Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.c > #127816
Show key headers only | View raw
supercat@casperkitty.com writes:
> On Wednesday, March 14, 2018 at 11:02:26 AM UTC-5, David Brown wrote:
>> On 14/03/18 16:48, supercat@casperkitty.com wrote:
>> > Systems that use frame pointers can handle VLAs reasonably well. How
>> > about systems that use stack-relative addressing without frame pointers?
>>
>> Well, let's think, shall we? Rub a few brain cells together? How about
>> - we use a f****** frame pointer! This really is not rocket science.
>> It does not matter if there is a register called "frame pointer" in the
>> cpu, or you use a different one. It's just a /pointer/. No more, no
>> less. If your compiler can't work with pointers - and can't handle
>> there being one more pointer in the function - then it is no C compiler!
>
> Nothing in the C Standard requires that an implementation have a
> contiguously-addressable stack, much less a frame pointer.
True. But something in the C standard (at least in the 1999 edition)
*does* require support for VLAs. I haven't heard about any compiler
implementers who wanted to support C99 having any particularly
difficulty supporting VLAs.
> Just about
> any implementation could, with enough effort, be made to support just
> about any feature, but if generated code using VLAs would be so horribly
> inefficient that a programmer would almost always be better off specifying
> a fixed size, I would think having the implementation reject programs using
> VIAs would typically be better than having it accept such programs while
> producing such horribly inefficient machine code as to be practically
> useless.
That's a big "if". You could say the same about any language feature.
If you can cite a C implementation whose maintainers had great
difficulty implementing VLAs in a reasonable manner, then you might
have a valid point.
Even if there is such an implementation, I disagree with your
conclusion. I can imagine that implementing VLAs correctly might
be difficult. I'm skeptical that, once that work is done, the
resulting code would be as horribly inefficient as you suggest.
And even if it were, a compiler could still support VLAs for the
sake of C99 conformance, and issue a (perhaps optional) warning
for their use, so that standard C code written for other compilers
would still work. That's the whole point of having a standard.
And of course VLAs are optional in C11, so your wish has been granted.
(I've never seen a good explanation for making VLAs optional in
C11, and there's no official C11 Rationale document. Could it be
that some implementer requested that change because implementing
VLAs would have been unreasonably difficult? Does anyone have any
further information?)
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar
Future of C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-03-08 06:28 -0800
Re: Future of C "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-08 22:48 +0800
Re: Future of C Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2018-03-08 09:53 -0500
Re: Future of C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-03-08 15:02 +0000
Re: Future of C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-03-08 07:32 -0800
Re: Future of C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-03-08 16:41 +0000
Re: Future of C Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-08 17:02 +0000
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-15 01:54 -0700
Re: Future of C Real Troll <real.troll@trolls.com> - 2018-03-08 11:55 -0400
Re: Future of C "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-03-08 12:15 -0800
Re: Future of C jacobnavia <jacob@jacob.remcomp.fr> - 2018-03-12 11:34 +0100
Re: Future of C "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-03-12 13:17 -0700
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-10 18:00 +0100
Re: Future of C Real Troll <Real.Troll@Trolls.com> - 2018-03-10 17:25 -0400
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-11 00:03 +0100
Re: Future of C David Kleinecke <dkleinecke@gmail.com> - 2018-03-10 16:52 -0800
Re: Future of C Robert Wessel <robertwessel2@yahoo.com> - 2018-03-10 23:41 -0600
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-11 16:15 +0100
Re: Future of C David Kleinecke <dkleinecke@gmail.com> - 2018-03-11 14:31 -0700
Re: Future of C Spiros Bousbouras <spibou@gmail.com> - 2018-03-11 21:50 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-11 15:02 -0700
Re: Future of C David Kleinecke <dkleinecke@gmail.com> - 2018-03-11 17:48 -0700
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-12 22:25 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-12 16:18 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-12 16:24 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-12 23:55 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-12 17:14 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-12 18:29 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-13 07:58 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:05 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-13 09:38 -0700
Re: Future of C Melzzzzz <Melzzzzz@zzzzz.com> - 2018-03-13 21:51 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-13 15:06 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 12:22 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-12 18:24 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 01:40 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:11 +0100
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:06 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 09:38 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 16:58 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-12 17:01 -0700
Re: Future of C Ian Collins <ian-news@hotmail.com> - 2018-03-13 12:25 +1300
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-13 10:19 +0100
Re: Future of C jameskuyper@verizon.net - 2018-03-13 07:45 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 16:15 +0000
Re: Future of C jameskuyper@verizon.net - 2018-03-13 10:20 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 17:45 +0000
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 11:51 -0700
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-13 21:12 +0100
Re: Future of C Tim Rentsch <txr@alumni.caltech.edu> - 2018-03-17 10:11 -0700
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-18 05:21 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:16 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 18:05 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 21:28 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 13:39 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 21:57 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 14:26 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 12:23 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 21:22 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 13:02 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-14 08:48 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 17:02 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-14 17:09 +0000
Re: Future of C Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-03-14 10:18 -0700
Re: Future of C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-03-14 20:04 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 21:46 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 14:03 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 09:22 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-14 14:55 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 09:36 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-15 07:55 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-16 00:19 +0100
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 13:53 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-14 11:37 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 12:12 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-14 13:04 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 13:37 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-14 14:16 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 15:27 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-14 15:50 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 17:09 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-14 20:18 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 10:25 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-15 11:27 -0700
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 19:42 +0000
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-15 22:03 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 12:54 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-15 14:31 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 15:27 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-15 15:47 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 16:05 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-16 08:19 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-16 10:23 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-16 17:21 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-16 18:37 -0700
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-16 21:25 -0700
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-20 11:46 +0100
Re: Future of C Tim Rentsch <txr@alumni.caltech.edu> - 2018-03-17 10:50 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-19 14:00 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-19 14:48 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-19 15:21 -0700
Re: Future of C "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-03-19 21:47 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 11:12 +0100
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-15 03:28 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 10:57 +0100
Re: Future of C William Ahern <william@25thandClement.com> - 2018-03-15 04:06 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 13:35 +0100
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-15 05:47 -0700
Re: Future of C supercat@casperkitty.com - 2018-03-15 08:25 -0700
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 16:14 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-15 09:56 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 10:45 -0700
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 18:15 +0000
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-15 11:22 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 12:38 -0700
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-15 20:46 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-15 15:14 -0700
Re: Future of C William Ahern <william@25thandClement.com> - 2018-03-15 22:56 -0700
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-16 00:39 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-19 11:35 +0100
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-19 03:46 -0700
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 10:35 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-16 00:36 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-15 10:40 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-16 00:26 +0100
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 10:36 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-15 14:43 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 16:03 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-15 09:46 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 09:45 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-14 17:35 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-15 11:25 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-15 14:57 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-16 00:45 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-16 00:34 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-16 09:29 +0100
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-16 01:42 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-16 11:40 +0000
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-16 05:03 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-19 13:49 +0100
Re: Future of C Steven Petruzzellis <frelwizzen@gmail.com> - 2018-03-19 06:55 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-19 14:37 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-19 22:23 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-19 13:28 -0700
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-19 23:39 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-19 23:47 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-20 00:59 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-20 00:20 +0000
Re: Future of C Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-20 12:42 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-20 14:09 +0100
Re: Future of C bartc <bc@freeuk.com> - 2018-03-16 01:36 +0000
Re: Future of C supercat@casperkitty.com - 2018-03-13 14:24 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 20:40 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 22:12 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 14:36 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-13 22:25 +0000
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-13 15:54 -0700
Re: Future of C bartc <bc@freeuk.com> - 2018-03-14 01:01 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 13:30 +0100
Re: Future of C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-03-14 01:02 +0000
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 10:04 -0700
Re: Future of C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-03-14 18:32 +0000
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-14 13:22 +0100
Re: Future of C Keith Thompson <kst-u@mib.org> - 2018-03-14 10:45 -0700
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-13 21:19 +0100
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-13 00:25 +0100
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-13 10:08 +0100
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-13 13:17 +0100
Re: Future of C Melzzzzz <Melzzzzz@zzzzz.com> - 2018-03-13 15:55 +0000
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-13 21:20 +0100
Re: Future of C supercat@casperkitty.com - 2018-03-11 14:55 -0700
Re: Future of C Robert Wessel <robertwessel2@yahoo.com> - 2018-03-10 23:44 -0600
Re: Future of C Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-03-11 06:17 +0000
Re: Future of C jacobnavia <jacob@jacob.remcomp.fr> - 2018-03-12 11:55 +0100
Re: Future of C john.ladasky@gmail.com - 2018-03-11 03:34 -0700
Re: Future of C Wouter Verhelst <w@uter.be> - 2018-03-12 22:47 +0100
Re: Future of C David Brown <david.brown@hesbynett.no> - 2018-03-13 17:25 +0100
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-13 09:40 -0700
Re: Future of C jacobnavia <jacob@jacob.remcomp.fr> - 2018-03-12 11:45 +0100
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 16:01 +0000
Re: Future of C jameskuyper@verizon.net - 2018-03-12 09:25 -0700
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 17:31 +0000
Re: Future of C jameskuyper@verizon.net - 2018-03-12 10:59 -0700
Re: Future of C jacobnavia <jacob@jacob.remcomp.fr> - 2018-03-12 11:44 +0100
Re: Future of C jacobnavia <jacob@jacob.remcomp.fr> - 2018-03-12 11:32 +0100
Re: Future of C asetofsymbols@gmail.com - 2018-03-12 08:18 -0700
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-08 09:31 -0800
Re: Future of C Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2018-03-08 13:46 -0500
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-08 12:26 -0800
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-08 12:36 -0800
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-08 12:55 -0800
Re: Future of C supercat@casperkitty.com - 2018-03-08 11:25 -0800
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-08 12:30 -0800
Re: Future of C supercat@casperkitty.com - 2018-03-08 13:20 -0800
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-09 04:17 -0800
Re: Future of C "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-11 22:58 +0800
Re: Future of C John Bode <jfbode1029@gmail.com> - 2018-03-08 14:36 -0800
Re: Future of C Thiago Adams <thiago.adams@gmail.com> - 2018-03-08 17:41 -0800
Re: Future of C jacobnavia <jacob@jacob.remcomp.fr> - 2018-03-09 03:15 +0100
Re: Future of C Reinhardt Behm <rbehm@hushmail.com> - 2018-03-09 12:58 +0800
Re: Future of C Les Cargill <lcargill99@comcast.com> - 2018-03-08 18:56 -0600
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-10 18:20 +0100
Re: Future of C "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-11 22:59 +0800
[OT] C vs World Trade Center 9/11 "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2018-03-11 23:11 +0800
Re: Future of C scott@slp53.sl.home (Scott Lurndal) - 2018-03-12 17:34 +0000
Re: Future of C GOTHIER Nathan <nathan.gothier@gmail.com> - 2018-03-12 19:33 +0100
Re: Future of C Davs <johndemeert0@gmail.com> - 2018-03-11 17:48 -0700
Re: Future of C Manfred <noname@invalid.add> - 2018-03-13 20:54 +0100
Re: Future of C cprime.twitter@gmail.com - 2018-03-13 13:50 -0700
Re: Future of C "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-03-15 22:05 -0700
Re: Future of C Manfred <noname@invalid.add> - 2018-03-16 19:07 +0100
csiph-web