if it comes to; when it comes to; if it becomes
Conditional expression used to set up a hypothetical or real situation, often with a nuance of 'if things reach that point' or 'when it comes to that'. Follows nouns, na-adjectives, or verbs in dictionary form.
If it comes to him coming, we have to hurry the preparations.
If it comes to failing the exam, I'll have to reconsider my path.
Derived from the conditional form of となる (to become), literally 'if it becomes'. The expression grammaticalized into a fixed conditional phrase.