L'aurais-je su, je vous l'aurais dit.
Had I known it, I would have told you.
L'aurais-je su, je vous l'aurais dit.
If I had known about it, I would have told you.
L'aurais-je su, je vous l'aurais dit.
If I'd known it, I'd have told you.
L'aurais-je su, je vous l'aurais dit.
If I had known it, I would have told you.
Si je l'avais su, je vous l'aurais dit.
Had I known about it, I would have told you.
Si je l'avais su, je vous l'aurais dit.
Had I known it, I would have told you.
Si je l'avais su, je vous l'aurais dit.
If I had known about it, I would have told you.
Si je l'avais su, je vous l'aurais dit.
If I'd known it, I'd have told you.
Si je l'avais su, je vous l'aurais dit.
If I had known it, I would have told you.
Examples from Tatoeba (CC BY 2.0 FR) and Europarl (OPUS). Sentences are not reviewed one by one.