In Elbrus2000 compiler (Elbrus2000 is a VLIW processor that was   
   developed by Elbrus company, now bought by Intel) we did this   
   optimization with:   
      
   1. Value Numbering (which we treated as analysis, not optimization)   
   that does constant folding on the fly and sets constant class of   
   congruency for "x + y" operation   
      
   2. Any kind of optimization that uses help of classes of congruences   
   (constant substitution, peephole... you name it).   
      
   Andrey   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)