PRE lossage

[law@redhat.com]

In message <64E3BF94-097A-11D8-A9DD-000A95AF1FAE@dberlin.org>, Daniel Berlin wr
ites:
 >I've been putting off these bugs until switch lowering happens, since 
 >that should allow us to pre-split the critical edges without any 
 >trouble, and once that happens, insertion shouldn't require creating 
 >new blocks, ever, and the whole problem goes away.
I would be very wary of pre-splitting critical edges.  In my experience, it
loses, badly.  Interestingly enough I was pre-splitting critical edges to
help with PRE when I ran into the lame behavior.

jeff