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Groups > comp.lang.forth > #56894

Re: LLVM and Forth

Newsgroups comp.lang.forth
Date 2017-04-08 21:18 -0700
References (9 earlier) <a-SdnVgDEexEVH7FnZ2dnUU7-RHNnZ2d@supernews.com> <2017Apr5.170145@mips.complang.tuwien.ac.at> <s4wFA.637264$3a3.286206@fx43.am4> <2e244166-da19-410e-9f13-332e1c0fc5b8@googlegroups.com> <OtednXt3y5cIyHrFnZ2dnUU7-eWdnZ2d@supernews.com>
Message-ID <cbeec18c-d0ee-4b89-8a85-e2c7720854fb@googlegroups.com> (permalink)
Subject Re: LLVM and Forth
From Joel Rees <joel.rees@gmail.com>

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On Friday, April 7, 2017 at 6:02:19 PM UTC+9, Andrew Haley wrote:
> Joel Rees <joel.rees@(something).(something)> wrote:
> > 
> > K&R C and the first ANSI standard acknowledged that a compiler
> > should never try to interpret too far beyond a pointer, because,
> > especially in a multiprocessing run-time, the compiler had no way of
> > knowing what was happening to the memory being pointed to when the
> > code was not accessing it.
> 
> I don't believe it.  Chapter and verse of the first ANSI standard,
> please.
> 
> Andrew.

I might be misremembering just when they decided to allow Microsoft to pretend that it is possible to always know what a pointer is pointing at. It might have been ANSI C that provided the volatile keyword to specifically prevent the compiler from looking deeper than it should. 

There was, of course, no standard for K&R, but quite a lot of discussion concerning optimization lamented the fact that C pointers could point to hardware registers and shared data and other things that could change behind the compiler's back. And that therefore, ForTran allowed parallel processing on array elements where C did not. 

It would have been far more correct, and have postponed a lot of standard-rot, to have provided, instead, a "non-volatile" keyword to tell the compiler it could decide it wouldn't need to repeat a dereference of such as pixels[ 10 ] every time it occurred.

Local optimizations are much safer and can be tightened to a far greater degree than global optimizations.

--
Joel Rees

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Thread

LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-01 06:36 -0700
  Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-01 14:57 +0000
    Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-01 11:55 -0700
      Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-02 15:24 +0000
  Re: LLVM and Forth rickman <gnuarm@gmail.com> - 2017-04-01 11:21 -0400
    Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-01 11:57 -0700
      Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-02 04:02 -0500
        Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-02 06:35 -0700
          Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-02 14:41 +0000
          Re: LLVM and Forth minforth@arcor.de - 2017-04-03 01:09 -0700
            Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-03 05:32 -0700
              Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 13:52 +0000
                Re: LLVM and Forth minforth@arcor.de - 2017-04-03 07:59 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 16:08 +0000
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-03 12:22 -0500
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-03 20:10 -0700
                Re: LLVM and Forth minforth@arcor.de - 2017-04-03 22:19 -0700
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-04 16:12 +0200
                Re: LLVM and Forth Walter Banks <walter@bytecraft.com> - 2017-04-05 17:27 -0400
            Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 14:29 +0000
          Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-03 03:17 -0500
            Re: LLVM and Forth minforth@arcor.de - 2017-04-03 05:04 -0700
            Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 12:55 +0000
              Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-03 10:08 -0500
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-03 17:05 +0000
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-04 11:29 -0500
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-04 19:11 +0200
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-04 21:29 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-05 15:01 +0000
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-05 18:42 +0100
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-06 04:01 -0500
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-06 18:48 +0000
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-06 18:42 -0700
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-07 04:02 -0500
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-08 21:18 -0700
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-08 22:43 +0000
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-08 20:54 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-09 14:53 +0000
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-10 00:38 +0000
                Re: LLVM and Forth James Kuyper <jameskuyper@verizon.net> - 2017-04-09 22:46 -0400
                Re: LLVM and Forth Robert Wessel <robertwessel2@yahoo.com> - 2017-04-09 22:27 -0500
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-10 12:36 +0000
                Re: LLVM and Forth Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-10 14:09 +0100
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-10 13:07 +0000
                Re: LLVM and Forth Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-10 16:18 +0100
                Re: LLVM and Forth "James R. Kuyper" <jameskuyper@verizon.net> - 2017-04-10 11:51 -0400
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-12 21:32 +0000
                Re: LLVM and Forth "James R. Kuyper" <jameskuyper@verizon.net> - 2017-04-12 18:29 -0400
                Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-12 15:29 -0700
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-13 02:55 +0200
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-10 18:38 -0700
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-10 11:54 -0500
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-10 10:17 -0700
              Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-03 17:02 +0100
              Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-03 10:03 -0700
            Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-04 03:25 -0700
              Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-04 11:24 +0000
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-04 04:55 -0700
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-04 12:28 +0000
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-04 16:16 +0000
              Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-04 15:38 +0200
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-04 16:06 +0200
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-04 17:57 -0700
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-05 00:44 -0400
                Re: LLVM and Forth minforth@arcor.de - 2017-04-05 00:00 -0700
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-05 08:47 -0700
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-05 11:04 -0500
                Re: LLVM and Forth john <anon@example.com> - 2017-04-05 18:04 +0100
                Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-05 13:04 -0700
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-05 18:20 -0700
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-05 20:14 -0700
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-06 12:33 +0000
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-06 10:49 -0700
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 18:55 +0100
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-06 20:41 +0000
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 21:47 +0100
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 21:56 +0100
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-06 23:59 -0400
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-06 17:10 -0700
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-07 03:33 -0400
                Re: LLVM and Forth Spiros Bousbouras <spibou@gmail.com> - 2017-04-08 22:48 +0000
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-09 15:06 -0400
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-08 22:45 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-09 14:27 +0000
                Re: LLVM and Forth Joel Rees <joel.rees@gmail.com> - 2017-04-09 21:26 -0700
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-09 13:35 -0400
                Re: LLVM and Forth Paul Rubin <no.email@nospam.invalid> - 2017-04-09 14:07 -0700
                Re: LLVM and Forth minforth@arcor.de - 2017-04-05 12:16 -0700
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-05 20:27 -0700
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-06 05:24 -0400
                Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-06 03:26 -0700
                Re: LLVM and Forth minforth@arcor.de - 2017-04-06 04:05 -0700
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-06 06:50 -0500
                Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-06 05:23 -0400
                Re: LLVM and Forth Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-04-06 04:44 -0500
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 10:57 +0100
                Re: LLVM and Forth peter.m.falth@gmail.com - 2017-04-05 05:29 -0700
                Re: LLVM and Forth "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-04-14 02:04 +0000
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-15 14:03 +0200
                Re: LLVM and Forth "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-04-16 00:44 +0000
                Re: LLVM and Forth alex@rivadpm.com - 2017-04-16 05:53 -0700
                Re: LLVM and Forth anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-04-16 15:43 +0000
                Re: LLVM and Forth "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-04-16 22:27 +0000
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-18 02:45 +0200
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-18 18:26 +0100
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-20 19:51 +0200
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-20 19:08 +0100
                Re: LLVM and Forth albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-04-20 20:42 +0200
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-20 20:29 +0100
                Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-20 20:48 +0100
                Re: LLVM and Forth "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-04-21 11:49 +0000
          Re: LLVM and Forth Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-04-03 20:39 -0400
  Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-02 21:15 +0100
    Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-02 15:18 -0700
      Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-03 13:07 +0100
        Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-03 09:45 -0700
          Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-03 22:52 +0100
            Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-03 15:25 -0700
              Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 09:35 +0100
      Re: LLVM and Forth antispam@math.uni.wroc.pl - 2017-04-06 01:36 +0000
        Re: LLVM and Forth minforth@arcor.de - 2017-04-05 22:00 -0700
          Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 09:52 +0100
        Re: LLVM and Forth hughaguilar96@gmail.com - 2017-04-06 20:15 -0700
    Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-03 05:20 -0700
      Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-03 17:11 +0100
  Re: LLVM and Forth Alex <alex@rivadpm.com> - 2017-04-06 17:43 +0100
    Re: LLVM and Forth krishna.myneni@ccreweb.org - 2017-04-06 10:53 -0700

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