From: miles@gnu.org   
      
   "Martin B." <0xCDCDCDCD@gmx.at> writes:   
   >>> Is this just a Quality of Implementation issue, or is it reasonable to   
   >>> expect that deleting a null pointer should be expensive?   
   >>   
   >> (...)  so I went snooping around for   
   >> opportunities to optimize. To my surprise, the compiler was not   
   >> checking to see if the argument of delete() was 0 before invoking the   
   >> machinery that effects delete().   
      
   Of course, even if it's not testing-for-zero around the call to   
   operator-delete, it's pretty likely that operator-delete looks   
   something like:   
      
      void ::operator delete(void *ptr, ...)   
      {   
         if (ptr)   
           { /* really do it */ }   
      }   
      
   and on a modern processor, the cost of the function call shouldn't be   
   horribly much... 30x seems ... surprising...   
      
   [In general, I'd expect delete of NULL pointers to be relatively rare,   
   so it seems to make good sense to optimize for the common case by   
   putting the test in the function, rather than around the call.]   
      
   -Miles   
      
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