Re: Z-ADD or Eval?

["Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>]

"
Hello Scott,

You wrote:
>Ummm...  why would Z-Add be more efficient than MOVE? That seems odd to
>me.  Math is slower than just moving bytes around...
 
Once upon a time ....  a really, really, really, really, long time ago ... 
probably 
before the S/38 (or possibly on early S/38 releases) I believe MOVE and Z-ADD 
did 
generate different code -- thus giving rise to the current myth that MOVE is 
'more 
efficient' than Z-ADD (or vice-versa depending on whom you talk to).  However 
the RPG 
III/400 compiler generates the same underlying MI code regardless of MOVE or 
Z-ADD -- 
they both result in a Copy Numeric Value (CPYNV).  No maths involved at all.

I see little reason to believe the ILE compiler behaves differently.  You can 
use SST to 
see the PowerPC instructions generated since it is a little difficult to see 
the w-code.

But even so, my view has always been character op-codes for character results, 
numeric 
op-codes for numeric results, indicator op-codes for indicator results.

This bloody discussion ..... again ..... :)

Regards,
Simon Coulter.

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