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Re: [RFC] Wrong register numbers in .dwarf_frame on Linux/PowerPC
- From: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- To: uweigand at de dot ibm dot com
- Cc: dje dot gcc at gmail dot com, geoffk at geoffk dot org, jakub at redhat dot com, gcc-patches at gcc dot gnu dot org, binutils at sourceware dot org, gdb-patches at sourceware dot org
- Date: Mon, 26 Nov 2012 21:14:21 +0100 (CET)
- Subject: Re: [RFC] Wrong register numbers in .dwarf_frame on Linux/PowerPC
- References: <201211261910.qAQJA63I009670@d06av02.portsmouth.uk.ibm.com>
> Date: Mon, 26 Nov 2012 20:10:06 +0100 (CET)
> From: "Ulrich Weigand" <firstname.lastname@example.org>
> I noticed what appears to be a long-standing bug in generating .dwarf_frame
> sections with GCC on Linux on PowerPC.
> So I'm wondering where to go from here. I guess we could:
> 1. Bring GCC (and gas) behaviour in compliance with the documented ABI
> by removing the #undef DBX_REGISTER_NUMBER and changing gas's
> md_reg_eh_frame_to_debug_frame to the original implementation from
> Jakub's patch. That would make GDB work well on new files, but
> there are a large number of binaries out there where we continue
> to have the same behaviour as today ...
> 2. Leave GCC and gas as-is and modify GDB to expect GCC numbering in
> .dwarf_frame, except for the condition code register. This would
> break debugging of files built with GCC 4.0 and 4.1 unless we
> want to add a special hack for that.
> 3. Like 2., but remove the condition code hack: simply use identical
> numbers in .eh_frame and .dwarf_frame. This would make PowerPC
> like other Linux platforms in that respect.
What do other compilers (in particular XLC) do? From a GDB standpoint
it would be a major PITA if different compilers would use different
encodings for .dwarf_frame.