Solution for memory leak in tblgen

[Andrew Trick]

> On Sep 22, 2014, at 8:03 AM, David Blaikie <dblaikie at gmail.com> wrote:
> 
> If you haev cycles, reference counting is not the right tool.
> 
> If you are working around the limitations of reference counting because you have cycles by defining a cleanup pass - why not just do all the ownership and destruction there? I'm still not really following, but haven't taken the time to look into the code in more detail.

I have the same question.
Andy