Skip to content

Commit 2cc9b84

Browse files
rhettingerrhettinger
authored
Improve code clarity for the set lookup logic (GH-20028)
1 parent 2fbc57a commit 2cc9b84

File tree

1 file changed

+55
-125
lines changed

1 file changed

+55
-125
lines changed

‎Objects/setobject.c

+55-125
Original file line numberDiff line numberDiff line change
@@ -57,77 +57,43 @@ set_lookkey(PySetObject *so, PyObject *key, Py_hash_t hash)
5757
{
5858
setentry *table;
5959
setentry *entry;
60-
size_t perturb;
60+
size_t perturb = hash;
6161
size_t mask = so->mask;
6262
size_t i = (size_t)hash & mask; /* Unsigned for defined overflow behavior */
63-
size_t j;
63+
int probes;
6464
int cmp;
6565

66-
entry = &so->table[i];
67-
if (entry->key == NULL)
68-
return entry;
69-
70-
perturb = hash;
71-
7266
while (1) {
73-
if (entry->hash == hash) {
74-
PyObject *startkey = entry->key;
75-
/* startkey cannot be a dummy because the dummy hash field is -1 */
76-
assert(startkey != dummy);
77-
if (startkey == key)
78-
return entry;
79-
if (PyUnicode_CheckExact(startkey)
80-
&& PyUnicode_CheckExact(key)
81-
&& _PyUnicode_EQ(startkey, key))
82-
return entry;
83-
table = so->table;
84-
Py_INCREF(startkey);
85-
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
86-
Py_DECREF(startkey);
87-
if (cmp < 0) /* unlikely */
88-
return NULL;
89-
if (table != so->table || entry->key != startkey) /* unlikely */
90-
return set_lookkey(so, key, hash);
91-
if (cmp > 0) /* likely */
67+
entry = &so->table[i];
68+
probes = (i + LINEAR_PROBES <= mask) ? LINEAR_PROBES: 0;
69+
do {
70+
if (entry->hash == 0 && entry->key == NULL)
9271
return entry;
93-
mask = so->mask; /* help avoid a register spill */
94-
}
95-
96-
if (i + LINEAR_PROBES <= mask) {
97-
for (j = 0 ; j < LINEAR_PROBES ; j++) {
98-
entry++;
99-
if (entry->hash == 0 && entry->key == NULL)
72+
if (entry->hash == hash) {
73+
PyObject *startkey = entry->key;
74+
assert(startkey != dummy);
75+
if (startkey == key)
10076
return entry;
101-
if (entry->hash == hash) {
102-
PyObject *startkey = entry->key;
103-
assert(startkey != dummy);
104-
if (startkey == key)
105-
return entry;
106-
if (PyUnicode_CheckExact(startkey)
107-
&& PyUnicode_CheckExact(key)
108-
&& _PyUnicode_EQ(startkey, key))
109-
return entry;
110-
table = so->table;
111-
Py_INCREF(startkey);
112-
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
113-
Py_DECREF(startkey);
114-
if (cmp < 0)
115-
return NULL;
116-
if (table != so->table || entry->key != startkey)
117-
return set_lookkey(so, key, hash);
118-
if (cmp > 0)
119-
return entry;
120-
mask = so->mask;
121-
}
77+
if (PyUnicode_CheckExact(startkey)
78+
&& PyUnicode_CheckExact(key)
79+
&& _PyUnicode_EQ(startkey, key))
80+
return entry;
81+
table = so->table;
82+
Py_INCREF(startkey);
83+
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
84+
Py_DECREF(startkey);
85+
if (cmp < 0)
86+
return NULL;
87+
if (table != so->table || entry->key != startkey)
88+
return set_lookkey(so, key, hash);
89+
if (cmp > 0)
90+
return entry;
91+
mask = so->mask;
12292
}
123-
}
124-
93+
entry++;
94+
} while (probes--);
12595
perturb >>= PERTURB_SHIFT;
12696
i = (i * 5 + 1 + perturb) & mask;
127-
128-
entry = &so->table[i];
129-
if (entry->key == NULL)
130-
return entry;
13197
}
13298
}
13399

@@ -141,7 +107,7 @@ set_add_entry(PySetObject *so, PyObject *key, Py_hash_t hash)
141107
size_t perturb;
142108
size_t mask;
143109
size_t i; /* Unsigned for defined overflow behavior */
144-
size_t j;
110+
int probes;
145111
int cmp;
146112

147113
/* Pre-increment is necessary to prevent arbitrary code in the rich
@@ -152,75 +118,39 @@ set_add_entry(PySetObject *so, PyObject *key, Py_hash_t hash)
152118

153119
mask = so->mask;
154120
i = (size_t)hash & mask;
155-
156-
entry = &so->table[i];
157-
if (entry->key == NULL)
158-
goto found_unused;
159-
160121
perturb = hash;
161122

162123
while (1) {
163-
if (entry->hash == hash) {
164-
PyObject *startkey = entry->key;
165-
/* startkey cannot be a dummy because the dummy hash field is -1 */
166-
assert(startkey != dummy);
167-
if (startkey == key)
168-
goto found_active;
169-
if (PyUnicode_CheckExact(startkey)
170-
&& PyUnicode_CheckExact(key)
171-
&& _PyUnicode_EQ(startkey, key))
172-
goto found_active;
173-
table = so->table;
174-
Py_INCREF(startkey);
175-
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
176-
Py_DECREF(startkey);
177-
if (cmp > 0) /* likely */
178-
goto found_active;
179-
if (cmp < 0)
180-
goto comparison_error;
181-
/* Continuing the search from the current entry only makes
182-
sense if the table and entry are unchanged; otherwise,
183-
we have to restart from the beginning */
184-
if (table != so->table || entry->key != startkey)
185-
goto restart;
186-
mask = so->mask; /* help avoid a register spill */
187-
}
188-
189-
if (i + LINEAR_PROBES <= mask) {
190-
for (j = 0 ; j < LINEAR_PROBES ; j++) {
191-
entry++;
192-
if (entry->hash == 0 && entry->key == NULL)
193-
goto found_unused;
194-
if (entry->hash == hash) {
195-
PyObject *startkey = entry->key;
196-
assert(startkey != dummy);
197-
if (startkey == key)
198-
goto found_active;
199-
if (PyUnicode_CheckExact(startkey)
200-
&& PyUnicode_CheckExact(key)
201-
&& _PyUnicode_EQ(startkey, key))
202-
goto found_active;
203-
table = so->table;
204-
Py_INCREF(startkey);
205-
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
206-
Py_DECREF(startkey);
207-
if (cmp > 0)
208-
goto found_active;
209-
if (cmp < 0)
210-
goto comparison_error;
211-
if (table != so->table || entry->key != startkey)
212-
goto restart;
213-
mask = so->mask;
214-
}
124+
entry = &so->table[i];
125+
probes = (i + LINEAR_PROBES <= mask) ? LINEAR_PROBES: 0;
126+
do {
127+
if (entry->hash == 0 && entry->key == NULL)
128+
goto found_unused;
129+
if (entry->hash == hash) {
130+
PyObject *startkey = entry->key;
131+
assert(startkey != dummy);
132+
if (startkey == key)
133+
goto found_active;
134+
if (PyUnicode_CheckExact(startkey)
135+
&& PyUnicode_CheckExact(key)
136+
&& _PyUnicode_EQ(startkey, key))
137+
goto found_active;
138+
table = so->table;
139+
Py_INCREF(startkey);
140+
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
141+
Py_DECREF(startkey);
142+
if (cmp > 0)
143+
goto found_active;
144+
if (cmp < 0)
145+
goto comparison_error;
146+
if (table != so->table || entry->key != startkey)
147+
goto restart;
148+
mask = so->mask;
215149
}
216-
}
217-
150+
entry++;
151+
} while (probes--);
218152
perturb >>= PERTURB_SHIFT;
219153
i = (i * 5 + 1 + perturb) & mask;
220-
221-
entry = &so->table[i];
222-
if (entry->key == NULL)
223-
goto found_unused;
224154
}
225155

226156
found_unused:

0 commit comments

Comments
 (0)