[ast-optimizer-branch] Merging CFG cleanups from trunk

[Nathan Sidwell]

Diego Novillo wrote:
> There have been some substantial changes to CFG routines in the
> trunk that affect the tree flowgraph.
> 
> I'd like to merge those changes into the ast-optimizer-branch to
> avoid future merging headaches.
sounds like a good plan. I'm not going to have much time to do things
on that branch in the near future, so do whatever you think is right

nathan

-- 
Dr Nathan Sidwell :: Computer Science Department :: Bristol University
           The voices in my head told me to say this
nathan@acm.org  http://www.cs.bris.ac.uk/~nathan/  nathan@cs.bris.ac.uk