Comment # 5 on bug 101442 from Gert Wollny

With a bit more digging I found out that the sb optimizer simply drops the ELSE
if no ALU instructions are found in the else branch, i.e. 

   while(cond1)
      if (cond2) {
          a = b + c; 
      } else {
          break; 
      }
   }

becomes 

   while(cond1)
      if (cond2) {
         a = b + c; 
         break; 
   }
}

after the first sb/dce_cleanup pass, and this is obviously wrong. With the
break in the if path this is not a problem. I'll attach two piglits that
illustrate the behaviour.