received with thx

It's 3rd conditional (contrary to fact past). The use of "would" in the if-clause is common in colloquial American usage, although there's no reason for a learner to use it (since it's still considered non-standard). In some cases, it can be used correctly in both American and British English with "would's" original meaning of "willingness," "wanting." For example: "If you would have only studied more, you would have passed the test." Here, the usage of "would" shows that the speaker believes the problem is his friend's lack of a will to study, as opposed to something outside of his control.