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   comp.compilers      Compiler construction, theory, etc. (Mod      2,753 messages   

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   Message 976 of 2,753   
   Rayiner Hashem to All   
   Dominance frontier example in "Engineeri   
   19 Jun 07 07:05:40   
   
   From: rayiner@gmail.com   
      
   I'm a little confused about the dominance frontier example given in   
   section 9.2 of Cooper & Torczon's "Engineering a Compiler". The   
   example in question is reproduced on page 12 of these slides:   
   http://www.cs.rice.edu/~keith/512/Lectures/08SSA.pdf   
      
   When I run the algorithm they give on the example CFG, I end up with   
   B1 in its own dominance frontier. This makes sense, since B1 dominates   
   a predecessor of itself (B7), but does not strictly dominate itself.   
   However, the worked example shows the dominance frontier of B being   
   empty. The book explains this by saying something along the lines of   
   "the compiler notices that B7's immediate dominator is B1, so it adds   
   B1 to DF(B7) and to no other node", but does not explain why the   
   algorithm terminates its backtracking before B1, instead of continuing   
   up the dominator tree to B0.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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