Revealed guards do not rename dominated successors

Bugzilla Link	1119
Created on	Mar 08, 2014 21:00
Version	svn
OS	Linux
Architecture	PC

Extended Description

I think this problem has been around forever, but it is certainly with us
as of:
sac2c v1.00-beta (Haggis And Apple)
 developer rev 18449 linux-gnu_x86_64
 (Sat Mar  8 13:24:26 EST 2014 by sac)
In ~/sac/testsuite/optimizations/constraintchecks/ipbb.sac,
we have something like:
   x = condfun(... colx);
   ...
   colx' = val_le_SxS_( 0, colx);
Eventually, condfun gets inlined, and with it comes a guard:
   colx2 = _non_neg_val( colx);
   x = blah;
   ...
   colx' = val_le_SxS_( 0, colx);
The latter guard can not be removed. However, since the guard
on colx dominates the second guard, we could arrange to rename
colx --> colx2, in all code dominated by the first guard,