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Groups > comp.lang.forth > #52693
| From | Alex <alex@rivadpm.com> |
|---|---|
| Newsgroups | comp.lang.forth |
| Subject | Re: Average swaps per word? |
| Date | 2016-11-17 14:02 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <o0kd8d$odl$1@dont-email.me> (permalink) |
| References | (4 earlier) <o0af90$5sf$1@cherry.spenarnc.xs4all.nl> <2016Nov14.183225@mips.complang.tuwien.ac.at> <MPG.3294f76dc332a2cc9896c8@news.virginmedia.com> <o0f0v7$ihp$1@dont-email.me> <2016Nov17.135123@mips.complang.tuwien.ac.at> |
On 11/17/2016 12:51, Anton Ertl wrote: > Alex <alex@rivadpm.com> writes: >> On 11/15/2016 10:44, jim wrote: >>> In article <2016Nov14.183225@mips.complang.tuwien.ac.at>, >>> anton@mips.complang.tuwien.ac.at says... >>>> >>>> Anyway, the general idea that you should check what the "optimizer" >>>> does indicates that what it does is not optimization, but >>>> miscompilation. >>>> >>>> - anton >>>> >>> >>> That is a very good point. > ... >> It's not as good as it appears, since for a large class of programming >> languages, compilation is the act of imprecise translation. Even simple >> statements such as a=b+1 translated to machine code such as ADD A, B, 1 >> are a form of optimisation, since overflow is unaccounted for in the >> source language (or at least, the programmer may not realise that it is >> an issue), and yet overflow is a feature of the target. > > That's not optimization, that's just filling the holes in the > specification. Optimization happens on the program with the holes > filled; i.e., if a=b+1 performs modulo arithmetic (wraparound) without > optimization, then it's an optimization to produce a faster program > that also performs modulo arithmetic, otherwise it's miscompilation. > > - anton > This paper (which I suspect you may already know of) makes the point that I believe you make as per the complaint; http://www.cs.utah.edu/~regehr/papers/overflow12.pdf pg 3 --- 2) Time Bombs: Undefined behavior also leads to time bombs: code that works under today’s compilers, but breaks unpredictably in the future as optimization technology improves. The Internet is rife with stories about problems caused by GCC’s ever-increasing power to exploit signed overflows. For example, in 2005 a principal PostgreSQL developer was annoyed that his code was broken by a recent version of GCC: It seems that gcc is up to some creative reinterpre- tation of basic C semantics again; specifically, you can no longer trust that traditional C semantics of integer overflow hold ... This highlights a fundamental and pervasive misunderstanding: the compiler was not “reinterpreting” the semantics but rather was beginning to take advantage of leeway explicitly provided by the C standard. --- The complaint about optimisation may be a complaint about ambiguous or under-specification; but the author of the compiler and the author of the optimiser cannot be held accountable for that, and it is (imho) your responsibility to make sure that your programmatic incantations are correctly treated by both. -- Alex
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Average swaps per word? trans <transfire@gmail.com> - 2016-11-08 22:03 -0800
Re: Average swaps per word? "Elizabeth D. Rather" <erather@forth.com> - 2016-11-08 20:20 -1000
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-09 08:16 +0000
Re: Average swaps per word? Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2016-11-09 03:34 -0500
Re: Average swaps per word? trans <transfire@gmail.com> - 2016-11-09 02:53 -0800
Re: Average swaps per word? rickman <gnuarm@gmail.com> - 2016-11-09 11:50 -0500
Re: Average swaps per word? stephen@mpeforth.com (Stephen Pelc) - 2016-11-09 18:37 +0000
Re: Average swaps per word? Harold <hzrabbie@gmail.com> - 2016-11-10 16:28 -0800
Re: Average swaps per word? stephen@mpeforth.com (Stephen Pelc) - 2016-11-11 17:51 +0000
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-12 12:23 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-12 16:09 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-13 14:55 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-13 20:34 +0100
Re: Average swaps per word? Paul Rubin <no.email@nospam.invalid> - 2016-11-13 11:43 -0800
Re: Average swaps per word? hughaguilar96@gmail.com - 2016-11-13 16:58 -0800
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-14 16:41 +0100
Re: Average swaps per word? hughaguilar96@gmail.com - 2016-11-14 16:38 -0800
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-14 17:42 +0000
Re: Average swaps per word? Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2016-11-14 16:39 -0500
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-17 12:40 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-17 14:10 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-18 15:14 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-20 18:16 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-22 10:29 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-22 15:54 +0100
Re: Average swaps per word? James Kuyper <jameskuyper@verizon.net> - 2016-11-22 11:50 -0500
Re: Average swaps per word? raltbos@xs4all.nl (Richard Bos) - 2016-11-24 17:27 +0000
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-15 03:55 -0600
Re: Average swaps per word? Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2016-11-15 17:49 -0500
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-16 02:59 -0600
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-17 13:07 +0000
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-16 22:57 +0000
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-17 03:12 -0600
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-17 12:32 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-18 15:02 +0000
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-17 13:23 +0000
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-17 08:54 -0600
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-18 15:54 +0000
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-18 12:37 -0600
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-14 17:32 +0000
Re: Average swaps per word? Mark Wills <markwills1970@gmail.com> - 2016-11-15 02:09 -0800
Re: Average swaps per word? jim <anon@example.com> - 2016-11-15 10:44 +0000
Re: Average swaps per word? Mark Wills <markwills1970@gmail.com> - 2016-11-15 03:12 -0800
Re: Average swaps per word? Alex <alex@rivadpm.com> - 2016-11-15 13:01 +0000
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-17 12:51 +0000
Re: Average swaps per word? Alex <alex@rivadpm.com> - 2016-11-17 14:02 +0000
Re: Average swaps per word? Alex <alex@rivadpm.com> - 2016-11-17 14:06 +0000
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-18 15:26 +0000
Re: Average swaps per word? Alex <alex@rivadpm.com> - 2016-11-18 18:33 +0000
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-19 03:32 -0600
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-17 14:29 +0100
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-15 13:51 +0100
Re: Average swaps per word? jim <anon@example.com> - 2016-11-15 13:01 +0000
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-17 12:46 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-17 14:16 +0100
Re: Average swaps per word? Harold <hzrabbie@gmail.com> - 2016-11-13 11:08 -0800
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-14 17:08 +0000
Re: Average swaps per word? Mark Wills <markwills1970@gmail.com> - 2016-11-15 02:04 -0800
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-15 14:04 +0100
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-15 14:05 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-17 12:58 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-17 15:16 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-18 15:41 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-20 18:12 +0100
Re: Average swaps per word? minforth@arcor.de - 2016-11-09 03:15 -0800
Re: Average swaps per word? trans <transfire@gmail.com> - 2016-11-09 11:22 -0800
Re: Average swaps per word? "HAA" <someone@microsoft.com> - 2016-11-10 12:20 +1100
Re: Average swaps per word? "Elizabeth D. Rather" <erather@forth.com> - 2016-11-09 21:04 -1000
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-10 03:45 -0600
Re: Average swaps per word? rickman <gnuarm@gmail.com> - 2016-11-10 11:52 -0500
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-10 11:42 -0600
Re: Average swaps per word? rickman <gnuarm@gmail.com> - 2016-11-10 13:34 -0500
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-10 12:54 -0600
Re: Average swaps per word? rickman <gnuarm@gmail.com> - 2016-11-10 16:33 -0500
Re: Average swaps per word? "Elizabeth D. Rather" <erather@forth.com> - 2016-11-10 15:56 -1000
Re: Average swaps per word? rickman <gnuarm@gmail.com> - 2016-11-10 21:30 -0500
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-11 03:04 -0600
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-12 13:25 +0000
Re: Average swaps per word? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-11-14 03:34 -0600
Re: Average swaps per word? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2016-11-11 10:41 +0000
Re: Average swaps per word? hughaguilar96@gmail.com - 2016-11-11 16:45 -0800
Re: Average swaps per word? jim <anon@example.com> - 2016-11-10 11:17 +0000
Re: Average swaps per word? Raimond Dragomir <raimond.dragomir@gmail.com> - 2016-11-10 04:34 -0800
Re: Average swaps per word? jim <anon@example.com> - 2016-11-10 12:44 +0000
Re: Average swaps per word? Raimond Dragomir <raimond.dragomir@gmail.com> - 2016-11-10 07:27 -0800
Re: Average swaps per word? Ron Aaron <rambamist@gmail.com> - 2016-11-10 18:26 +0200
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-10 16:05 +0000
Re: Average swaps per word? stephen@mpeforth.com (Stephen Pelc) - 2016-11-10 14:55 +0000
Re: Average swaps per word? "HAA" <someone@microsoft.com> - 2016-11-12 11:36 +1100
Re: Average swaps per word? hughaguilar96@gmail.com - 2016-11-11 16:56 -0800
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-12 16:14 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-12 12:14 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-12 16:16 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-13 14:51 +0000
Re: Average swaps per word? albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2016-11-13 20:41 +0100
Re: Average swaps per word? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-11-10 14:42 +0000
Re: Average swaps per word? hughaguilar96@gmail.com - 2016-11-11 15:54 -0800
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