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Re: String literals in __init functions
- From: Andrew Morton <akpm at linux-foundation dot org>
- To: Joe Perches <joe at perches dot com>
- Cc: gcc at gcc dot gnu dot org, Mathias Krause <minipli at googlemail dot com>, Mason <slash dot tmp at free dot fr>, Linux ARM <linux-arm-kernel at lists dot infradead dot org>, LKML <linux-kernel at vger dot kernel dot org>, Ingo Molnar <mingo at kernel dot org>
- Date: Thu, 26 Mar 2015 15:15:57 -0700
- Subject: Re: String literals in __init functions
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- References: <5512F6C6 dot 1020304 at free dot fr> <1427306517 dot 2717 dot 0 dot camel at perches dot com> <5513FE2F dot 3040306 at free dot fr> <1427386390 dot 15849 dot 13 dot camel at perches dot com> <CA+rthh9Fb2q+O_wicc6eNcbo6SzwOVZed=tnThJLF-xuoQ-+Cw at mail dot gmail dot com> <1427392393 dot 15849 dot 16 dot camel at perches dot com> <CA+rthh8irf+tTSbomivu=bgN-L1k99TQ-q6UYgmMRC1PNOG7qw at mail dot gmail dot com> <20150326144058 dot 56ef6916b00ad38030296089 at linux-foundation dot org> <1427407120 dot 15849 dot 34 dot camel at perches dot com>
On Thu, 26 Mar 2015 14:58:40 -0700 Joe Perches <joe@perches.com> wrote:
> > I'd have thought that a function-wide
> > __attribute__((__string_section__(foo))
> > wouldn't be a ton of work to implement.
>
> Maybe not.
>
> Could some future version of gcc move string constants
> in a function to a specific section marked in a manner
> similar to what Andrew described above?
One thing which might complexicate this is
void foo()
{
p("bar");
}
void __attribute__((__string_section__(.init.rodata)) zot()
{
p("bar");
}
It would be silly to create two instances of "bar".
Change it thusly:
#define __mark_str(str) \
({ static const char var[] __attribute__((__section__(".init.string"))) = str; var; })
void foo()
{
p("bar");
}
void zot()
{
p(__mark_str("bar"));
}
and we indeed get two copies of "bar".
It would be nice not to do that, but I guess that losing this
optimization is a reasonable compromise.