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Groups > comp.lang.forth > #26712
| From | anton@mips.complang.tuwien.ac.at (Anton Ertl) |
|---|---|
| Newsgroups | comp.lang.forth |
| Subject | Re: Floating Point : To Stack or Not To Stack |
| Date | 2013-10-27 12:41 +0000 |
| Organization | Institut fuer Computersprachen, Technische Universitaet Wien |
| Message-ID | <2013Oct27.134114@mips.complang.tuwien.ac.at> (permalink) |
| References | (6 earlier) <7xbo2co681.fsf@ruckus.brouhaha.com> <k4CdnQLNyIKW6fbPnZ2dnUVZ_sadnZ2d@supernews.com> <3_idnWekjL7WAPbPnZ2dnUVZ_qmdnZ2d@supernews.com> <2013Oct26.154815@mips.complang.tuwien.ac.at> <EOadnQ8On7VBivHPnZ2dnUVZ_r-dnZ2d@supernews.com> |
Andrew Haley <andrew29@littlepinkcloud.invalid> writes:
>Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
>> Andrew Haley <andrew29@littlepinkcloud.invalid> writes:
>>>That's suprising to me too. ?DUP WHILE is natural and elegant when
>>>iterating over lists, for example.
>>
>> ?DUP IF can save an ELSE DROP, and, depending on layout style,q up to
>> two lines. So i can understand the urge to use ?DUP IF there.
>>
>> ?DUP WHILE only saves a DROP. Natural and elegant?
>
>Sure, it reduces stack noise. What's not to like? ;-)
A word with a variable stack effect.
>> As for putting the burden on the compiler to correct for the
>> programmer's use of ?DUP: This is Forth. We argue even about good
>> practices if they complicate the compiler. Why should we complicate
>> the compiler for "?DUP"? Better let the programmers fix the
>> programs.
>
>There's no need: as well as not panicking about the compiler, it's
>also good Forth style (IMO, YMMV, ect.) not to panic about
>microseconds which don't matter. Having said that, ?DUP IF avoids
>a couple of trips through NEXT , and this is a speed advantage in some
>implementatons.
If you care about speed, you will use a native code compiler, and
there are no trips through NEXT there; if you don't care about speed
(as the preceeding sentence indicates), why argue with speed?
Anyway, even if we want to optimize for a threaded-code
implementation, ?DUP IF is slower then ?DUP-IF, because it needs an
additional test and an additional NEXT.
Now for ?DUP WHILE ... REPEAT compared to DUP WHILE ... REPEAT DROP:
This costs one test per loop iteration, and saves one DROP for the
whole loop. For loops with many iterations, it's a performance loss.
>However, if you're going to write a full optimizing compiler, it's a
>bit pathetic not to be able to turn ?DUP IF ... THEN into
>DUP IF ... ELSE DROP THEN . I suppose it makes sense if that's
>an idiom you don't use.
I guess I won't be writing a "full optimizing compiler", whatever that
may be. The compilation techniques that I have in mind are capable of
producing good native code for a lot of Forth code, but they don't
produce good code for anything involving ?DUP. One can add complexity
to the compiler for optimizing some of the code that uses ?DUP, but
that requires more than just adding a few more entries to an existing
table; it requires adding an otherwise unnecessary sequence
recognition capability; that's very low on my ToDo list.
- 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 2013: http://www.euroforth.org/ef13/
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Floating Point : To Stack or Not To Stack rickman <gnuarm@gmail.com> - 2013-10-14 16:18 -0400
Re: Floating Point : To Stack or Not To Stack "Elizabeth D. Rather" <erather@forth.com> - 2013-10-14 10:34 -1000
Re: Floating Point : To Stack or Not To Stack Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-14 15:41 -0500
Re: Floating Point : To Stack or Not To Stack Paul Rubin <no.email@nospam.invalid> - 2013-10-14 20:32 -0700
Re: Floating Point : To Stack or Not To Stack rickman <gnuarm@gmail.com> - 2013-10-15 17:14 -0400
Re: Floating Point : To Stack or Not To Stack anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-15 16:22 +0000
Re: Floating Point : To Stack or Not To Stack Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-14 15:42 -0500
Re: Floating Point : To Stack or Not To Stack Hans Bezemer <the.beez.speaks@gmail.com> - 2013-10-16 11:16 +0200
Re: Floating Point : To Stack or Not To Stack anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-15 16:09 +0000
Re: Floating Point : To Stack or Not To Stack krishna.myneni@ccreweb.org - 2013-10-15 18:51 -0700
Re: Floating Point : To Stack or Not To Stack Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-16 03:47 -0500
Re: Floating Point : To Stack or Not To Stack anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-16 12:27 +0000
Re: Floating Point : To Stack or Not To Stack rickman <gnuarm@gmail.com> - 2013-10-25 14:20 -0400
Re: Floating Point : To Stack or Not To Stack Paul Rubin <no.email@nospam.invalid> - 2013-10-25 12:08 -0700
Re: Floating Point : To Stack or Not To Stack rickman <gnuarm@gmail.com> - 2013-10-26 02:34 -0400
Re: Floating Point : To Stack or Not To Stack Paul Rubin <no.email@nospam.invalid> - 2013-10-26 00:13 -0700
Re: Floating Point : To Stack or Not To Stack "Elizabeth D. Rather" <erather@forth.com> - 2013-10-25 21:49 -1000
Re: Floating Point : To Stack or Not To Stack Paul Rubin <no.email@nospam.invalid> - 2013-10-26 01:26 -0700
Re: Floating Point : To Stack or Not To Stack Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-26 05:45 -0500
Re: Floating Point : To Stack or Not To Stack anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-26 13:48 +0000
Re: Floating Point : To Stack or Not To Stack Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-26 14:28 -0500
Re: Floating Point : To Stack or Not To Stack anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-27 12:41 +0000
Re: Floating Point : To Stack or Not To Stack Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-27 08:31 -0500
?DUP (was: Floating Point : To Stack or Not To Stack) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-28 15:19 +0000
Re: ?DUP Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-28 13:54 -0500
Re: ?DUP "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2013-10-28 16:30 -0400
Re: ?DUP "Elizabeth D. Rather" <erather@forth.com> - 2013-10-28 11:11 -1000
Re: ?DUP anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-29 11:51 +0000
Re: ?DUP Bernd Paysan <bernd.paysan@gmx.de> - 2013-10-29 16:48 +0100
Re: ?DUP anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-29 16:10 +0000
Re: ?DUP albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-10-29 16:24 +0000
Re: ?DUP Bernd Paysan <bernd.paysan@gmx.de> - 2013-10-29 20:00 +0100
Re: ?DUP anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-30 07:44 +0000
Re: ?DUP Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-29 16:29 -0500
Re: ?DUP "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2013-10-29 18:58 -0400
Re: ?DUP Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-30 03:15 -0500
Re: ?DUP albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-10-30 01:14 +0000
Re: ?DUP anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-30 08:22 +0000
Re: ?DUP "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2013-10-30 08:03 -0400
Re: ?DUP anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-30 12:24 +0000
Re: ?DUP Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-30 12:44 -0500
Re: ?DUP "Alex McDonald" <blog@rivadpm.com> - 2013-10-30 22:43 +0000
Re: ?DUP anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-31 12:09 +0000
Re: ?DUP Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-31 12:23 -0500
Re: ?DUP (was: Floating Point : To Stack or Not To Stack) "Rod Pemberton" <dont_use_email@xnohavenotit.cnm> - 2013-10-28 16:30 -0400
Re: ?DUP "Elizabeth D. Rather" <erather@forth.com> - 2013-10-28 11:16 -1000
Re: ?DUP Bernd Paysan <bernd.paysan@gmx.de> - 2013-10-29 01:58 +0100
Re: ?DUP Stefan Mauerhofer <smauerhofer@androsoft.ch> - 2013-10-28 18:41 -0700
Re: ?DUP Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-29 04:37 -0500
Re: ?DUP m.a.m.hendrix@tue.nl - 2013-10-29 04:27 -0700
Re: ?DUP anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-29 12:51 +0000
Re: Floating Point : To Stack or Not To Stack anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2013-10-26 09:45 +0000
Re: Floating Point : To Stack or Not To Stack albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-10-26 11:30 +0000
Re: Floating Point : To Stack or Not To Stack Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-26 08:05 -0500
Re: Floating Point : To Stack or Not To Stack mhx@iae.nl - 2013-10-26 06:09 -0700
Re: Floating Point : To Stack or Not To Stack "Rod Pemberton" <dont_use_email@nohavenotit.com> - 2013-10-27 03:01 -0400
Re: Floating Point : To Stack or Not To Stack "Elizabeth D. Rather" <erather@forth.com> - 2013-10-26 22:23 -1000
Re: Floating Point : To Stack or Not To Stack albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-10-26 09:39 +0000
Re: Floating Point : To Stack or Not To Stack albert@spenarnc.xs4all.nl (Albert van der Horst) - 2013-10-26 09:44 +0000
Re: Floating Point : To Stack or Not To Stack "Ed" <invalid@invalid.com> - 2013-10-18 14:09 +1000
Re: Floating Point : To Stack or Not To Stack "Elizabeth D. Rather" <erather@forth.com> - 2013-10-17 21:21 -1000
Re: Floating Point : To Stack or Not To Stack "Ed" <invalid@invalid.com> - 2013-10-19 12:14 +1000
Re: Floating Point : To Stack or Not To Stack "Elizabeth D. Rather" <erather@forth.com> - 2013-10-18 17:17 -1000
Re: Floating Point : To Stack or Not To Stack Paul Rubin <no.email@nospam.invalid> - 2013-10-19 02:58 -0700
Re: Floating Point : To Stack or Not To Stack "Ed" <invalid@invalid.com> - 2013-10-27 22:33 +1100
Re: Floating Point : To Stack or Not To Stack mhx@iae.nl - 2013-10-27 06:21 -0700
Re: Floating Point : To Stack or Not To Stack "Ed" <invalid@invalid.com> - 2013-10-29 22:40 +1100
Re: Floating Point : To Stack or Not To Stack Andrew Haley <andrew29@littlepinkcloud.invalid> - 2013-10-27 08:23 -0500
Re: Floating Point : To Stack or Not To Stack Stefan Mauerhofer <smauerhofer@androsoft.ch> - 2013-10-28 18:38 -0700
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