While bugpoint helps narrowing down a miscompiling test case down to a single
function, even sometimes to a single loop (or removes unnecessary loops from a
function), at times it leaves around a complex CFG with many instructions.

What would be nice to have is the ability for bugpoint to use the CodeExtractor
facility to remove a block at a time into a new function. Note that the downside
is that it may not always replicate the problem, as straight-line code then has
the additional call + register saves, and the callee code has register restores,
etc. This may mask the problem, but in many cases BEFORE and AFTER the affected
region, it may delete substantial amounts of code.

Note that the code extractor will probably be improved to handle this.  I
believe that it adds the  switch and dispatch blocks unconditionally right now.
 If extracting a single basic block, we would want the callee side of the code
to be a simple as possible...

-Chris

Oh yeah, I forgot there was a bug for this.  This has been implemented for a
while now.

-Chris