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Re: [PATCH roland/arm-mcount] ARM: Disable compat mcount code when unneeded.
- From: Roland McGrath <roland at hack dot frob dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: <libc-ports at sourceware dot org>
- Date: Thu, 29 Aug 2013 16:26:58 -0700 (PDT)
- Subject: Re: [PATCH roland/arm-mcount] ARM: Disable compat mcount code when unneeded.
- Authentication-results: sourceware.org; auth=none
- References: <20130827173014 dot D264D2C097 at topped-with-meat dot com> <Pine dot LNX dot 4 dot 64 dot 1308291219461 dot 32214 at digraph dot polyomino dot org dot uk>
> Isn't this about objects built with old compilers (before GCC 4.4, when
> __gnu_mcount_nc was introduced; arm*-*-linux-gnueabi support was added in
> 4.1), which is generally supported, rather than objects built with old
> library headers, which isn't?
I see. I'd still like to find a way to exclude this code from
configurations that will never use it, i.e. a target for which there was
never a compiler that produced _mcount calls. But perhaps there is no
"generic" way to achieve that. I suppose I can just move it to a separate
file and let my configuration drop that file from sysdep-routines.
I think the ideal would be if we dropped it from the shared library (except
for a compat_symbol where needed, of course) and had it only in
libc_nonshared.a. But I can't see a way to e.g. write _mcount in terms of
calling __gnu_mcount_nc (without breaking the profile so that it only
tracks _mcount itself as the callee), and I don't want to expose something
like __mcount_internal in the ABI just so that _mcount can call it.
Can you think of anything better?
Thanks,
Roland