Callback that assigns a custom location for a calling-convention value.
Declared in <llvm/CodeGen/CallingConvLower.h>
typedef bool CCCustomFn(unsigned int&, MVT&, MVT&, CCValAssign::LocInfo&, ISD::ArgFlagsTy&, CCState&);The function may update all arguments to reflect changes and indicates whether it handled the value. It must set isCustom if it handles the arg and returns true.