LineageOS/android_external_libcxx
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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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16
include/__hash_table
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@@ -32,13 +32,8 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
#ifndef _LIBCPP_CXX03_LANG
template <class _Key, class _Tp>
union __hash_value_type;
#else
template <class _Key, class _Tp>
struct __hash_value_type;
#endif
template <class _Key, class _Cp, class _Hash,
bool = is_empty<_Hash>::value && !__libcpp_is_final<_Hash>::value>
@@ -172,7 +167,7 @@ struct __hash_key_value_types {
}
#ifndef _LIBCPP_CXX03_LANG
_LIBCPP_INLINE_VISIBILITY
static __container_value_type&& __move(__node_value_type& __v) {
static __container_value_type&& __move(__node_value_type& __v) {
return _VSTD::move(__v);
}
#endif
@@ -184,7 +179,6 @@ struct __hash_key_value_types<__hash_value_type<_Key, _Tp> > {
typedef _Tp mapped_type;
typedef __hash_value_type<_Key, _Tp> __node_value_type;
typedef pair<const _Key, _Tp> __container_value_type;
typedef pair<_Key, _Tp> __nc_value_type;
typedef __container_value_type __map_value_type;
static const bool __is_map = true;
@@ -198,7 +192,7 @@ struct __hash_key_value_types<__hash_value_type<_Key, _Tp> > {
static typename enable_if<__is_same_uncvref<_Up, __node_value_type>::value,
__container_value_type const&>::type
__get_value(_Up& __t) {
return __t.__cc;
return __t.__get_value();
}
template <class _Up>
@@ -211,12 +205,12 @@ struct __hash_key_value_types<__hash_value_type<_Key, _Tp> > {
_LIBCPP_INLINE_VISIBILITY
static __container_value_type* __get_ptr(__node_value_type& __n) {
return _VSTD::addressof(__n.__cc);
return _VSTD::addressof(__n.__get_value());
}
#ifndef _LIBCPP_CXX03_LANG
_LIBCPP_INLINE_VISIBILITY
static __nc_value_type&& __move(__node_value_type& __v) {
return _VSTD::move(__v.__nc);
static pair<key_type&&, mapped_type&&> __move(__node_value_type& __v) {
return __v.__move();
}
#endif