Yes. Together with the above it looks then optimal.
Attached patch tested on x86-64 Linux.
OK for mainline?
* expr.c (get_bit_range): Handle *MEM_REF's.
Index: expr.c
===================================================================
--- expr.c (revision 176824)
+++ expr.c (working copy)
@@ -4158,7 +4158,10 @@ get_bit_range (unsigned HOST_WIDE_INT *b
/* If other threads can't see this value, no need to restrict stores. */
if (ALLOW_STORE_DATA_RACES
- || (!ptr_deref_may_alias_global_p (innerdecl)
+ || ((TREE_CODE (innerdecl) == MEM_REF ||
+ TREE_CODE (innerdecl) == TARGET_MEM_REF)
+ && !ptr_deref_may_alias_global_p (TREE_OPERAND (innerdecl, 0)))
+ || (DECL_P (innerdecl)
&& (DECL_THREAD_LOCAL_P (innerdecl)
|| !TREE_STATIC (innerdecl))))
{
