-/// reflect the change.
-typedef bool CCAssignFn(unsigned ValNo, MVT::ValueType ValVT,
- MVT::ValueType LocVT, CCValAssign::LocInfo LocInfo,
- unsigned ArgFlags, CCState &State);
+/// reflect the change. It returns 'true' if it failed to handle Val.
+typedef bool CCAssignFn(unsigned ValNo, MVT ValVT,
+ MVT LocVT, CCValAssign::LocInfo LocInfo,
+ ISD::ArgFlagsTy ArgFlags, CCState &State);
+
+/// CCCustomFn - This function assigns a location for Val, possibly updating
+/// all args to reflect changes and indicates if it handled it. It must set
+/// isCustom if it handles the arg and returns true.
+typedef bool CCCustomFn(unsigned &ValNo, MVT &ValVT,
+ MVT &LocVT, CCValAssign::LocInfo &LocInfo,
+ ISD::ArgFlagsTy &ArgFlags, CCState &State);
+
+/// ParmContext - This enum tracks whether calling convention lowering is in
+/// the context of prologue or call generation. Not all backends make use of
+/// this information.
+typedef enum { Unknown, Prologue, Call } ParmContext;