From: Alejandro Colomar <alx.manpages@gmail.com>
To: "Joseph Myers" <joseph@codesourcery.com>,
"Cristian Rodríguez" <crrodriguez@opensuse.org>
Cc: "G. Branden Robinson" <g.branden.robinson@gmail.com>,
Jonny Grant <jg@jguk.org>, Florian Weimer <fweimer@redhat.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
linux-man <linux-man@vger.kernel.org>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Internal organization of "the implementation" (was: [PATCH] Add example to rand.3)
Date: Fri, 30 Dec 2022 22:15:14 +0100 [thread overview]
Message-ID: <49e90587-8f1a-111e-8937-40afbbf55106@gmail.com> (raw)
In-Reply-To: <db22324-e427-d9bb-f6ee-ec155c3ff33c@codesourcery.com>
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Hi Joseph,
On 12/30/22 22:08, Joseph Myers wrote:
> On Fri, 30 Dec 2022, Cristian Rodríguez via Libc-alpha wrote:
>
>> On Fri, Dec 30, 2022 at 3:15 PM Joseph Myers <joseph@codesourcery.com> wrote:
>>
>>> I expect to implement these functions in due course for glibc (not GCC,
>>> since these are library functions, with the usual requirements for
>>> definitions with external linkage, though most would also have inline
>>> header implementations based on existing longstanding built-in functions).
>>
>> Unless I am seriously missing something, the compiler is required to
>> provide an implementation
>> of them as it is a freestanding header..right ?
>
> "freestanding" versus "hosted" isn't the right distinction for which
> component in a (compiler + library) implementation provides which pieces
> any more. The actual distinction is closer to whether a feature involves
> library functions (with external linkage): if it does, it belongs in the
> library (glibc), whereas if a header doesn't involve such functions, it
> belongs in the compiler (GCC), along with the library support (in libgcc)
> for language features (i.e. library code that can be needed even by
> programs that don't include any standard library header or call any
> function from the standard library). My list of things to be done for C2x
> in GCC includes updating the GCC documentation (standards.texi) to reflect
> this: that is, to say that GCC provides the compiler part of a
> freestanding or hosted implementation, and library support for language
> features and headers not involving external linkage functions, to be used
> together with a corresponding library implementation - not that it's a
> freestanding implementation by itself.
>
> (It wasn't quite right for C11 either; GCC provides <stdatomic.h> and
> libatomic, and while there are a few atomic_* functions with external
> linkage, the bulk of the operations in <stdatomic.h> are only generic
> functions with no defined external-linkage functions underlying them,
> while it's been documented for a long time that a corresponding library is
> always needed to provided memcpy, memmove and memset as those may be
> generated from use of language features without being called explicitly by
> the user's code. But C2x makes it a lot more visible that the previously
> documented rule of thumb for where a feature goes is no longer
> appropriate.)
>
Why is this duplication of responsibility for libc functions? Why isn't there a
smaller say libmem that provides a unique implementation for these memcpy(),
memmove(), memset() functions, and both gcc and glibc (and even the kernel
could, with static linking) depend on it?
Cheers,
Alex
--
<http://www.alejandro-colomar.es/>
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next prev parent reply other threads:[~2022-12-30 21:15 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <105835f5-359c-2646-f609-e73459ee2d3b@jguk.org>
2022-12-26 22:29 ` [PATCH] Add example to rand.3 Alejandro Colomar
2022-12-27 13:07 ` Cristian Rodríguez
2022-12-27 23:33 ` Alejandro Colomar
2022-12-28 0:00 ` G. Branden Robinson
2022-12-28 0:41 ` Alejandro Colomar
2022-12-28 12:21 ` Cristian Rodríguez
2022-12-30 18:15 ` Joseph Myers
2022-12-30 18:20 ` Alejandro Colomar
2022-12-30 18:50 ` Joseph Myers
2022-12-30 18:58 ` Alejandro Colomar
2022-12-30 19:11 ` Cristian Rodríguez
2022-12-30 21:08 ` Joseph Myers
2022-12-30 21:15 ` Alejandro Colomar [this message]
2022-12-30 21:50 ` Internal organization of "the implementation" (was: [PATCH] Add example to rand.3) Joseph Myers
2022-12-27 21:37 ` [PATCH] Add example to rand.3 Jonny Grant
2022-12-27 23:11 ` Alejandro Colomar
2022-12-28 20:51 ` Jonny Grant
2022-12-28 20:56 ` Alejandro Colomar
2022-12-28 21:03 ` Alejandro Colomar
2022-12-28 21:04 ` Alejandro Colomar
2022-12-28 21:25 ` Jonny Grant
2022-12-28 21:32 ` Alejandro Colomar
2022-12-28 21:04 ` Cristian Rodríguez
2022-12-28 21:11 ` Alejandro Colomar
2022-12-28 21:19 ` Jonny Grant
2022-12-28 21:18 ` Alejandro Colomar
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