Groups > comp.lang.forth > #20788

Re: Difficulty with Brad Rodriguez' screenful

From	Bernd Paysan <bernd.paysan@gmx.de>
Newsgroups	comp.lang.forth
Subject	Re: Difficulty with Brad Rodriguez' screenful
Date	2013-03-18 17:23 +0100
Organization	1&1 Internet AG
Message-ID	<ki7f2h$cp3$1@online.de> (permalink)
References	<8ea2fd45-14b0-45ba-b49d-e3144b9f06ab@googlegroups.com> <05170318008434@frunobulax.edu> <ki35b7$jnn$1@online.de> <5147093c.396277031@news.demon.co.uk>

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Stephen Pelc wrote:

> On Sun, 17 Mar 2013 02:13:11 +0100, Bernd Paysan <bernd.paysan@gmx.de>
> wrote:
> 
>>b) actually understand that an inlined sequnce has some virtual additional
>>element on the return stack, which is pointing to the end of the inlined
>>sequence, and which is consumed by all its EXITs (can be converted into a
>>forward branch).  And if there is an rdrop, this virtual element
>>disappears,
>>so the EXIT is going to be a real EXIT.  If the compiler knows that this
>>return stack element is never used (after constant folding, which converts
>>the premature EXITs to forward branches, and removes the final EXIT), it
>>can be optimized away.
> 
> With very little effort, one can define a return stack active word
> than affects execution any number of levels up the return stack
>   r> drop
>   r> drop  r> drop
>   r> drop  r> drop  r> drop
>   ...
> 
> Given my experience with the ingenuity of Forth programmers, I have
> not been able to prove to myself that *all* dangerous return stack
> actions can be determined by an analytic compiler.

My idea is that you should *not* prove this, or need to prove this.  You 
should simply maintain the return stack semantics, even when you do inlining 
(i.e. push the return address at entering the inlined chunk, and pop it when 
you exit it).  You can optimize the return stack manipulation away if you 
can prove it's dead code; which usually will be easy.  If the inlined word 
contains either a "tainted" word, or accesses return stack beyond what it 
pushed itself, you can't optimize this away.  EXECUTE is probably a tainted 
primitive... but maybe you can "untaint" the use of EXECUTE in guru code to 
allow optimizations on higher-order functions.

> Until then, the guru programmer who wishes to write guru code and
> have it ported needs to put "here there be dragons" markers in his
> (and I emphasise 'his') code. If he cannot be bothered to do this,
> why should I be bothered to port or maintain his code?

Because you perform optimizations that break his code.  And we don't have a 
standard word for "here be dragons", something like "don't-inline" or so.  
And maybe you should have a "here aren't dragons", i.e. a "inline" word, 
too, which cleans the "taint" marker.  We just declared return stack 
manipulations as non-standard, removing a capability from standard Forth 
which is not often used, but when it's used, there might be no reasonable 
alternative.  Or the alternative might be equally non-portable.

C has such an "inline" statement, which tells the compiler that it's free to 
inline that function.  The compiler can inline other functions, as well, 
when he's sure it won't break any code.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://bernd-paysan.de/

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Difficulty with Brad Rodriguez' screenful Eduardo Costa <edu500ac@gmail.com> - 2013-03-15 07:10 -0700
  Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-03-15 17:06 +0000
    Re: Difficulty with Brad Rodriguez' screenful Eduardo Costa <edu500ac@gmail.com> - 2013-03-15 11:27 -0700
    Re: Difficulty with Brad Rodriguez' screenful Eduardo Costa <edu500ac@gmail.com> - 2013-03-15 13:06 -0700
    Re: Difficulty with Brad Rodriguez' screenful Eduardo Costa <edu500ac@gmail.com> - 2013-03-15 13:43 -0700
      Re: Difficulty with Brad Rodriguez' screenful "Elizabeth D. Rather" <erather@forth.com> - 2013-03-15 12:17 -1000
        Re: Difficulty with Brad Rodriguez' screenful Eduardo Costa <edu500ac@gmail.com> - 2013-03-16 13:25 -0700
          Re: Difficulty with Brad Rodriguez' screenful mhx@iae.nl (Marcel Hendrix) - 2013-03-17 00:18 +0200
            Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-17 02:13 +0100
              Re: Difficulty with Brad Rodriguez' screenful "Elizabeth D. Rather" <erather@forth.com> - 2013-03-16 15:29 -1000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-18 02:03 +0100
                Re: Difficulty with Brad Rodriguez' screenful "Elizabeth D. Rather" <erather@forth.com> - 2013-03-17 15:23 -1000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-18 04:16 +0100
                Re: Difficulty with Brad Rodriguez' screenful "Elizabeth D. Rather" <erather@forth.com> - 2013-03-17 18:20 -1000
                Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-03-18 13:07 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-18 21:45 +0100
                Re: Difficulty with Brad Rodriguez' screenful Elizabeth D Rather <erather@forth.com> - 2013-03-18 12:13 -1000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 03:46 +0100
                Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-03-19 09:42 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 17:04 +0100
                Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-03-19 17:54 +0000
                Re: Difficulty with Brad Rodriguez' screenful Brad Eckert <hwfwguy@gmail.com> - 2013-03-19 13:30 -0700
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 22:33 +0100
                Re: Difficulty with Brad Rodriguez' screenful albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-03-19 13:03 +0000
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-19 14:56 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 21:55 +0100
                Re: Difficulty with Brad Rodriguez' screenful Alex McDonald <blog@rivadpm.com> - 2013-03-19 14:16 -0700
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 02:09 +0100
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 20:35 +0100
                Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-03-19 09:52 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 18:56 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-19 13:18 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 22:37 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 03:33 -0500
                Re: Difficulty with Brad Rodriguez' screenful "Rod Pemberton" <do_not_have@notemailnotq.cpm> - 2013-03-20 05:30 -0400
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-18 11:28 -0500
                Re: Difficulty with Brad Rodriguez' screenful Alex McDonald <blog@rivadpm.com> - 2013-03-18 15:39 -0700
                Re: Difficulty with Brad Rodriguez' screenful albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-03-19 13:07 +0000
                Re: Difficulty with Brad Rodriguez' screenful m.a.m.hendrix@tue.nl - 2013-03-19 06:58 -0700
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 03:05 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-19 05:27 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 19:24 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 03:42 -0500
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 03:54 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 17:49 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 12:51 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 20:25 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-21 04:31 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-21 16:31 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-21 14:48 -0500
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-21 18:07 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-21 14:49 -0500
                Re: Difficulty with Brad Rodriguez' screenful Coos Haak <chforth@hccnet.nl> - 2013-03-22 00:07 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-21 18:31 -0500
                Re: Difficulty with Brad Rodriguez' screenful Coos Haak <chforth@hccnet.nl> - 2013-03-22 00:48 +0100
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-22 01:49 +0100
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-27 17:30 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-22 03:57 -0500
                Re: Difficulty with Brad Rodriguez' screenful Alex McDonald <blog@rivadpm.com> - 2013-03-22 03:39 -0700
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-22 09:03 -0500
                Re: Difficulty with Brad Rodriguez' screenful Alex McDonald <blog@rivadpm.com> - 2013-03-23 08:13 -0700
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-23 12:39 -0500
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-23 14:19 -0500
                Re: Difficulty with Brad Rodriguez' screenful Alex McDonald <blog@rivadpm.com> - 2013-03-23 13:01 -0700
                Re: Difficulty with Brad Rodriguez' screenful Brad Eckert <hwfwguy@gmail.com> - 2013-03-22 08:13 -0700
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-22 14:44 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-22 10:34 -0500
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-22 15:39 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-22 20:38 +0100
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-22 20:54 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-22 12:27 -0500
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-22 17:38 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-22 13:48 -0500
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-23 11:53 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-24 01:46 +0100
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-27 17:04 +0000
                Re: Difficulty with Brad Rodriguez' screenful Brad Eckert <hwfwguy@gmail.com> - 2013-03-25 10:06 -0700
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-19 16:05 +0000
                Re: Difficulty with Brad Rodriguez' screenful Alex McDonald <blog@rivadpm.com> - 2013-03-19 12:32 -0700
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-18 18:28 +0000
              Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-03-18 12:40 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-18 17:23 +0100
                Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-03-18 17:35 +0000
                Re: Difficulty with Brad Rodriguez' screenful Brad Eckert <hwfwguy@gmail.com> - 2013-03-18 11:02 -0700
                Re: Difficulty with Brad Rodriguez' screenful "WJ" <w_a_x_man@yahoo.com> - 2013-03-19 03:25 +0000
                Re: Difficulty with Brad Rodriguez' screenful albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-03-18 19:35 +0000
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-18 18:17 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 03:29 +0100
                Re: Difficulty with Brad Rodriguez' screenful Paul Rubin <no.email@nospam.invalid> - 2013-03-19 00:06 -0700
                Re: Difficulty with Brad Rodriguez' screenful Paul Rubin <no.email@nospam.invalid> - 2013-03-19 00:11 -0700
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 16:16 +0100
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-19 15:06 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-19 22:27 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 03:49 -0500
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-20 11:09 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 10:25 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 18:08 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-20 13:04 -0500
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 20:12 +0100
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-21 04:39 -0500
                Re: Difficulty with Brad Rodriguez' screenful albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-03-20 19:22 +0000
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-30 17:35 +0000
                Re: Difficulty with Brad Rodriguez' screenful Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-03-31 08:51 -0500
                Re: Difficulty with Brad Rodriguez' screenful Alex McDonald <blog@rivadpm.com> - 2013-03-20 10:27 -0700
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-20 12:03 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-20 18:47 +0100
                Re: Difficulty with Brad Rodriguez' screenful anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-03-30 16:40 +0000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-04-01 02:12 +0200
            Re: Difficulty with Brad Rodriguez' screenful Eduardo Costa <edu500ac@gmail.com> - 2013-03-16 22:27 -0700
              Re: Difficulty with Brad Rodriguez' screenful mhx@iae.nl (Marcel Hendrix) - 2013-03-17 10:10 +0200
                Re: Difficulty with Brad Rodriguez' screenful mhx@iae.nl (Marcel Hendrix) - 2013-03-17 18:15 +0200
                Re: Difficulty with Brad Rodriguez' screenful Eduardo Costa <edu500ac@gmail.com> - 2013-03-17 13:00 -0700
                Re: Difficulty with Brad Rodriguez' screenful mhx@iae.nl (Marcel Hendrix) - 2013-03-17 23:34 +0200
                Re: Difficulty with Brad Rodriguez' screenful Eduardo Costa <edu500ac@gmail.com> - 2013-03-17 16:44 -0700
                Re: Difficulty with Brad Rodriguez' screenful "WJ" <w_a_x_man@yahoo.com> - 2013-03-17 23:53 +0000
                Re: Difficulty with Brad Rodriguez' screenful mhx@iae.nl (Marcel Hendrix) - 2013-03-18 23:32 +0200
                Re: Difficulty with Brad Rodriguez' screenful Lars Brinkhoff <lars.spam@nocrew.org> - 2013-03-19 08:12 +0100
                Re: Difficulty with Brad Rodriguez' screenful m.a.m.hendrix@tue.nl - 2013-03-19 00:33 -0700
                Re: Difficulty with Brad Rodriguez' screenful Lars Brinkhoff <lars.spam@nocrew.org> - 2013-03-19 09:39 +0100
                Re: Difficulty with Brad Rodriguez' screenful mhx@iae.nl (Marcel Hendrix) - 2013-03-19 21:11 +0200
                Re: Difficulty with Brad Rodriguez' screenful Elizabeth D Rather <erather@forth.com> - 2013-03-19 10:30 -1000
                Re: Difficulty with Brad Rodriguez' screenful Roelf Toxopeus <rt4all@notthis.hetnet.nl> - 2013-03-19 22:31 +0100
                Re: Difficulty with Brad Rodriguez' screenful Elizabeth D Rather <erather@forth.com> - 2013-03-19 12:09 -1000
                Re: Difficulty with Brad Rodriguez' screenful Bernd Paysan <bernd.paysan@gmx.de> - 2013-03-18 19:23 +0100
      Re: Difficulty with Brad Rodriguez' screenful stephenXXX@mpeforth.com (Stephen Pelc) - 2013-03-16 06:34 +0000
  Re: Difficulty with Brad Rodriguez' screenful junnia@gmail.com - 2013-03-19 07:45 -0700
    Re: Difficulty with Brad Rodriguez' screenful mhx@iae.nl (Marcel Hendrix) - 2013-03-19 21:38 +0200
      Re: Difficulty with Brad Rodriguez' screenful mhx@iae.nl (Marcel Hendrix) - 2013-03-23 01:31 +0200

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