why doesnt Delhp use cmov?

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4 total messages Started by chris jones Mon, 09 Sep 2002 22:58

#212

Author: chris jones
Date: Mon, 09 Sep 2002 22:58

17 lines
1176 bytes

Ive been checking the code generated by the compiler and

if x1 < clip.left then x1 := clip.left;

compiles to

mov ecx,[eax+$20]
comp edx,ecx
jnl +$03
mov [eax+$30],ecx

Is there anyway to get it to use cmov or is there some reason for it not to
use it?

thanks,

chris

Re: why doesnt Delhp use cmov?

#214

Author: Torjei Kvinen
Date: Tue, 10 Sep 2002 00:18

12 lines
1221 bytes

"chris jones" <flak@clara.co.uk> wrote in message

> Is there anyway to get it to use cmov or is there some reason for it not
> to use it?

The cmov instruction was introduced with pentium and will not work on 386
and 486.


--
Regards
Torjei Kvinen

Re: why doesnt Delhp use cmov?

#220

Author: chris jones
Date: Tue, 10 Sep 2002 11:39

17 lines
1502 bytes

"Torjei Kvinen" <torjei@hahaha_bluezone.no> wrote in message
news:3d7d3a4b$1@newsgroups.borland.com...
> "chris jones" <flak@clara.co.uk> wrote in message
>
> > Is there anyway to get it to use cmov or is there some reason for it not
> > to use it?
>
> The cmov instruction was introduced with pentium and will not work on 386
> and 486.

Would it be worthwile to have a compiler switch to request the use of cmov?
I am geusesing it will be significantly faster that branching.

thanks,

chris

Re: why doesnt Delhp use cmov?

#242

Author: Will DeWitt
Date: Wed, 11 Sep 2002 10:20

6 lines
1180 bytes

As a side note, I opened up a Quality Central report on this very subject of
the compiler having more advanced CPU targets.  Look up entry #2323 in the
Delphi project and vote/rate as appropriate.  Post comments to it if you'd
like to see some things not covered by the description.  =)

Will

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