so->used--; so->used--;
so->finger = i + 1; /* next place to start */ so->finger = entry - so->table + 1; /* next place to start */
return key; return key;
} }