bpo-29304: Simplify dict lookup functions (GH-2407)

* remove hashpos parameter from lookdict functions.
* remove many duplicated code from lookdict functions.

1 files changed, 130 insertions, 267 deletions

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index c44ff47..e395f4d 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -223,18 +223,14 @@ equally good collision statistics, needed less code & used less memory.
 
 /* forward declarations */
 static Py_ssize_t lookdict(PyDictObject *mp, PyObject *key,
-                           Py_hash_t hash, PyObject **value_addr,
-                           Py_ssize_t *hashpos);
+                           Py_hash_t hash, PyObject **value_addr);
 static Py_ssize_t lookdict_unicode(PyDictObject *mp, PyObject *key,
-                                   Py_hash_t hash, PyObject **value_addr,
-                                   Py_ssize_t *hashpos);
+                                   Py_hash_t hash, PyObject **value_addr);
 static Py_ssize_t
 lookdict_unicode_nodummy(PyDictObject *mp, PyObject *key,
-                         Py_hash_t hash, PyObject **value_addr,
-                         Py_ssize_t *hashpos);
+                         Py_hash_t hash, PyObject **value_addr);
 static Py_ssize_t lookdict_split(PyDictObject *mp, PyObject *key,
-                                 Py_hash_t hash, PyObject **value_addr,
-                                 Py_ssize_t *hashpos);
+                                 Py_hash_t hash, PyObject **value_addr);
 
 static int dictresize(PyDictObject *mp, Py_ssize_t minused);
 
@@ -672,118 +668,59 @@ never raise an exception; that function can never return DKIX_ERROR when key
 is string.  Otherwise, it falls back to lookdict().
 lookdict_unicode_nodummy is further specialized for string keys that cannot be
 the <dummy> value.
-For both, when the key isn't found a DKIX_EMPTY is returned. hashpos returns
-where the key index should be inserted.
+For both, when the key isn't found a DKIX_EMPTY is returned.
 */
 static Py_ssize_t _Py_HOT_FUNCTION
 lookdict(PyDictObject *mp, PyObject *key,
-         Py_hash_t hash, PyObject **value_addr, Py_ssize_t *hashpos)
+         Py_hash_t hash, PyObject **value_addr)
 {
-    size_t i, mask;
-    Py_ssize_t ix, freeslot;
-    int cmp;
+    size_t i, mask, perturb;
     PyDictKeysObject *dk;
-    PyDictKeyEntry *ep0, *ep;
-    PyObject *startkey;
+    PyDictKeyEntry *ep0;
 
 top:
     dk = mp->ma_keys;
-    mask = DK_MASK(dk);
     ep0 = DK_ENTRIES(dk);
+    mask = DK_MASK(dk);
+    perturb = hash;
     i = (size_t)hash & mask;
 
-    ix = dk_get_index(dk, i);
-    if (ix == DKIX_EMPTY) {
-        if (hashpos != NULL)
-            *hashpos = i;
-        *value_addr = NULL;
-        return DKIX_EMPTY;
-    }
-    if (ix == DKIX_DUMMY) {
-        freeslot = i;
-    }
-    else {
-        ep = &ep0[ix];
-        assert(ep->me_key != NULL);
-        if (ep->me_key == key) {
-            *value_addr = ep->me_value;
-            if (hashpos != NULL)
-                *hashpos = i;
-            return ix;
-        }
-        if (ep->me_hash == hash) {
-            startkey = ep->me_key;
-            Py_INCREF(startkey);
-            cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
-            Py_DECREF(startkey);
-            if (cmp < 0) {
-                *value_addr = NULL;
-                return DKIX_ERROR;
-            }
-            if (dk == mp->ma_keys && ep->me_key == startkey) {
-                if (cmp > 0) {
-                    *value_addr = ep->me_value;
-                    if (hashpos != NULL)
-                        *hashpos = i;
-                    return ix;
-                }
-            }
-            else {
-                /* The dict was mutated, restart */
-                goto top;
-            }
-        }
-        freeslot = -1;
-    }
-
-    for (size_t perturb = hash;;) {
-        perturb >>= PERTURB_SHIFT;
-        i = (i*5 + perturb + 1) & mask;
-        ix = dk_get_index(dk, i);
+    for (;;) {
+        Py_ssize_t ix = dk_get_index(dk, i);
         if (ix == DKIX_EMPTY) {
-            if (hashpos != NULL) {
-                *hashpos = (freeslot == -1) ? (Py_ssize_t)i : freeslot;
-            }
             *value_addr = NULL;
             return ix;
         }
-        if (ix == DKIX_DUMMY) {
-            if (freeslot == -1)
-                freeslot = i;
-            continue;
-        }
-        ep = &ep0[ix];
-        assert(ep->me_key != NULL);
-        if (ep->me_key == key) {
-            if (hashpos != NULL) {
-                *hashpos = i;
-            }
-            *value_addr = ep->me_value;
-            return ix;
-        }
-        if (ep->me_hash == hash) {
-            startkey = ep->me_key;
-            Py_INCREF(startkey);
-            cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
-            Py_DECREF(startkey);
-            if (cmp < 0) {
-                *value_addr = NULL;
-                return DKIX_ERROR;
+        if (ix >= 0) {
+            PyDictKeyEntry *ep = &ep0[ix];
+            assert(ep->me_key != NULL);
+            if (ep->me_key == key) {
+                *value_addr = ep->me_value;
+                return ix;
             }
-            if (dk == mp->ma_keys && ep->me_key == startkey) {
-                if (cmp > 0) {
-                    if (hashpos != NULL) {
-                        *hashpos = i;
+            if (ep->me_hash == hash) {
+                PyObject *startkey = ep->me_key;
+                Py_INCREF(startkey);
+                int cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
+                Py_DECREF(startkey);
+                if (cmp < 0) {
+                    *value_addr = NULL;
+                    return DKIX_ERROR;
+                }
+                if (dk == mp->ma_keys && ep->me_key == startkey) {
+                    if (cmp > 0) {
+                        *value_addr = ep->me_value;
+                        return ix;
                     }
-                    *value_addr = ep->me_value;
-                    return ix;
                 }
-            }
-            else {
-                /* The dict was mutated, restart */
-                goto top;
+                else {
+                    /* The dict was mutated, restart */
+                    goto top;
+                }
             }
         }
+        perturb >>= PERTURB_SHIFT;
+        i = (i*5 + perturb + 1) & mask;
     }
     assert(0);          /* NOT REACHED */
     return 0;
@@ -792,13 +729,8 @@ top:
 /* Specialized version for string-only keys */
 static Py_ssize_t _Py_HOT_FUNCTION
 lookdict_unicode(PyDictObject *mp, PyObject *key,
-                 Py_hash_t hash, PyObject **value_addr, Py_ssize_t *hashpos)
+                 Py_hash_t hash, PyObject **value_addr)
 {
-    size_t i;
-    size_t mask = DK_MASK(mp->ma_keys);
-    Py_ssize_t ix, freeslot;
-    PyDictKeyEntry *ep, *ep0 = DK_ENTRIES(mp->ma_keys);
-
     assert(mp->ma_values == NULL);
     /* Make sure this function doesn't have to handle non-unicode keys,
        including subclasses of str; e.g., one reason to subclass
@@ -806,59 +738,34 @@ lookdict_unicode(PyDictObject *mp, PyObject *key,
        that here. */
     if (!PyUnicode_CheckExact(key)) {
         mp->ma_keys->dk_lookup = lookdict;
-        return lookdict(mp, key, hash, value_addr, hashpos);
-    }
-    i = (size_t)hash & mask;
-    ix = dk_get_index(mp->ma_keys, i);
-    if (ix == DKIX_EMPTY) {
-        if (hashpos != NULL)
-            *hashpos = i;
-        *value_addr = NULL;
-        return DKIX_EMPTY;
-    }
-    if (ix == DKIX_DUMMY) {
-        freeslot = i;
-    }
-    else {
-        ep = &ep0[ix];
-        assert(ep->me_key != NULL);
-        if (ep->me_key == key
-            || (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
-            if (hashpos != NULL)
-                *hashpos = i;
-            *value_addr = ep->me_value;
-            return ix;
-        }
-        freeslot = -1;
+        return lookdict(mp, key, hash, value_addr);
     }
 
-    for (size_t perturb = hash;;) {
-        perturb >>= PERTURB_SHIFT;
-        i = mask & (i*5 + perturb + 1);
-        ix = dk_get_index(mp->ma_keys, i);
+    PyDictKeyEntry *ep0 = DK_ENTRIES(mp->ma_keys);
+    size_t mask = DK_MASK(mp->ma_keys);
+    size_t perturb = (size_t)hash;
+    size_t i = (size_t)hash & mask;
+
+    for (;;) {
+        Py_ssize_t ix = dk_get_index(mp->ma_keys, i);
         if (ix == DKIX_EMPTY) {
-            if (hashpos != NULL) {
-                *hashpos = (freeslot == -1) ? (Py_ssize_t)i : freeslot;
-            }
             *value_addr = NULL;
             return DKIX_EMPTY;
         }
-        if (ix == DKIX_DUMMY) {
-            if (freeslot == -1)
-                freeslot = i;
-            continue;
-        }
-        ep = &ep0[ix];
-        assert(ep->me_key != NULL);
-        if (ep->me_key == key
-            || (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
-            *value_addr = ep->me_value;
-            if (hashpos != NULL) {
-                *hashpos = i;
+        if (ix >= 0) {
+            PyDictKeyEntry *ep = &ep0[ix];
+            assert(ep->me_key != NULL);
+            assert(PyUnicode_CheckExact(ep->me_key));
+            if (ep->me_key == key ||
+                    (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
+                *value_addr = ep->me_value;
+                return ix;
             }
-            return ix;
         }
+        perturb >>= PERTURB_SHIFT;
+        i = mask & (i*5 + perturb + 1);
     }
+
     assert(0);          /* NOT REACHED */
     return 0;
 }
@@ -867,14 +774,8 @@ lookdict_unicode(PyDictObject *mp, PyObject *key,
  * will be present. */
 static Py_ssize_t _Py_HOT_FUNCTION
 lookdict_unicode_nodummy(PyDictObject *mp, PyObject *key,
-                         Py_hash_t hash, PyObject **value_addr,
-                         Py_ssize_t *hashpos)
+                         Py_hash_t hash, PyObject **value_addr)
 {
-    size_t i;
-    size_t mask = DK_MASK(mp->ma_keys);
-    Py_ssize_t ix;
-    PyDictKeyEntry *ep, *ep0 = DK_ENTRIES(mp->ma_keys);
-
     assert(mp->ma_values == NULL);
     /* Make sure this function doesn't have to handle non-unicode keys,
        including subclasses of str; e.g., one reason to subclass
@@ -882,47 +783,31 @@ lookdict_unicode_nodummy(PyDictObject *mp, PyObject *key,
        that here. */
     if (!PyUnicode_CheckExact(key)) {
         mp->ma_keys->dk_lookup = lookdict;
-        return lookdict(mp, key, hash, value_addr, hashpos);
+        return lookdict(mp, key, hash, value_addr);
     }
-    i = (size_t)hash & mask;
-    ix = dk_get_index(mp->ma_keys, i);
-    assert (ix != DKIX_DUMMY);
-    if (ix == DKIX_EMPTY) {
-        if (hashpos != NULL)
-            *hashpos = i;
-        *value_addr = NULL;
-        return DKIX_EMPTY;
-    }
-    ep = &ep0[ix];
-    assert(ep->me_key != NULL);
-    assert(PyUnicode_CheckExact(ep->me_key));
-    if (ep->me_key == key ||
-        (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
-        if (hashpos != NULL)
-            *hashpos = i;
-        *value_addr = ep->me_value;
-        return ix;
-    }
-    for (size_t perturb = hash;;) {
-        perturb >>= PERTURB_SHIFT;
-        i = mask & (i*5 + perturb + 1);
-        ix = dk_get_index(mp->ma_keys, i);
+
+    PyDictKeyEntry *ep0 = DK_ENTRIES(mp->ma_keys);
+    size_t mask = DK_MASK(mp->ma_keys);
+    size_t perturb = (size_t)hash;
+    size_t i = (size_t)hash & mask;
+
+    for (;;) {
+        Py_ssize_t ix = dk_get_index(mp->ma_keys, i);
         assert (ix != DKIX_DUMMY);
         if (ix == DKIX_EMPTY) {
-            if (hashpos != NULL)
-                *hashpos = i;
             *value_addr = NULL;
             return DKIX_EMPTY;
         }
-        ep = &ep0[ix];
-        assert(ep->me_key != NULL && PyUnicode_CheckExact(ep->me_key));
+        PyDictKeyEntry *ep = &ep0[ix];
+        assert(ep->me_key != NULL);
+        assert(PyUnicode_CheckExact(ep->me_key));
         if (ep->me_key == key ||
             (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
-            if (hashpos != NULL)
-                *hashpos = i;
             *value_addr = ep->me_value;
             return ix;
         }
+        perturb >>= PERTURB_SHIFT;
+        i = mask & (i*5 + perturb + 1);
     }
     assert(0);          /* NOT REACHED */
     return 0;
@@ -935,61 +820,40 @@ lookdict_unicode_nodummy(PyDictObject *mp, PyObject *key,
  */
 static Py_ssize_t _Py_HOT_FUNCTION
 lookdict_split(PyDictObject *mp, PyObject *key,
-               Py_hash_t hash, PyObject **value_addr, Py_ssize_t *hashpos)
+               Py_hash_t hash, PyObject **value_addr)
 {
-    size_t i;
-    size_t mask = DK_MASK(mp->ma_keys);
-    Py_ssize_t ix;
-    PyDictKeyEntry *ep, *ep0 = DK_ENTRIES(mp->ma_keys);
-
     /* mp must split table */
     assert(mp->ma_values != NULL);
     if (!PyUnicode_CheckExact(key)) {
-        ix = lookdict(mp, key, hash, value_addr, hashpos);
+        Py_ssize_t ix = lookdict(mp, key, hash, value_addr);
         if (ix >= 0) {
             *value_addr = mp->ma_values[ix];
         }
         return ix;
     }
 
-    i = (size_t)hash & mask;
-    ix = dk_get_index(mp->ma_keys, i);
-    if (ix == DKIX_EMPTY) {
-        if (hashpos != NULL)
-            *hashpos = i;
-        *value_addr = NULL;
-        return DKIX_EMPTY;
-    }
-    assert(ix >= 0);
-    ep = &ep0[ix];
-    assert(ep->me_key != NULL && PyUnicode_CheckExact(ep->me_key));
-    if (ep->me_key == key ||
-        (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
-        if (hashpos != NULL)
-            *hashpos = i;
-        *value_addr = mp->ma_values[ix];
-        return ix;
-    }
-    for (size_t perturb = hash;;) {
-        perturb >>= PERTURB_SHIFT;
-        i = mask & (i*5 + perturb + 1);
-        ix = dk_get_index(mp->ma_keys, i);
+    PyDictKeyEntry *ep0 = DK_ENTRIES(mp->ma_keys);
+    size_t mask = DK_MASK(mp->ma_keys);
+    size_t perturb = (size_t)hash;
+    size_t i = (size_t)hash & mask;
+
+    for (;;) {
+        Py_ssize_t ix = dk_get_index(mp->ma_keys, i);
+        assert (ix != DKIX_DUMMY);
         if (ix == DKIX_EMPTY) {
-            if (hashpos != NULL)
-                *hashpos = i;
             *value_addr = NULL;
             return DKIX_EMPTY;
         }
-        assert(ix >= 0);
-        ep = &ep0[ix];
-        assert(ep->me_key != NULL && PyUnicode_CheckExact(ep->me_key));
+        PyDictKeyEntry *ep = &ep0[ix];
+        assert(ep->me_key != NULL);
+        assert(PyUnicode_CheckExact(ep->me_key));
         if (ep->me_key == key ||
             (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
-            if (hashpos != NULL)
-                *hashpos = i;
             *value_addr = mp->ma_values[ix];
             return ix;
         }
+        perturb >>= PERTURB_SHIFT;
+        i = mask & (i*5 + perturb + 1);
     }
     assert(0);          /* NOT REACHED */
     return 0;
@@ -1061,23 +925,19 @@ _PyDict_MaybeUntrack(PyObject *op)
 
    The dict must be combined. */
 static Py_ssize_t
-find_empty_slot(PyDictKeysObject *keys, PyObject *key, Py_hash_t hash)
+find_empty_slot(PyDictKeysObject *keys, Py_hash_t hash)
 {
-    size_t i;
-    size_t mask = DK_MASK(keys);
-    Py_ssize_t ix;
-
-    assert(key != NULL);
+    assert(keys != NULL);
 
-    i = hash & mask;
-    ix = dk_get_index(keys, i);
-    for (size_t perturb = hash; ix != DKIX_EMPTY;) {
+    const size_t mask = DK_MASK(keys);
+    size_t i = hash & mask;
+    Py_ssize_t ix = dk_get_index(keys, i);
+    for (size_t perturb = hash; ix >= 0;) {
         perturb >>= PERTURB_SHIFT;
-        i = i*5 + perturb + 1;
-        ix = dk_get_index(keys, i & mask);
+        i = (i*5 + perturb + 1) & mask;
+        ix = dk_get_index(keys, i);
     }
-    assert(DK_ENTRIES(keys)[keys->dk_nentries].me_value == NULL);
-    return i & mask;
+    return i;
 }
 
 static int
@@ -1096,7 +956,6 @@ insertdict(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject *value)
 {
     PyObject *old_value;
     PyDictKeyEntry *ep;
-    Py_ssize_t hashpos, ix;
 
     Py_INCREF(key);
     Py_INCREF(value);
@@ -1105,7 +964,7 @@ insertdict(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject *value)
             goto Fail;
     }
 
-    ix = mp->ma_keys->dk_lookup(mp, key, hash, &old_value, &hashpos);
+    Py_ssize_t ix = mp->ma_keys->dk_lookup(mp, key, hash, &old_value);
     if (ix == DKIX_ERROR)
         goto Fail;
 
@@ -1120,7 +979,6 @@ insertdict(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject *value)
          (ix == DKIX_EMPTY && mp->ma_used != mp->ma_keys->dk_nentries))) {
         if (insertion_resize(mp) < 0)
             goto Fail;
-        hashpos = find_empty_slot(mp->ma_keys, key, hash);
         ix = DKIX_EMPTY;
     }
 
@@ -1131,8 +989,8 @@ insertdict(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject *value)
             /* Need to resize. */
             if (insertion_resize(mp) < 0)
                 goto Fail;
-            hashpos = find_empty_slot(mp->ma_keys, key, hash);
         }
+        Py_ssize_t hashpos = find_empty_slot(mp->ma_keys, hash);
         ep = &DK_ENTRIES(mp->ma_keys)[mp->ma_keys->dk_nentries];
         dk_set_index(mp->ma_keys, hashpos, mp->ma_keys->dk_nentries);
         ep->me_key = key;
@@ -1411,14 +1269,14 @@ PyDict_GetItem(PyObject *op, PyObject *key)
         /* preserve the existing exception */
         PyObject *err_type, *err_value, *err_tb;
         PyErr_Fetch(&err_type, &err_value, &err_tb);
-        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, NULL);
+        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
         /* ignore errors */
         PyErr_Restore(err_type, err_value, err_tb);
         if (ix < 0)
             return NULL;
     }
     else {
-        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, NULL);
+        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
         if (ix < 0) {
             PyErr_Clear();
             return NULL;
@@ -1443,7 +1301,7 @@ _PyDict_GetItem_KnownHash(PyObject *op, PyObject *key, Py_hash_t hash)
         return NULL;
     }
 
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, NULL);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
     if (ix < 0) {
         return NULL;
     }
@@ -1475,7 +1333,7 @@ PyDict_GetItemWithError(PyObject *op, PyObject *key)
         }
     }
 
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, NULL);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
     if (ix < 0)
         return NULL;
     return value;
@@ -1514,14 +1372,14 @@ _PyDict_LoadGlobal(PyDictObject *globals, PyDictObject *builtins, PyObject *key)
     }
 
     /* namespace 1: globals */
-    ix = globals->ma_keys->dk_lookup(globals, key, hash, &value, NULL);
+    ix = globals->ma_keys->dk_lookup(globals, key, hash, &value);
     if (ix == DKIX_ERROR)
         return NULL;
     if (ix != DKIX_EMPTY && value != NULL)
         return value;
 
     /* namespace 2: builtins */
-    ix = builtins->ma_keys->dk_lookup(builtins, key, hash, &value, NULL);
+    ix = builtins->ma_keys->dk_lookup(builtins, key, hash, &value);
     if (ix < 0)
         return NULL;
     return value;
@@ -1577,12 +1435,15 @@ _PyDict_SetItem_KnownHash(PyObject *op, PyObject *key, PyObject *value,
 }
 
 static int
-delitem_common(PyDictObject *mp, Py_ssize_t hashpos, Py_ssize_t ix,
+delitem_common(PyDictObject *mp, Py_hash_t hash, Py_ssize_t ix,
                PyObject *old_value)
 {
     PyObject *old_key;
     PyDictKeyEntry *ep;
 
+    Py_ssize_t hashpos = lookdict_index(mp->ma_keys, hash, ix);
+    assert(hashpos >= 0);
+
     mp->ma_used--;
     mp->ma_version_tag = DICT_NEXT_VERSION();
     ep = &DK_ENTRIES(mp->ma_keys)[ix];
@@ -1616,7 +1477,7 @@ PyDict_DelItem(PyObject *op, PyObject *key)
 int
 _PyDict_DelItem_KnownHash(PyObject *op, PyObject *key, Py_hash_t hash)
 {
-    Py_ssize_t hashpos, ix;
+    Py_ssize_t ix;
     PyDictObject *mp;
     PyObject *old_value;
 
@@ -1627,25 +1488,24 @@ _PyDict_DelItem_KnownHash(PyObject *op, PyObject *key, Py_hash_t hash)
     assert(key);
     assert(hash != -1);
     mp = (PyDictObject *)op;
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value, &hashpos);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value);
     if (ix == DKIX_ERROR)
         return -1;
     if (ix == DKIX_EMPTY || old_value == NULL) {
         _PyErr_SetKeyError(key);
         return -1;
     }
-    assert(dk_get_index(mp->ma_keys, hashpos) == ix);
 
     // Split table doesn't allow deletion.  Combine it.
     if (_PyDict_HasSplitTable(mp)) {
         if (dictresize(mp, DK_SIZE(mp->ma_keys))) {
             return -1;
         }
-        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value, &hashpos);
+        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value);
         assert(ix >= 0);
     }
 
-    return delitem_common(mp, hashpos, ix, old_value);
+    return delitem_common(mp, hash, ix, old_value);
 }
 
 /* This function promises that the predicate -> deletion sequence is atomic
@@ -1671,27 +1531,30 @@ _PyDict_DelItemIf(PyObject *op, PyObject *key,
     if (hash == -1)
         return -1;
     mp = (PyDictObject *)op;
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value, &hashpos);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value);
     if (ix == DKIX_ERROR)
         return -1;
     if (ix == DKIX_EMPTY || old_value == NULL) {
         _PyErr_SetKeyError(key);
         return -1;
     }
-    assert(dk_get_index(mp->ma_keys, hashpos) == ix);
 
     // Split table doesn't allow deletion.  Combine it.
     if (_PyDict_HasSplitTable(mp)) {
         if (dictresize(mp, DK_SIZE(mp->ma_keys))) {
             return -1;
         }
-        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value, &hashpos);
+        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value);
         assert(ix >= 0);
     }
 
     res = predicate(old_value);
     if (res == -1)
         return -1;
+
+    hashpos = lookdict_index(mp->ma_keys, hash, ix);
+    assert(hashpos >= 0);
+
     if (res > 0)
         return delitem_common(mp, hashpos, ix, old_value);
     else
@@ -1828,7 +1691,7 @@ _PyDict_Pop_KnownHash(PyObject *dict, PyObject *key, Py_hash_t hash, PyObject *d
         _PyErr_SetKeyError(key);
         return NULL;
     }
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value, &hashpos);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value);
     if (ix == DKIX_ERROR)
         return NULL;
     if (ix == DKIX_EMPTY || old_value == NULL) {
@@ -1845,10 +1708,12 @@ _PyDict_Pop_KnownHash(PyObject *dict, PyObject *key, Py_hash_t hash, PyObject *d
         if (dictresize(mp, DK_SIZE(mp->ma_keys))) {
             return NULL;
         }
-        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value, &hashpos);
+        ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value);
         assert(ix >= 0);
     }
 
+    hashpos = lookdict_index(mp->ma_keys, hash, ix);
+    assert(hashpos >= 0);
     assert(old_value != NULL);
     mp->ma_used--;
     mp->ma_version_tag = DICT_NEXT_VERSION();
@@ -2107,7 +1972,7 @@ dict_subscript(PyDictObject *mp, PyObject *key)
         if (hash == -1)
             return NULL;
     }
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, NULL);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
     if (ix == DKIX_ERROR)
         return NULL;
     if (ix == DKIX_EMPTY || value == NULL) {
@@ -2718,7 +2583,7 @@ dict_equal(PyDictObject *a, PyDictObject *b)
             /* ditto for key */
             Py_INCREF(key);
             /* reuse the known hash value */
-            b->ma_keys->dk_lookup(b, key, ep->me_hash, &bval, NULL);
+            b->ma_keys->dk_lookup(b, key, ep->me_hash, &bval);
             if (bval == NULL) {
                 Py_DECREF(key);
                 Py_DECREF(aval);
@@ -2783,7 +2648,7 @@ dict___contains__(PyDictObject *self, PyObject *key)
         if (hash == -1)
             return NULL;
     }
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, NULL);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
     if (ix == DKIX_ERROR)
         return NULL;
     if (ix == DKIX_EMPTY || value == NULL)
@@ -2815,7 +2680,7 @@ dict_get_impl(PyDictObject *self, PyObject *key, PyObject *default_value)
         if (hash == -1)
             return NULL;
     }
-    ix = (self->ma_keys->dk_lookup) (self, key, hash, &val, NULL);
+    ix = (self->ma_keys->dk_lookup) (self, key, hash, &val);
     if (ix == DKIX_ERROR)
         return NULL;
     if (ix == DKIX_EMPTY || val == NULL) {
@@ -2831,7 +2696,6 @@ PyDict_SetDefault(PyObject *d, PyObject *key, PyObject *defaultobj)
     PyDictObject *mp = (PyDictObject *)d;
     PyObject *value;
     Py_hash_t hash;
-    Py_ssize_t hashpos, ix;
 
     if (!PyDict_Check(d)) {
         PyErr_BadInternalCall();
@@ -2850,7 +2714,7 @@ PyDict_SetDefault(PyObject *d, PyObject *key, PyObject *defaultobj)
             return NULL;
     }
 
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, &hashpos);
+    Py_ssize_t ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
     if (ix == DKIX_ERROR)
         return NULL;
 
@@ -2860,7 +2724,6 @@ PyDict_SetDefault(PyObject *d, PyObject *key, PyObject *defaultobj)
         if (insertion_resize(mp) < 0) {
             return NULL;
         }
-        hashpos = find_empty_slot(mp->ma_keys, key, hash);
         ix = DKIX_EMPTY;
     }
 
@@ -2871,8 +2734,8 @@ PyDict_SetDefault(PyObject *d, PyObject *key, PyObject *defaultobj)
             if (insertion_resize(mp) < 0) {
                 return NULL;
             }
-            hashpos = find_empty_slot(mp->ma_keys, key, hash);
         }
+        Py_ssize_t hashpos = find_empty_slot(mp->ma_keys, hash);
         ep0 = DK_ENTRIES(mp->ma_keys);
         ep = &ep0[mp->ma_keys->dk_nentries];
         dk_set_index(mp->ma_keys, hashpos, mp->ma_keys->dk_nentries);
@@ -3167,7 +3030,7 @@ PyDict_Contains(PyObject *op, PyObject *key)
         if (hash == -1)
             return -1;
     }
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, NULL);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
     if (ix == DKIX_ERROR)
         return -1;
     return (ix != DKIX_EMPTY && value != NULL);
@@ -3181,7 +3044,7 @@ _PyDict_Contains(PyObject *op, PyObject *key, Py_hash_t hash)
     PyObject *value;
     Py_ssize_t ix;
 
-    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value, NULL);
+    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value);
     if (ix == DKIX_ERROR)
         return -1;
     return (ix != DKIX_EMPTY && value != NULL);