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   comp.lang.c++.moderated      Moderated discussion of C++ superhackery      33,346 messages   

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   Message 31,406 of 33,346   
   Joshua Maurice to asif.lse   
   Re: RVO, Move Constructors & Exception U   
   25 Aug 11 05:31:05   
   
   a50de3a6   
   0486fbaf   
   From: joshuamaurice@gmail.com   
      
   On Aug 8, 11:01 am, "asif.lse"  wrote:   
   > Hi,   
   >   
   > Though I haven't read much about the latest C++ 0x stuff, do you think   
   > that the latest C++0x optimizations such as RVO / move constructors,   
   > etc. will also optimize unwinding of exceptions substantially? Thanks   
   > in advance, Asif   
      
   Any good implementation of C++ exceptions optimizes the not-thrown   
   code paths at the expense of pessimizing the thrown code paths. The   
   good implementation technique is to consult the program counter   
   register when an exception is thrown, and go to a giant lookup table   
   to find the appropriate exception handler. This global table lookup   
   and out of line execution makes handling executions several orders of   
   magnitude slower than normal straight line code. The time spent in   
   destructor code is not the "big hit" of throwing an exception.   
      
      
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