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Re: CMOVE/CMOVE>

From anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups comp.lang.forth
Subject Re: CMOVE/CMOVE>
Date 2015-08-19 08:04 +0000
Organization Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID <2015Aug19.100400@mips.complang.tuwien.ac.at> (permalink)
References <62627f57-1e63-4156-844a-db5708923aaf@googlegroups.com> <2015Aug18.180551@mips.complang.tuwien.ac.at> <c3289222-a562-44db-a30a-1f8d58d0fc6b@googlegroups.com> <cc2c79a3-48ce-400e-b3b6-4474c9c47917@googlegroups.com>

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Michael Barry <barrym95838@yahoo.com> writes:
>On Tuesday, August 18, 2015 at 9:59:02 AM UTC-7, Mark Wills wrote:
>> 
>> > : move ( from to count -- )
>> >   >r 2dup u< if
>> >     r> cmove>
>> >   else
>> >     r> cmove
>> >   then ;
>> > 
>> > Better branch prediction accuracy:
>> > 
>> > : move ( from to count -- )
>> >   >r 2dup dup r@ + within if
>> >     r> cmove
>> >   else
>> >     r> cmove>
>> >   then ;
>> > 
>> > Both not tested.
>> > 
>> > - anton
>> > -- 
>> >
>>  
>> That's nice code, thank you. Mine also included WITHIN but your first 
>> example is neater IMO. I just tested it quickly and it seems to work fine.
>> 
>> Thanks.
>> 
>> Mark
>
>Isn't it true that the decision can be made based simply on whether source start is less than destination start, regardless of count?

Correct (assuming that neither source nor destination regions cross
the -1..0 boundary), that's what the U< version does.  The WITHIN
version always uses CMOVE> for the non-overlap case, and thus will
probably produce better branch prediction (if the CPU has a branch
predictor).

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
   EuroForth 2015: http://www.mpeforth.com/euroforth2015/euroforth2015.htm

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CMOVE/CMOVE> Mark Wills <markwills1970@gmail.com> - 2015-08-18 08:44 -0700
  Re: CMOVE/CMOVE> anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-18 16:05 +0000
    Re: CMOVE/CMOVE> november.nihal@gmail.com - 2015-08-18 09:34 -0700
      Re: CMOVE/CMOVE> anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-18 16:41 +0000
    Re: CMOVE/CMOVE> Mark Wills <markwills1970@gmail.com> - 2015-08-18 09:59 -0700
      Re: CMOVE/CMOVE> Michael Barry <barrym95838@yahoo.com> - 2015-08-18 10:10 -0700
        Re: CMOVE/CMOVE> hughaguilar96@gmail.com - 2015-08-18 10:41 -0700
          Re: CMOVE/CMOVE> "Alex McDonald" <blog@rivadpm.com> - 2015-08-18 23:55 +0100
            Re: CMOVE/CMOVE> anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-19 08:40 +0000
              Re: CMOVE/CMOVE> "Alex McDonald" <blog@rivadpm.com> - 2015-08-19 12:15 +0100
        Re: CMOVE/CMOVE> Mark Wills <markwills1970@gmail.com> - 2015-08-18 11:35 -0700
          Re: CMOVE/CMOVE> Mark Wills <markwills1970@gmail.com> - 2015-08-18 11:36 -0700
            Re: CMOVE/CMOVE> "HAA" <someone@microsoft.com> - 2015-08-20 04:39 +1000
          Re: CMOVE/CMOVE> "Elizabeth D. Rather" <erather@forth.com> - 2015-08-19 09:15 -1000
          Re: CMOVE/CMOVE> "HAA" <someone@microsoft.com> - 2015-08-28 22:39 +1000
            Re: CMOVE/CMOVE> Coos Haak <chforth@hccnet.nl> - 2015-08-28 15:06 +0200
              Re: CMOVE/CMOVE> "HAA" <someone@microsoft.com> - 2015-08-29 17:15 +1000
                Re: CMOVE/CMOVE> Coos Haak <chforth@hccnet.nl> - 2015-08-29 13:24 +0200
                Re: CMOVE/CMOVE> "HAA" <someone@microsoft.com> - 2015-08-31 11:38 +1000
                Re: CMOVE/CMOVE> "Elizabeth D. Rather" <erather@forth.com> - 2015-08-29 07:59 -1000
                Re: CMOVE/CMOVE> "HAA" <someone@microsoft.com> - 2015-08-30 13:00 +1000
            Re: CMOVE/CMOVE> Mark Wills <markwills1970@gmail.com> - 2015-08-28 07:33 -0700
            Re: CMOVE/CMOVE> Mark Wills <markwills1970@gmail.com> - 2015-08-28 07:36 -0700
              Re: CMOVE/CMOVE> "HAA" <someone@microsoft.com> - 2015-08-29 02:23 +1000
            Re: CMOVE/CMOVE> mhx@iae.nl - 2015-08-28 11:41 -0700
              Re: CMOVE/CMOVE> "HAA" <someone@microsoft.com> - 2015-08-29 17:30 +1000
        Re: CMOVE/CMOVE> anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-08-19 08:04 +0000
      Re: CMOVE/CMOVE> "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-08-19 02:48 -0400
        Re: CMOVE/CMOVE> Mark Wills <markwills1970@gmail.com> - 2015-08-19 00:49 -0700
    Re: CMOVE/CMOVE> Bernd Paysan <bernd.paysan@gmx.de> - 2015-08-19 02:58 +0200

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