diff -r a8589d88deb4 Modules/_collectionsmodule.c
--- a/Modules/_collectionsmodule.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Modules/_collectionsmodule.c	Sun Mar 06 16:47:55 2016 +0200
@@ -1742,6 +1742,12 @@ PyDoc_STRVAR(length_hint_doc, "Private m
 static PyObject *
 dequeiter_reduce(dequeiterobject *it)
 {
+    if (it->deque == NULL) {
+        return Py_BuildValue("N(())", _PyObject_GetBuiltin("iter"));
+    }
+    if (it->counter == Py_SIZE(it->deque)) {
+        return Py_BuildValue("O(O)", Py_TYPE(it), it->deque);
+    }
     return Py_BuildValue("O(On)", Py_TYPE(it), it->deque, Py_SIZE(it->deque) - it->counter);
 }
 
diff -r a8589d88deb4 Modules/arraymodule.c
--- a/Modules/arraymodule.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Modules/arraymodule.c	Sun Mar 06 16:47:55 2016 +0200
@@ -2906,8 +2906,14 @@ static PyObject *
 array_arrayiterator___reduce___impl(arrayiterobject *self)
 /*[clinic end generated code: output=7898a52e8e66e016 input=a062ea1e9951417a]*/
 {
-    return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
-                         self->ao, self->index);
+    PyObject *func = _PyObject_GetBuiltin("iter");
+    if (self->ao == NULL) {
+        return Py_BuildValue("N(())", func);
+    }
+    if (self->index == 0) {
+        return Py_BuildValue("N(O)", func, self->ao);
+    }
+    return Py_BuildValue("N(O)n", func, self->ao, self->index);
 }
 
 /*[clinic input]
diff -r a8589d88deb4 Modules/itertoolsmodule.c
--- a/Modules/itertoolsmodule.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Modules/itertoolsmodule.c	Sun Mar 06 16:47:55 2016 +0200
@@ -960,10 +960,13 @@ cycle_reduce(cycleobject *lz)
             }
             Py_DECREF(res);
         }
-        return Py_BuildValue("O(N)(Oi)", Py_TYPE(lz), it, lz->saved, 1);
+        return Py_BuildValue("O(N)(OO)", Py_TYPE(lz), it, lz->saved, Py_True);
     }
-    return Py_BuildValue("O(O)(Oi)", Py_TYPE(lz), lz->it, lz->saved,
-                         lz->firstpass);
+    if (!lz->firstpass && PyList_GET_SIZE(lz->saved) == 0) {
+        return Py_BuildValue("O(O)", Py_TYPE(lz), lz->it);
+    }
+    return Py_BuildValue("O(O)(OO)", Py_TYPE(lz), lz->it, lz->saved,
+                         lz->firstpass ? Py_True : Py_False);
 }
 
 static PyObject *
@@ -1046,7 +1049,7 @@ typedef struct {
     PyObject_HEAD
     PyObject *func;
     PyObject *it;
-    long start;
+    int start;
 } dropwhileobject;
 
 static PyTypeObject dropwhile_type;
@@ -1113,7 +1116,7 @@ dropwhile_next(dropwhileobject *lz)
         item = iternext(it);
         if (item == NULL)
             return NULL;
-        if (lz->start == 1)
+        if (lz->start)
             return item;
 
         good = PyObject_CallFunctionObjArgs(lz->func, item, NULL);
@@ -1136,7 +1139,10 @@ dropwhile_next(dropwhileobject *lz)
 static PyObject *
 dropwhile_reduce(dropwhileobject *lz)
 {
-    return Py_BuildValue("O(OO)l", Py_TYPE(lz), lz->func, lz->it, lz->start);
+    if (!lz->start) {
+        return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->func, lz->it);
+    }
+    return Py_BuildValue("O(OO)O", Py_TYPE(lz), lz->func, lz->it, Py_True);
 }
 
 static PyObject *
@@ -1214,7 +1220,7 @@ typedef struct {
     PyObject_HEAD
     PyObject *func;
     PyObject *it;
-    long stop;
+    int stop;
 } takewhileobject;
 
 static PyTypeObject takewhile_type;
@@ -1300,7 +1306,10 @@ takewhile_next(takewhileobject *lz)
 static PyObject *
 takewhile_reduce(takewhileobject *lz)
 {
-    return Py_BuildValue("O(OO)l", Py_TYPE(lz), lz->func, lz->it, lz->stop);
+    if (!lz->stop) {
+        return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->func, lz->it);
+    }
+    return Py_BuildValue("O(OO)O", Py_TYPE(lz), lz->func, lz->it, Py_True);
 }
 
 static PyObject *
@@ -1532,16 +1541,7 @@ islice_reduce(isliceobject *lz)
     PyObject *stop;
 
     if (lz->it == NULL) {
-        PyObject *empty_list;
-        PyObject *empty_it;
-        empty_list = PyList_New(0);
-        if (empty_list == NULL)
-            return NULL;
-        empty_it = PyObject_GetIter(empty_list);
-        Py_DECREF(empty_list);
-        if (empty_it == NULL)
-            return NULL;
-        return Py_BuildValue("O(Nn)n", Py_TYPE(lz), empty_it, 0, 0);
+        return Py_BuildValue("N(())", _PyObject_GetBuiltin("iter"));
     }
     if (lz->stop == -1) {
         stop = Py_None;
@@ -1551,6 +1551,22 @@ islice_reduce(isliceobject *lz)
         if (stop == NULL)
             return NULL;
     }
+    if (lz->step == 1) {
+        if (lz->next == 0) {
+            return Py_BuildValue("O(ON)", Py_TYPE(lz),
+                lz->it, stop);
+        }
+        if (lz->cnt == 0) {
+            return Py_BuildValue("O(OnN)", Py_TYPE(lz),
+                lz->it, lz->next, stop);
+        }
+        return Py_BuildValue("O(OnN)n", Py_TYPE(lz),
+            lz->it, lz->next, stop, lz->cnt);
+    }
+    if (lz->cnt == 0) {
+        return Py_BuildValue("O(OnNn)", Py_TYPE(lz),
+            lz->it, lz->next, stop, lz->step);
+    }
     return Py_BuildValue("O(OnNn)n", Py_TYPE(lz),
         lz->it, lz->next, stop, lz->step,
         lz->cnt);
@@ -3464,6 +3480,8 @@ accumulate_next(accumulateobject *lz)
 static PyObject *
 accumulate_reduce(accumulateobject *lz)
 {
+    PyObject *state;
+
     if (lz->total == Py_None) {
         PyObject *it;
 
@@ -3481,9 +3499,12 @@ accumulate_reduce(accumulateobject *lz)
             return NULL;
         return Py_BuildValue("O(NiO)", &islice_type, it, 1, Py_None);
     }
-    return Py_BuildValue("O(OO)O", Py_TYPE(lz),
-                            lz->it, lz->binop?lz->binop:Py_None,
-                            lz->total?lz->total:Py_None);
+
+    state = lz->total ? lz->total : Py_None;
+    if (!lz->binop) {
+        return Py_BuildValue("O(O)O", Py_TYPE(lz), lz->it, state);
+    }
+    return Py_BuildValue("O(OO)O", Py_TYPE(lz), lz->it, lz->binop, state);
 }
 
 static PyObject *
@@ -4049,8 +4070,12 @@ count_repr(countobject *lz)
 static PyObject *
 count_reduce(countobject *lz)
 {
-    if (lz->cnt == PY_SSIZE_T_MAX)
+    if (lz->cnt == PY_SSIZE_T_MAX) {
         return Py_BuildValue("O(OO)", Py_TYPE(lz), lz->long_cnt, lz->long_step);
+    }
+    if (lz->cnt == 0) {
+        return Py_BuildValue("O()", Py_TYPE(lz));
+    }
     return Py_BuildValue("O(n)", Py_TYPE(lz), lz->cnt);
 }
 
diff -r a8589d88deb4 Objects/bytearrayobject.c
--- a/Objects/bytearrayobject.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Objects/bytearrayobject.c	Sun Mar 06 16:47:55 2016 +0200
@@ -2838,23 +2838,17 @@ static PyObject *
     }
 
     buf = PyByteArray_AS_STRING(self);
+    if (!Py_SIZE(self)) {
+        return Py_BuildValue("(O()N)", Py_TYPE(self), dict);
+    }
     if (proto < 3) {
         /* use str based reduction for backwards compatibility with Python 2.x */
-        PyObject *latin1;
-        if (Py_SIZE(self))
-            latin1 = PyUnicode_DecodeLatin1(buf, Py_SIZE(self), NULL);
-        else
-            latin1 = PyUnicode_FromString("");
+        PyObject *latin1 = PyUnicode_DecodeLatin1(buf, Py_SIZE(self), NULL);
         return Py_BuildValue("(O(Ns)N)", Py_TYPE(self), latin1, "latin-1", dict);
     }
     else {
         /* use more efficient byte based reduction */
-        if (Py_SIZE(self)) {
-            return Py_BuildValue("(O(y#)N)", Py_TYPE(self), buf, Py_SIZE(self), dict);
-        }
-        else {
-            return Py_BuildValue("(O()N)", Py_TYPE(self), dict);
-        }
+        return Py_BuildValue("(O(y#)N)", Py_TYPE(self), buf, Py_SIZE(self), dict);
     }
 }
 
@@ -3136,15 +3130,14 @@ PyDoc_STRVAR(length_hint_doc,
 static PyObject *
 bytearrayiter_reduce(bytesiterobject *it)
 {
-    if (it->it_seq != NULL) {
-        return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
-                             it->it_seq, it->it_index);
-    } else {
-        PyObject *u = PyUnicode_FromUnicode(NULL, 0);
-        if (u == NULL)
-            return NULL;
-        return Py_BuildValue("N(N)", _PyObject_GetBuiltin("iter"), u);
+    PyObject *func = _PyObject_GetBuiltin("iter");
+    if (it->it_seq == NULL) {
+        return Py_BuildValue("N(())", func);
     }
+    if (it->it_index == 0) {
+        return Py_BuildValue("N(O)", func, it->it_seq);
+    }
+    return Py_BuildValue("N(O)n", func, it->it_seq, it->it_index);
 }
 
 static PyObject *
diff -r a8589d88deb4 Objects/bytesobject.c
--- a/Objects/bytesobject.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Objects/bytesobject.c	Sun Mar 06 16:47:55 2016 +0200
@@ -3816,15 +3816,14 @@ PyDoc_STRVAR(length_hint_doc,
 static PyObject *
 striter_reduce(striterobject *it)
 {
-    if (it->it_seq != NULL) {
-        return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
-                             it->it_seq, it->it_index);
-    } else {
-        PyObject *u = PyUnicode_FromUnicode(NULL, 0);
-        if (u == NULL)
-            return NULL;
-        return Py_BuildValue("N(N)", _PyObject_GetBuiltin("iter"), u);
+    PyObject *func = _PyObject_GetBuiltin("iter");
+    if (it->it_seq == NULL) {
+        return Py_BuildValue("N(())", func);
     }
+    if (it->it_index == 0) {
+        return Py_BuildValue("N(O)", func, it->it_seq);
+    }
+    return Py_BuildValue("N(O)n", func, it->it_seq, it->it_index);
 }
 
 PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
diff -r a8589d88deb4 Objects/enumobject.c
--- a/Objects/enumobject.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Objects/enumobject.c	Sun Mar 06 16:47:55 2016 +0200
@@ -161,10 +161,13 @@ enum_next(enumobject *en)
 static PyObject *
 enum_reduce(enumobject *en)
 {
-    if (en->en_longindex != NULL)
+    if (en->en_longindex != NULL) {
         return Py_BuildValue("O(OO)", Py_TYPE(en), en->en_sit, en->en_longindex);
-    else
-        return Py_BuildValue("O(On)", Py_TYPE(en), en->en_sit, en->en_index);
+    }
+    if (en->en_index == 0) {
+        return Py_BuildValue("O(O)", Py_TYPE(en), en->en_sit);
+    }
+    return Py_BuildValue("O(On)", Py_TYPE(en), en->en_sit, en->en_index);
 }
 
 PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
diff -r a8589d88deb4 Objects/iterobject.c
--- a/Objects/iterobject.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Objects/iterobject.c	Sun Mar 06 16:47:55 2016 +0200
@@ -101,11 +101,14 @@ PyDoc_STRVAR(length_hint_doc, "Private m
 static PyObject *
 iter_reduce(seqiterobject *it)
 {
-    if (it->it_seq != NULL)
-        return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
-                             it->it_seq, it->it_index);
-    else
-        return Py_BuildValue("N(())", _PyObject_GetBuiltin("iter"));
+    PyObject *func = _PyObject_GetBuiltin("iter");
+    if (it->it_seq == NULL) {
+        return Py_BuildValue("N(())", func);
+    }
+    if (it->it_index == 0) {
+        return Py_BuildValue("N(O)", func, it->it_seq);
+    }
+    return Py_BuildValue("N(O)n", func, it->it_seq, it->it_index);
 }
 
 PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
diff -r a8589d88deb4 Objects/listobject.c
--- a/Objects/listobject.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Objects/listobject.c	Sun Mar 06 16:47:55 2016 +0200
@@ -2674,7 +2674,7 @@ static void listiter_dealloc(listiterobj
 static int listiter_traverse(listiterobject *, visitproc, void *);
 static PyObject *listiter_next(listiterobject *);
 static PyObject *listiter_len(listiterobject *);
-static PyObject *listiter_reduce_general(void *_it, int forward);
+static PyObject *listiter_reduce_general(PyListObject *, Py_ssize_t, int);
 static PyObject *listiter_reduce(listiterobject *);
 static PyObject *listiter_setstate(listiterobject *, PyObject *state);
 
@@ -2796,7 +2796,7 @@ listiter_len(listiterobject *it)
 static PyObject *
 listiter_reduce(listiterobject *it)
 {
-    return listiter_reduce_general(it, 1);
+    return listiter_reduce_general(it->it_seq, it->it_index, 1);
 }
 
 static PyObject *
@@ -2935,7 +2935,7 @@ listreviter_len(listreviterobject *it)
 static PyObject *
 listreviter_reduce(listreviterobject *it)
 {
-    return listiter_reduce_general(it, 0);
+    return listiter_reduce_general(it->it_seq, it->it_index, 0);
 }
 
 static PyObject *
@@ -2957,25 +2957,15 @@ listreviter_setstate(listreviterobject *
 /* common pickling support */
 
 static PyObject *
-listiter_reduce_general(void *_it, int forward)
+listiter_reduce_general(PyListObject *seq, Py_ssize_t index, int forward)
 {
-    PyObject *list;
-
-    /* the objects are not the same, index is of different types! */
-    if (forward) {
-        listiterobject *it = (listiterobject *)_it;
-        if (it->it_seq)
-            return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
-                                 it->it_seq, it->it_index);
-    } else {
-        listreviterobject *it = (listreviterobject *)_it;
-        if (it->it_seq)
-            return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("reversed"),
-                                 it->it_seq, it->it_index);
+    PyObject *func;
+    if (!seq) {
+        return Py_BuildValue("N(())", _PyObject_GetBuiltin("iter"));
     }
-    /* empty iterator, create an empty list */
-    list = PyList_New(0);
-    if (list == NULL)
-        return NULL;
-    return Py_BuildValue("N(N)", _PyObject_GetBuiltin("iter"), list);
+    func = _PyObject_GetBuiltin(forward ? "iter" : "reversed");
+    if (index == (forward ? 0 : PyList_GET_SIZE(seq) - 1)) {
+        return Py_BuildValue("N(O)", func, seq);
+    }
+    return Py_BuildValue("N(O)n", func, seq, index);
 }
diff -r a8589d88deb4 Objects/sliceobject.c
--- a/Objects/sliceobject.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Objects/sliceobject.c	Sun Mar 06 16:47:55 2016 +0200
@@ -515,6 +515,12 @@ handling of normal slices.");
 static PyObject *
 slice_reduce(PySliceObject* self)
 {
+    if (self->step == Py_None) {
+        if (self->start == Py_None) {
+            return Py_BuildValue("O(O)", Py_TYPE(self), self->stop);
+        }
+        return Py_BuildValue("O(OO)", Py_TYPE(self), self->start, self->stop);
+    }
     return Py_BuildValue("O(OOO)", Py_TYPE(self), self->start, self->stop, self->step);
 }
 
diff -r a8589d88deb4 Objects/tupleobject.c
--- a/Objects/tupleobject.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Objects/tupleobject.c	Sun Mar 06 16:47:55 2016 +0200
@@ -980,11 +980,14 @@ PyDoc_STRVAR(length_hint_doc, "Private m
 static PyObject *
 tupleiter_reduce(tupleiterobject *it)
 {
-    if (it->it_seq)
-        return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
-                             it->it_seq, it->it_index);
-    else
-        return Py_BuildValue("N(())", _PyObject_GetBuiltin("iter"));
+    PyObject *func = _PyObject_GetBuiltin("iter");
+    if (it->it_seq == NULL) {
+        return Py_BuildValue("N(())", func);
+    }
+    if (it->it_index == 0) {
+        return Py_BuildValue("N(O)", func, it->it_seq);
+    }
+    return Py_BuildValue("N(O)n", func, it->it_seq, it->it_index);
 }
 
 static PyObject *
diff -r a8589d88deb4 Objects/unicodeobject.c
--- a/Objects/unicodeobject.c	Sun Mar 06 15:03:47 2016 +0200
+++ b/Objects/unicodeobject.c	Sun Mar 06 16:47:55 2016 +0200
@@ -15420,15 +15420,14 @@ PyDoc_STRVAR(length_hint_doc, "Private m
 static PyObject *
 unicodeiter_reduce(unicodeiterobject *it)
 {
-    if (it->it_seq != NULL) {
-        return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
-                             it->it_seq, it->it_index);
-    } else {
-        PyObject *u = PyUnicode_FromUnicode(NULL, 0);
-        if (u == NULL)
-            return NULL;
-        return Py_BuildValue("N(N)", _PyObject_GetBuiltin("iter"), u);
-    }
+    PyObject *func = _PyObject_GetBuiltin("iter");
+    if (it->it_seq == NULL) {
+        return Py_BuildValue("N(())", func);
+    }
+    if (it->it_index == 0) {
+        return Py_BuildValue("N(O)", func, it->it_seq);
+    }
+    return Py_BuildValue("N(O)n", func, it->it_seq, it->it_index);
 }
 
 PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");