I would've if I could've

Reader Elaine, The Grammar Lady, notes in a comment:

Avoid the use of "would have" in "if clauses" expressing the earlier of two past actions. Use the past perfect.

Wrong: If he would have worked harder, he would have made the honor roll.

Right: If he had worked harder, he would have made the honor roll.

Wrong: If I would have thought of it, I'd have called you.

Right: I'd never dream of calling you, you shmuck. (Sorry, editor's license.)

--Warriner's Grammar: The Complete Course