Kill every call to @clang.arc.use in the ARC contract phase.

llvm-svn: 177769
diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARC.h b/llvm/lib/Transforms/ObjCARC/ObjCARC.h
index e062b66..6160226 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARC.h
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARC.h
@@ -89,6 +89,7 @@
   IC_CopyWeak,            ///< objc_copyWeak (derived)
   IC_DestroyWeak,         ///< objc_destroyWeak (derived)
   IC_StoreStrong,         ///< objc_storeStrong (derived)
+  IC_IntrinsicUser,       ///< clang.arc.use
   IC_CallOrUser,          ///< could call objc_release and/or "use" pointers
   IC_Call,                ///< could call objc_release
   IC_User,                ///< could "use" a pointer
@@ -97,6 +98,13 @@
 
 raw_ostream &operator<<(raw_ostream &OS, const InstructionClass Class);
 
+/// \brief Test if the given class is a kind of user.
+inline static bool IsUser(InstructionClass Class) {
+  return Class == IC_User ||
+         Class == IC_CallOrUser ||
+         Class == IC_IntrinsicUser;
+}
+
 /// \brief Test if the given class is objc_retain or equivalent.
 static inline bool IsRetain(InstructionClass Class) {
   return Class == IC_Retain ||