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| From | Eric Sosman <esosman@comcast-dot-net.invalid> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: What's new in C? |
| Date | 2012-12-04 21:05 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <k9ma64$9i4$1@dont-email.me> (permalink) |
| References | (8 earlier) <MoCdnWbKR-yIJyDNnZ2dnUVZ_qidnZ2d@supernews.com> <k9kt3r$qjf$1@dont-email.me> <k9lpb4$mhi$1@speranza.aioe.org> <k9lvhe$ffd$1@dont-email.me> <k9m7e8$m42$1@speranza.aioe.org> |
On 12/4/2012 8:19 PM, glen herrmannsfeldt wrote:
> Eric Sosman <esosman@comcast-dot-net.invalid> wrote:
>[... Glen snipped his own attribution ...]
>>> Well, I suppose in some processors the stack operation might
>>> be predefined well enough that there weren't any possible
>>> variations.
>
>> Sorry; I don't understand this.
>
> Is it, in general, possible to write a C library, including
> longjmp(), that is independent of the compiler?
I'd say "No." The setjmp()/longjmp() pair are an obvious
case of interdependency: They can't know what to save and restore
unless they know about the code the compiler generates, and the
compiler itself must suppress some optimizations around a use
of setjmp().
Other examples exist, but seem somewhat weaker. The malloc()
suite is supposed to deliver memory that is properly aligned for
any C data type, but the required alignment depends on what kind
of code the compiler generates. The <math.h> functions may rely
on the compiler to establish certain modes for rounding or NaN
handling, and/or the compiler may assume those modes are in force
for the in-line code it generates. I have not studied C11's
thread support in any detail, but it seems probable that the
compiler and library cooperate to provide at least some of it.
Don't overlook the Old Standbys: Compilers that recognize
sqrt() and memcpy() and assorted other library functions, and
generate in-line no-call code for them.[*] Yes, the library still
needs to provide an actual, callable function (so you can aim a
function pointer at it), but `#define sqrt(x) _builtin_sqrt(x)'
is, I think, evidence of at least a compiler-library detente.
(These aren't mandatory, of course, so they don't contradict your
"possible" -- but they're evidence for the "desirable" question.)
[*] A former colleague who'd been a compiler jockey told me of
tweaking his employer's compiler to recognize `printf("%s\n", p)'
and replace it with `puts(p)'. Why? "It helped the SPECmark."
That, I'd say, is a clear example of the compiler and library being
caught in flagrante delicto! At compile-time, gcc's inspection of
printf() and scanf() formats vis-a-vis the other arguments is another
example of the compiler and library using knowledge of each other.
--
Eric Sosman
esosman@comcast-dot-net.invalid
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What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-11-28 19:41 -0700
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-28 19:15 -0800
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 02:43 -0700
Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 07:45 -0500
Re: What's new in C? Noob <root@127.0.0.1> - 2012-11-29 10:36 +0100
Re: What's new in C? Weland <weland@sdf.lonestar.org> - 2012-11-29 10:17 +0000
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:45 -0700
Re: What's new in C? Weland <weland@sdf.lonestar.org> - 2012-11-29 09:48 +0000
Re: What's new in C? David Brown <david@westcontrol.removethisbit.com> - 2012-11-29 13:50 +0100
Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-29 05:55 -0800
Re: What's new in C? Les Cargill <lcargill99@comcast.com> - 2012-11-29 12:48 -0600
Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-30 10:46 +0000
Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-30 05:31 -0800
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-11-30 14:22 +0000
Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-30 15:04 +0000
Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 16:41 +0000
Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-11-30 11:49 -0500
Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-30 10:12 -0800
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-30 11:12 -0800
Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 22:26 +0000
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-11-30 22:36 +0000
Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-30 23:27 +0000
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:39 -0700
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-04 00:43 -0800
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 03:14 -0700
Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-04 12:50 +0000
Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-12-04 05:54 -0800
Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-04 20:51 +0000
Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 16:09 -0500
Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-04 16:19 -0500
Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-04 21:45 +0000
Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-05 01:13 +0000
Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-04 20:36 -0500
Re: What's new in C? Robert Wessel <robertwessel2@yahoo.com> - 2012-12-04 20:26 -0600
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-04 18:48 -0800
Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-05 02:57 +0000
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-05 01:42 +0000
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 02:06 -0700
Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 07:50 -0500
Re: What's new in C? JohnF <john@please.see.sig.for.email.com> - 2012-12-06 13:46 +0000
Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 09:39 -0500
Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-11-30 15:52 -0500
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 01:53 -0700
Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 08:16 -0500
Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-04 21:18 +0000
Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 18:04 -0500
Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-05 01:19 +0000
Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-04 21:05 -0500
Re: What's new in C? Noob <root@127.0.0.1> - 2012-12-05 16:45 +0100
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 01:45 -0700
Re: What's new in C? James Kuyper <jameskuyper@verizon.net> - 2012-12-06 08:12 -0500
Re: What's new in C? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-06 21:13 +0000
Re: What's new in C? Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-06 09:15 -0500
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-12 18:28 -0700
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-11-30 11:22 -0800
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-04 03:04 -0700
Re: What's new in C? Rui Maciel <rui.maciel@gmail.com> - 2012-11-29 18:19 +0000
Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-29 11:41 -0800
Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-11-30 20:50 +0000
Re: What's new in C? Jens Gustedt <jens.gustedt@loria.fr> - 2012-11-30 23:35 +0100
Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-05 03:26 +0000
Re: What's new in C? gwowen <gwowen@gmail.com> - 2012-12-05 23:49 -0800
Re: What's new in C? Cal Dershowitz <cal@example.invalid> - 2012-12-06 01:49 -0700
Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 07:55 +0000
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 13:29 +0000
Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 15:23 +0000
Re: What's new in C? Martin Shobe <martin.shobe@yahoo.com> - 2012-12-08 17:46 +0000
Re: What's new in C? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-12-08 10:45 -0800
Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 19:32 +0000
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 18:55 +0000
Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 08:26 +1300
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 20:12 +0000
Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 09:18 +1300
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 21:21 +0000
Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 10:27 +1300
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 13:36 -0800
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 12:59 -0800
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 22:10 +0000
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 16:15 -0800
Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 14:23 +1300
Re: What's new in C? Ian Collins <ian-news@hotmail.com> - 2012-12-09 14:20 +1300
Re: What's new in C? Keith Thompson <kst-u@mib.org> - 2012-12-08 11:32 -0800
Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-09 02:52 +0000
Re: What's new in C? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-09 02:53 +0000
Re: What's new in C? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-08 20:08 +0000
Re: What's new in C? "BartC" <bc@freeuk.com> - 2012-12-08 20:25 +0000
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