if n.Op() != ir.OAPPEND {
		return false
	}
	call := n.(*ir.CallExpr)
	if !call.IsDDD || len(call.Args) != 2 || call.Args[1].Op() != ir.OMAKESLICE {
		return false
	}

	mk := call.Args[1].(*ir.MakeExpr)
	if mk.Cap != nil {
		return false
	}

	// y must be either an integer constant or the largest possible positive value
	// of variable y needs to fit into a uint.