。
She cried clear through the night.
Literal
She [topic-は] all-night cried-through.
泣き通す is a compound verb of completion: 泣く ('cry') + 通す ('pass through, do throughout'). The ~通す suffix marks doing something all the way through to the end without stopping — sustained completion rather than mere continuation. Compare ~続ける ('keep doing,' continuation in process) with ~通す ('do through to the end,' framing the entire span). Together with 一晩中 ('all night long'), the sentence emphasizes that crying filled the night from start to finish — a vivid and slightly literary phrasing for grief or distress.