Fix a strict aliasing violation in map and unordered_map.
These containers type-punned between pair<K, V> and pair<const K, V> as an
optimization. This commit instead provides access to the pair via a pair of
references that assign through to the underlying object. It's still undefined to
mutate a const object, but clang doesn't optimize on this for data members, so
this should be safe.
Differential revision: https://reviews.llvm.org/D47607
llvm-svn: 333948
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: f52318b47b333126c862d9a973d6e59ccaf713dc
diff --git a/include/map b/include/map
index 8a72260..97ce4d0 100644
--- a/include/map
+++ b/include/map
@@ -470,13 +470,13 @@
const _Compare& key_comp() const _NOEXCEPT {return *this;}
_LIBCPP_INLINE_VISIBILITY
bool operator()(const _CP& __x, const _CP& __y) const
- {return static_cast<const _Compare&>(*this)(__x.__cc.first, __y.__cc.first);}
+ {return static_cast<const _Compare&>(*this)(__x.__get_value().first, __y.__get_value().first);}
_LIBCPP_INLINE_VISIBILITY
bool operator()(const _CP& __x, const _Key& __y) const
- {return static_cast<const _Compare&>(*this)(__x.__cc.first, __y);}
+ {return static_cast<const _Compare&>(*this)(__x.__get_value().first, __y);}
_LIBCPP_INLINE_VISIBILITY
bool operator()(const _Key& __x, const _CP& __y) const
- {return static_cast<const _Compare&>(*this)(__x, __y.__cc.first);}
+ {return static_cast<const _Compare&>(*this)(__x, __y.__get_value().first);}
void swap(__map_value_compare&__y)
_NOEXCEPT_(__is_nothrow_swappable<_Compare>::value)
{
@@ -489,13 +489,13 @@
_LIBCPP_INLINE_VISIBILITY
typename enable_if<__is_transparent<_Compare, _K2>::value, bool>::type
operator () ( const _K2& __x, const _CP& __y ) const
- {return static_cast<const _Compare&>(*this) (__x, __y.__cc.first);}
+ {return static_cast<const _Compare&>(*this) (__x, __y.__get_value().first);}
template <typename _K2>
_LIBCPP_INLINE_VISIBILITY
typename enable_if<__is_transparent<_Compare, _K2>::value, bool>::type
operator () (const _CP& __x, const _K2& __y) const
- {return static_cast<const _Compare&>(*this) (__x.__cc.first, __y);}
+ {return static_cast<const _Compare&>(*this) (__x.__get_value().first, __y);}
#endif
};
@@ -518,13 +518,13 @@
_LIBCPP_INLINE_VISIBILITY
bool operator()(const _CP& __x, const _CP& __y) const
- {return comp(__x.__cc.first, __y.__cc.first);}
+ {return comp(__x.__get_value().first, __y.__get_value().first);}
_LIBCPP_INLINE_VISIBILITY
bool operator()(const _CP& __x, const _Key& __y) const
- {return comp(__x.__cc.first, __y);}
+ {return comp(__x.__get_value().first, __y);}
_LIBCPP_INLINE_VISIBILITY
bool operator()(const _Key& __x, const _CP& __y) const
- {return comp(__x, __y.__cc.first);}
+ {return comp(__x, __y.__get_value().first);}
void swap(__map_value_compare&__y)
_NOEXCEPT_(__is_nothrow_swappable<_Compare>::value)
{
@@ -537,13 +537,13 @@
_LIBCPP_INLINE_VISIBILITY
typename enable_if<__is_transparent<_Compare, _K2>::value, bool>::type
operator () ( const _K2& __x, const _CP& __y ) const
- {return comp (__x, __y.__cc.first);}
+ {return comp (__x, __y.__get_value().first);}
template <typename _K2>
_LIBCPP_INLINE_VISIBILITY
typename enable_if<__is_transparent<_Compare, _K2>::value, bool>::type
operator () (const _CP& __x, const _K2& __y) const
- {return comp (__x.__cc.first, __y);}
+ {return comp (__x.__get_value().first, __y);}
#endif
};
@@ -597,9 +597,9 @@
void operator()(pointer __p) _NOEXCEPT
{
if (__second_constructed)
- __alloc_traits::destroy(__na_, _VSTD::addressof(__p->__value_.__cc.second));
+ __alloc_traits::destroy(__na_, _VSTD::addressof(__p->__value_.__get_value().second));
if (__first_constructed)
- __alloc_traits::destroy(__na_, _VSTD::addressof(__p->__value_.__cc.first));
+ __alloc_traits::destroy(__na_, _VSTD::addressof(__p->__value_.__get_value().first));
if (__p)
__alloc_traits::deallocate(__na_, __p, 1);
}
@@ -614,23 +614,67 @@
#ifndef _LIBCPP_CXX03_LANG
template <class _Key, class _Tp>
-union __value_type
+struct __value_type
{
typedef _Key key_type;
typedef _Tp mapped_type;
typedef pair<const key_type, mapped_type> value_type;
- typedef pair<key_type, mapped_type> __nc_value_type;
+ typedef pair<key_type&, mapped_type&> __nc_ref_pair_type;
+ typedef pair<key_type&&, mapped_type&&> __nc_rref_pair_type;
+private:
value_type __cc;
- __nc_value_type __nc;
+
+public:
+ _LIBCPP_INLINE_VISIBILITY
+ value_type& __get_value()
+ {
+#if _LIBCPP_STD_VER > 14
+ return *_VSTD::launder(_VSTD::addressof(__cc));
+#else
+ return __cc;
+#endif
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ const value_type& __get_value() const
+ {
+#if _LIBCPP_STD_VER > 14
+ return *_VSTD::launder(_VSTD::addressof(__cc));
+#else
+ return __cc;
+#endif
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ __nc_ref_pair_type __ref()
+ {
+ value_type& __v = __get_value();
+ return __nc_ref_pair_type(const_cast<key_type&>(__v.first), __v.second);
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
+ __nc_rref_pair_type __move()
+ {
+ value_type& __v = __get_value();
+ return __nc_rref_pair_type(
+ _VSTD::move(const_cast<key_type&>(__v.first)),
+ _VSTD::move(__v.second));
+ }
_LIBCPP_INLINE_VISIBILITY
__value_type& operator=(const __value_type& __v)
- {__nc = __v.__cc; return *this;}
+ {
+ __ref() = __v.__get_value();
+ return *this;
+ }
_LIBCPP_INLINE_VISIBILITY
__value_type& operator=(__value_type&& __v)
- {__nc = _VSTD::move(__v.__nc); return *this;}
+ {
+ __ref() = __v.__move();
+ return *this;
+ }
template <class _ValueTp,
class = typename enable_if<
@@ -638,8 +682,10 @@
>::type
>
_LIBCPP_INLINE_VISIBILITY
- __value_type& operator=(_ValueTp&& __v) {
- __nc = _VSTD::forward<_ValueTp>(__v); return *this;
+ __value_type& operator=(_ValueTp&& __v)
+ {
+ __ref() = _VSTD::forward<_ValueTp>(__v);
+ return *this;
}
private:
@@ -658,8 +704,15 @@
typedef _Tp mapped_type;
typedef pair<const key_type, mapped_type> value_type;
+private:
value_type __cc;
+public:
+ _LIBCPP_INLINE_VISIBILITY
+ value_type& __get_value() { return __cc; }
+ _LIBCPP_INLINE_VISIBILITY
+ const value_type& __get_value() const { return __cc; }
+
private:
__value_type();
__value_type(__value_type const&);
@@ -701,9 +754,9 @@
__map_iterator(_TreeIterator __i) _NOEXCEPT : __i_(__i) {}
_LIBCPP_INLINE_VISIBILITY
- reference operator*() const {return __i_->__cc;}
+ reference operator*() const {return __i_->__get_value();}
_LIBCPP_INLINE_VISIBILITY
- pointer operator->() const {return pointer_traits<pointer>::pointer_to(__i_->__cc);}
+ pointer operator->() const {return pointer_traits<pointer>::pointer_to(__i_->__get_value());}
_LIBCPP_INLINE_VISIBILITY
__map_iterator& operator++() {++__i_; return *this;}
@@ -764,9 +817,9 @@
: __i_(__i.__i_) {}
_LIBCPP_INLINE_VISIBILITY
- reference operator*() const {return __i_->__cc;}
+ reference operator*() const {return __i_->__get_value();}
_LIBCPP_INLINE_VISIBILITY
- pointer operator->() const {return pointer_traits<pointer>::pointer_to(__i_->__cc);}
+ pointer operator->() const {return pointer_traits<pointer>::pointer_to(__i_->__get_value());}
_LIBCPP_INLINE_VISIBILITY
__map_const_iterator& operator++() {++__i_; return *this;}
@@ -809,7 +862,6 @@
typedef _Key key_type;
typedef _Tp mapped_type;
typedef pair<const key_type, mapped_type> value_type;
- typedef pair<key_type, mapped_type> __nc_value_type;
typedef _Compare key_compare;
typedef _Allocator allocator_type;
typedef value_type& reference;
@@ -1308,7 +1360,7 @@
const_iterator __e = cend();
while (!__m.empty())
__tree_.__insert_unique(__e.__i_,
- _VSTD::move(__m.__tree_.remove(__m.begin().__i_)->__value_.__nc));
+ __m.__tree_.remove(__m.begin().__i_)->__value_.__move());
}
}
@@ -1319,7 +1371,7 @@
return __tree_.__emplace_unique_key_args(__k,
_VSTD::piecewise_construct,
_VSTD::forward_as_tuple(__k),
- _VSTD::forward_as_tuple()).first->__cc.second;
+ _VSTD::forward_as_tuple()).first->__get_value().second;
}
template <class _Key, class _Tp, class _Compare, class _Allocator>
@@ -1329,7 +1381,7 @@
return __tree_.__emplace_unique_key_args(__k,
_VSTD::piecewise_construct,
_VSTD::forward_as_tuple(_VSTD::move(__k)),
- _VSTD::forward_as_tuple()).first->__cc.second;
+ _VSTD::forward_as_tuple()).first->__get_value().second;
}
#else // _LIBCPP_CXX03_LANG
@@ -1340,9 +1392,9 @@
{
__node_allocator& __na = __tree_.__node_alloc();
__node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
- __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.first), __k);
+ __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__get_value().first), __k);
__h.get_deleter().__first_constructed = true;
- __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.second));
+ __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__get_value().second));
__h.get_deleter().__second_constructed = true;
return _LIBCPP_EXPLICIT_MOVE(__h); // explicitly moved for C++03
}
@@ -1360,7 +1412,7 @@
__tree_.__insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
__r = __h.release();
}
- return __r->__value_.__cc.second;
+ return __r->__value_.__get_value().second;
}
#endif // _LIBCPP_CXX03_LANG
@@ -1375,7 +1427,7 @@
if (__child == nullptr)
throw out_of_range("map::at: key not found");
#endif // _LIBCPP_NO_EXCEPTIONS
- return static_cast<__node_pointer>(__child)->__value_.__cc.second;
+ return static_cast<__node_pointer>(__child)->__value_.__get_value().second;
}
template <class _Key, class _Tp, class _Compare, class _Allocator>
@@ -1388,7 +1440,7 @@
if (__child == nullptr)
throw out_of_range("map::at: key not found");
#endif // _LIBCPP_NO_EXCEPTIONS
- return static_cast<__node_pointer>(__child)->__value_.__cc.second;
+ return static_cast<__node_pointer>(__child)->__value_.__get_value().second;
}
@@ -1465,7 +1517,6 @@
typedef _Key key_type;
typedef _Tp mapped_type;
typedef pair<const key_type, mapped_type> value_type;
- typedef pair<key_type, mapped_type> __nc_value_type;
typedef _Compare key_compare;
typedef _Allocator allocator_type;
typedef value_type& reference;
@@ -1852,7 +1903,7 @@
const_iterator __e = cend();
while (!__m.empty())
__tree_.__insert_multi(__e.__i_,
- _VSTD::move(__m.__tree_.remove(__m.begin().__i_)->__value_.__nc));
+ _VSTD::move(__m.__tree_.remove(__m.begin().__i_)->__value_.__move()));
}
}
#endif