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Re: [PATCH][BZ 18960] setlocale.c: Mark *_used symbols as unaligned.
- From: Rich Felker <dalias at libc dot org>
- To: Marcin KoÅcielnicki <koriakin at 0x04 dot net>
- Cc: libc-alpha at sourceware dot org
- Date: Mon, 28 Sep 2015 10:18:24 -0400
- Subject: Re: [PATCH][BZ 18960] setlocale.c: Mark *_used symbols as unaligned.
- Authentication-results: sourceware.org; auth=none
- References: <1443360385-20079-1-git-send-email-koriakin at 0x04 dot net>
On Sun, Sep 27, 2015 at 03:26:25PM +0200, Marcin KoÅcielnicki wrote:
> This ensures that compiler doesn't get the values of these symbols
> using instructions that have alignment requirements (eg. larl on s390).
> ---
> locale/setlocale.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/locale/setlocale.c b/locale/setlocale.c
> index ead030d..028496d 100644
> --- a/locale/setlocale.c
> +++ b/locale/setlocale.c
> @@ -35,7 +35,7 @@
> Also use a weak reference for the _nl_current_CATEGORY thread variable. */
>
> # define DEFINE_CATEGORY(category, category_name, items, a) \
> - extern char _nl_current_##category##_used; \
> + extern char _nl_current_##category##_used __attribute__((__aligned__(1))); \
> weak_extern (_nl_current_##category##_used) \
> weak_extern (_nl_current_##category)
> # include "categories.def"
Can you explain how/why you think this is needed? char has no
alignment requirements (inherently) so as far as I can tell, the
compiler may not make any alignment assumptions about an extern object
of type char.
Rich