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Re: Why are VLAs optional in C11?

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Am 18.08.2012 01:23, schrieb Keith Thompson:
> Jens Gustedt <jens.gustedt@loria.fr> writes:
>> Am 18.08.2012 00:42, schrieb Keith Thompson:
>>> Why did C11 make VLAs optional?
>>
>> I vaguely remember reading that the motif was similar as for the
>> complex data types. There are platforms with specialized compilers
>> that really don't need VLA (embedded stuff comes into mind). They
>> shouldn't lag behind in addopting the core features of modern C. The
>> same strategy has been followed for other new features such as
>> threads, for example.
> 
> Then let me add to my previous question: Would it have been reasonable
> to make VLAs mandatory for hosted implementations but optional for
> freestanding implementations?

Probably not. There will be more and more borderline architectures in
the future that combine aspects of hosted and freestanding
environments. Best example are platforms with GPU. E.g OpenCL is
supposed to implement most elements of C99, but not VLA. It combines
compilation on the host environment and on the GPU device.

And programming for devices will become more specialized. For a device
like GPU that does parallel geometric processing you might want
complex numbers (so you'd support that option), atomics and threads
(maybe the C11 can be made compatible with their lowlevel threads) but
you don't want VLA on the device.

The programming model would be very close of what nowadays is a hosted
environment, but without VLA.

Jens

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Why are VLAs optional in C11? Keith Thompson <kst-u@mib.org> - 2012-08-17 15:42 -0700
  Re: Why are VLAs optional in C11? Jens Gustedt <jens.gustedt@loria.fr> - 2012-08-18 01:19 +0200
    Re: Why are VLAs optional in C11? Keith Thompson <kst-u@mib.org> - 2012-08-17 16:23 -0700
      Re: Why are VLAs optional in C11? Jens Gustedt <jens.gustedt@loria.fr> - 2012-08-18 10:12 +0200
    Re: Why are VLAs optional in C11? John Nagle <nagle@animats.com> - 2012-08-17 21:04 -0700
      Re: Why are VLAs optional in C11? pacman@kosh.dhis.org (Alan Curry) - 2012-08-18 05:34 +0000
        Re: Why are VLAs optional in C11? John Nagle <nagle@animats.com> - 2012-08-17 23:07 -0700
          Re: Why are VLAs optional in C11? pacman@kosh.dhis.org (Alan Curry) - 2012-08-18 08:29 +0000
            Re: Why are VLAs optional in C11? John Nagle <nagle@animats.com> - 2012-08-18 09:37 -0700
              Re: Why are VLAs optional in C11? pa@see.signature.invalid (Pierre Asselin) - 2012-08-19 02:27 +0000
            Re: Why are VLAs optional in C11? Ike Naar <ike@sverige.freeshell.org> - 2012-08-18 17:49 +0000
      Re: Why are VLAs optional in C11? Jens Gustedt <jens.gustedt@loria.fr> - 2012-08-18 08:32 +0200
      Re: Why are VLAs optional in C11? Keith Thompson <kst-u@mib.org> - 2012-08-18 02:50 -0700
      Re: Why are VLAs optional in C11? jacob navia <jacob@spamsink.net> - 2012-08-18 14:33 +0200
        Re: Why are VLAs optional in C11? Ike Naar <ike@sverige.freeshell.org> - 2012-08-18 13:23 +0000
        Re: Why are VLAs optional in C11? Keith Thompson <kst-u@mib.org> - 2012-08-18 13:48 -0700
          Re: Why are VLAs optional in C11? jacob navia <jacob@spamsink.net> - 2012-08-18 23:31 +0200
            Re: Why are VLAs optional in C11? Keith Thompson <kst-u@mib.org> - 2012-08-18 18:14 -0700
              Re: Why are VLAs optional in C11? jacob navia <jacob@spamsink.net> - 2012-08-19 09:38 +0200
                Re: Why are VLAs optional in C11? Keith Thompson <kst-u@mib.org> - 2012-08-19 03:07 -0700
                Re: Why are VLAs optional in C11? jacob navia <jacob@spamsink.net> - 2012-08-19 12:29 +0200
                Re: Why are VLAs optional in C11? John Nagle <nagle@animats.com> - 2012-08-19 10:38 -0700
                Re: Why are VLAs optional in C11? Keith Thompson <kst-u@mib.org> - 2012-08-19 13:14 -0700
                Re: Why are VLAs optional in C11? Keith Thompson <kst-u@mib.org> - 2012-08-19 13:59 -0700
                Re: Why are VLAs optional in C11? Owen Shepherd <nntp@owenshepherd.net> - 2012-08-27 22:17 +0100
                Re: Why are VLAs optional in C11? Jens Gustedt <jens.gustedt@loria.fr> - 2012-08-28 00:34 +0200
                Re: Why are VLAs optional in C11? John Nagle <nagle@animats.com> - 2012-08-27 19:36 -0700
                Re: Why are VLAs optional in C11? James Kuyper <jameskuyper@verizon.net> - 2012-08-27 22:54 -0400
                Re: Why are VLAs optional in C11? John Nagle <nagle@animats.com> - 2012-08-27 22:39 -0700
        Re: Why are VLAs optional in C11? "pdx_scooter@yahoo.com" <pdx_scooter@yahoo.com> - 2022-10-01 13:15 -0700
          Re: Why are VLAs optional in C11? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-10-01 14:33 -0700
          Re: Why are VLAs optional in C11? Tomasz Stanislawski <stanislawski.tomasz@googlemail.com> - 2023-01-25 04:21 -0800
  Re: Why are VLAs optional in C11? Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-17 20:54 -0400
  Re: Why are VLAs optional in C11? John Nagle <nagle@animats.com> - 2012-08-17 20:56 -0700

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