"hadn't have killed" vs "hadn't killed"

In his book The Syntactic Phenomena of English, McCawley argues that in a position requiring a non-finite form, a past tense is shifted to perfect "have", and that multiple "have"s are shifted to just a single "have". According to this analysis, in your example "if you hadn't have killed him", there are 3 logical past tenses, "if you Past Past n't Past kill him", the second two get changed to "have": "if you Past have n't have killed him", then the multiple occurrences of "have" are reduced to just one: "if you Past have n't killed him". Then, with the realization of "Past have" as "had", we wind up with "if you hadn't killed him".

It's an interesting and rather intricate analysis. However that may be, in the standard dialect that McCawley describes, you can't wind up with the perfect of a perfect, because one of the two perfect "have"s is lost by an arbitrary adjustment, in order to fit the logic of constructions into the restrictive morphological system of English.

I think your understanding is correct.

I am not sure, but I think the phrase 'hadn't have' is equivalent (in this sentence) to 'hadn't' that I associate with some English dialects.