The next level delegation for `CallBase` is slightly more complex in order to support visiting cases where the call is also a terminator.

Next level propagators: If the user does not overload a specific instruction type, they can overload one of these to get the whole class of instructio

Handle the special instrinsic instruction classes.

Specific Instruction type classes... note that all of the casts are necessary because we use the instruction classes as opaque types...

If the user wants a 'default' case, they can choose to override this function. If this function is not overloaded in the user's subclass, then this i

While terminators don't have a distinct type modeling them, we support intercepting them with dedicated a visitor callback.

Return a VT for an integer vector type with the size of the elements doubled. The typed returned may be an extended type.

A SizeChangeStrategy for the common case where legalization for a particular operation consists of widening the type to a large legal type, unless the

Determine if the function will return.

Specialized opaque value conversions.