Hi,   
      
   On Thursday, August 31, 2017 at 10:49:11 AM UTC-5, Robert Prins wrote:   
   >   
   > my hacked-about code comes out as:   
   >   
   > {$ifdef mmx}   
   > ...   
   > {$else}   
   >    mov   ecx, [ebx + offset lift_list.dtime]   
   >    mov   [esi + offset s_rec.dtime], ecx   
   >   
   >    mov   ecx, [ebx + offset lift_list.atime]   
   >    mov   [esi + offset s_rec.atime], ecx   
   >   
   >    mov   ecx, [ebx + offset lift_list.wtime]   
   >    mov   [esi + offset s_rec.wtime], ecx   
   >   
   >    mov   ecx, [ebx + offset lift_list.itime]   
   >    mov   [esi + offset s_rec.itime], ecx   
   > {$endif}   
   >   
   > I would expect that GCC or the Intel C compiler would both   
   > generate at least the code in the {$else} branch above when   
   > the original Pascal is replaced by C(++).   
      
   So why not rewrite in C? It can't be that hard (famous last words!).   
      
   Though personally I'd suggest rather fixing to work with FPC,   
   that's more useful and important (IMHO).   
      
   > Both VP and FPC seem to make way too much use of EAX...   
      
   I'm not an optimization guru. I haven't read Agner Fog's manuals   
   closely. Modern cpus probably do heavy register renaming and   
   lots of out-of-order (pipelined, superscalar, whatever) stuff.   
   I think older ones were pickier about certain things, but I   
   don't know if you care about (or test your code on) such machines.   
      
   Relying too much on one register is probably a bad idea, but   
   they probably just want to simplify register shuffling.   
   I had thought I read that alternating registers was a better   
   idea, so maybe try not relying too heavily on ECX either.   
      
   Actually, your {$else} code seems pretty sequential. I would   
   just use "push dword[], pop dword[]" (but not for 486) and   
   avoid ECX altogether. Maybe I'm naive, but that's a quick   
   simplification. No idea if it really helps you, though.   
      
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