[CodeGen] Fix generation of TBAA tags for may-alias accesses

This patch fixes creating TBAA access descriptors for
may_alias-marked access types. Currently, for such types we
generate ordinary descriptors with char as its access type. The
patch changes this to produce proper may-alias descriptors.

Differential Revision: https://reviews.llvm.org/D42366

llvm-svn: 325575
diff --git a/clang/lib/CodeGen/CodeGenTBAA.h b/clang/lib/CodeGen/CodeGenTBAA.h
index c3e5c30..86ba407 100644
--- a/clang/lib/CodeGen/CodeGenTBAA.h
+++ b/clang/lib/CodeGen/CodeGenTBAA.h
@@ -177,6 +177,10 @@
   /// given type.
   llvm::MDNode *getTypeInfo(QualType QTy);
 
+  /// getAccessInfo - Get TBAA information that describes an access to
+  /// an object of the given type.
+  TBAAAccessInfo getAccessInfo(QualType AccessType);
+
   /// getVTablePtrAccessInfo - Get the TBAA information that describes an
   /// access to a virtual table pointer.
   TBAAAccessInfo getVTablePtrAccessInfo(llvm::Type *VTablePtrType);