commit f66e336f455b5a6bb0ca857d61c43be410d0df13
author Cheryl Sabella <cheryl.sabella@gmail.com> Fri Apr 05 06:08:43 2019 -0400
committer Inada Naoki <songofacandy@gmail.com> Fri Apr 05 19:08:43 2019 +0900
tree e95bc9d4f381c4772ca14e47646503ce00907b61
parent 6a8c3139ae9ada89d4a95985ec7cf8bb7d03bc01

bpo-29202: improve dict iteration (GH-11900)

Use fewer iterations instead of iterating over the whole entry table.

Objects/dictobject.c

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index bba27dd..c1187c2 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -2147,7 +2147,7 @@
     PyObject *v;
     Py_ssize_t i, j;
     PyDictKeyEntry *ep;
-    Py_ssize_t size, n, offset;
+    Py_ssize_t n, offset;
     PyObject **value_ptr;
 
   again:
@@ -2163,7 +2163,6 @@
         goto again;
     }
     ep = DK_ENTRIES(mp->ma_keys);
-    size = mp->ma_keys->dk_nentries;
     if (mp->ma_values) {
         value_ptr = mp->ma_values;
         offset = sizeof(PyObject *);
@@ -2172,7 +2171,7 @@
         value_ptr = &ep[0].me_value;
         offset = sizeof(PyDictKeyEntry);
     }
-    for (i = 0, j = 0; i < size; i++) {
+    for (i = 0, j = 0; j < n; i++) {
         if (*value_ptr != NULL) {
             PyObject *key = ep[i].me_key;
             Py_INCREF(key);
@@ -2191,7 +2190,7 @@
     PyObject *v;
     Py_ssize_t i, j;
     PyDictKeyEntry *ep;
-    Py_ssize_t size, n, offset;
+    Py_ssize_t n, offset;
     PyObject **value_ptr;
 
   again:
@@ -2207,7 +2206,6 @@
         goto again;
     }
     ep = DK_ENTRIES(mp->ma_keys);
-    size = mp->ma_keys->dk_nentries;
     if (mp->ma_values) {
         value_ptr = mp->ma_values;
         offset = sizeof(PyObject *);
@@ -2216,7 +2214,7 @@
         value_ptr = &ep[0].me_value;
         offset = sizeof(PyDictKeyEntry);
     }
-    for (i = 0, j = 0; i < size; i++) {
+    for (i = 0, j = 0; j < n; i++) {
         PyObject *value = *value_ptr;
         value_ptr = (PyObject **)(((char *)value_ptr) + offset);
         if (value != NULL) {
@@ -2234,7 +2232,7 @@
 {
     PyObject *v;
     Py_ssize_t i, j, n;
-    Py_ssize_t size, offset;
+    Py_ssize_t offset;
     PyObject *item, *key;
     PyDictKeyEntry *ep;
     PyObject **value_ptr;
@@ -2265,7 +2263,6 @@
     }
     /* Nothing we do below makes any function calls. */
     ep = DK_ENTRIES(mp->ma_keys);
-    size = mp->ma_keys->dk_nentries;
     if (mp->ma_values) {
         value_ptr = mp->ma_values;
         offset = sizeof(PyObject *);
@@ -2274,7 +2271,7 @@
         value_ptr = &ep[0].me_value;
         offset = sizeof(PyDictKeyEntry);
     }
-    for (i = 0, j = 0; i < size; i++) {
+    for (i = 0, j = 0; j < n; i++) {
         PyObject *value = *value_ptr;
         value_ptr = (PyObject **)(((char *)value_ptr) + offset);
         if (value != NULL) {