Re: Integers outperform Packed in a big way

["Mark S. Waterbury" <mark.s.waterbury@xxxxxxx>]

Hi, Joe:

Packed decimal arithmetic is inherently a CISC kind of operation. 
Machines without microcode
and the ability to execute whole subroutines in microcode (including the 
PowerPC family) are at
a disadvantage, because the compiler must either generate a call to 
runtime routines or generate
quite a few in-line instructions to do the job.

Some time ago, Mr. Dave McKenzie posted some details on the MI400 list. 
Here is a link:
  
   http://archive.midrange.com/mi400/200703/msg00003.html      

Stop speculating, and do some reading. Educate yourselves. :-)

Enjoy!

Mark S. Waterbury

> Joe Pluta wrote:
> Walden H. Leverich wrote:
>   
> > I assume you mean you doubt the MI codes use the wrong instructions. I
> > doubt it too, but they why such a difference? I guess it's just a nature
> > of the beast given that the integer math is mostly shift and other
> > low-cycle (single-cycle) operations where the packed math is
> > multi-cycle. But I would have assumed that the built-in hardware was
> > optimized for just that purpose, almost an ASIC on a CPU. :)
> >   
> >     
> Perhaps when the machine was moved from CISC to RISC, any CPU-level 
> packed decimal opcodes were removed.
>
> Joe
>