From: Florian Weimer <fweimer@redhat.com>
To: Fangrui Song via Libc-alpha <libc-alpha@sourceware.org>
Cc: Fangrui Song <maskray@google.com>
Subject: Re: [PATCH] Set the retain attribute on _elf_set_element if CC supports [BZ #27492]
Date: Mon, 15 Mar 2021 08:28:18 +0100 [thread overview]
Message-ID: <878s6ozxil.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20210315011050.309228-1-maskray@google.com> (Fangrui Song via Libc-alpha's message of "Sun, 14 Mar 2021 18:10:50 -0700")
* Fangrui Song via Libc-alpha:
> So that text_set_element/data_set_element/bss_set_element defined
> variables will be retained by the linker.
>
> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable
> will not be optimized out; 'retain' prevents section garbage collection
> if the linker support SHF_GNU_RETAIN.
This needs recent-ish GCC 11, see commit 6347f4a0904fce17e ("Add retain
attribute to place symbols in SHF_GNU_RETAIN section).
> +#ifdef __has_attribute
> +#if __has_attribute (retain)
> +# ifdef SHARED
Indentation is off there.
It's probably simpler to define a new macro, like
ELEMENT_SECTION_ATTRIBUTES, and use that unconditionally, perhaps like
this?
#ifndef __ASSEMBLER__
# if defined (__has_attribute) && __has_attribute (retain)
# define ELEMENT_SECTION_ATTRIBUTES used, retain
# else
# define ELEMENT_SECTION_ATTRIBUTES used
# endif
#endif
Have you checked that __has_attribute (retain) is only true on GCC if
the underlying linker has retain support and the attribute does not
produce a warning?
Thanks,
Florian
next prev parent reply other threads:[~2021-03-15 7:28 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 1:10 Fangrui Song
2021-03-15 7:28 ` Florian Weimer [this message]
2021-03-15 7:45 ` Fāng-ruì Sòng
2021-03-15 8:13 ` Florian Weimer
2021-03-22 4:00 ` [PATCH v2] " Fangrui Song
2021-03-22 4:24 ` H.J. Lu
2021-03-22 4:40 ` Fangrui Song
2021-03-22 20:28 ` H.J. Lu
2021-03-23 4:14 ` Fangrui Song
2021-03-29 23:11 ` H.J. Lu
2021-03-29 23:24 ` [PATCH v3] " Fangrui Song
2021-03-30 18:17 ` H.J. Lu
2021-03-30 19:17 ` Fāng-ruì Sòng
2021-03-30 19:30 ` H.J. Lu
2021-03-31 4:34 ` Fāng-ruì Sòng
2021-03-31 16:17 ` H.J. Lu
2021-03-31 18:09 ` Fāng-ruì Sòng
2021-03-31 18:57 ` H.J. Lu
2021-03-31 19:39 ` [PATCH v4] " Fangrui Song
2021-03-31 23:38 ` H.J. Lu
2021-04-01 0:02 ` Fangrui Song
2021-04-01 1:00 ` H.J. Lu
2021-04-01 1:06 ` [PATCH v5] " Fangrui Song
2021-04-01 12:52 ` H.J. Lu
2021-04-02 3:23 ` Fangrui Song
2021-04-02 14:14 ` H.J. Lu
2021-04-02 17:09 ` Fangrui Song
2021-04-02 17:33 ` H.J. Lu
2021-04-03 18:02 ` Fangrui Song
2021-04-03 20:47 ` H.J. Lu
2021-04-03 21:57 ` Fangrui Song
2021-04-05 1:55 ` H.J. Lu
2021-04-05 18:17 ` Fangrui Song
2021-04-05 20:35 ` H.J. Lu
2021-04-05 21:03 ` Fangrui Song
2021-04-05 21:58 ` H.J. Lu
2021-04-06 21:46 ` Fangrui Song
2021-04-09 22:36 ` Fāng-ruì Sòng
2021-04-16 3:51 ` Fāng-ruì Sòng
2021-04-16 13:00 ` H.J. Lu
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