Mark Liberman writes an interesting article on the history of this spurious "rule" in his Language Log blog.
There are some usage guides and older grammars (and the distinction between the two is important) which decree that an adverb shall never intervene between the parts of a compound verb. This so-called "split verb rule" is still being taught here and there, and perhaps due to the continued use of older textbooks in some non-English speaking countries, may be more often encountered by a new learner of English outside of English speaking countries than by a student in the U.S., the U.K., etc.
The current writer, having been taught the language in the mid-1950's in the U.S., was inculcated with this nonsense. However, the truth is that there is nothing in English grammar which prohibits separating the parts of a compound verb.
Where this "rule" arose is not known, but the Fowler Brothers, Henry and Francis, are prime suspects, because their The King's English (1908) was taken in its time as "gospel" by many teachers of the language (and is still viewed as authoritative by some.)
Today, as in 1908, there is no grammatical rule that requires that the parts of a compound verb like "would have liked" be forced together when good sense dictates that they should not be. You can and should write any of:
- I would always have liked to have...
- I would have always liked to have...
- I always would have liked to have...
...or even:
- I would have liked always to have...
If you should encounter an instructor who insists that the parts of a compound verb must always be yoked together, refer that person to the Language Log link above (or send them here!)
It would be very unusual (in contemporary English) to use "Would I had ..." or "Would I have had ..." to mean "If I had..." or "If I had had..."
Normally we'd say (in eye-dialect):
If I woulda hadda gun, Ida shot him dead, then and there.
If only ...
Would that I had a horse!
means "If only I had a horse!" or "I wish I had a horse!"
Would that I'd had a gun, I'd have shot him then and there.
If only I had had a gun, I'd have shot him, then and there.
Best Answer
If I knew him, I would say hello. But I don't know him so I don't say hello. We say this now about a situation. [called: conditional type 2,for a hypothetical condition and its probable result)
If I had known him, I would have said hello. But I didn't know him so I didn't say hello. We say this now about a past situation. [also called conditional type 3, a hypothetical condition in the past ]
If I knew him, I would have said hello.= can be called many things: ungrammatical, non-standard, uneducated or even "dialectal" in cases other speech features are present. This is heard a lot in speech when the speakers actually mean: If I had known him.....
Kindly note: the present is called conditional 1: I if know him, I will say hello. Conditional type 1 for a possibility and/or general truth.
There are much fancier names and descriptions for all this. There are even mixed conditionals, but the posted sentence is not one.