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Fix a strict aliasing violation in map and unordered_map.

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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

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@333948 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Erik Pilkington
2018-06-04 20:38:23 +00:00
parent 8d476cd679
commit 55513c8efb
4 changed files with 177 additions and 89 deletions
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119
include/map
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@@ -470,13 +470,13 @@ public:
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 @@ public:
_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 @@ public:
_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 @@ public:
_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 @@ public:
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 @@ template <class _TreeIterator> class __map_const_iterator;
#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 @@ union __value_type
>::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 @@ struct __value_type
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 @@ public:
__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 @@ public:
: __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 @@ public:
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 @@ map<_Key, _Tp, _Compare, _Allocator>::map(map&& __m, const allocator_type& __a)
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 @@ map<_Key, _Tp, _Compare, _Allocator>::operator[](const key_type& __k)
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 @@ map<_Key, _Tp, _Compare, _Allocator>::operator[](key_type&& __k)
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 @@ map<_Key, _Tp, _Compare, _Allocator>::__construct_node_with_key(const key_type&
{
__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 @@ map<_Key, _Tp, _Compare, _Allocator>::operator[](const key_type& __k)
__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 @@ map<_Key, _Tp, _Compare, _Allocator>::at(const key_type& __k)
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 @@ map<_Key, _Tp, _Compare, _Allocator>::at(const key_type& __k) const
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 @@ public:
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 @@ multimap<_Key, _Tp, _Compare, _Allocator>::multimap(multimap&& __m, const alloca
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