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Issue #23269: Tighten search_loop in set_insert_clean() 

Instead of masking and shifting every loopup, move the wrap-around
test outside of the inner-loop.
This commit is contained in:
Raymond Hettinger 2015-01-26 21:33:48 -08:00
parent 618e315f93
commit 3037e84ad1
1 changed files with 17 additions and 6 deletions
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23
Objects/setobject.c
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@ -138,17 +138,28 @@ set_insert_clean(PySetObject *so, PyObject *key, Py_hash_t hash)
setentry *entry; setentry *entry;
size_t perturb = hash; size_t perturb = hash;
size_t mask = (size_t)so->mask; size_t mask = (size_t)so->mask;
size_t i = (size_t)hash; size_t i = (size_t)hash & mask;
size_t j; size_t j;
while (1) { while (1) {
for (j = 0 ; j <= LINEAR_PROBES ; j++) { entry = &table[i];
entry = &table[(i + j) & mask]; if (entry->key == NULL)
if (entry->key == NULL) goto found_null;
goto found_null; if (i + LINEAR_PROBES <= mask) {
for (j = 1; j <= LINEAR_PROBES; j++) {
entry = &table[i + j];
if (entry->key == NULL)
goto found_null;
}
} else {
for (j = 1; j <= LINEAR_PROBES; j++) {
entry = &table[(i + j) & mask];
if (entry->key == NULL)
goto found_null;
}
} }
perturb >>= PERTURB_SHIFT; perturb >>= PERTURB_SHIFT;
i = i * 5 + 1 + perturb; i = (i * 5 + 1 + perturb) & mask;
} }
found_null: found_null:
entry->key = key; entry->key = key;