From: terje.mathisen@nospicedham.tmsw.no   
      
   Bernhard Schornak wrote:   
   > R.Wieser wrote:   
   >   
   >   
   >> Terje,   
   >>   
   >>> As long as you are using a post-1986 CPU you can use stack-relative   
   >>> adressing, in which case EBP is perfectly usable as a regular register,   
   >>   
   >> I know, and I'm sure bernard knows that as well.   
   >   
   > Yes. What I called "Intelligent Design" is code for recent   
   > processors, not for hardware shown in museums. I developed   
   > it before iNTEL came up with the less sophisticated, down-   
   > graded version they publish in their 'optimisation guides'   
   > since a couple of years.   
   >   
   > And, since I research this in depth for more than a decade   
   > now, I do know (and can prove it experimentally) that this   
   > kind of stack management is faster than abusing rBP. As it   
      
   This is where you are wrong!   
      
   Not specifically, i.e. using a single ESP update followed by MOV is   
   probably faster on many cpus, but not in general:   
      
   Simply because long series of PUSH/POP are so common in both compiler   
   and assembler code, cpu architects have a lot of good reasons for trying   
   to make this sort of code significantly faster, and they almost   
   certainly will do so. (The most obvious hw optimization is to regard   
   multiple sequential PUSH or POP operations as a single macro op, this is   
   effectively the same as using explicit MOV operations while avoiding the   
   code size impact.)   
      
   In the meantime you have to ask yourself:   
      
   Did you measure these speedups in smaller micro benchmarks, or as part   
   of a substantial code base? The reason I'm asking is because time and   
   time again it turns out that smaller code is faster code!   
      
   A few PUSH/POP instructions of one byte each saves significant code   
   space compared with MOV EAX,[ESP+nnn] operations taking at least 3 bytes   
   each.   
      
   Terje   
      
   --   
   -    
   "almost all programming can be viewed as an exercise in caching"   
      
   --- SoupGate-Win32 v1.05   
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