Gerhard speaks in much they same way as we would regarding the fate of those who commit suicide, urging caution, the avoidance of rash judgments, and the omniscience of God who knows the hearts of all (On Death, § 37). He cites several examples of complicated Biblical cases or case where those who tempted by suicide repented: Samson, Job and Jeremiah (both of whom cursed the day they were born), and the jailer at Philippi. The hand of the Lord is not too short to save those who repent to Christ after having struck the fatal blow.
Questions for further study: the Photinians seemed to have damned suicides indiscriminately. Who else did? Papists, Methodists?