* Clarification on section variable attribute usage [try #2]
@ 2007-12-10 20:59 Franck Bui-Huu
2007-12-11 16:17 ` Ian Lance Taylor
0 siblings, 1 reply; 4+ messages in thread
From: Franck Bui-Huu @ 2007-12-10 20:59 UTC (permalink / raw)
To: gcc, gcc-help
[ example updated ]
Hi,
Since at least 3.4, the GCC manual says:
Use the `section' attribute with an _initialized_ definition of a
_global_ variable, as shown in the example. GCC issues a warning
and otherwise ignores the `section' attribute in uninitialized
variable declarations.
but this doesn't seem correct.
For example compiling the following tiny program:
int foo __attribute__ ((__section__ (".init.data")));
int main(int argc, char **argv)
{
foo = 4;
return 0;
}
produces no warning and the section attribute is not ignored at all:
$ readelf -S a.out | grep -A1 init.data
[24] .init.data PROGBITS 000000000060080c 0000080c
0000000000000004 0000000000000000 WA 0 0 4
This is with 4.1.2 from fedora, but I guess other GCC give the same result.
Could anybody clarify this point ?
Thanks,
Franck
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Clarification on section variable attribute usage [try #2]
2007-12-10 20:59 Clarification on section variable attribute usage [try #2] Franck Bui-Huu
@ 2007-12-11 16:17 ` Ian Lance Taylor
2007-12-11 20:27 ` Franck Bui-Huu
0 siblings, 1 reply; 4+ messages in thread
From: Ian Lance Taylor @ 2007-12-11 16:17 UTC (permalink / raw)
To: Franck Bui-Huu; +Cc: gcc-help
Please never send a message to both gcc@gcc.gnu.org and
gcc-help@gcc.gnu.org. Thanks. I've dropped gcc@gcc.gnu.org from this
reply.
Franck Bui-Huu <vagabon.xyz@gmail.com> writes:
> Since at least 3.4, the GCC manual says:
>
> Use the `section' attribute with an _initialized_ definition of a
> _global_ variable, as shown in the example. GCC issues a warning
> and otherwise ignores the `section' attribute in uninitialized
> variable declarations.
>
> but this doesn't seem correct.
Yes, I'm fairly sure that is no longer correct. gcc is now smart
enough to not treat a variable with a section attribute as a common
variable. I think the documentation is simply wrong.
Ian
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Clarification on section variable attribute usage [try #2]
2007-12-11 16:17 ` Ian Lance Taylor
@ 2007-12-11 20:27 ` Franck Bui-Huu
2007-12-11 23:15 ` Ian Lance Taylor
0 siblings, 1 reply; 4+ messages in thread
From: Franck Bui-Huu @ 2007-12-11 20:27 UTC (permalink / raw)
To: Ian Lance Taylor; +Cc: gcc-help
Hi Ian
Ian Lance Taylor wrote:
> Please never send a message to both gcc@gcc.gnu.org and
> gcc-help@gcc.gnu.org. Thanks.
>
OK.
> Yes, I'm fairly sure that is no longer correct. gcc is now smart
> enough to not treat a variable with a section attribute as a common
> variable.
Do you know when this happened ? Before GCC 3.2 ?
> I think the documentation is simply wrong.
It's probably high time to fix it up.
Thanks,
Franck
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Clarification on section variable attribute usage [try #2]
2007-12-11 20:27 ` Franck Bui-Huu
@ 2007-12-11 23:15 ` Ian Lance Taylor
0 siblings, 0 replies; 4+ messages in thread
From: Ian Lance Taylor @ 2007-12-11 23:15 UTC (permalink / raw)
To: Franck Bui-Huu; +Cc: gcc-help
Franck Bui-Huu <vagabon.xyz@gmail.com> writes:
> > Yes, I'm fairly sure that is no longer correct. gcc is now smart
> > enough to not treat a variable with a section attribute as a common
> > variable.
>
> Do you know when this happened ? Before GCC 3.2 ?
I don't know when it happened, no.
> > I think the documentation is simply wrong.
>
> It's probably high time to fix it up.
Yep.
Ian
^ permalink raw reply [flat|nested] 4+ messages in thread
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2007-12-10 20:59 Clarification on section variable attribute usage [try #2] Franck Bui-Huu
2007-12-11 16:17 ` Ian Lance Taylor
2007-12-11 20:27 ` Franck Bui-Huu
2007-12-11 23:15 ` Ian Lance Taylor
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