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Re: rhel 7 and kforth

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anton@mips.complang.tuwien.ac.at (Anton Ertl) writes:
>>The standard was written with those optimizations in mind
> You repeat that claim without supplying evidence. 

Here are some posts from committee member Doug Gwyn, concerning a UB
when a variable is read and modified without an intervening sequence
point other than with autoincrement:

1. He explains that the UB is to enable special optimizations on vector
machines:

https://groups.google.com/forum/#!original/comp.std.c/DP_WFjf1Ug0/7fSMidjs044J

    ...if a swath of a vector is being operated on it might be that
    nominally the "same" element has different values at different
    places in the pipeline.  It is in order to avoid forcing the
    generated code to have to pessimistically flush pipelines etc. (nor
    to have to add a preliminary test of whether j == a[j]) that the
    default policy is to not require such pessimism by the
    implementation.

2. He says it's fine for a given code fragment to be UB as long as the
standard gives the programmer a way to get the desired sequencing:

https://groups.google.com/forum/#!original/comp.std.c/DP_WFjf1Ug0/L9blvboMpL0J

    Even if it is "obvious" by Tom St Denis thought he meant by that
    source, in a real implementation one can have register caching,
    vector instructions, etc. which all could make the fast code that
    almost every user would expect to be generated produce an effect
    different from what Tom thought it should be.  The license for
    implementations to be *efficient* is important in the success of C
    as a systems programming language, and in order to prevent excessive
    liberties being taken by code optimizers the standard provides ways
    for programmers to *portably* and *reliably* express what they
    intend; the most notable tool in this regard being the sequence
    point guarantees.

3. Here he's explicit, C's philosophy is to generate fast code for
careful users:

https://groups.google.com/forum/#!original/comp.std.c/DP_WFjf1Ug0/xgVrnRbpV84J

    Rather than penalize *everybody* by default, we support the best
    code generation for the careful user by default, and when a more
    strict order of evaluation is necessary for the correctness of some
    algorithms there are ways for those programmers to obtain it.

He was always writing stuff like that, and I got into long discussions
with him that are now hard to find because of the crappy new interface
of Google Groups.  His basic attitude was that C programmers were
supposed to use NASA-like processes to ensure freedom from UB and other
errors.  He blamed the whole phenomenon of buffer overruns on failure to
use those processes.
    
> As mentioned, P.J.Plaugers articles explaining what happened in the
> C89 committee contained nothing of the kind.

Are these articles online?  Did they discuss the issue of UB at all?

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rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-15 11:20 -0700
  Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-15 19:09 -0700
  Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 04:13 -0700
    Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 04:55 -0700
      Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-16 12:08 +0000
        Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 05:29 -0700
          Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 07:07 -0700
            Re: rhel 7 and kforth franck.bensusan@gmail.com - 2015-04-16 07:44 -0700
              Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 08:14 -0700
          Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-16 14:02 +0000
            Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 08:12 -0700
      Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 12:25 -0700
        Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 17:02 -0700
          Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 17:06 -0700
            Re: rhel 7 and kforth foxaudioresearch@gmail.com - 2015-04-16 17:24 -0700
              Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 17:39 -0700
              Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-16 17:47 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 18:44 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 18:50 -0700
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-16 19:10 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 19:29 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-16 20:10 -0700
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-16 20:27 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-17 02:04 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-17 11:41 +0000
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-17 14:45 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-18 14:01 +0000
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-17 07:47 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-17 08:35 -0700
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-17 10:33 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-17 11:15 -0700
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-17 11:47 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-17 14:51 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-18 14:41 +0000
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-24 11:42 -0700
                Re: rhel 7 and kforth "Elizabeth D. Rather" <erather@forth.com> - 2015-04-24 09:02 -1000
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-02 10:53 +0000
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-05-03 17:22 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-04 10:23 +0000
                Re: rhel 7 and kforth Bernd Paysan <bernd.paysan@gmx.de> - 2015-04-22 00:10 +0200
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-21 17:45 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-22 13:08 +0000
                Re: rhel 7 and kforth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-17 20:27 +0000
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-17 14:41 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-18 14:11 +0000
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-17 15:47 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-18 14:34 +0000
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-18 14:09 -0700
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-19 20:31 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-20 11:35 +0000
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-21 18:07 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-22 11:21 +0000
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-24 19:34 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-25 08:36 +0000
                Re: rhel 7 and kforth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-25 11:36 +0000
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-25 16:29 +0000
                Re: rhel 7 and kforth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-19 10:08 +0000
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-19 20:11 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-20 12:05 +0000
                Re: rhel 7 and kforth Bernd Paysan <bernd.paysan@gmx.de> - 2015-04-22 01:27 +0200
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-21 18:18 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-22 11:00 +0000
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-24 11:28 -0700
                Re: rhel 7 and kforth Bernd Paysan <bernd.paysan@gmx.de> - 2015-04-25 01:34 +0200
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-24 21:07 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-25 16:41 +0000
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-25 10:06 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-26 14:56 +0000
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-26 20:22 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-27 09:02 +0000
                Re: rhel 7 and kforth mhx@iae.nl - 2015-04-27 03:59 -0700
                Re: rhel 7 and kforth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-27 15:45 +0000
                Re: rhel 7 and kforth "Rod Pemberton" <bork@lllljunkqwer.cpm> - 2015-04-27 18:09 -0400
                Re: rhel 7 and kforth Bernd Paysan <bernd.paysan@gmx.de> - 2015-04-28 03:55 +0200
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-27 19:30 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-27 19:44 -0700
                Re: rhel 7 and kforth "Rod Pemberton" <bork@lllljunkqwer.cpm> - 2015-04-28 02:03 -0400
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-28 01:44 -0700
                Re: rhel 7 and kforth Mark Wills <markwills1970@gmail.com> - 2015-04-28 02:44 -0700
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-28 16:47 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-28 17:00 -0700
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-28 17:14 -0700
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-28 17:59 -0700
                Re: rhel 7 and kforth Paul Rubin <no.email@nospam.invalid> - 2015-04-28 21:41 -0700
                Re: rhel 7 and kforth Bernd Paysan <bernd.paysan@gmx.de> - 2015-04-29 03:07 +0200
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-28 18:13 -0700
                Re: rhel 7 and kforth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-29 00:07 +0000
                Re: rhel 7 and kforth Bernd Paysan <bernd.paysan@gmx.de> - 2015-04-28 22:22 +0200
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-28 14:23 -0700
                Re: rhel 7 and kforth Bernd Paysan <bernd.paysan@gmx.de> - 2015-04-28 23:51 +0200
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-28 16:50 -0700
                Re: rhel 7 and kforth David Thompson <dave.thompson2@verizon.net> - 2015-05-10 12:24 -0400
                Re: rhel 7 and kforth mhx@iae.nl - 2015-04-26 22:16 -0700
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-04-27 09:19 +0000
                Re: rhel 7 and kforth mhx@iae.nl - 2015-04-27 04:03 -0700
                Re: rhel 7 and kforth "Rod Pemberton" <bork@lllljunkqwer.cpm> - 2015-04-27 18:21 -0400
                Re: rhel 7 and kforth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-05-01 14:46 +0000
                Re: rhel 7 and kforth Bernd Paysan <bernd.paysan@gmx.de> - 2015-04-23 16:46 +0200
                Re: rhel 7 and kforth albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-17 10:35 +0000
                Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-17 08:43 -0700
  Re: rhel 7 and kforth krishna.myneni@ccreweb.org - 2015-04-17 08:41 -0700

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