From: anton@mips.complang.tuwien.ac.at   
      
   MitchAlsup  writes:   
   >   
   >anton@mips.complang.tuwien.ac.at (Anton Ertl) posted:   
   >   
   >> ERROR "unexpected byte sequence starting at index 356: '\xC3'" while   
   decoding:   
   >>   
   >> scott@slp53.sl.home (Scott Lurndal) writes:   
   >> >In general,   
   >> >any programmer should have a solid understanding of the   
   >> >underlying hardware - generically, and specifically   
   >> >for the hardware being programmed.   
   >>   
   >> Certainly.  But do they need to know between a a Wallace multiplier   
   >> and a Dadda multiplier?   
   >   
   >You do realize that all Wallace multipliers are Dadda multipliers ??   
   >But there are Dadda Multipliers that are not Wallace multipliers ?!?!?!   
      
   Good to know, but does not answer the question.   
      
   >>                          If not, what is it about pipelined processors   
   >> that would require CS graduates to know about them?   
   >   
   >How execution order disturbs things like program order and memory order.   
   >That is how and when they need to insert Fences in their multi-threaded   
   >code.   
      
   And the relevance of pipelined processors for that issue is what?   
      
   Memory-ordering shenanigans come from the unholy alliance of   
   cache-coherent multiprocessing and the supercomputer attitude.  If you   
   implement per-CPU caches and multiple memory controllers as shoddily   
   as possible while providing features for programs to slow themselves   
   down heavily in order to get memory-ordering guarantess, then you get   
   a weak memory model; slightly less shoddy, and you get a "strong" memory   
   model.  Processor pipelines have no relevance here.   
      
   And, as Niklas Holsti observed, dealing with memory-ordering   
   shenanigans is something that a few specialists do; no need for others   
   to know about the memory model, except that common CPUs unfortunately   
   do not implement sequential consistency.   
      
   - anton   
   --   
   'Anyone trying for "industrial quality" ISA should avoid undefined behavior.'   
     Mitch Alsup,    
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)