Fix undefined behavior in __hash_table
Summary:
This patch attempts to fix the undefined behavior in __hash_table by changing the node pointer types used throughout. The pointer types are changed for raw pointers in the current ABI and for fancy pointers in ABI V2 (since the fancy pointer types may not be ABI compatible).
The UB in `__hash_table` arises because tree downcasts the embedded end node and then deferences that pointer. Currently there are 2 node types in __hash_table:
* `__hash_node_base` which contains the `__next_` pointer.
* `__hash_node` which contains `__hash_` and `__value_`.
Currently the bucket list, iterators, and `__next_` pointers store pointers to `__hash_node` even though they all need to store `__hash_node_base` pointers.
This patch makes that change by introducing a `__next_pointer` typedef which is a pointer to `__hash_node` in the current ABI and `__hash_node_base` afterwards.
One notable change is to the type of `__bucket_list` which used to be defined as `unique_ptr<__node_pointer[], ...>` and is now `unique_ptr<__next_pointer[], ...>` meaning that we now allocate and deallocate different types using a different allocator. I'm going to give this part of the change more thought since it may introduce compatibility issues.
This change is similar to D20786.
Reviewers: mclow.lists, EricWF
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D20787
llvm-svn: 276533
diff --git a/libcxx/include/__config b/libcxx/include/__config
index 6edcd3d..353ca10 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -43,6 +43,8 @@
#define _LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB
// Fix undefined behavior in how __tree stores its end and parent nodes.
#define _LIBCPP_ABI_TREE_REMOVE_NODE_POINTER_UB
+// Fix undefined behavior in how __hash_table stores it's pointer types
+#define _LIBCPP_ABI_FIX_UNORDERED_NODE_POINTER_UB
#define _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB
#define _LIBCPP_ABI_FIX_UNORDERED_CONTAINER_SIZE_TYPE
#define _LIBCPP_ABI_VARIADIC_LOCK_GUARD