===================================================================
@@ -316,14 +316,49 @@
size_type _M_element_count;
_RehashPolicy _M_rehash_policy;
+ // A single bucket used when only need for 1 bucket. Especially
+ // interesting in move semantic to leave hashtable with only 1 buckets
+ // which is not allocated so that we can have those operations noexcept
+ // qualified.
+ // Note that we can't leave hashtable with 0 bucket without adding
+ // numerous checks in the code to avoid 0 modulus.
+ __bucket_type _M_single_bucket;
+
+ bool
+ _M_uses_single_bucket(__bucket_type* __bkts) const
+ { return __builtin_expect(_M_buckets == &_M_single_bucket, false); }
+
+ bool
+ _M_uses_single_bucket() const
+ { return _M_uses_single_bucket(_M_buckets); }
+
__hashtable_alloc&
_M_base_alloc() { return *this; }
- using __hashtable_alloc::_M_deallocate_buckets;
+ __bucket_type*
+ _M_allocate_buckets(size_type __n)
+ {
+ if (__builtin_expect(__n == 1, false))
+ {
+ _M_single_bucket = nullptr;
+ return &_M_single_bucket;
+ }
+ return __hashtable_alloc::_M_allocate_buckets(__n);
+ }
+
void
+ _M_deallocate_buckets(__bucket_type* __bkts, size_type __n)
+ {
+ if (_M_uses_single_bucket(__bkts))
+ return;
+
+ __hashtable_alloc::_M_deallocate_buckets(__bkts, __n);
+ }
+
+ void
_M_deallocate_buckets()
- { this->_M_deallocate_buckets(_M_buckets, _M_bucket_count); }
+ { _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
// Gets bucket begin, deals with the fact that non-empty buckets contain
// their before begin node.
@@ -703,11 +738,7 @@
size_type
erase(const key_type& __k)
- {
- if (__builtin_expect(_M_bucket_count == 0, false))
- return 0;
- return _M_erase(__unique_keys(), __k);
- }
+ { return _M_erase(__unique_keys(), __k); }
iterator
erase(const_iterator, const_iterator);
@@ -768,7 +799,7 @@
_M_rehash_policy()
{
_M_bucket_count = _M_rehash_policy._M_next_bkt(__bucket_hint);
- _M_buckets = this->_M_allocate_buckets(_M_bucket_count);
+ _M_buckets = _M_allocate_buckets(_M_bucket_count);
}
template<typename _Key, typename _Value,
@@ -796,7 +827,7 @@
std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
__bucket_hint));
- _M_buckets = this->_M_allocate_buckets(_M_bucket_count);
+ _M_buckets = _M_allocate_buckets(_M_bucket_count);
__try
{
for (; __f != __l; ++__f)
@@ -833,9 +864,9 @@
{
// Replacement allocator cannot free existing storage.
this->_M_deallocate_nodes(_M_begin());
- if (__builtin_expect(_M_bucket_count != 0, true))
- _M_deallocate_buckets();
- _M_reset();
+ _M_before_begin._M_nxt = nullptr;
+ _M_deallocate_buckets();
+ _M_buckets = nullptr;
std::__alloc_on_copy(__this_alloc, __that_alloc);
__hashtable_base::operator=(__ht);
_M_bucket_count = __ht._M_bucket_count;
@@ -867,7 +898,7 @@
if (_M_bucket_count != __ht._M_bucket_count)
{
__former_buckets = _M_buckets;
- _M_buckets = this->_M_allocate_buckets(__ht._M_bucket_count);
+ _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
_M_bucket_count = __ht._M_bucket_count;
}
else
@@ -885,8 +916,7 @@
[&__roan](const __node_type* __n)
{ return __roan(__n->_M_v()); });
if (__former_buckets)
- this->_M_deallocate_buckets(__former_buckets,
- __former_bucket_count);
+ _M_deallocate_buckets(__former_buckets, __former_bucket_count);
}
__catch(...)
{
@@ -917,7 +947,7 @@
{
__bucket_type* __buckets = nullptr;
if (!_M_buckets)
- _M_buckets = __buckets = this->_M_allocate_buckets(_M_bucket_count);
+ _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
__try
{
@@ -964,8 +994,9 @@
_M_reset() noexcept
{
_M_rehash_policy._M_reset();
- _M_bucket_count = 0;
- _M_buckets = nullptr;
+ _M_bucket_count = 1;
+ _M_single_bucket = nullptr;
+ _M_buckets = &_M_single_bucket;
_M_before_begin._M_nxt = nullptr;
_M_element_count = 0;
}
@@ -980,12 +1011,16 @@
_M_move_assign(_Hashtable&& __ht, std::true_type)
{
this->_M_deallocate_nodes(_M_begin());
- if (__builtin_expect(_M_bucket_count != 0, true))
- _M_deallocate_buckets();
-
+ _M_deallocate_buckets();
__hashtable_base::operator=(std::move(__ht));
_M_rehash_policy = __ht._M_rehash_policy;
- _M_buckets = __ht._M_buckets;
+ if (!__ht._M_uses_single_bucket())
+ _M_buckets = __ht._M_buckets;
+ else
+ {
+ _M_buckets = &_M_single_bucket;
+ _M_single_bucket = __ht._M_single_bucket;
+ }
_M_bucket_count = __ht._M_bucket_count;
_M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
_M_element_count = __ht._M_element_count;
@@ -1019,7 +1054,7 @@
if (_M_bucket_count != __ht._M_bucket_count)
{
__former_buckets = _M_buckets;
- _M_buckets = this->_M_allocate_buckets(__ht._M_bucket_count);
+ _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
_M_bucket_count = __ht._M_bucket_count;
}
else
@@ -1093,10 +1128,18 @@
_M_element_count(__ht._M_element_count),
_M_rehash_policy(__ht._M_rehash_policy)
{
+ // Update, if necessary, buckets if __ht is using its single bucket.
+ if (__ht._M_uses_single_bucket())
+ {
+ _M_buckets = &_M_single_bucket;
+ _M_single_bucket = __ht._M_single_bucket;
+ }
+
// Update, if necessary, bucket pointing to before begin that hasn't
// moved.
if (_M_begin())
_M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
+
__ht._M_reset();
}
@@ -1139,7 +1182,14 @@
{
if (__ht._M_node_allocator() == this->_M_node_allocator())
{
- _M_buckets = __ht._M_buckets;
+ if (__ht._M_uses_single_bucket())
+ {
+ _M_buckets = &_M_single_bucket;
+ _M_single_bucket = __ht._M_single_bucket;
+ }
+ else
+ _M_buckets = __ht._M_buckets;
+
_M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
// Update, if necessary, bucket pointing to before begin that hasn't
// moved.
@@ -1189,15 +1239,34 @@
std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
std::swap(_M_rehash_policy, __x._M_rehash_policy);
- std::swap(_M_buckets, __x._M_buckets);
+
+ // Deal properly with potentially moved instances.
+ if (this->_M_uses_single_bucket())
+ {
+ if (!__x._M_uses_single_bucket())
+ {
+ _M_buckets = __x._M_buckets;
+ __x._M_buckets = &__x._M_single_bucket;
+ }
+ }
+ else if (__x._M_uses_single_bucket())
+ {
+ __x._M_buckets = _M_buckets;
+ _M_buckets = &_M_single_bucket;
+ }
+ else
+ std::swap(_M_buckets, __x._M_buckets);
+
std::swap(_M_bucket_count, __x._M_bucket_count);
std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
std::swap(_M_element_count, __x._M_element_count);
+ std::swap(_M_single_bucket, __x._M_single_bucket);
// Fix buckets containing the _M_before_begin pointers that can't be
// swapped.
if (_M_begin())
_M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
+
if (__x._M_begin())
__x._M_buckets[__x._M_bucket_index(__x._M_begin())]
= &__x._M_before_begin;
@@ -1230,9 +1299,6 @@
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
find(const key_type& __k)
{
- if (__builtin_expect(_M_bucket_count == 0, false))
- return end();
-
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_find_node(__n, __k, __code);
@@ -1250,9 +1316,6 @@
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
find(const key_type& __k) const
{
- if (__builtin_expect(_M_bucket_count == 0, false))
- return end();
-
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_find_node(__n, __k, __code);
@@ -1270,9 +1333,6 @@
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
count(const key_type& __k) const
{
- if (__builtin_expect(_M_bucket_count == 0, false))
- return 0;
-
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_bucket_begin(__n);
@@ -1287,7 +1347,7 @@
else if (__result)
// All equivalent values are next to each other, if we
// found a non-equivalent value after an equivalent one it
- // means that we won't find any more equivalent values.
+ // means that we won't find any new equivalent value.
break;
if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
break;
@@ -1311,9 +1371,6 @@
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
equal_range(const key_type& __k)
{
- if (__builtin_expect(_M_bucket_count == 0, false))
- return std::make_pair(end(), end());
-
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_find_node(__n, __k, __code);
@@ -1347,9 +1404,6 @@
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
equal_range(const key_type& __k) const
{
- if (__builtin_expect(_M_bucket_count == 0, false))
- return std::make_pair(end(), end());
-
__hash_code __code = this->_M_hash_code(__k);
std::size_t __n = _M_bucket_index(__k, __code);
__node_type* __p = _M_find_node(__n, __k, __code);
@@ -1944,7 +1998,7 @@
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_rehash_aux(size_type __n, std::true_type)
{
- __bucket_type* __new_buckets = this->_M_allocate_buckets(__n);
+ __bucket_type* __new_buckets = _M_allocate_buckets(__n);
__node_type* __p = _M_begin();
_M_before_begin._M_nxt = nullptr;
std::size_t __bbegin_bkt = 0;
@@ -1969,8 +2023,7 @@
__p = __next;
}
- if (__builtin_expect(_M_bucket_count != 0, true))
- _M_deallocate_buckets();
+ _M_deallocate_buckets();
_M_bucket_count = __n;
_M_buckets = __new_buckets;
}
@@ -1986,7 +2039,7 @@
_H1, _H2, _Hash, _RehashPolicy, _Traits>::
_M_rehash_aux(size_type __n, std::false_type)
{
- __bucket_type* __new_buckets = this->_M_allocate_buckets(__n);
+ __bucket_type* __new_buckets = _M_allocate_buckets(__n);
__node_type* __p = _M_begin();
_M_before_begin._M_nxt = nullptr;
@@ -2060,8 +2113,7 @@
__new_buckets[__next_bkt] = __prev_p;
}
- if (__builtin_expect(_M_bucket_count != 0, true))
- _M_deallocate_buckets();
+ _M_deallocate_buckets();
_M_bucket_count = __n;
_M_buckets = __new_buckets;
}
===================================================================
@@ -0,0 +1,38 @@
+// { dg-options "-std=gnu++11" }
+
+// Copyright (C) 2014 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// libstdc++/61143
+
+#include <unordered_set>
+
+void test01()
+{
+ std::unordered_set<int> us1, us2;
+ us1.insert(1);
+
+ us2 = std::move(us1);
+
+ us1.insert(1);
+}
+
+int main()
+{
+ test01();
+ return 0;
+}
===================================================================
@@ -0,0 +1,65 @@
+// Copyright (C) 2014 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++11" }
+
+#include <unordered_set>
+#include <testsuite_hooks.h>
+
+void test01()
+{
+ bool test __attribute__((unused)) = true;
+ std::unordered_set<int> us1 { 0, 1 };
+ {
+ std::unordered_set<int> us2(std::move(us1));
+
+ us1.swap(us2);
+
+ VERIFY( us1.find(0) != us1.end() );
+
+ us1.insert(2);
+
+ VERIFY( us1.size() == 3 );
+
+ us2.swap(us1);
+
+ VERIFY( us2.size() == 3 );
+ VERIFY( us2.find(2) != us2.end() );
+
+ us1 = { 3, 4, 5 };
+
+ VERIFY( us1.size() == 3 );
+ VERIFY( us1.bucket_count() >= 3 );
+
+ std::unordered_set<int> us3(std::move(us1));
+ us3 = std::move(us2);
+
+ us1.swap(us2);
+
+ VERIFY( us1.empty() );
+ VERIFY( us2.empty() );
+ }
+
+ us1 = { 0, 1 };
+ VERIFY( us1.size() == 2 );
+}
+
+int main()
+{
+ test01();
+ return 0;
+}