From: Jens Gustedt <jens.gustedt@inria.fr>
To: musl@lists.openwall.com
Subject: Re: Use of size_t and ssize_t in mseek
Date: Thu, 04 Jul 2013 13:58:49 +0200 [thread overview]
Message-ID: <1372939129.29653.143.camel@eris.loria.fr> (raw)
In-Reply-To: <20130704111054.GY15323@port70.net>
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Am Donnerstag, den 04.07.2013, 13:10 +0200 schrieb Szabolcs Nagy:
> it seems to me that if a qsort_s call sets the tls and then before
> the callee reads that pointer a signal interrupts with a handler that
> calls qsort_s again then the tls is overwritten by another pointer
>
> so you lose signal-safety with the tls design
this would in fact not be good
in any case I don't think that the tls design is the way to go for
qsort_s, the overhead would be too large
> > > (In P99 I do that with inlining and gcc shows to be able to expand all
> > > comparisons in place and to optimize that smoothly.)
> >
> > Nice. I'll have to take a look -- I've always wanted to see a fully
> > inlined qsort that could be compared to the C++ template-based sorts
> > to demonstrate that inline functions in C can do just as good or
> > better, inlining the comparison callback... :)
>
> * Jens Gustedt <jens.gustedt@inria.fr> [2013-07-04 10:45:47 +0200]:
> > http://gustedt.wordpress.com/2012/12/04/inline-functions-as-good-as-templates/
>
> good to know that this works now..
>
> it's not clear from the article how the compiler knew that the
> last arg for qsort_s is supposed to be passed to the comparision
> function: was it lto+static linking or was the internal of
> qsort_s visible in the same translation unit?
it is visible. P99 is all inline, there isn't even a precompiled
libp99 to link to.
> a few years ago i did similar experiments but those failed back then:
> https://groups.google.com/d/msg/comp.lang.c/sO2oYdZGdd8/bqFZ4i81P7AJ
I see. So yes, the situation has substantially improved since
then. gcc and clang are both capable of doing such optimizations
nowadays, if they are presented with clean code.
Jens
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next prev parent reply other threads:[~2013-07-04 11:58 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-27 3:52 Matthew Fernandez
2013-06-27 4:10 ` Rich Felker
2013-06-27 4:16 ` Matthew Fernandez
2013-06-27 4:23 ` Rich Felker
2013-06-27 4:31 ` Matthew Fernandez
2013-06-27 15:34 ` Rich Felker
2013-06-28 0:49 ` Matthew Fernandez
2013-06-28 1:22 ` Rich Felker
2013-06-28 1:34 ` Matthew Fernandez
2013-06-28 1:48 ` Rich Felker
2013-06-28 1:56 ` Matthew Fernandez
2013-06-29 4:13 ` Rich Felker
2013-06-29 13:38 ` Matthew Fernandez
2013-06-29 14:17 ` Rich Felker
2013-06-29 14:56 ` Jens Gustedt
2013-06-29 15:48 ` Rich Felker
2013-06-29 16:01 ` Jens Gustedt
2013-06-29 16:13 ` Rich Felker
2013-06-29 16:39 ` Jens Gustedt
2013-07-04 1:28 ` Rich Felker
2013-07-04 6:11 ` Jens Gustedt
2013-07-04 6:37 ` Rich Felker
2013-07-04 7:11 ` Jens Gustedt
2013-07-04 8:12 ` Rich Felker
2013-07-04 8:45 ` Jens Gustedt
2013-07-04 15:24 ` Rich Felker
2013-07-04 11:10 ` Szabolcs Nagy
2013-07-04 11:58 ` Jens Gustedt [this message]
2013-07-04 15:26 ` Rich Felker
2013-06-27 10:35 ` Szabolcs Nagy
2013-06-27 15:05 ` Rich Felker
2013-06-27 16:47 ` Rich Felker
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