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Re: structure and interpretation of computer programs exercsie 1.3 in forth

From anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups comp.lang.forth
Subject Re: structure and interpretation of computer programs exercsie 1.3 in forth
Date 2013-01-14 12:53 +0000
Organization Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID <2013Jan14.135352@mips.complang.tuwien.ac.at> (permalink)
References (3 earlier) <e9ea8ae4-4b51-42cd-9a44-eca5ba9a8683@10g2000yqo.googlegroups.com> <ae2d5ea7-b58a-4a22-b929-f5a1331208f1@k6g2000yqf.googlegroups.com> <7xobgsp5u3.fsf@ruckus.brouhaha.com> <c330752a-7a1b-4e74-8f06-76b15379758a@x3g2000yqo.googlegroups.com> <n-SdnfbZcdO6Tm7NnZ2dnUVZ_vWdnZ2d@supernews.com>

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"Elizabeth D. Rather" <erather@forth.com> writes:
>Aren't you ignoring the fact that there's a conditional in min? Why so 
>important to avoid a conditional?

It's a good idea to avoid conditional branches, for several reasons:

1) On the CPU level, conditional branches can be expensive, especially
if they are hard to predict.  A word like MIN can be implemented with
a (often cheaper) conditional move.

2) On the programming and testing level, each conditonal branch
increases the number of test cases that have to be used in checking
the result.  E.g., for Forth, if the stack management in one of the
branches is ok, there could still be a stack depth bug (among others)
in the other branch.

Of course, like many rules, this one has to be balanced.  if you have
to add too much complication for avoiding a conditional branch, it's
not a good idea.

- 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 2012: http://www.euroforth.org/ef12/

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structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 04:22 -0800
  Re: structure and interpretation of computer programs exercsie 1.3 in forth Alex McDonald <blog@rivadpm.com> - 2013-01-11 05:47 -0800
    Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 06:12 -0800
      Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 06:18 -0800
        Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 06:20 -0800
      Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 06:19 -0800
        Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 06:38 -0800
          Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 06:51 -0800
            Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 07:10 -0800
            Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 07:58 -0800
              Re: structure and interpretation of computer programs exercsie 1.3 in forth rickman <gnuarm@gmail.com> - 2013-01-14 10:01 -0500
      Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 06:25 -0800
        Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 06:28 -0800
        Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 06:33 -0800
          Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 06:37 -0800
      Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 06:56 -0800
        Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 08:03 -0800
          Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 08:06 -0800
            Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 12:27 -0800
              Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-13 17:32 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-13 23:21 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-13 23:41 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-13 23:43 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-14 00:02 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Elizabeth D. Rather" <erather@forth.com> - 2013-01-14 22:43 +1300
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-14 02:41 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-01-14 11:13 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-01-14 11:16 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth mhx@iae.nl (Marcel Hendrix) - 2013-01-14 21:27 +0200
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Howerd <howerdo@yahoo.co.uk> - 2013-01-14 03:34 -0800
                Re: structure and interpretation of computer programs exercsie 1.3  in forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-01-14 12:53 +0000
                Re: structure and interpretation of computer programs exercsie 1.3  in forth "Elizabeth D. Rather" <erather@forth.com> - 2013-01-17 17:31 +1300
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Hugh Aguilar <hughaguilar96@yahoo.com> - 2013-01-21 19:35 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-14 02:55 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth rickman <gnuarm@gmail.com> - 2013-01-14 10:14 -0500
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Bernd Paysan <bernd.paysan@gmx.de> - 2013-01-14 20:04 +0100
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Hugh Aguilar <hughaguilar96@yahoo.com> - 2013-01-21 19:57 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-21 23:19 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Hugh Aguilar <hughaguilar96@yahoo.com> - 2013-01-24 18:58 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Alex McDonald <blog@rivadpm.com> - 2013-01-25 15:46 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Pablo Hugo Reda <pabloreda@gmail.com> - 2013-01-25 19:09 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Alex McDonald <blog@rivadpm.com> - 2013-01-26 01:12 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth mhx@iae.nl (Marcel Hendrix) - 2013-01-26 12:58 +0200
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Alex McDonald <blog@rivadpm.com> - 2013-01-26 04:42 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-01-26 14:35 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-21 22:38 -0800
            Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 12:36 -0800
              Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-13 17:33 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Elizabeth D. Rather" <erather@forth.com> - 2013-01-14 22:46 +1300
                Re: structure and interpretation of computer programs exercsie 1.3 in forth rickman <gnuarm@gmail.com> - 2013-01-14 10:20 -0500
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-01-14 10:41 -0600
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Elizabeth D. Rather" <erather@forth.com> - 2013-01-17 17:34 +1300
                Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-21 22:48 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-21 22:49 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-21 23:55 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Ed" <invalid@nospam.com> - 2013-01-18 12:50 +1100
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Bernd Paysan <bernd.paysan@gmx.de> - 2013-01-18 23:31 +0100
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Ed" <invalid@nospam.com> - 2013-01-20 12:42 +1100
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <markrobertwills@yahoo.co.uk> - 2013-01-20 01:24 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Hugh Aguilar <hughaguilar96@yahoo.com> - 2013-01-20 15:51 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Elizabeth D. Rather" <erather@forth.com> - 2013-01-21 22:14 +1300
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Hugh Aguilar <hughaguilar96@yahoo.com> - 2013-01-21 19:14 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "A. K." <akk@nospam.org> - 2013-01-20 11:13 +0100
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-20 02:45 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-01-21 17:14 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-23 01:52 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-01-23 04:25 -0600
                Re: structure and interpretation of computer programs exercsie 1.3 in forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-01-23 15:20 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-23 09:29 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-01-23 17:40 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-23 22:03 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Elizabeth D. Rather" <erather@forth.com> - 2013-01-24 22:13 +1300
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-24 02:57 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-26 13:49 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Elizabeth D. Rather" <erather@forth.com> - 2013-01-26 12:40 -1000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Paul Rubin <no.email@nospam.invalid> - 2013-01-26 23:20 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth mhx@iae.nl (Marcel Hendrix) - 2013-01-27 09:52 +0200
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2013-01-23 23:05 +0000
                Re: structure and interpretation of computer programs exercsie 1.3  in forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-01-21 17:05 +0000
                Re: structure and interpretation of computer programs exercsie 1.3  in forth "A. K." <akk@nospam.org> - 2013-01-21 19:28 +0100
                Re: structure and interpretation of computer programs exercsie 1.3   in forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-01-22 17:43 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2013-01-22 19:12 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth stephenXXX@mpeforth.com (Stephen Pelc) - 2013-01-21 12:13 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-01-21 17:28 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-01-22 18:06 +0000
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Bernd Paysan <bernd.paysan@gmx.de> - 2013-01-22 19:30 +0100
              Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-21 23:06 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-22 02:20 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-22 03:36 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-22 06:51 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth marko <marko@marko.marko> - 2013-01-24 22:14 +1100
                Re: structure and interpretation of computer programs exercsie 1.3 in forth the_gavino_himself <visphatesjava@gmail.com> - 2013-01-27 20:39 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth marko <marko@marko.marko> - 2013-02-01 22:07 +1100
                Re: structure and interpretation of computer programs exercsie 1.3 in forth marko <marko@marko.marko> - 2013-02-01 22:53 +1100
                Re: structure and interpretation of computer programs exercsie 1.3 in forth the_gavino_himself <visphatesjava@gmail.com> - 2013-02-08 19:50 -0800
                Re: structure and interpretation of computer programs exercsie 1.3 in forth Elizabeth D Rather <erather@forth.com> - 2013-02-08 19:22 -1000
      Re: structure and interpretation of computer programs exercsie 1.3 in forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-01-11 11:44 -0600
        Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-11 12:34 -0800
    Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-11 06:18 -0800
  Re:structure and interpretation of computer programs exercsie 1.3 in forth Hans Bezemer <the.beez.speaks@gmail.com> - 2013-01-14 00:13 +0100
    Re: structure and interpretation of computer programs exercsie 1.3 in forth Doug Hoffman <glidedog@gmail.com> - 2013-01-13 19:12 -0500
      Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-13 18:26 -0800
      Re: structure and interpretation of computer programs exercsie 1.3 in forth Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2013-01-14 08:29 +0000
        Re: structure and interpretation of computer programs exercsie 1.3 in forth Hans Bezemer <the.beez.speaks@gmail.com> - 2013-01-14 23:52 +0100
    Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-13 18:31 -0800
    Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-13 23:19 -0800
      Re: structure and interpretation of computer programs exercsie 1.3 in forth gavino_himself <visploveslisp@gmail.com> - 2013-01-21 22:46 -0800
        Re: structure and interpretation of computer programs exercsie 1.3 in forth Mark Wills <forthfreak@gmail.com> - 2013-01-21 23:40 -0800

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