From: dnovillo@acm.org   
      
   On Mon, Mar 31, 2008 at 8:36 PM, Chris Cox  wrote:   
      
   >     if (x == 1 && y == 2)   
   >         z = 300 / (x + y)   
   >  ==>   
   >     if (x == 1 && y == 2)   
   >         z = 100   
      
   In GCC we call it VRP, value range propagation.   
      
   It falls out of the singularity that happens when you have ranges   
   where min == max:  In this case, inside the then clause of that if(),   
   the range for x is [1, 1], the range for y is [2, 2].  After   
   propagation, GCC substitutes x with 1, y with 2 and the folders do the   
   rest.   
      
      
   Diego.   
      
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